Recent developments in tandem laser ablation mass spectrometer
technology have demonstrated the capacity for separating parent and daughter
isotopes of the same mass online. As a result, beta-decay chronometers can
now be applied to the geological archive in situ as opposed to through traditional whole-rock digestions. One novel application of this technique is the in situ Rb–Sr
dating of Proterozoic shales that are dominated by authigenic clays such as
illite. This method can provide a depositional window for shales by
differentiating signatures of early diagenetic processes versus late-stage
secondary alteration. However, the hydrothermal sensitivity of the Rb–Sr
isotopic system across geological timescales in shale-hosted clay minerals
is not well understood. As such, we dated the Mesoproterozoic Velkerri
Formation from the Altree 2 well in the Beetaloo Sub-basin (greater McArthur Basin), northern Australia, using this approach. We then constrained the thermal history of these units using common hydrocarbon maturity indicators and modelled effects of contact heating due to the intrusion of the Derim Derim Dolerite.
In situ Rb–Sr dating of mature, oil-prone shales in the diagenetic zone from the Velkerri Formation yielded ages of 1448 ± 81, 1434 ± 19, and 1421 ± 139 Ma. These results agree with previous Re–Os dating of the unit and are interpreted as recording the timing of an early diagenetic event soon after deposition. Conversely, overmature, gas-prone shales in the
anchizone sourced from deeper within the borehole were dated at 1322 ± 93 and 1336 ± 40 Ma. These ages are younger than the expected depositional window for the Velkerri Formation. Instead, they are consistent
with the age of the Derim Derim Dolerite mafic intrusion intersected 800 m
below the Velkerri Formation. Thermal modelling suggests that a single
intrusion of 75 m thickness would have been capable of producing a
significant hydrothermal perturbation radiating from the sill top. The
intrusion width proposed by this model is consistent with similar Derim
Derim Dolerite sill thicknesses found elsewhere in the McArthur Basin. The
extent of the hydrothermal aureole induced by this intrusion coincides with
the window in which kerogen from the Velkerri Formation becomes overmature.
As a result, the mafic intrusion intersected here is interpreted to have
caused kerogen in these shales to enter the gas window, induced fluids that
mobilize trace elements, and reset the Rb–Sr chronometer. Consequently, we
propose that the Rb–Sr chronometer in shales may be sensitive to
temperatures of ca. 120 ∘C in hydrothermal reactions but can
withstand temperatures of more than 190 ∘C in thermal systems not
dominated by fluids. Importantly, this study demonstrates a framework for
the combined use of in situ Rb–Sr dating and kerogen maturation indicators to help reveal the thermochronological history of Proterozoic sedimentary basins. As such, this approach can be a powerful tool for identifying the hydrocarbon potential of source rocks in similar geological settings.
Introduction
The Rb–Sr isotopic system has historically been one of the most powerful
dating tools in Earth science. Rb is abundant in K-rich minerals such as
micas, clays, and K-feldspar, and these minerals are commonly found in a
wide range of geological settings (Simmons, 1998). Therefore, it is an
effective technique to date processes such as igneous emplacement,
metamorphism, sedimentation, clay authigenesis, and hydrothermal alteration
when these phases can be differentiated (Nebel, 2014). Its long
half-life also makes it applicable to date events as early as the infant
stages of our solar system (Nebel et al., 2011; Minster et al., 1979;
Papanastassiou and Wasserburg, 1970). Traditionally, the application of this
method required an arduous process of column chromatography to chemically
separate the parent (87Rb) and daughter (87Sr) isotopes and avoid
isobaric interference between the two elements (Hahn and Walling, 1938;
Hahn et al., 1943; Charlier et al., 2006; Faure, 1977; Yang et al., 2010;
Dickin, 2018). Alas, this approach has historically been expensive and time
consuming and results in the loss of the genetic relationships between the
minerals analysed, which has caused the technique to lose its popularity in recent
years (Nebel, 2014).
Recent advancements in tandem laser ablation inductively coupled plasma mass
spectrometry (LA-ICP-MS/MS) and similar instruments have revitalized the use
of Rb–Sr by allowing them to be applied in situ (Zack and Hogmalm, 2016;
Hogmalm et al., 2017; Bevan et al., 2021; Redaa et al., 2021a; Yim et al.,
2021; Gorojovsky and Alard, 2020). Reactive gases such as N2O and
SF6 can be introduced into a reaction cell between quadrupoles in an
LA-ICP-MS/MS system, which permits the online separation of 87Sr from
87Rb through the measurement of the mass-shifted Sr reaction product
(Zack and Hogmalm, 2016; Redaa et al., 2021a; Hogmalm et al., 2017). This
allows for a more rapid and economic analysis time, as well as the ability
to preserve petrographic relationships during these analyses. Consequently,
secondary input of Rb or Sr from inclusions, zonation, alteration, and
detritus can be isolated, resulting in a better understanding of the
geochronological results. However, it should be noted that nanometre- or micrometre-sized mineral intergrowths of different origins still provide challenges
when large spot sizes are used. The application of similar setups with other
beta-decay dating systems have also yielded promising results (Tamblyn et
al., 2021; Simpson et al., 2021; Ribeiro et al., 2021; Harrison et al.,
2010; Hogmalm et al., 2019; Brown et al., 2022; Simpson et al., 2022;
Scheiblhofer et al., 2022; Rösel and Zack, 2022; Gorojovsky and Alard,
2020; Bevan et al., 2021).
Hence, the in situ Rb–Sr dating method can now be used very similarly to laser ablation U–Pb dating, where age information can be obtained reliably,
rapidly, and cheaply. In addition, the initial 87Sr /86Sr ratio
from the calculated isochron and the elemental data concurrently collected
with the Rb and Sr isotopes can fingerprint the geochemical nature of the
samples analysed (Subarkah et al., 2021; Redaa et al., 2021b; Tamblyn et
al., 2020; Li et al., 2020). This approach has been shown to be capable of
dating paragenetic sequences in deformation structures (Armistead et al.,
2020; Tillberg et al., 2020), hydrothermal alteration assemblages
(Laureijs et al., 2021), magmatic and
metamorphic events (Li et al., 2020; Tamblyn et al., 2020), and
metallogenic systems (Redaa et al., 2021b; Olierook et al., 2020;
Şengün et al., 2019), whilst still preserving their micro-scale
textural context.
Another novel use of this technique is to date Proterozoic shales in order
to constrain their depositional window (Subarkah et al., 2021).
Evidence suggests that clay minerals in Proterozoic shales are dominated by
authigenic products from reverse weathering processes during reactions in
equilibrium with the formation waters (Rafiei and Kennedy, 2019; Rafiei
et al., 2020; Isson and Planavsky, 2018; Mackenzie and Kump, 1995; Kennedy
et al., 2006; Deepak et al., 2022). Conversely, clay assemblages in late
Ediacaran and Phanerozoic shales are commonly dominated by detrital products
from continental weathering and erosion of soils and unstable parent rocks
(Baldermann et al., 2020; Galán, 2006; Singer, 1980; Rafiei et al.,
2020; Chamley, 1989; Hillier, 1995; Wilson, 1999; Kennedy et al., 2006).
Simple multicellular organisms such as fungi and lichen have been shown to
dramatically influence the rate of chemical weathering in continental rocks
(Kennedy et al., 2006; Rafiei et al., 2020; Mergelov et al., 2018; Lee
and Parsons, 1999; Cuadros, 2017; McMahon and Davies, 2018; Chen et al.,
2000). As such, the surge in abundance of detrital clays in shales in the
Ediacaran and Phanerozoic has been attributed to the production of soils
driven by emergence of these microorganisms (Kennedy et al., 2006; Rafiei
and Kennedy, 2019; Mergelov et al., 2018; Lee and Parsons, 1999; Zambell et
al., 2012; McMahon and Davies, 2018). Thus, the primarily authigenic nature
of clay minerals in Proterozoic shales makes them ideal targets for in situ Rb–Sr dating (Subarkah et al., 2021).
Despite the promising potential of the Rb–Sr isotopic system, the
chronometer still holds some limitations. Rb and Sr are large ion lithophile
elements that can sit in well-bound interstitial sites within a mineral
lattice and be adsorbed onto the surface where they are more susceptible
to fluid mobilization (Nebel, 2014; Villa, 1998; Li et al., 2019). In
these environments, fluid-induced recrystallization and alteration can drive
element and isotopic exchange at lower effective closure temperatures than
those empirically determined for classic thermal volume diffusion reactions
(Dodson, 1973; Field and Råheim, 1979; Jenkin et al., 1995; Villa,
1998). Nevertheless, these complications can in turn be used advantageously
to date secondary events such as episodes of hydrothermal fluid flow
(Dodson, 1973; Shepherd and Darbyshire, 1981; Tamblyn et al., 2020; Li et
al., 2020; Subarkah et al., 2021; Redaa et al., 2021b). However, it should
be noted that the Rb–Sr system in shale-hosted illite may also be affected
during diagenesis via the transformation of smectite to illite–smectite
mixed-layer minerals.
In this study, we dated the Mesoproterozoic Velkerri Formation from the
Roper Group of the McArthur Basin in northern Australia using in situ Rb–Sr
geochronology and show that clay-mineral recrystallization in these shales
occur at similar temperatures to kerogen catagenesis. The Roper Group is a
good case study for in situ Rb–Sr shale dating, as it has been shown to be
dominated by authigenic clays (Rafiei and Kennedy, 2019; Subarkah et al.,
2021) and is chronologically well constrained (Ahmad and Munson, 2013;
Kendall et al., 2009; Southgate et al., 2000; Bodorkos et al., 2022; Yang et
al., 2020; Subarkah et al., 2021; Cox et al., 2022). Furthermore, the
resurgence of interest in the resource potential of the organic-rich
Velkerri Formation has also yielded a framework of palaeotemperature data
that aim to discern the maturation history of hydrocarbons within the unit
(Ahmad and Munson, 2013; Cox et al., 2016; George and Ahmed, 2002;
Jarrett et al., 2019; Crick et al., 1988; Taylor et al., 1994; Summons et
al., 1994; Volk et al., 2005; Lemiux, 2011; Revie, 2014; Capogreco, 2017).
(a) Schematic stratigraphy and geochronological summary of the Roper Group (Abbott et al., 2001; Subarkah et al., 2021; Jackson et al.,
1999; Southgate et al., 2000; Yang et al., 2020; Kendall et al., 2009). (b) Sample location and depth to basement map for the McArthur Basin,
adapted from Frogtech Geoscience (2018).
Here, we targeted the Velkerri Formation (Fig. 1) from the thoroughly
investigated well Altree 2 (Cox et al., 2016; NTGS, 1989; Lemiux, 2011;
Revie, 2014; George and Ahmed, 2002; Jarrett et al., 2019; Nguyen et al.,
2019; Nixon et al., 2021; Sander et al., 2018; NTGS, 2009, 2010, 2012; Yang
et al., 2018; Capogreco, 2017; Cox et al., 2022). We show that common
hydrocarbon maturation proxies such as Tmax data from Rock-Eval
pyrolysis, aromatic hydrocarbons, bitumen reflectance, and illite
crystallinity can help define the temperature sensitivity of the Rb–Sr
isotopic system in organic-rich shales. In addition, we have also modelled
the geothermal aureole of a mafic intrusion that may have matured the
kerogen into the gas window, altered trace elemental signatures, and reset
the Rb–Sr isotopic system within the unit. As a result, we demonstrate that
combining this novel dating method with traditional kerogen maturation
proxies can be a powerful tool for reconstructing the thermochronological
evolution of Proterozoic basin systems. This approach can then be applied to
aid in hydrocarbon exploration for similar settings.
Geological background
The Palaeoproterozoic-to-Mesoproterozoic greater McArthur Basin is an intra-cratonic
sedimentary system exposed across 180 000 km2 of northern Australia
(Ahmad and Munson, 2013). The basin is sub-divided into five
unconformity-bounded sedimentary packages characterized by similarities in
age, lithology, and stratigraphic position (Rawlings, 1999; Jackson et
al., 1999). The Roper Group is part of the Wilton Package, which is the
youngest of these sub-divisions (Rawlings, 1999; Jackson et al., 1987, 1999; Munson, 2016). The thickness of the Roper Group varies from
around 1 to 5 km across several different fault zones (Jackson et al.,
1987; Abbott and Sweet, 2000; Rawlings, 1999; Ahmad and Munson, 2013; Abbott
et al., 2001). The Beetaloo Sub-basin (Fig. 1) is interpreted to be the
main depocentre of the sedimentary system and preserves the thickest Roper
Group sequences (Plumb and Wellman, 1987; Ahmad and Munson, 2013; Jackson
et al., 1987; Abbott and Sweet, 2000). Lithologically, the Roper Group
comprises a series of coarsening-upward sequences dominated by marine
mudstone and interbedded sandstone with minor successions of intraclastic
limestone (Abbott and Sweet, 2000; Jackson et al., 1987; Yang et al.,
2018; Munson, 2016). Records of water-column euxinia and redox
stratification, as well as fluctuating salinity levels, suggest that the
Roper Group formed in an intermittently restricted marine basin within an
epicontinental setting similar to the modern Black Sea or Baltic Sea
(Revie and MacDonald, 2017; Yang et al., 2018; Ahmad and Munson, 2013;
Mukherjee and Large, 2016; Cox et al., 2016, 2022).
