Recent  

Calcite is frequently formed during alteration processes in the basaltic, uppermost layer of juvenile oceanic crust. Weathered oceanic basalts are hard to date with conventional radiometric methods. We show in a case study from the North Pamir, Central Asia, that calcite U-Pb age data – supported by geochemistry and petrological microscopy – has the potential to date sufficiently old oceanic basalts, if the time span between basalt extrusion and latest calcite precipitation (~ 25 Ma) is considered.

This paper outlines a method that helps mineral explore for gold. When can see the alteration caused by the mineralising fluids, it is possible to use geochemical methods to vector towards the deposit. But such methods failed at Martabe. We decided to work out why. Our results showed that there were several distinct and separate very short-lived alteration events. The answer might be that vectoring is possible only when samples are compared from the same mineralising system.

This study presents erosion rates of the George River and seven of its tributaries in northeast Tasmania, Australia. These erosion rates are the first measures of landscape change over millennial timescales for Tasmania. We demonstrate that erosion is closely linked to a topographic rainfall gradient across George River. Our findings may be useful for efforts to restore ecological health to Georges Bay by determining a pre-disturbance level of erosion and sediment delivery to this estuary.

We develop in-situ produced terrestrial cosmogenic krypton as a new tool to date and quantify Earth surface processes; the motivation being the availability of six stable and one radioactive isotope (⁸¹Kr, half-life 229 kyr) and of an extremely weathering-resistant target mineral (zircon). We provide proof of principle that terrestrial Kr_it can be quantified and used to unravel Earth surface processes.

Phanerozoic sedimentary rocks of northern Canada have compositionally heterogeneous detrital apatite with high age dispersion caused by differential thermal annealing. Discrete AFT kinetic populations with variable annealing temperatures are defined using elemental data but are poorly resolved using conventional parameters (D_par and Cl). Inverse thermal modelling of samples from northern Yukon reveals a complicated record of multiple heating-cooling cycles consistent with geological constraints.

Cosmogenic nuclide surface exposure dating is commonly used to constrain the timing of past glacier extents. However, Antarctic exposure age datasets are often scattered and difficult to interpret. We compiled new and existing exposure ages of a glacial deposit with independently known age constraints and identify surface processes that increase or reduce the likelihood of exposure age scatter. Then we present new data for a previously unmapped and undated older deposit from the same region.

We present a 3100 year annually banded lake mud record, with an error of −13/+7 %, representing more undercounting than overcounting. Our results provide realistic sedimentation rates that can be used to calculate flux. Our method expands the possibility to overcome the obstacles of indistinct or interrupted banding that can affect the quality and amount of information about environmental change and age. Our results provide realistic sedimentation rates that can be used to calculate flux.

The µDose-system is an innovative analytical instrument developed for the cost- and time-efficient determination of environmental radionuclide concentrations required for the calculation of sedimentation ages in palaeo-environmental and geo-archaeological research. The results of our study suggest that accuracy and precision of µDose-measurements are comparable to those of well-established methods and that the new approach shows the potential to become a standard tool in environmental dosimetry.

Subarctic/Arctic lake sediments provide key data to understand natural climate variability and future climate change, but are difficult to date and of limited use without a robust chronology. A ~21,000 year climate record from Cascade Lake (Alaska) has divergent age models based on two dating methods. We resolve this using volcanic ash deposits; proving paleosecular variation is a viable dating technique in the region, reporting new ash isochrons, and providing a reconciled Bayesian age model.

Paleomagnetic data from Cascade Lake (Brooks Range, Alaska) extend the radiometric-based age model of the sedimentary sequence extending back 21 kyr. Correlated ages based on prominent features in paleomagnetic secular variations (PSV) diverge from the radiometric ages in the upper 1.6 m, by up to about 2000 years at around 4 ka. Four late Holocene cryptotephra in this section support the PSV chronology and suggest the influence of hard water or aged organic material.