Age constraints of the Roper Group have been established through several
geochronological methods (Page et al., 2000; Ahmad and Munson, 2013;
Subarkah et al., 2021; Kendall et al., 2009; Yang et al., 2019,
2020, 2018; Jackson et al., 1999; Nixon et al., 2021; Southgate
et al., 2000). The beginning of the group's genesis is bracketed by a SHRIMP
U–Pb zircon study from a tuff within the unconformably underlying Nathan
Group as well as minimum depositional age from an in situ Rb–Sr analysis in the lower Roper Group that yielded ages of 1589 ± 3 and 1577 ± 56 Ma, respectively (Subarkah et al., 2021; Page et al., 2000). The unconformity between the Roper Group and the immediately underlying Nathan Group is likely related to the Isan Orogeny ca. 1.58 Ga (Jackson et al., 1999; Ahmad and Munson, 2013). Absolute dating of the Roper Group has been obtained through two SHRIMP U–Pb zircon studies from tuff layers in the
Mainoru Formation, resulting in ages of 1492 ± 4 and 1493 ± 4 Ma (Jackson et al., 1999; Southgate et al., 2000). On the other hand, the
Kyalla Formation at the top of the Roper Group is constrained to being
deposited between the U–Pb age of its youngest detrital zircon at 1313 ± 47 Ma (Yang et al., 2018) and the age of crosscutting
Derim Derim Dolerite intrusions at 1313 ± 1, 1324 ± 4, and
1327.5 ± 0.6 Ma (Yang et al., 2020; Bodorkos et al., 2022).
Mature organic-rich shales from the Velkerri Formation have been dated by
Re–Os analysis at 1417 ± 29 and 1361 ± 21 Ma
(Kendall et al., 2009). These ages have been interpreted to be the
depositional age of the formation. The geochronological constraints of the
Roper Group are summarized in Fig. 1. The Velkerri Formation is dominated
by deep-basinal lithologies such as mudstones and siltstones that coarsens upward
into the cross-bedded Moroak Sandstone and Sherwin Ironstone
(Abbott et al., 2001). The Velkerri Formation is
interpreted to represent a deep-water, high-stand system tract within a
marine environment (Abbott et al., 2001; Warren et al., 1998). The
Velkerri Formation is commonly sub-divided into three distinct members (from
bottom to top, the Kalala, Amungee, and Wyworrie members) based on
variations in total organic carbon (TOC) content, gamma ray response,
geochemistry, sedimentology, and mineralogy (Munson and Revie, 2018; Cox
et al., 2016, 2019; Warren et al., 1998; Revie, 2016; Ahmad and
Munson, 2013; Jarrett et al., 2019).
Importantly, the McArthur Basin experienced a complex thermal history,
following the deposition of the Roper Group, Mafic sills of the Derim Derim
Dolerite widely intrude all units in the Roper Group at ca. 1330–1300 Ma,
with the oldest intrusions likely contemporaneous with the end of
sedimentation in the basin (Yang et al., 2020; Bodorkos et al., 2022;
Nixon et al., 2021; Subarkah et al., 2021; Ahmad and Munson, 2013). Little
evidence of subsequent tectono-thermal perturbation is present within the
basin until much of the region was overlain by subaerial basaltic lavas of
the Kalkarindji Large Igneous Province (LIP) extruded at ca. 510 Ma
(Evins et al., 2009; Glass and Phillips, 2006; Jourdan et al., 2014;
Nixon et al., 2022). Following the Cambrian eruption of the Kalkarindji
lavas, no significant (> 110 ∘C) heating has been
detected within the shallow parts of the basin (Duddy et al., 2004; Nixon
et al., 2022).
Summary of reprocessed downhole well log data for Altree 2.
The Altree 2 well drilled in the Beetaloo Sub-basin was chosen for this
study as it intersects the entirety of the Velkerri Formation (Fig. 2). In
addition, the well also intersected lavas of the Kalkarindji LIP directly
overlying the Proterozoic sedimentary rocks and terminated at an intrusion
of the Derim Derim Dolerite. Importantly, this well has also been the focus
of numerous geochronological, geochemical, and geobiological investigations
from academia, private explorers, and the Northern Territory
Geological Survey (NTGS) that provide important complementary data to
supplement this study (Cox et al., 2016, 2019; Jarrett et
al., 2019; Yang et al., 2018; Nixon et al., 2021; Warren et al., 1998;
George and Ahmed, 2002; Nguyen et al., 2019; Sander et al., 2018; Lemiux,
2011; NTGS, 2009, 2010, 2012; Bodorkos et al., 2022; Cox et al., 2022).
Methodology
Rock-Eval pyrolysis, aromatic hydrocarbon results, bitumen reflectance
values, bulk x-ray diffraction (XRD) mineralogical compositions, and well
log data were collated from several sources and compiled together in this
study (NTGS, 1989, 2009, 2010, 2012; Cox et al., 2016; Lemiux, 2011;
Revie, 2014; Capogreco, 2017; Revie et al., 2022; Jarrett et al., 2019). As
such, their corresponding methodologies can be found in the references
therein. The lithology of the Velkerri Formation was interpreted in detail
(Fig. 2) using the electrical logs gamma ray (GR), neutron (NPRS), and
density (RHOB) of the Altree-2 well (NTGS, 1989). Four lithologies
were defined after applying cut-offs at each electrical log. They are then
correlated along depth. Sandstone units corresponds to a GR < 130 API, NPRS < 0.20 %, and RHOB of around 2.5 g cm-3. This relates
to a crossover between the RHOB and NPRS logs and competent material at the
GR. Interbedded shale and sands are defined by a GR > 130 and
< 250 API, NPRS > 0.20 and < 0.25 m3 m-3, and RHOB between 2.5 and 2.53 g cm-3. This lithology reflected a smaller
breach between the density and neutron logs in comparison to the previous
sandstone lithology. Shale units were constrained by a GR > 250 API, NPRS > 0.25 m3 m-3, and RHOB > 2.53 g cm-3, with a minimum separation (or no separation) between the porosity logs. On the other hand, dolomitic siltstones have a GR response similar to the sandstone, with NPRS ranging between 0.25 to 0.27 and RHOB > 2.62 g cm-3. This indicates a competent lithology in the GR with a gap between the neutron and density curves. In addition, Tmax data were also
collated to discriminate the hydrocarbon maturation levels downhole. From
this, a shift in hydrocarbon potential and Tmax gradients were
identified at around 900 m (Fig. 2), where kerogen enters the gas window
and becomes overmature. Five shale chips were then sampled from the Velkerri
Formation in Altree 2 at depths of 415, 520, 696, 938, and 1220 m
for further characterization.
Samples were first imaged for their mineral composition and petrographic
relationships. Backscatter electron (BSE) imaging and mineral liberation
analysis (MLA) maps of samples were collected using a Hitachi SU3800
automated mineralogy scanning electron microscope at Adelaide Microscopy.
BSE image tiles were done at 10 mm working distance and 20 kV acceleration
voltage with MLA maps completed using a raster analysis using spectra
collected at 0.35 µm per pixel resolution. Minerals previously
categorized by bulk XRD analysis of the Velkerri Formation from
Cox et al. (2016) were used to develop a “library” to help
identify phases found by spectral reflectance MLA mapping. In situ Rb–Sr
geochronology and trace element analysis studies were undertaken at Adelaide
Microscopy using a laser ablation (RESOlution-LR ArF 193 nm excimer laser)
inductively coupled plasma tandem mass spectrometer (Agilent 8900x
ICP-MS/MS) with analytical parameters and tuning conditions following
Redaa et al. (2021a). The laser setup used in this study is
provided in the Supplement. Laser ablation data and error
correlations were processed using the LADR software package (Norris and
Danyushevsky, 2018; Schmitz and Schoene, 2007). During the data-processing
step, Zr, Si, Ti, and rare-earth element signatures were monitored to filter
the detrital component of each analysis. Non-stable isotopic and elemental
signatures were also culled or cropped during the processing of each
analysis to aid in ensuring spot homogeneity. The 87Rb decay constant
used was 0.000013972 ± 4.5 × 10-7 Myr-1 following Villa et al. (2015). Isochron and single-spot ages were calculated with ISOPLOTR (Vermeesch, 2018). Single-spot ages were calculated using the
isochron intercept as their initial 87Sr /86Sr ratios
(Vermeesch, 2018; Nebel, 2014; Rösel and Zack, 2022). In addition,
kernel density estimation (KDE) graphs (Vermeesch, 2012),
cumulative age distribution (CAD) plots (Vermeesch, 2007), and
multidimensional scaling (MDS) graphs (Vermeesch, 2013) were also
constructed using ISOPLOTR (Vermeesch, 2018) to differentiate
between the population of single-spot ages from each sample.
The phlogopite nano-powder Mica-Mg (Govindaraju et al.,
1994) was used as the primary reference material, and its natural mineral
equivalent, MDC from the Ampandrandava Mine in Madagascar (Hogmalm et al.,
2017; Armistead et al., 2020; Redaa et al., 2021a; Li et al., 2020), and glauconite grain reference material GL-O (Derkowski et al., 2009;
Charbit et al., 1998) were used secondary age standards. As previously
discussed in Subarkah et al. (2021), nano-powdered reference
materials have similar ablation characteristics to fine-grained shales, with
analogous matrix effects. As such, they are ideal standards for in situ analyses of these samples.
When anchored to a 87Sr /86Sr initial ratio of 0.72607 ± 0.00363 as reported by Hogmalm et al. (2017), MDC yielded an age of 524 ± 7 Ma. This is within the error of the published mean age of Mica-Mg at 519 ± 7 Ma (Hogmalm et al., 2017). In addition,
the independent reference material GL-O gave an age of 96 ± 4 Ma,
accurate to its published K–Ar age of 95 ± 1.5 Ma (Charbit et al.,
1998; Derkowski et al., 2009). It should be noted that this age is younger
than the tuff-horizon age of the GL-O host rock, dated at 113 ± 0.3 Ma
(Selby, 2009). Consequently, the ages yielded from GL-O have
instead been proposed to be indicative of the formation of glauconite
occurring early after the deposition of the host rock (Selby, 2009).
Glass standard NIST SRM 610 was used as a primary standard for elemental
quantification in this study. Analysis of secondary standard BCR-2G yielded a combined
major, trace, and rare-earth element composition that was in good agreement
(Pearson R> 0.999, Pearson R2> 0.999, and p Value < 0.0001) with their published values as compiled in the
GeoREM database (Jochum et al., 2005; Pearce et al., 1997; Jochum et al.,
2011; Jochum and Stoll, 2008).
One-dimensional thermal modelling of the Altree 2 well was conducted using
the SILLi 1.0 numerical model, which is designed for simulating thermal
perturbation associated with sill emplacement within sedimentary basins
(Iyer et al., 2018). First, palaeotemperatures were
estimated from the compiled thermal maturity data (Disnar, 1994, 1986;
Waliczek et al., 2021) following equations based on similar sedimentary
systems that experienced a heating event due to burial and a subsequent
igneous intrusion (Piedad-Sánchez et al., 2004). Forward
modelling was then conducted to replicate maximum thermal conditions
calculated in the well from the thermal maturity data, where
palaeotemperatures suggest that the Wyworrie and Amungee members experienced
significant additional sedimentary cover in the Mesoproterozoic. During
modelling, an additional 1.5 km of sedimentary rocks were added above the
erosional unconformity now present above the McArthur Basin fill
(Hall et al., 2021), while all post-Mesoproterozoic units were
excluded. The upper contact of a sill with an initial temperature of
1150 ∘C (Wang et al., 2012) was set at 2868 m, in accordance
with adjusted burial depths during the Mesoproterozoic. As sill thickness is
unconstrained within the Altree 2 well, multiple iterations were run with
different thicknesses in order to establish the scenario able to best
satisfy the thermal aureole extent observed in this well. From this, a sill
thickness of 75 m was considered most appropriate and is consistent with
Derim Derim sill thicknesses of ∼ 10–100 m commonly observed
across the basin (Lanigan and Torkington, 1991; Lanigan and Ledlie, 1990;
Ledlie and Maim, 1989; NTGS, 2014, 2015, 2016). Full modelling parameters
and petrophysical properties are provided in
Tables S2 and S3 in the Supplement.
ResultsCompilation of legacy data
All legacy data are compiled in the Supplement and were checked
for quality before interpretation, as several factors, such as contamination
of cuttings due to drilling fluid or poor organic content, can make results
unreliable (Carvajal-Ortiz and Gentzis, 2015; Dembicki, 2009; Peters,
1986). Rock-Eval pyrolysis values were screened using the thresholds
described by Hall et al. (2016). Data were subsequently excluded from
interpretation if these criteria were not met. More than 90 % of the data
yielded S2 > 0.1 mg HC g-1, indicating that they were sufficiently
abundant in organic content to provide well-defined peaks for characterizing
Tmax and hydrogen index. Importantly, compilation of Rock-Eval
pyrolysis values were all internally consistent (e.g. hydrogen index that is equal to S2 / TOC × 100). Next, there was no evidence of anomalously low Tmax values (< 380 ∘C) present. Extremely low Tmax
values are commonly a product of incorrect selection of the S2 peak by the
programme or the widening of the S1 peak from non-indigenous free
hydrocarbons. Tmax results compiled in this study range between
384 and 502 ∘C with a mean of 433 ∘C (SD = 17). TOC content in the Velkerri Formation varies from 0.07 % to
8.07 %, averaging 2.25 % (SD = 2.26). Clay mineral
crystallinity and size data sourced for this compilation were standardized
for interlaboratory comparisons (Warr and Rice, 1994; Warr and
Mählmann, 2015). Full width at half maximum values from Altree 2 shale
samples were computationally remeasured as a secondary check (Capogreco,
2017; NTGS, 2010, 2012). A total of 13 samples from the Velkerri Formation were
analysed for their illite crystallinity. The Kübler index for these
shales range between 0.88 to 0.36, with decreasing values at depth and the
lowest data originating from the Kalala Member. The methylphenanthrene
distribution factor (MPDF), methylphenanthrene ratios (MPR), and bitumen
reflectance data collated from Jarrett et al. (2019) and
Revie et al. (2022) also display an increasing trend downhole.
Mineralogy of the Velkerri Formation
A total of 11 mineral phases were identified by bulk XRD analysis of the Velkerri
Formation from Cox et al. (2016). The major mineral phases were
quartz, kaolinite, illite, and orthoclase, which on average make up 90 %
of the total composition of the samples. Trace minerals include glauconite,
montmorillonite, pyrite, magnetite, siderite, dolomite, and plagioclase. Our
MLA mapping also identified these assemblages. Importantly, the two
different methods categorized these minerals at similar abundances. However,
results from MLA mapping also found other mineral assemblages not identified
by bulk XRD analysis, including biotite, chlorite, clinochlore, apatite, and
zircon. These differences could be due to the slightly different
sub-intervals from which samples were analysed. Bulk XRD is a destructive
procedure, and therefore the same section cannot be reused for in situ analysis. As
a result, samples spaced 1–2 cm apart may yield different results. In
addition, the targeted areas for MLA are often spatially localized and only
based on 2D information. As such, they may not be representative for the
bulk rock, making the comparison with XRD datasets difficult. The complete
mineralogical abundance and correlations between the results of bulk XRD analysis and MLA
mapping are summarized in Table 1. Extensive petrographic descriptions of
all samples can be found in the Supplement.
(a) Mineralogical abundance of the Velkerri Formation shales collected by bulk XRD analysis from Cox et al. (2016) and spectral
reflectance MLA mapping in this study. All values are in weight percentage. (b) Covariation between the mineral phases categorized by both methods.
Geochronological results yielded by samples from the Wyworrie and Amungee
members gave ages within error of each other. The sample from 415 m depth
was dated at 1448 ± 81 Ma. Next, the mudstone analysed from 520 m
depth yielded an age of 1434 ± 19 Ma. Thirdly, the shale sample
studied from 696 m depth resulted in an age of 1411 ± 139 Ma. A Kalala
Member shale chip from 938 m at depth was dated at 1322 ± 93 Ma.
Another sample from this member, towards the boundary with the underlying
Bessie Creek Sandstone at depth 1220 m resulted in an age of 1336 ± 40 Ma. The range of precision from these Rb–Sr ages is primarily constrained by a substantial spread in 87Rb /86Sr ratios, the number of data
points defining the regression line, and errors in each individual
analysis (Nebel, 2014). The most precisely dated samples, extracted from
520 and 1220 m depth, had the widest range of 87Rb /86Sr ratios (0–50), whilst the other two samples preserved a range of
87Rb /86Sr values less than 10 (Fig. 6). The variability in these values could be a subject of future studies in order to improve the success of this dating method. Single-spot ages were calculated for all spot
analyses in each sample, and their populations categorically differ (Fig. 8).
Elemental concentrations of each sample were concurrently collected during
the in situ Rb–Sr laser ablation investigation, and they are in good agreement with data collected by bulk geochemical analysis from Cox et al. (2016). Samples from depths of 415, 520, and 696 m do not show any
covariation between their total rare-earth elements and yttrium (REEY) concentrations and Sm / Nd ratios (Fig. 7). On the other hand, the sample from 938 m showed a statistically significant
relationship between these two parameters (Pearson R= 0.58; Pearson
R2= 0.336; p value < 0.0001). In addition, Velkerri
Formation shale sourced from 1220 m depth also showed a strong covariation
between total REEY values and Sm / Nd (Pearson R=-0.545; Pearson R2= 0.297; p value < 0.0001). These associations were also identified in the whole-rock geochemical data collected from
Cox et al. (2016). Figure 7b shows that samples between 390 and 900 m depth hold no statistically significant relationships between the two
factors. However, samples from deeper than 900 m display a strong
relationship between the two variables (Pearson R=-0.559; Pearson
R2= 0.312; p value = 0.003). The full geochronological and
inorganic geochemical dataset for samples in this study can be found in the
Supplement.
Thermal modelling
One-dimensional thermal modelling of the emplacement of a 75 m thick Derim
Derim Dolerite sill at the base of the Altree 2 well is sufficient to
produce a thermal aureole reaching temperatures > 110 ∘C, ca. 800 m above the top contact of the sill (Fig. 9a). Maximum
palaeotemperatures recorded in the Wyworrie Member exceed those predicted
in this simulation; however, this may be attributed to elevated temperatures
in the shallow basin during eruption of the Kalkarindji LIP in the Cambrian
(Nixon et al., 2022). The resultant maximum thermal profile
is consistent with palaeotemperature estimates derived from Tmax and is thus
considered a plausible model for the observed data from the well.
Post-intrusion temperatures at depths that match the samples with reset
Rb–Sr ages are much lower than observed in comparable isotopic systems for
thermally induced diffusion (Dodson, 1973; Tillberg et al., 2020;
Torgersen et al., 2015; Yoder and Eugster, 1955), with the shallowest reset
sample peaking at ca. 120 ∘C. Furthermore, elevated temperatures
predicted by the modelling are geologically short lived, with temperatures
returning to steady-state conditions by approximately half a million years
after sill intrusion (Fig. 9b).
Thermal maturity of the Velkerri Formation
Geochemical and mineralogical-based thermal maturity indicators collected
via Rock-Eval studies and bulk XRD analyses were compiled in this study in
order to establish a vertical profile of the Velkerri Formation and assess
the local palaeo-thermal structure. The Tmax parameter is the
temperature at which the maximum rate of hydrocarbon generation occurs
during pyrolysis analysis and is a common method used to reconstruct thermal
histories of basin systems (Espitalié, 1986; Espitalié et al.,
1977; Peters and Cassa, 1994; Welte and Tissot, 1984). Additionally, the
Kübler index (KI) is determined by the XRD reflection of illite and is
also a popular maturation proxy used to classify low-grade metamorphism in
pelitic rocks (Kubler, 1967; Guggenheim et al., 2002; Blenkinsop, 1988).
However, both of these thermal indicators can be influenced by multiple
factors other than burial-related heating, and they therefore struggle to resolve
absolute quantitative palaeotemperatures. Changes in heating rate; abundance
in hydrogen, sulfur, and uranium content; or the organic richness of samples
can result in inaccurate Tmax values (Yang and Horsfield, 2020;
Peters, 1986; Dembicki, 2009; Espitalié et al., 1977). Similarly, the
KI has also been shown to be sensitive to several parameters, such as changes in
heating rate and geochemical variability in the sample's initial mineralogy
(Eberl and Velde, 1989; Warr and Mählmann, 2015; Abad and Nieto,
2007; Mählmann et al., 2012). In addition, variations in procedures
between laboratories can further complicate the direct comparison of these
values (Cornford et al., 1998; Jarvie, 1991; Peters and Cassa, 1994;
Tissot et al., 1987). Consequently, these thermal indicators need to be
treated with caution when applied independently and are more suitable as
qualitative discriminators as opposed to absolute quantitative parameters.
However, such proxies can be more confidently used to estimate
palaeotemperatures in sedimentary successions if they show a strong
relationship with each other (Dellisanti et al., 2010; Ola et al., 2018;
Waliczek et al., 2021; Burtner and Warner, 1986; Velde and Espitalié,
1989). Ultimately, both organic and inorganic indicators are essential for a
robust understanding of the thermal histories of sedimentary sequences
through time.
In this study, we examine the covariation between the Tmax values and
KI to reconstruct the thermal history of the Velkerri Formation in the
Altree 2 well (Fig. 3). In our compilation, samples with immature kerogen
(Tmax< 435 ∘C) correspond to rocks in the
diagenetic zone (KI > 0.45∘Δ2θ). This
relationship is true in similar studies and generally translates to
palaeotemperatures of ca. 100 ∘C (Dellisanti et al., 2010;
Espitalié et al., 1977; Kosakowski et al., 1999; Kubler, 1967; Abad and
Nieto, 2007).
Covariation between Tmax values from pyrolysis analysis and
illite crystallinity KI in the Velkerri Formation. An increase in
Tmax coincides with a decrease in KI, suggesting that these proxies are both mainly sensitive to changes in palaeotemperature.
Interestingly, the samples within the mature oil window (435 ∘C <Tmax< 465 ∘C) show a wide range of KI values between 0.39 and 0.65∘Δ2θ (Fig. 3). This
is possibly due to the delay between thermal reactions in clay minerals as
opposed to organic matter (Ola et al., 2018). Although the maturation of
organic matter and the morphology of clay minerals both largely depend on
temperature, other processes such as the kinetics of the thermal reaction
and geochemical composition of the sample can make these relationships
non-linear (Ola et al., 2018; Velde and Vasseur, 1992; Pollastro, 1993;
Varajao and Meunier, 1995; Meunier et al., 2004). The disparity between
kerogen evolution and the equilibrium stage of illitization at these
temperatures may also play a role in this variability (Dellisanti et
al., 2010). Nevertheless, an increase in Tmax pyrolysis results from
these samples still appears to correlate with a decrease in KI values. These
thermometers would approximately equate to palaeotemperatures between 100
and 150 ∘C (Merriman and Frey, 1999; Árkai et al., 2002;
Kosakowski et al., 1999; Welte and Tissot, 1984).
On the other hand, the sample displaying overmature kerogen (Tmax> 465 ∘C) corresponds to the smallest KI value
(Fig. 3) of 0.36∘Δ2θ (Dellisanti et al.,
2010). These values commonly define the gas window and the anchizone,
corresponding to palaeotemperatures of ca. 200 ∘C (Kosakowski
et al., 1999; Árkai et al., 2002; Dellisanti et al., 2010). Overall, a
trend between increasing Tmax and decreasing KI values (Fig. 3)
confirms the feasibility of these parameters as thermal maturation proxies
(Dellisanti et al., 2010).
Lastly, the thermal parameters for the Velkerri Formation can be further
examined by inspecting the changes in MPDF (Kvalheim et al.,
1987; Boreham et al., 1988), MPR (Wilhelms et al., 1998; Radke et al.,
1982), and bitumen reflectance (Riediger, 1993). Previous studies
have shown that aromatic hydrocarbons were effective in providing thermal
constraints for the Velkerri Formation (George and Ahmed, 2002; Jarrett
et al., 2019). These proxies were similarly sensitive to maturity variations
from the thermally immature window to late oil window. As such, we normalize the
thermal indicators used in this study by converting them all (Jarvie et
al., 2001; Revie et al., 2022; Jarrett et al., 2019) to calculated vitrinite
reflectance values (VRCALC; Fig. 4). The VRCALC values from four different thermal indicators show that the Velkerri Formation quickly
elevated in maturity and enters the gas window at ca. 900 m depths (Fig. 4). The agreement of all proxies add further confidence to the temperature
constrains used in this study.
Calculated vitrinite reflectance (VRCALC) data
modelled downhole from Tmax, MPR, MPDF, and bitumen reflectance data compiled in
this study (NTGS, 1989, 2009, 2010, 2012; Cox et al., 2016; Lemiux, 2011;
Revie, 2014; Capogreco, 2017; Revie et al., 2022; Jarrett et al., 2019).
VRCALC from all proxies indicate an elevation in thermal maturity into the gas window at depths ca. 900 m.
Multiple geochemical and mineralogical thermal parameters from our compiled
dataset demonstrate strong correlation between them, suggesting that the
proxies used in this study primarily recorded changes in palaeotemperature
as opposed to other possible variables. Notably, five different,
independent, source-rock maturation proxies statistically agree and recorded
similar step-wise increases in thermal history downhole. As such, we
investigated five samples approaching the geothermal anomaly in the Kalala
Member for in situ Rb–Sr and trace element analysis. The changes in thermal
maturation indexes throughout the well are used to help constrain the
parameters of the Rb–Sr isotopic system in Proterozoic shales.
Thermochronological history of the Velkerri Formation
Although some of the geochronological results of these samples may overlap
due to their errors (Fig. 6), they are still categorically different
downhole (Fig. 8). We display these differences by plotting the
population of single-spot ages from each sample against each other. Kernel
distribution estimate (KDE) plots of these results show that the
distribution of single-spot ages from samples shallower than 900 m largely
overlaps with the Re–Os age constraint (Fig. 8a; light pink) for the
Velkerri Formation (Kendall et al., 2009). On the other hand, the
population of single-spot ages from shales deeper than 900 m instead agree
with the age for the Derim Derim Dolerite (Fig. 8a; dark pink) intrusion
ca. 1330–1300 Ma (Bodorkos et al., 2022; Yang et al., 2020; Nixon et
al., 2021; Ahmad and Munson, 2013).
Importantly, these sample sets are statistically different from each other.
This is graphically shown by their cumulative age distribution (CAD, Fig. 8b) and multidimensional scaling (MDS, Fig. 8c) plots. The second of these
techniques statistically measures the dissimilarity between different age
distributions through the Kolmogorov–Smirnov test (Vermeesch,
2013). In short, similar age distributions will plot closely to each other,
whilst distributions that are increasingly dissimilar will plot further away
(Vermeesch, 2013, 2012). Figure 8b and c show that samples shallower
than 900 m had age distributions that are similar to each other (Fig. 8).
Overall, these ages are statistically similar to the Re–Os constraint of
the Velkerri Formation (Kendall et al., 2009), suggesting that they
likely represent an early diagenetic age or burial age soon after deposition. On
the other hand, the single-age distributions of samples deeper than 900 m
are statistically different to the previous sample set. They form their own
cluster, which in turn coincides with the age of the Derim Derim Dolerites
(Bodorkos et al., 2022; Yang et al., 2020; Nixon et al., 2021; Ahmad and
Munson, 2013). Consequently, the Rb–Sr shale ages from this section are
unlikely to date the deposition of the Velkerri Formation, but they instead
reflect a late-stage hydrothermal resetting induced by the intrusion.
The petrographic characteristics of assemblages in these samples are further
evidence that the shales in the Velkerri Formation recorded two distinct
thermochronological events. The abundant clays in samples from depths of 415,
520, and 696 m are predominantly illite, with trace amounts of chlorite,
kaolinite, and montmorillonite (Table 1). However, they do not show typical
irregular, angular detrital morphologies (Figs. 5, S2a–c). Instead,
clay minerals in these samples form a matrix cement, filling in porous
spaces and wrapping around detrital grains, suggesting that they formed
within the sediment during burial diagenesis (Rafiei and Kennedy, 2019;
Rafiei et al., 2020; Subarkah et al., 2021). Primary sedimentary structures
with a similar compaction of clays along the bedding plane can also still be
identified in these samples (Figs. 5, S2a–c, and Supplement). These petrographic relationships are further discussed in the
Supplement and were similarly found in Roper Group shales
elsewhere, indicating an early diagenetic origin (Subarkah et al., 2021;
Rafiei and Kennedy, 2019). Moreover, the ages from these samples are all in
agreement with the deposition of the Velkerri Formation dated at 1417 ± 29 Ma by Re–Os geochronology (Kendall et al., 2009),
suggesting that the majority of illite formed relatively soon after sediment
deposition.
Spectral reflectance MLA maps of samples selected for in situ laser
ablation analysis in this study overlain on top of their respective BSE
images. Dashed white lines show illite assemblages wrapping around detrital
grains and forming cements. Dashed black arrows show foliation in illite
crystals. Dashed black lines show large illite crystals replacing previous
clay assemblages. Solid white lines are 100 µm scale bars.
Summary of in situ Rb–Sr geochronological results from this study.
Statistical relationships between alteration proxies obtained from
this study through laser ablation analysis (a) and whole-rock geochemical data (b) compiled from Cox et al. (2016).
Single-spot ages from samples in this study illustrated by KDE (a), CAD (b), and MDS (c) plots. Note that the population of single-spot ages for samples at 415, 520, and 696 m depths all overlap with previous Velkerri Formation Re–Os age constraints shown in light pink (Kendall et al., 2009). On the other hand, samples at 938
and 1220 m depth are statistically different and instead agree with the Derim Derim Dolerite intrusion ca. 1330–1300 Ma (displayed in dark pink)
(Bodorkos et al., 2022).
(a) One-dimensional thermal model for sill intrusion of 75 m thickness within the Altree 2 well depicting time steps following
emplacement at 0 ka. Sill intrusion and Rb–Sr sample depths have been
normalized to palaeodepths with 1.5 km of additional Mesoproterozoic
sediments (Hall et al., 2021). Median palaeotemperature estimates from VRCALC data from the Altree 2 well have been included
for comparison to modelled temperatures. (b) Time–temperature profile for sample intervals within the Altree 2 well following intrusions of a sill of 75 m thick.
Nevertheless, we also sought to identify any potential secondary alteration
of these shales by analysing their geochemical signatures. Sm / Nd ratios are common geochemical proxies for screening alteration in shales because Nd is
preferentially lost relative to Sm during post-depositional processes
(Awwiller and Mack, 1989, 1991). In
addition, fluid–rock reactions also have a significant impact on rare-earth
element and yttrium solubility and transportation during hydrothermal events
(Williams-Jones et al., 2012; Lev et al., 1999).
Therefore, these parameters can be an effective tool for highlighting
fingerprints of post-depositional geochemical mobilization (Fig. 7).
Samples from depths shallower than 900 m show no significant relationships
between their total REEY concentrations
and Sm / Nd ratios collected by laser ablation analysis or through traditional bulk trace element geochemistry (Cox et al., 2016). These
support an interpretation that these ages form a minimum depositional age
for the unit, recording an early diagenetic event as opposed to a late-stage
secondary overprint. Furthermore, temperature constrains for the Velkerri
Formation at depths 390–900 m suggest that they are well within the oil
window (Figs. 3 and 4). As a result, we propose that this temperature
window is not sufficient to disturb the Rb–Sr and trace element systems in
these shales.
Conversely, shales collected from depths > 900 m showed
petrographic evidence of post-depositional alteration (Figs. 5 and S2d–e). Clay minerals the 938 m sample are fissile and foliated (Fig. 5).
In addition, pyrite and apatite can be observed overgrowing illite and
chlorite. Moreover, illite grains from the Kalala Member shale at 1220 m
depth are notably larger and crystalline (Figs. 5 and S2d–e), with
features inconsistent with an early diagenetic origin (Fig. S2d–e). Clay
minerals were also found interlocking with quartz overgrowth and appear to
replace earlier assemblages (Figs. 5 and S2d–e).
In addition to petrographic and geochronological disparities, samples from
depths below 900 m display statistically significant relationships between
total REEY concentrations and Sm / Nd ratios (Fig. 7). The shale chip
analysed from 938 m had a positive relationship between an increase in Sm / Nd
ratio and total REEY concentration (Pearson r: 0.580; R2: 0.336), while the sample collected from depth 1220 m preserved a negative relationship between Sm / Nd ratio and total REEY values (Pearson r: -0.545;
R2: 0.297). These associations are similarly reflected in the bulk
trace element data collated from Cox et al. (2016). In the
compiled data, shales from deeper than 900 m demonstrate a strong affinity
between these controls (Pearson r: -0.559; R2: 0.312). These
alteration indicators are further evidence that the Kalala Member at depths
below 900 m experienced a late-stage secondary heating event, as trace
elements are more readily mobilized in hydrothermal reactions
(Williams-Jones et al., 2012; Poitrasson et al., 1995; Condie, 1991; Lev
et al., 1999; Awwiller and Mack, 1989, 1991).
Importantly, thermal indicators from this interval suggest that kerogen in
these shales are thermally overmature (Figs. 3 and 4). Previous studies
have shown that the source rocks in the Velkerri Formation became overmature
only when affected by magmatic events (Crick et al., 1988; George and
Ahmed, 2002). As such, it is plausible that the Derim Derim Dolerite
intersected in this well has imposed a hydrothermal alteration footprint
onto the surrounding sediments via conductive heat loss and/or heat transfer
fluids. This magmatic pulse would have recrystallized the former mineral
assemblages or induced a second mineralization of clays, mobilized trace
elements, and heated the kerogen within the Kalala Member to overmaturity.
Thermal indicators (Figs. 4 and 9) suggest that source rocks within this
interval may have experienced palaeotemperatures of at least 150 ∘C (Dellisanti et al., 2010; Merriman and Frey, 1999; Hunt, 1995; Welte
and Tissot, 1984). This is in good agreement with evidence from aqueous
fluid inclusions in quartz veins within the Derim Derim Dolerite elsewhere,
which have suggested that hydrocarbons from the Velkerri Formation migrated
in the cooling sill at similar temperatures (Dutkiewicz et
al., 2004). Importantly, such hydrothermal systems seem to be sufficient for
disturbing the Rb–Sr isotopic system of these samples.
Modelled predictions of the geothermal aureole induced by the Derim Derim Dolerite
Resetting of Rb–Sr geochronology and overmaturation of hydrocarbons in the
Kalala Member within the Altree 2 well implies the presence of a secondary
hydrothermal aureole extending ca. 800 m away from the Derim Derim Dolerite
sill, which is intersected at present-day depth 1696 m. One-dimensional
thermal modelling for a sill thickness of 75 m in the Mesoproterozoic
suggests temperatures exceeding the oil window over 120 ∘C
(Tissot et al., 1974; Waples, 1980) only extended ca. 700 m from the
intrusion (Fig. 9a).
Samples at present-day depths of 938 and 1220 m yield Rb–Sr ages
corresponding to emplacement timing of the Derim Derim Dolerite (Nixon et
al., 2021; Yang et al., 2020), which suggests that the intrusion caused the
chronometer to reset or induced a second mineralization of clay phases.
Predicted temperatures experienced by the shallowest reset sample, however,
are lower than the inferred closure temperatures for observed K–Ar and
Rb–Sr in sheet silicates (Dodson, 1973; Tillberg et al., 2020; Torgersen
et al., 2015; Yoder and Eugster, 1955). In a scenario in which a sill of
thickness 75 m was intruded below samples, rocks from present-day depth of
938 m are only predicted to have experienced maximum heating to ca.
110 ∘C (Fig. 9c), with temperatures exceeding 100 ∘C
for a duration of only ca. 150 ka (Fig. 9b).
Additionally, the eruption of lavas from the Kalkarindji LIP (Evins et
al., 2009; Glass and Phillips, 2006; Jourdan et al., 2014) within the same
vertical profile offer an intriguing opportunity to evaluate thermal
resistance of the Rb–Sr system in shale-hosted clays in different
conditions. Basaltic lavas of the ca. 510 Ma Cambrian Kalkarindji LIP
(Evins et al., 2009; Glass and Phillips, 2006; Jourdan et al., 2014) are
preserved above Proterozoic sedimentary rocks in the Altree 2 well.
Furthermore, regional apatite fission track data suggest that the thermal
pulses induced during this LIP extrusion were short-lived but sufficient
(> 190 ∘C) to anneal tracks in the upper
∼ 500 m of the basin (Nixon et al., 2022). However, the shallowest samples taken in this study (at depths 415, 520,
and 696 m) did not have their Rb–Sr isotopic system disturbed despite
experiencing such temperatures from this reheating event. Consequently, the
thermal profile for the sample at 415 m depth provides a minimum closure
temperature constraint for short-lived conditions that have not reset the
Rb–Sr chronometer in these (presumably) dry shales over 800 million years
after the Derim Derim Dolerite intrusion. Interestingly, the Cambrian
palaeotemperatures imposed by the Kalkarindji lavas (Nixon et
al., 2022) are notably higher (> 190 ∘C) than
Mesoproterozoic palaeotemperatures reached by samples with Rb–Sr ages reset
by the Derim Derim Dolerite (ca. 120 ∘C; Fig. 9a and b).
Such a disparity suggests that the presence of fluid (either connate or
sourced from the intrusion), rather than just temperature, is likely to play
a critical role in determining whether the Rb–Sr record in a shale is
reset. As such, the geochemical system in shales within the aureole may be
disturbed at lower temperatures, as trace and rare-earth elements are more
easily mobilized in hydrothermal fluid systems (Villa, 1998; Nebel, 2014;
Poitrasson et al., 1995; Williams-Jones et al., 2012; Li et al., 2019).
Conclusion
We show that the Velkerri Formation shales intersected by the Altree 2 well
preserve evidence of an elevated Mesoproterozoic thermal gradient through an
∼ 800 m thick section away from the intrusion of a Derim Derim
Dolerite sill (Figs. 3, 4, and 9). In situ Rb–Sr isotopic ages from the Wyworrie and Amungee members above this hydrothermal aureole yielded ages (Figs. 6 and 8) within error of their depositional age (Kendall et al.,
2009). In addition, unaltered trace element compositions (Fig. 7) and
petrographic relationships indicate that the shales preserve an
early diagenetic origin (Fig. 5 and Supplement). However, the
older Kalala Member that lies within the hydrothermal aureole yielded
younger Rb–Sr ages (Figs. 6 and 8) consistent with the age of the Derim
Derim Dolerite (Bodorkos et al., 2022; Ahmad and Munson, 2013; Nixon et
al., 2021; Yang et al., 2020). Samples from this subset also recorded
perturbed trace element signatures (Fig. 7) and fissile, foliated,
and crystalline illite morphologies (Fig. 5 and Supplement).
This interval corresponds with disturbed thermal maturity indicators (Figs. 2, 3, and 4), suggesting that the Rb–Sr system is stable up to the
maturation oil window and reset when the kerogen is overmature. Thermal
modelling of the Derim Derim Dolerite suggests that a 75 m thick intrusion
at the base of the Altree 2 well would have significantly elevated
temperatures within 800 m of the sill, driving kerogen into the gas window,
mobilizing trace elements and resetting the Rb–Sr isotopic system in the
Kalala Member.
In conclusion, we show that the in situ Rb–Sr dating of the Velkerri Formation
combined with common hydrocarbon maturity proxies can help reveal the
thermochronological history of Proterozoic argillaceous rocks. When used in
tandem, these methods can constrain the age of deposition and
subsequent secondary, late-stage geological events. Importantly, we
demonstrate that this technique can aid sedimentary-hosted resource
exploration, as hydrothermal overprints can be identified and dated as
previously demonstrated in Subarkah et al. (2021). Specifically,
for hydrocarbon exploration, we show that the thermo-kinetic parameters of
shale-hosted Rb–Sr isotopic system in hydrothermal settings can coincide
with the maturation of kerogen into the gas window (Dodson, 1973;
Espitalié, 1986; Kubler, 1967).
Code availability
Code to calculate error correlations on LADR can be accessed through https://github.com/jarredclloyd/PowerShell_LADR_errorcorrelation_workaround (last access: 25 August 2022, Lloyd, 2022).
Data availability
Data used in this study can be accessed through the Supplement. Additional figures can be found in 10.25909/6315ea488cc5f (Subarkah et al., 2022).
The supplement related to this article is available online at: https://doi.org/10.5194/gchron-4-577-2022-supplement.
Author contributions
DS is responsible for the conceptualization, method development, data collection, and drafting of the paper. ALN is responsible for the conceptualization, computational modelling, and drafting of the paper. MJ is responsible for the conceptualization and drafting of the paper. ASC is responsible for primary supervision, project funding, and drafting of the paper. MLB is responsible for sampling, method development, experimentation, secondary supervision, and drafting of the paper. JF is responsible for method development, secondary supervision, and drafting of the paper. SEG is responsible for the method development and drafting of the paper. SH is responsible for conceptualization and drafting of the paper. AJ is responsible for the data collection and drafting of the paper.
Competing interests
The contact author has declared that none of the authors has any competing interests.
Disclaimer
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Acknowledgements
This work was supported by the Australian Research Council Projects
LP160101353 and LP200301457 with Santos Ltd, Empire Energy Group Ltd,
Northern Territory Geological Survey, Teck Resources, BHP, and Origin as
partners. The initial development and validation of in situ Rb-Sr dating technique at the University of Adelaide was also supported by Agilent Technologies Australia Ltd. This paper forms MinEx CRC contribution no. 2022/60. Aoife McFadden is thanked for their assistance in the MLA mapping of the samples in this study. Jarred Lloyd is thanked for his help in the laser data processing. Jarred Lloyd's code to process error correlations on LADR can be found at https://github.com/jarredclloyd/PowerShell_LADR_errorcorrelation_workaround (last access: 25 August 2022).
Financial support
This research has been supported by the Australian Research Council (grant nos. LP160101353 and LP200301457) and the MinEx CRC.
Review statement
This paper was edited by Daniela Rubatto and reviewed by two anonymous referees.
ReferencesAbad, I. and Nieto, F.: Physical meaning and applications of the illite
Kübler index: measuring reaction progress in low-grade metamorphism,
Diagenesis and Low-Temperature Metamorphism, Theory, Methods and Regional
Aspects, Seminarios, Sociedad Espanola: Sociedad Espanola Mineralogia,
53–64, https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.556.7352&rep=rep1&type=pdf (last access: 25 August 2022), 2007.Abbott, S. T. and Sweet, I. P.: Tectonic control on third-order sequences
in a siliciclastic ramp-style basin: An example from the Roper Superbasin
(Mesoproterozoic), northern Australia, Aust. J. Earth Sci.,
47, 637–657, 10.1046/j.1440-0952.2000.00795.x, 2000.Abbott, S. T., Sweet, I. P., Plumb, K. A., Young, D. N., Cutovinos, A.,
Ferenczi, P. A., and Pietsch, B. A.: Roper Region: Urapunga and Roper River
Special, Northern Territory (Second Edition), 1 : 250 000 geological map series explanatory notes, SD 53-10, 11, Northern Territory Geological Survey and Geoscience Australia, Darwin, https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/81859 (last access: 25 August 2022), 2001.Ahmad, A. and Munson, T. J.: Geology and mineral resources of the Northern
Territory, Special Publication, edited by: Munson, T. J., Johnston, K. J.,
and Fuller, M. H., Northern Territory Geological Survey, https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/81446 (last access: 25 August 2022), 2013.Árkai, P., Sassi, F., and Desmons, J.: Towards a unified nomenclature in
metamorphic petrology: 4, Very low-to low-grade metamorphic rocks. A
proposal on behalf of the IUGS Subcommission on the Systematics of
Metamorphic Rocks, International Union of Geological Sciences (IUGS), https://www.ugr.es/~agcasco/personal/IUGS/pdf-IUGS/scmr_low_r2_verylowtolowgrademetamorphicrocks.pdf (last access: 25 August 2022), 2002.Armistead, S. E., Collins, A. S., Redaa, A., Jepson, G., Gillespie, J.,
Gilbert, S., Blades, M. L., Foden, J. D., and Razakamanana, T.: Structural
evolution and medium-temperature thermochronology of central Madagascar:
implications for Gondwana amalgamation, J. Geol. Soc. Aust., 177, 784, 10.1144/jgs2019-132, 2020.Awwiller, D. N. and Mack, L. E.: Diagenetic Resetting of Sm-Nd Isotope
Systematics in Wilcox Group Sandstones and Shales, San Marcos Arch,
South-Central Texas, AAPG Bull., 39, 321–330, https://archives.datapages.com/data/gcags/data/039/039001/0321.htm (last access: 25 August 2022), 1989.Awwiller, D. N. and Mack, L. E.: Diagenetic modification of Sm-Nd model
ages in Tertiary sandstones and shales, Texas Gulf Coast, Geology, 19,
311–314, 10.1130/0091-7613(1991)019<0311:Dmosnm>2.3.Co;2, 1991.
Baldermann, A., Abdullayev, E., Taghiyeva, Y., Alasgarov, A., and
Javad-Zada, Z.: Sediment petrography, mineralogy and geochemistry of the
Miocene Islam Dağ Section (Eastern Azerbaijan): Implications for the
evolution of sediment provenance, palaeo-environment and (post-)
depositional alteration patterns, Sedimentology, 67, 152–172, 2020.
Bevan, D., Coath, C. D., Lewis, J., Schwieters, J., Lloyd, N., Craig, G.,
Wehrs, H., and Elliott, T.: In situ Rb–Sr dating by collision cell,
multicollection inductively-coupled plasma mass-spectrometry with pre-cell
mass-filter,(CC-MC-ICPMS/MS), J. Anal. Atom. Spectrom., 36,
917–931, 2021.
Blenkinsop, T. G.: Definition of low-grade metamorphic zones using illite
crystallinity, J. Metamorph. Geol., 6, 623–636, 1988.Bodorkos, S., Crowley, J. L., Claoué-Long, J. C., Anderson, J. R., and
Magee, C. W.: Precise U–Pb baddeleyite dating of the Derim Derim Dolerite,
McArthur Basin, Northern Territory: old and new SHRIMP and ID-TIMS
constraints, Aust. J. Earth Sci., 68, 1–15, 10.1080/08120099.2020.1749929, 2022.
Boreham, C., Crick, I., and Powell, T.: Alternative calibration of the
Methylphenanthrene Index against vitrinite reflectance: Application to
maturity measurements on oils and sediments, Org. Geochem., 12,
289–294, 1988.Brown, D. A., Simpson, A., Hand, M., Morrissey, L. J., Gilbert, S., Tamblyn,
R., and Glorie, S.: Laser-ablation Lu-Hf dating reveals Laurentian garnet in
subducted rocks from southern Australia, Geology, 50, 837–842, 10.1130/G49784.1, 2022.
Burtner, R. L. and Warner, M. A.: Relationship between illite/smectite
diagenesis and hydrocarbon generation in Lower Cretaceous Mowry and Skull
Creek shales of the northern Rocky Mountain area, Clay. Clay Miner.,
34, 390–402, 1986.Capogreco, N.: Provenance and thermal history of the Beetaloo Basin using
illite crystallinity and zircon geochronology and trace element data, BSc thesis, University of Adelaide, https://hdl.handle.net/2440/126541 (last access: 25 August 2022), 2017.
Carvajal-Ortiz, H. and Gentzis, T.: Critical considerations when assessing hydrocarbon plays using Rock-Eval pyrolysis and organic petrology data: Data quality revisited, Int. J. Coal Geol., 152, 113–122, 2015.Chamley, H.: Clay formation through weathering, in: Clay sedimentology,
Springer, 21–50, 10.1007/978-3-642-85916-8_2, 1989.
Charbit, S., Guillou, H., and Turpin, L.: Cross calibration of K–Ar
standard minerals using an unspiked Ar measurement technique, Chem.
Geol., 150, 147–159, 1998.
Charlier, B. L., Ginibre, C., Morgan, D., Nowell, G. M., Pearson, D.,
Davidson, J. P., and Ottley, C.: Methods for the microsampling and
high-precision analysis of strontium and rubidium isotopes at single crystal
scale for petrological and geochronological applications, Chem. Geol.,
232, 114–133, 2006.
Chen, J., Blume, H.-P., and Beyer, L.: Weathering of rocks induced by lichen
colonization – a review, Catena, 39, 121–146, 2000.Condie, K. C.: Another look at rare earth elements in shales, Geochim.
Cosmochim. Ac., 55, 2527–2531, 10.1016/0016-7037(91)90370-K, 1991.
Cornford, C., Gardner, P., and Burgess, C.: Geochemical truths in large data
sets. I: Geochemical screening data, Org. Geochem., 29, 519–530,
1998.Cox, G. M., Jarrett, A., Edwards, D., Crockford, P. W., Halverson, G. P.,
Collins, A. S., Poirier, A., and Li, Z.-X.: Basin redox and primary
productivity within the Mesoproterozoic Roper Seaway, Chem. Geol., 440,
101–114, 10.1016/j.chemgeo.2016.06.025, 2016.Cox, G. M., Sansjofre, P., Blades, M. L., Farkas, J., and Collins, A. S.:
Dynamic interaction between basin redox and the biogeochemical nitrogen
cycle in an unconventional Proterozoic petroleum system, Sci. Rep., 9, 5200, 10.1038/s41598-019-40783-4, 2019.Cox, G. M., Collins, A. S., Jarrett, A. J., Blades, M. L., Shannon, A. V.,
Yang, B., Farkas, J., Hall, P. A., O'Hara, B., and Close, D., and Baruch, E. T.: A
very unconventional hydrocarbon play: the Mesoproterozoic Velkerri Formation
of northern Australia, AAPG Bulletin, 106, 1213–1237, 10.1306/12162120148, 2022.
Crick, I., Boreham, C., Cook, A., and Powell, T.: Petroleum geology and
geochemistry of Middle Proterozoic McArthur Basin, northern Australia II:
Assessment of source rock potential, AAPG Bull., 72, 1495–1514, 1988.
Cuadros, J.: Clay minerals interaction with microorganisms: a review, Clay
Miner., 52, 235–261, 2017.Deepak, A., Löhr, S., Abbott, A. N., Han, S., Wheeler, C., and Sharma,
M.: Testing the Precambrian reverse weathering hypothesis using a
1-billion-year record of marine shales, 2022 Goldschmidt Conference, 12 July 2022, Honolulu, Hawai'i, USA, https://conf.goldschmidt.info/goldschmidt/2022/meetingapp.cgi/Paper/10825 (last access: 25 August 2022), 2022.
Dellisanti, F., Pini, G. A., and Baudin, F.: Use of T max as a thermal
maturity indicator in orogenic successions and comparison with clay mineral
evolution, Clay Miner., 45, 115–130, 2010.
Dembicki Jr., H.: Three common source rock evaluation errors made by
geologists during prospect or play appraisals, AAPG Bull., 93, 341–356,
2009.Derkowski, A., Środoń, J., Franus, W., Uhlík, P., Banaś,
M., Zieliński, G., Čaplovičová, M., and Franus, M.: Partial
dissolution of glauconitic samples: Implications for the methodology of K-Ar
and Rb-Sr dating, Clay. Clay Miner., 57, 531–554, 10.1346/CCMN.2009.0570503, 2009.
Dickin, A. P.: Radiogenic isotope geology, Cambridge university press, ISBN 9781107099449, 2018.
Disnar, J. R.: Détermination de paléotempératures maximales
d'enfouissement de sédiments charbonneux à partir de données de
pyrolyse, CR. Acad. Sci. II B, 303, 691–696, 1986.Disnar, J. R.: Determination of maximum paleotemperatures of burial (MPTB)
of sedimentary rocks from pyrolysis data on the associated organic matter:
basic principles and practical application, Chem. Geol., 118, 289–299,
10.1016/0009-2541(94)90182-1, 1994.Dodson, M. H.: Closure temperature in cooling geochronological and
petrological systems, Contrib. Mineral. Petr., 40,
259–274, 10.1007/BF00373790, 1973.Duddy, I., Green, P., Gibson, H., and Hegarty, K.: Regional Palaeothermal
episodes in Northern Australia, Timor Sea Petrol. Geosci., Proc. Timor Sea
Symp. 2003, 20 June 2003, Darwin, Australia, http://www.geotrack.com.au/papers/timor_sea_symposium_duddy_et_al.pdf (last access: 25 August 2022), 2004.Dutkiewicz, A., Volk, H., Ridley, J., and George, S. C.: Geochemistry of oil
in fluid inclusions in a middle Proterozoic igneous intrusion: implications
for the source of hydrocarbons in crystalline rocks, Org. Geochem.,
35, 937–957, 10.1016/j.orggeochem.2004.03.007, 2004.
Eberl, D., and Velde, B.: Beyond the Kubler index, Clay Miner., 24,
571–577, 1989.Espitalié, J.: Use of Tmax as a maturation index for different types of
organic matter: comparison with vitrinite reflectance, Collection colloques
et séminaires – Institut français du pétrole, 475–496, http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=7895690 (last access: 25 August 2022), 1986.Espitalié, J., Madec, M., Tissot, B., Mennig, J., and Leplat, P.: Source
rock characterization method for petroleum exploration, Offshore Technology
Conference, 1 May 1977, Houston, Texas, USA, 10.4043/2935-MS, 1977.Evins, L. Z., Jourdan, F., and Phillips, D. J. L.: The Cambrian Kalkarindji
Large Igneous Province: Extent and characteristics based on new 40Ar /39Ar and geochemical data, Lithos, 110, 294–304, 2009.Faure, G.: Principles of isotope geology, Wiley, https://www.osti.gov/biblio/7100564 (last access: 25 August 2022), 1977.Field, D. and Råheim, A.: A geologically meaningless Rb–Sr total rock
isochron, Nature, 282, 497–499, 10.1038/282497a0, 1979.Merriman, R. J. and Frey, M.: Patterns of very low-grade metamorphism in metapelitic rocks, Low-grade Metamorphism, Blackwell, Oxford, 61–107, 10.1002/9781444313345.ch3, 1999.Frogtech Geoscience: Digital Information Package, DIP: SEEBASE® study and GIS for greater McArthur Basin, Northern Territory Geological Survey, 17, https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/87064 (last access: 25 August 2022), 2018.
Galán, E.: Genesis of clay minerals, Developments in clay science, 1,
1129–1162, 2006.George, S. and Ahmed, M.: Use of aromatic compound distributions to
evaluate organic maturity of the Proterozoic middle Velkerri Formation,
McArthur Basin, Australia, https://archives.datapages.com/data/petroleum-exploration-society-of-australia/conferences/014/014001/pdfs/253.htm (last access: 25 August 2022), 2002.
Glass, L. M. and Phillips, D. J. G.: The Kalkarindji continental flood
basalt province: A new Cambrian large igneous province in Australia with
possible links to faunal extinctions, Geolog, 34, 461–464, 2006.Gorojovsky, L. and Alard, O.: Optimisation of laser and mass spectrometer
parameters for the in situ analysis of Rb / Sr ratios by LA-ICP-MS/MS, J. Anal. Atom. Spectrom., 35, 2322–2336, 10.1039/D0JA00308E, 2020.Govindaraju, K., Rubeska, I., and Paukert, T.: 1994 Report On Zinnwaldite
Zw-C Analysed By Ninety-Two Git-Iwg Member-Laboratories, Geostandard.
Newslett., 18, 1–42, 10.1111/j.1751-908X.1994.tb00502.x, 1994.
Guggenheim, S., Bain, D. C., Bergaya, F., Brigatti, M. F., Drits, V. A.,
Eberl, D. D., Formoso, M. L., Galán, E., Merriman, R. J., and Peacor, D.
R.: Report of the Association Internationale pour l'Etude des Argiles
(AIPEA) Nomenclature Committee for 2001: order, disorder and crystallinity
in phyllosilicates and the use of the “crystallinity index”, Clay Miner.,
37, 389–393, 2002.
Hahn, O. and Walling, E.: Über die Möglichkeit geologischer
Altersbestimmungen rubidiumhaltiger Mineralien und Gesteine, Z. Anorg. Allg. Chem., 236, 78–82, 1938.
Hahn, O., Strassman, F., Mattauch, J., and Ewald, H.: Geologische
Altersbestimmungen mit der strontiummethode, Chem. Ztg., 67, 55–56, 1943.Hall, L., Boreham, C. J., Edwards, D. S., Palu, T., Buckler, T., Troup, A.,
and Hill, A.: Cooper Basin Source Rock Geochemistry, Geoscience Australia, 10.11636/Record.2016.006, 2016.
Hall, L. S., Orr, M. L., Lech, M. E., Lewis, S., Bailey, A. H. E., Owens,
R., Bradshaw, B. E., and Bernardel, G.: Geological and Bioregional
Assessments: assessing the prospectivity for tight, shale and deep-coal
resources in the Cooper Basin, Beetaloo Subbasin and Isa Superbasin, The
APPEA Journal, 61, 477–484, 2021.Harrison, T. M., Heizler, M. T., McKeegan, K. D., and Schmitt, A. K.: In
situ 40K–40Ca “double-plus” SIMS dating resolves Klokken feldspar 40K–40Ar paradox, Earth Planet. Sc. Lett., 299, 426–433, 2010.Hillier, S.: Erosion, sedimentation and sedimentary origin of clays, in:
Origin and mineralogy of clays, Springer, 162–219, 10.1007/978-3-662-12648-6_4, 1995.Hogmalm, K. J., Zack, T., Karlsson, A. K. O., Sjöqvist, A. S. L., and
Garbe-Schönberg, D.: In situ Rb–Sr and K–Ca dating by LA-ICP-MS/MS: an
evaluation of N2O and SF6 as reaction gases, J. Anal. Atom. Spectrom., 32, 305-313, 10.1039/c6ja00362a, 2017.
Hogmalm, K. J., Dahlgren, I., Fridolfsson, I., and Zack, T.: First in situ
Re-Os dating of molybdenite by LA-ICP-MS/MS, Miner. Deposita, 54,
821–828, 2019.Hunt, J. M.: Petroleum geochemistry and geology, W. H. Freeman, ISBN 9780716724414, https://hero.epa.gov/hero/index.cfm/reference/details/reference_id/8737015 (last access: 25 August 2022), 1995.Isson, T. T. and Planavsky, N. J.: Reverse weathering as a long-term
stabilizer of marine pH and planetary climate, Nature, 560, 471–475, 10.1038/s41586-018-0408-4, 2018.Iyer, K., Svensen, H., and Schmid, D. W.: SILLi 1.0: a 1-D numerical tool quantifying the thermal effects of sill intrusions, Geosci. Model Dev., 11, 43–60, 10.5194/gmd-11-43-2018, 2018.
Jackson, M., Sweet, I., Page, R., and Bradshaw, B.: The South Nicholson and
Roper Groups: evidence for the early Mesoproterozoic Roper Superbasin,
Integrated Basin Analysis of the Isa Superbasin using Seismic, Well-log, and
Geopotential Data: An Evaluation of the Economic Potential of the Northern
Lawn Hill Platform: Canberra, Australia, Australian Geological Survey
Organisation Record, 19 pp., 1999.Jackson, M. J., Muir, M. D., and Plumb, K. A.: Geology of the Southern McArthur Basin, Northern Territory, Australian Government Pub. Service, https://dev.ecat.ga.gov.au/geonetwork/srv/api/records/a05f7892-9cf6-7506-e044-00144fdd4fa6 (last access: 25 August 2022), 1987.
Jarrett, A. J., Cox, G. M., Brocks, J. J., Grosjean, E., Boreham, C. J., and
Edwards, D. S.: Microbial assemblage and palaeoenvironmental reconstruction
of the 1.38 Ga Velkerri Formation, McArthur Basin, northern Australia,
Geobiology, 17, 360–380, 2019.
Jarvie, D. M.: Factors affecting Rock-Eval derived kinetic parameters,
Chem. Geol., 93, 79–99, 1991.Jarvie, D. M., Claxton, B. L., Henk, F., and Breyer, J. T.: Oil and shale
gas from the Barnett Shale, Ft, Worth Basin, Texas (abs.): AAPG Annual
Meeting Program, 3 June 2001, Denver, Colorado, USA, A100, https://www.searchanddiscovery.com/abstracts/html/2001/annual/abstracts/0386.htm (last access: 25 August 2022), 2001.
Jenkin, G. R., Rogers, G., Fallick, A. E., and Farrow, C. M.: Rb-Sr closure
temperatures in bi-mineralic rocks: a mode effect and test for different
diffusion models, Chem. Geol., 122, 227–240, 1995.Jochum, K. and Stoll, B.: Reference materials for elemental and isotopic
analyses by LA-(MC)-ICP-MS: Successes and outstanding needs, in: Laser ablation ICP-MS in the Earth sciences: Current practices and outstanding issues, edited by: Sylvestor, P., Economic Geology, ISBN 9-0-921294-49-8, 40, 147–168, http://hdl.handle.net/11858/00-001M-0000-0014-8633-5 (last access: 25 August 2022), 2008.
Jochum, K. P., Willbold, M., Raczek, I., Stoll, B., and Herwig, K.: Chemical
Characterisation of the USGS Reference Glasses GSA-1G, GSC-1G, GSD-1G,
GSE-1G, BCR-2G, BHVO-2G and BIR-1G Using EPMA, ID-TIMS, ID-ICP-MS and
LA-ICP-MS, Geostand. Geoanal. Res., 29, 285–302, 2005.Jochum, K. P., Weis, U., Stoll, B., Kuzmin, D., Yang, Q., Raczek, I., Jacob,
D. E., Stracke, A., Birbaum, K., Frick, D. A., Günther, D., and
Enzweiler, J.: Determination of Reference Values for NIST SRM 610–617
Glasses Following ISO Guidelines, Geostand. Geoanal. Res.,
35, 397–429, 10.1111/j.1751-908X.2011.00120.x, 2011.
Jourdan, F., Hodges, K., Sell, B., Schaltegger, U., Wingate, M., Evins, L.,
Söderlund, U., Haines, P., Phillips, D., and Blenkinsop, T. J. G.:
High-precision dating of the Kalkarindji large igneous province, Australia,
and synchrony with the Early–Middle Cambrian (Stage 4–5) extinction, Geology, 42, 543–546, 2014.Kendall, B., Creaser, R., Gordon, G., and Anbar, A.: Re-Os and Mo isotope
systematics of black shales from the Middle Proterozoic Velkerri and
Wollogorang Formations, McArthur Basin, northern Australia, Geochim.
Cosmochim. Ac., 73, 2534–2558, 10.1016/j.gca.2009.02.013, 2009.
Kennedy, M., Droser, M., Mayer, L. M., Pevear, D., and Mrofka, D.: Late
Precambrian oxygenation; inception of the clay mineral factory, Science,
311, 1446–1449, 2006.Kosakowski, G., Kunert, V., Clauser, C., Franke, W., and Neugebauer, H. J.:
Hydrothermal transients in Variscan crust: paleo-temperature mapping and
hydrothermal models, Tectonophysics, 306, 325–344, 10.1016/S0040-1951(99)00064-5, 1999.Kubler, B.: La cristallinité de l'illite et les zones tout à fait
supérieures du métamorphisme, Etages tectoniques, 105–121, http://refhub.elsevier.com/S0048-9697(14)00679-2/rf0220 (last access: 25 August 2022), 1967.Kvalheim, O. M., Christy, A. A., Telnæs, N., and Bjørseth, A.:
Maturity determination of organic matter in coals using the
methylphenanthrene distribution, Geochim. Cosmochim. Ac., 51,
1883–1888, 10.1016/0016-7037(87)90179-7, 1987.
Lanigan, K. and Ledlie, I. M.: Walton-1,2 EP 24 McArthur Basin, Northern
Territory Well Completion Report, Pacific Oil and Gas, Northern Territory,
AustraliaPR1989-0088, 1990.
Lanigan, K. and Torkington, J.: Well Completion Report EP19 – Sever 1, Daly
Sub-basin of the McArthur Basin, Pacific Oil and Gas, Northern Territory,
AustraliaPR1990-0069, 1991.Laureijs, C. T., Coogan, L. A., and Spence, J.: In-situ RbSr dating of
celadonite from altered upper oceanic crust using laser ablation ICP-MS/MS,
Chem. Geol., 579, 120339, 10.1016/j.chemgeo.2021.120339, 2021.
Ledlie, I. M. and Maim, K.: Lawrence 1 EP 5 McArthur Basin, Northern
Territory Well Completion Report, Pacific Oil and Gas, Northern Territory,
AustraliaPR1989-0005, 1989.
Lee, M. and Parsons, I.: Biomechanical and biochemical weathering of
lichen-encrusted granite: textural controls on organic–mineral interactions
and deposition of silica-rich layers, Chem. Geol., 161, 385–397, 1999.
Lemiux, Y.: Altree 2, Burdo 1, Chanin 1, Jamison 1, McManus 1, Shenandoah
1A, Walton 2, Balmain-1, Elliott-1 pyrolysis and tight rock analysis,
Talisman Energy, Advanced Well Technologies,
Northern Territory Geological Survey, Northern Territory, AustraliaCSR0192,
2011.Lev, S. M., McLennan, S. M., and Hanson, G. N.: Mineralogic controls on REE
mobility during black-shale diagenesis, J. Sediment. Res., 69,
1071–1082, 10.2110/jsr.69.1071, 1999.
Li, S., Wang, X.-C., Li, C.-F., Wilde, S. A., Zhang, Y., Golding, S. D.,
Liu, K., and Zhang, Y.: Direct Rubidium-Strontium Dating of Hydrocarbon
Charge Using Small Authigenic Illitic Clay Aliquots from the Silurian
Bituminous Sandstone in the Tarim Basin, NW China, Sci. Rep., 9,
1–13, 2019.Li, S.-S., Santosh, M., Farkaš, J., Redaa, A., Ganguly, S., Kim, S. W.,
Zhang, C., Gilbert, S., and Zack, T.: Coupled U-Pb and Rb-Sr laser ablation
geochronology trace Archean to Proterozoic crustal evolution in the Dharwar
Craton, India, Precambrian Res., 343, 105709, 10.1016/j.precamres.2020.105709, 2020.Lloyd, J. C.: PowerShell LADR error correlation workaround, GitHub [code], https://github.com/jarredclloyd/PowerShell_LADR_errorcorrelation_workaround, last access: 25 August 2022.
Mackenzie, F. T. and Kump, L. R.: Reverse weathering, clay mineral
formation, and oceanic element cycles, Science, 270, 586–586, 1995.
Mählmann, R. F., Bozkaya, Ö., Potel, S., Le Bayon, R.,
Šegvić, B., and Nieto, F.: The pioneer work of Bernard Kübler
and Martin Frey in very low-grade metamorphic terranes: paleo-geothermal
potential of variation in Kübler-Index/organic matter reflectance
correlations. A review, Swiss J. Geosci., 105, 121–152, 2012.
McMahon, W. J. and Davies, N. S.: Evolution of alluvial mudrock forced by
early land plants, Science, 359, 1022–1024, 2018.
Mergelov, N., Mueller, C. W., Prater, I., Shorkunov, I., Dolgikh, A.,
Zazovskaya, E., Shishkov, V., Krupskaya, V., Abrosimov, K., and Cherkinsky,
A.: Alteration of rocks by endolithic organisms is one of the pathways for
the beginning of soils on Earth, Sci. Rep., 8, 1–15, 2018.
Meunier, A., Velde, B., and Velde, B.: Illite: Origins, evolution and
metamorphism, Springer Science & Business Media, ISBN 9783540204862, 2004.Minster, J. F., Ricard, L. P., and Allègre, C. J.: 87Rb-87Sr chronology of enstatite meteorites, Earth Planet. Sc. Lett., 44, 420–440,
10.1016/0012-821X(79)90081-5, 1979.Mukherjee, I. and Large, R. R.: Pyrite trace element chemistry of the
Velkerri Formation, Roper Group, McArthur Basin: Evidence for atmospheric
oxygenation during the Boring Billion, Precambrian Res., 281, 13–26,
10.1016/j.precamres.2016.05.003, 2016.Munson, T.: Sedimentary Characterisation of the Wilton Package, Greater
MacArthur Basin, Northern Territory, Northern Territory Geological Survey, https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/83806 (last access: 25 August 2022), 2016.Munson, T. and Revie, D.: Stratigraphic
subdivision of the Velkerri Formation, Roper Group, McArthur Basin, Northern
Territory, Northern Territory Geological Survey, Record 2018-006, https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/87322 (last access: 25 August 2022), 2018.Nebel, O.: Rb–Sr Dating, in: Encyclopedia of Scientific Dating Methods, edited by: Rink, W. J. and Thompson, J. W., Springer Dordrecht,
1–19, 10.1007/978-94-007-6326-5_116-1, 2014.Nebel, O., Scherer, E. E., and Mezger, K.: Evaluation of the 87Rb decay
constant by age comparison against the U–Pb system, Earth Planet. Sc. Lett., 301, 1–8, 10.1016/j.epsl.2010.11.004, 2011.
Nguyen, K., Love, G. D., Zumberge, J. A., Kelly, A. E., Owens, J. D.,
Rohrssen, M. K., Bates, S. M., Cai, C., and Lyons, T. W.: Absence of
biomarker evidence for early eukaryotic life from the Mesoproterozoic Roper
Group: Searching across a marine redox gradient in mid-Proterozoic
habitability, Geobiology, 17, 247–260, 2019.Nixon, A. L., Glorie, S., Collins, A. S., Blades, M. L., Simpson, A., and
Whelan, J. A.: Inter-cratonic geochronological and geochemical correlations
of the Derim Derim–Galiwinku/Yanliao reconstructed Large Igneous Province
across the North Australian and North China cratons, Gondwana Res., 103, 473–486, 10.1016/j.gr.2021.10.027, 2021.Nixon, A. L., Glorie, S., Hasterok, D., Collins, A. S., Fernie, N., and
Fraser, G.: Low-temperature thermal history of the McArthur Basin: Influence
of the Cambrian Kalkarindji Large Igneous Province on hydrocarbon
maturation, Basin Res., 10.1111/bre.12691, online first, 2022.Norris, A. and Danyushevsky, L.: Towards Estimating the Complete
Uncertainty Budget of Quantified Results Measured by LA-ICP-MS, Goldschmidt,
Boston, MA, USA, https://goldschmidtabstracts.info/2018/1894.pdf (last access: 25 August 2022), 2018.NTGS: Altree 1 and 2 EP 24 McArthur Basin, Northern Territory Well
Completion Report, Pacific Oil and Gas, Northern Territory, Australia, https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/79405 (last access: 25 August 2022), 1989.NTGS: Core Sample Analysis. Total Organic Carbon, Programmed Pyrolysis Data.
Altree 2, Balmain 1, Elliott 1, Jamison 1, in: Core Sampling Reports, Falcon
Oil & Gas Weatherford Laboratories, Northern Territory, Australia, https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/84880 (last access: 25 August 2022), 2009.NTGS: EP24 Altree 2 Petrology and organic geochemistry, Eni Australia,
Geotechnical Services, Falcon Oil & Gas, Northern Territory Geological
Survey, Northern Territory, Australia, CSR0185, https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/84887 (last access: 25 August 2022), 2010.NTGS: Quantitative X-Ray Diffraction Analysis of 30 samples, edited by: Northern Territory Geological Survey, Core Sampling Reports, Northern Territory Geological Survey, Northern Territory, Australia, https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/84920 (last access: 25 August 2022), 2012.NTGS: Basic Well Completion Report, NT EP167, Tarlee S3, Pangaea Resources,
Northern Territory, Australia, PR2015-0016, https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/83524 (last access: 25 August 2022), 2014.NTGS: Basic Well Completion Report NT EP167 Birdum Creek 1, Pangaea
Resources, Northern Territory, Australia, PR2016-W006, https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/86120 (last access: 25 August 2022), 2015.NTGS: Basic Well Completion Report NT – EP167 Wyworrie 1, Pangaea Resources,
Northern Territory, Australia, PR2016-W007, https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/86440 (last access: 25 August 2022), 2016.
Ola, P. S., Aidi, A. K., and Bankole, O. M.: Clay mineral diagenesis and
source rock assessment in the Bornu Basin, Nigeria: Implications for thermal
maturity and source rock potential, Mar. Petrol. Geol., 89,
653–664, 2018.Olierook, H. K. H., Rankenburg, K., Ulrich, S., Kirkland, C. L., Evans, N. J., Brown, S., McInnes, B. I. A., Prent, A., Gillespie, J., McDonald, B., and Darragh, M.: Resolving multiple geological events using in situ Rb–Sr geochronology: implications for metallogenesis at Tropicana, Western Australia, Geochronology, 2, 283–303, 10.5194/gchron-2-283-2020, 2020.Page, R. W., Jackson, M. J., and Krassay, A. A.: Constraining sequence
stratigraphy in north Australian basins: SHRIMP U–Pb zircon geochronology
between Mt Isa and McArthur River, Aust. J. Earth Sci.,
47, 431–459, 10.1046/j.1440-0952.2000.00797.x, 2000.Papanastassiou, D. A. and Wasserburg, G. J.: RbSr ages from the ocean of
storms, Earth Planet. Sc. Lett., 8, 269–278, 10.1016/0012-821X(70)90111-1, 1970.
Pearce, N. J., Perkins, W. T., Westgate, J. A., Gorton, M. P., Jackson, S.
E., Neal, C. R., and Chenery, S. P.: A compilation of new and published
major and trace element data for NIST SRM 610 and NIST SRM 612 glass
reference materials, Geostandard. Newslett., 21, 115–144, 1997.
Peters, K. E.: Guidelines for evaluating petroleum source rock using
programmed pyrolysis, AAPG Bull., 70, 318–329, 1986.Peters, K. E. and Cassa, M. R.: Applied source rock geochemistry: Chapter
5: Part II. Essential elements, American Association of Petroleum Geologists, 93–120, https://archives.datapages.com/data/specpubs/methodo2/data/a077/a077/0001/0050/0093.htm (last access: 25 August 2022), 1994.Piedad-Sánchez, N., Izart, A., Martıìnez, L., Suárez-Ruiz, I.,
Elie, M., and Menetrier, C.: Paleothermicity in the Central Asturian Coal
Basin, North Spain, Int. J. Coal Geol., 58, 205–229,
10.1016/j.coal.2004.02.001, 2004.
Plumb, K. and Wellman, P.: McArthur Basin, Northern Territory: mapping of
deep troughs using gravity and magnetic anomalies, BMR J. Aust. Geol. Geop., 10, 243–251, 1987.Poitrasson, F., Pin, C., and Duthou, J.-L.: Hydrothermal remobilization of
rare earth elements and its effect on Nd isotopes in rhyolite and granite,
Earth Planet. Sc. Lett., 130, 1–11, 10.1016/0012-821X(94)00257-Y, 1995.
Pollastro, R. M.: Considerations and applications of the illite/smectite
geothermometer in hydrocarbon-bearing rocks of Miocene to Mississippian age,
Clay. Clay Miner., 41, p. 119, 1993.
Radke, M., Willsch, H., Leythaeuser, D., and Teichmüller, M.: Aromatic
components of coal: relation of distribution pattern to rank, Geochim. Cosmochim. Ac., 46, 1831–1848, 1982.Rafiei, M. and Kennedy, M.: Weathering in a world without terrestrial life
recorded in the Mesoproterozoic Velkerri Formation, Nat. Commun.,
10, 3448, 10.1038/s41467-019-11421-4, 2019.Rafiei, M., Löhr, S., Baldermann, A., Webster, R., and Kong, C.:
Quantitative petrographic differentiation of detrital vs diagenetic clay
minerals in marine sedimentary sequences: Implications for the rise of
biotic soils, Precambrian Res., 350, 105948, 10.1016/j.precamres.2020.105948, 2020.Rawlings, D. J.: Stratigraphic resolution of a multiphase intracratonic
basin system: the McArthur Basin, northern Australia, Aust. J. Earth Sci., 46, 703–723, 10.1046/j.1440-0952.1999.00739.x, 1999.Redaa, A., Farkaš, J., Gilbert, S., Collins, A. S., Wade, B., Löhr,
S., Zack, T., and Garbe-Schönberg, D.: Assessment of elemental
fractionation and matrix effects during in situ Rb–Sr dating of phlogopite
by LA-ICP-MS/MS: implications for the accuracy and precision of mineral
ages, J. Anal. Atom. Spectrom., 36, 322–344, 10.1039/D0JA00299B, 2021a.Redaa, A., Farkaš, J., Hassan, A., Collins, A. S., Gilbert, S., and
Löhr, S. C.: Constraints from in-situ Rb-Sr dating on the timing of
tectono-thermal events in the Umm Farwah shear zone and associated Cu-Au
mineralisation in the Southern Arabian Shield, Saudi Arabia, J.
Asian Earth Sci., 224, 105037, 10.1016/j.jseaes.2021.105037, 2021b.Revie, D.: XRD analysis greater McArthur Basin. NTGS Core Sampling Reports,
Northern Territory Geological Survey, Northern Territory, Australia, https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/85053 (last access: 25 August 2022), 2014.
Revie, D.: Interpretive summary of integrated petroleum geochemistry of
selected wells in the greater McArthur Basin, NT, Australia, Northern
Territory Geological Survey, Weatherford Laboratories, Northern Territory, Australia, CSR0413, 2016.Revie, D. and MacDonald, G.: Volumetric resource assessment of the lower
Kyalla and middle Velkerri formations of the McArthur Basin, Annual
Geoscience Exploration Seminar (AGES) Proceedings, 29 March 2017, Alice Springs, Northern Territory, Australia, 29, https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/85107 (last access: 25 August 2022), 2017.
Revie, D., Normington, V., and Jarrett, A.: Shale resource data from the
greater McArthur Basin, Northern Territory Geological Survey, 1445-5358, 2022.Ribeiro, B. V., Finch, M. A., Cawood, P. A., Faleiros, F. M., Murphy, T. D.,
Simpson, A., Glorie, S., Tedeschi, M., Armit, R., and Barrote, V. R.: From
microanalysis to supercontinents: Insights from the Rio Apa Terrane into the
Mesoproterozoic SW Amazonian Craton evolution during Rodinia assembly,
J. Metamorph. Geol., 40, 631–663, 10.1111/jmg.12641, 2021.Riediger, C. L.: Solid bitumen reflectance and Rock-Eval Tmax as maturation
indices: an example from the “Nordegg Member”, Western Canada Sedimentary
Basin, Int. J. Coal Geol., 22, 295–315, 10.1016/0166-5162(93)90031-5, 1993.Rösel, D. and Zack, T.: LA-ICP-MS/MS Single-Spot Rb-Sr Dating,
Geostand. Geoanal. Res., 46, 143–168, 10.1111/ggr.12414, 2022.
Sander, R., Pan, Z., Connell, L. D., Camilleri, M., Grigore, M., and Yang,
Y.: Controls on methane sorption capacity of Mesoproterozoic gas shales from
the Beetaloo Sub-basin, Australia and global shales, Int. J. Coal Geol., 199, 65–90, 2018.Scheiblhofer, E., Moser, U., Löhr, S., Wilmsen, M., Farkaš, J.,
Gallhofer, D., Bäckström, A. M., Zack, T., and Baldermann, A.:
Revisiting Glauconite Geochronology: Lessons Learned from In Situ
Radiometric Dating of a Glauconite-Rich Cretaceous Shelfal Sequence,
Minerals, 12, 818, 10.3390/min12070818, 2022.Schmitz, M. D. and Schoene, B.: Derivation of isotope ratios, errors, and
error correlations for U-Pb geochronology using 205Pb-235U-(233U)-spiked
isotope dilution thermal ionization mass spectrometric data, Geochem.
Geophy. Geosy., 8, Q08006, 10.1029/2006GC001492, 2007.Selby, D.: U-Pb zircon geochronology of the Aptian/Albian boundary implies
that the GL-O international glauconite standard is anomalously young,
Cretaceous Res., 30, 1263–1267, 10.1016/j.cretres.2009.07.001, 2009.Şengün, F., Bertrandsson Erlandsson, V., Hogmalm, J., and Zack, T.:
In situ Rb-Sr dating of K-bearing minerals from the orogenic Akçaabat
gold deposit in the Menderes Massif, Western Anatolia, Turkey, J.
Asian Earth Sci., 185, 104048, 10.1016/j.jseaes.2019.104048, 2019.Shepherd, T. J. and Darbyshire, D. P. F.: Fluid inclusion Rb–Sr isochrons
for dating mineral deposits, Nature, 290, 578–579, 10.1038/290578a0, 1981.Simmons, E. C.: rubidiumRubidium: Element and geochemistry, in:
Geochemistry, Springer Netherlands, Dordrecht, 555–556, 10.1007/1-4020-4496-8_278, 1998.Simpson, A., Gilbert, S., Tamblyn, R., Hand, M., Spandler, C., Gillespie,
J., Nixon, A., and Glorie, S.: In-situ LuHf geochronology of garnet, apatite
and xenotime by LA ICP MS/MS, Chem. Geol., 577, 120299, 10.1016/j.chemgeo.2021.120299, 2021.Simpson, A., Glorie, S., Hand, M., Spandler, C., Gilbert, S., and Cave, B.: In situ Lu–Hf geochronology of calcite, Geochronology, 4, 353–372, 10.5194/gchron-4-353-2022, 2022.
Singer, A.: The paleoclimatic interpretation of clay minerals in soils and
weathering profiles, Earth-Sci. Rev., 15, 303–326, 1980.Southgate, P. N., Bradshaw, B. E., Domagala, J., Jackson, M. J., Idnurm, M.,
Krassay, A. A., Page, R. W., Sami, T. T., Scott, D. L., Lindsay, J. F.,
McConachie, B. A., and Tarlowski, C.: Chronostratigraphic basin framework
for Palaeoproterozoic rocks (1730–1575 Ma) in northern Australia and
implications for base-metal mineralisation, Aust. J. Earth Sci., 47, 461–483, 10.1046/j.1440-0952.2000.00787.x, 2000.Subarkah, D., Blades, M. L., Collins, A. S., Farkaš, J., Gilbert, S.,
Löhr, S. C., Redaa, A., Cassidy, E., and Zack, T.: Unraveling the
histories of Proterozoic shales through in situ Rb-Sr dating and trace
element laser ablation analysis, Geology, 50, 66–70, 10.1130/G49187.1, 2021.Subarkah, D., Nixon, A., Jimenez Lloreda, M., Collins, A., Blades, M., Farkas, J., Gilbert, S., Holford, S., and Jarrett, A.: GCHRON-2022-8_SuppFigures, The University of Adelaide [figure], 10.25909/6315ea488cc5f, 2022.
Summons, R. E., Taylor, D., and Boreham, C. J.: Geochemical Tools For
Evaluating Petroleum Generation In Middle Proterozoic Sediments Of The
Mcarthur Basin, Northern Territory, Australia, The APPEA Journal, 34,
692–706, 1994.Tamblyn, R., Hand, M., Morrissey, L., Zack, T., Phillips, G., and Och, D.:
Resubduction of lawsonite eclogite within a serpentinite-filled subduction
channel, Contrib. Mineral. Petr., 175, 74, 10.1007/s00410-020-01712-1, 2020.Tamblyn, R., Hand, M., Simpson, A., Gilbert, S., Wade, B., and Glorie, S.:
In situ laser ablation Lu–Hf geochronology of garnet across the Western
Gneiss Region: campaign-style dating of metamorphism, J.
Geol. Soc., 179, 4, 10.1144/jgs2021-094, 2021.
Taylor, D., Kontorovich, A. E., Larichev, A. I., and Glikson, M.: Petroleum
Source Rocks In The Roper Group Of The Mcarthur Basin: Source
Characterisation And Maturity Determinations Using Physical And Chemical
Methods, The APPEA Journal, 34, 279–296, 1994.Tillberg, M., Drake, H., Zack, T., Kooijman, E., Whitehouse, M. J., and
Åström, M. E.: In situ Rb-Sr dating of slickenfibres in deep
crystalline basement faults, Sci. Rep., 10, 562, 10.1038/s41598-019-57262-5, 2020.
Tissot, B., Durand, B., Espitalie, J., and Combaz, A.: Influence of nature
and diagenesis of organic matter in formation of petroleum, AAPG Bull.,
58, 499–506, 1974.
Tissot, B., Pelet, R., and Ungerer, P.: Thermal history of sedimentary
basins, maturation indices, and kinetics of oil and gas generation, AAPG Bull., 71, 1445–1466, 1987.Torgersen, E., Viola, G., Zwingmann, H., and Harris, C.: Structural and
temporal evolution of a reactivated brittle–ductile fault – Part II:
Timing of fault initiation and reactivation by K–Ar dating of synkinematic
illite/muscovite, Earth Planet. Sc. Lett., 410, 212–224,
10.1016/j.epsl.2014.09.051, 2015.
Varajao, A. and Meunier, A.: Particle morphological evolution during the
conversion of I/S to illite in Lower Cretaceous shales from Sergipe-Alagoas
Basin, Brazil, Clay. Clay Miner., 43, 14–28, 1995.
Velde, B. and Espitalié, J.: Comparison of kerogen maturation and
illite/smectite somposition in diagnesis, J. Petrol. Geol., 12,
103–110, 1989.
Velde, B. and Vasseur, G.: Estimation of the diagenetic smectite to illite
transformation in time-temperature space, Am. Mineral., 77,
967–976, 1992.Vermeesch, P.: Quantitative geomorphology of the White Mountains
(California) using detrital apatite fission track thermochronology, J. Geophys. Res.-Earth, 112, F03004, 10.1029/2006JF000671, 2007.Vermeesch, P.: On the visualisation of detrital age distributions, Chem. Geol., 312–313, 190–194, 10.1016/j.chemgeo.2012.04.021, 2012.Vermeesch, P.: Multi-sample comparison of detrital age distributions,
Chem. Geol., 341, 140–146, 10.1016/j.chemgeo.2013.01.010, 2013.Vermeesch, P.: IsoplotR : A free and open toolbox for geochronology,
Geosci. Front., 9, 1479–1493, 10.1016/j.gsf.2018.04.001, 2018.Villa, I. M.: Isotopic closure, Terra Nova, 10, 42–47, 10.1046/j.1365-3121.1998.00156.x, 1998.Villa, I. M., De Bièvre, P., Holden, N., and Renne, P.: IUPAC-IUGS
recommendation on the half life of 87Rb, Geochim. Cosmochim. Ac.,
164, 382–385, 2015.Volk, H., George, S. C., Dutkiewicz, A., and Ridley, J.: Characterisation of
fluid inclusion oil in a Mid-Proterozoic sandstone and dolerite (Roper
Superbasin, Australia), Chem. Geol., 223, 109–135, 10.1016/j.chemgeo.2004.12.024, 2005.Waliczek, M., Machowski, G., Poprawa, P., Świerczewska, A., and
Więcław, D.: A novel VRo, Tmax, and S indices conversion formulae on
data from the fold-and-thrust belt of the Western Outer Carpathians
(Poland), Int. J. Coal Geol., 234, 103672, 10.1016/j.coal.2020.103672, 2021.Wang, X.-C., Li, Z.-X., Li, X.-H., Li, J., Liu, Y., Long, W.-G., Zhou,
J.-B., and Wang, F. J. J. O. P.: Temperature, pressure, and composition of
the mantle source region of Late Cenozoic basalts in Hainan Island, SE Asia:
a consequence of a young thermal mantle plume close to subduction zones?, J. Petrology, 53, 177–233, 10.1093/petrology/egr061, 2012.
Waples, D. W.: Time and temperature in petroleum formation: application of
Lopatin's method to petroleum exploration, AAPG Bull., 64, 916–926, 1980.
Warr, L. and Mählmann, R. F.: Recommendations for Kübler index
standardization, Clay Miner., 50, 283–286, 2015.
Warr, L. N. and Rice, A. H. N.: Interlaboratory standardization and
calibration of day mineral crystallinity and crystallite size data, J. Metamorph. Geol., 12, 141–152, 1994.Warren, J. K., George, S. C., Hamilton, P. J., and Tingate, P.: Proterozoic
Source Rocks: Sedimentology and Organic Characteristics of the Velkerri
Formation, Northern Territory, Australia1, AAPG Bull., 82, 442–463, 10.1306/1D9BC435-172D-11D7-8645000102C1865D, 1998.
Welte, D. and Tissot, P.: Petroleum formation and occurrence, Springer, ISBN 9783642878138, 1984.Wilhelms, A., Teln, N., Steen, A., and Augustson, J.: A quantitative study
of aromatic hydrocarbons in a natural maturity shale sequence – the
3-methylphenanthrene/retene ratio, a pragmatic maturity parameter, Org. Geochem., 29, 97–105, 10.1016/S0146-6380(98)00112-0, 1998.Williams-Jones, A., Migdisov, A., and Samson, I.: Hydrothermal Mobilisation
of the Rare Earth Elements – a Tale of “Ceria” and “Yttria”, Elements, 8, 355–360, 10.2113/gselements.8.5.355, 2012.
Wilson, M. J.: The origin and formation of clay minerals in soils: past,
present and future perspectives, Clay Miner., 34, 7–25, 1999.Yang, B., Smith, T. M., Collins, A. S., Munson, T. J., Schoemaker, B.,
Nicholls, D., Cox, G., Farkas, J., and Glorie, S.: Spatial and temporal
variation in detrital zircon age provenance of the hydrocarbon-bearing upper
Roper Group, Beetaloo Sub-basin, Northern Territory, Australia, Precambrian
Res., 304, 140–155, 10.1016/j.precamres.2017.10.025, 2018.Yang, B., Collins, A., Blades, M., Capogreco, N., Payne, J., Munson, T.,
Cox, G., and Glorie, S.: Middle-late Mesoproterozoic tectonic geography of
the North Australia Craton: U–Pb and Hf isotopes of detrital zircon grains
in the Beetaloo Sub-basin, Northern Territory, Australia, J.
Geol. Soci., 176, 771, 10.1144/jgs2018-159, 2019.Yang, B., Collins, A. S., Cox, G. M., Jarrett, A. J. M., Denyszyn, S.,
Blades, M. L., Farkaš, J., and Glorie, S.: Using Mesoproterozoic
Sedimentary Geochemistry to Reconstruct Basin Tectonic Geography and Link
Organic Carbon Productivity to Nutrient Flux from a Northern Australian
Large Igneous Province, Basin Res., 32, 1734–1750, 10.1111/bre.12450, 2020.
Yang, S. and Horsfield, B.: Critical review of the uncertainty of Tmax in
revealing the thermal maturity of organic matter in sedimentary rocks,
Int. J. Coal Geol., 225, 103500, 10.1016/j.coal.2020.103500, 2020.
Yang, Y.-H., Zhang, H.-F., Chu, Z.-Y., Xie, L.-W., and Wu, F.-Y.: Combined
chemical separation of Lu, Hf, Rb, Sr, Sm and Nd from a single rock digest
and precise and accurate isotope determinations of Lu–Hf, Rb–Sr and Sm–Nd
isotope systems using Multi-Collector ICP-MS and TIMS, Int. J. Mass Spectrom., 290, 120–126, 2010.Yim, S.-G., Jung, M.-J., Jeong, Y.-J., Kim, Y., and Cheong, A. C.-s.: Mass
fractionation of Rb and Sr isotopes during laser
ablation-multicollector-ICPMS: in situ observation and correction, Journal
of Analytical Science and Technology, 12, 10, 10.1186/s40543-021-00263-9, 2021.Yoder, H. S. and Eugster, H. P.: Synthetic and natural muscovites,
Geochim. Cosmochim. Ac., 8, 225–280, 10.1016/0016-7037(55)90001-6, 1955.Zack, T., and Hogmalm, K. J.: Laser ablation Rb / Sr dating by online chemical separation of Rb and Sr in an oxygen-filled reaction cell, Chem. Geol., 437, 120–133, 10.1016/j.chemgeo.2016.05.027,
2016.
Zambell, C., Adams, J., Gorring, M., and Schwartzman, D.: Effect of lichen
colonization on chemical weathering of hornblende granite as estimated by
aqueous elemental flux, Chem. Geol., 291, 166–174, 2012.