Abstracted/indexed

Baddeleyite is commonly used for U–Pb dating, but textural complexities, alteration features and discordance often make age interpretation difficult. Based on this case study, we discuss strategies for obtaining more accurate baddeleyite ages by high-precision and high spatial resolution methods, including analytical challenges and discordance interpretation. An evaluation of microtextures allows us to distinguish among seven different types of baddeleyite–zircon intergrowths.

The generation of highly precise and accurate ages requires crushing of the original sample so that individual mineral grains may be separated out for dating. Here, we use a focused ion beam to extract grains directly from a subset of a sample, effectively performing microsurgery to isolate individual crystals from the rock itself. This approach opens the door to high-precision dating for a variety of precious planetary materials that have previously been challenging to date.

Geologic dating methods generally do not directly measure ages. Instead, interpreting a geochemical measurement as an age requires a middle layer of calculations and supporting data, and the fact that this layer continually improves is an obstacle to synoptic analysis of geochronological data. This paper describes a prototype data management and analysis system that addresses this obstacle by making the middle-layer calculations transparent and dynamic to the user.

The dating of carbonates by laser ablation inductively coupled plasma mass spectrometry is improved by an additional, newly characterised reference material and adapted data evaluation protocols: the shape (diameter to depth) of the ablation crater has to be as similar as possible in the reference material used and the unknown samples to avoid an offset. Different carbonates have different ablation rates per laser pulse. With robust uncertainty propagation, precision can be as good as 2–3 %.

Our study presents the first seasonally laminated (varved) sediment record covering almost the entire Holocene in high mountainous arid Central Asia. The established floating varve chronology is confirmed by two terrestrial radiocarbon dates, whereby aquatic radiocarbon dates reveal decreasing reservoir ages up core. Changes in seasonal deposition characteristics are attributed to changes in runoff and precipitation and/or to evaporative summer conditions.

The U–Pb method is one of the most powerful and versatile methods in the geochronological toolbox. With two isotopes of uranium decaying to two different isotopes of lead, the U–Pb method offers an internal quality control that is absent from most other geochronological techniques. U-bearing minerals often contain significant amounts of Th, which decays to a third Pb isotope. This paper presents an algorithm to jointly process all three chronometers at once.

Optically stimulated luminescence dates the last exposure of quartz and feldspar minerals to sunlight. We investigated its sub-methods (TT-OSL, VSL, and pIRIR) to date middle and early Pleistocene sediments. Inspection of natural signals of samples can reveal saturated samples that produce only minimum ages. Using these sub-methods, minimum ages of up to the early Pleistocene can be obtained for eastern Mediterranean aeolian sediments of Nilotic origin.

Nikon–TRACKFlow is a new system with dedicated modules for automated microscope control and imaging for fission track laboratories. It is based on the Nikon Eclipse Ni-E motorised upright microscope and embedded within Nikon NIS-Elements software. The system decouples image acquisition from analysis based on a number of automated user-friendly designs and protocols. Nikon–TRACKFlow aims to grow towards a high-throughput imaging system for Earth Sciences and other material-oriented sciences.

In this study we present a new marine chronology of the last ~30 000 years for a sediment core retrieved from the central Arctic Ocean. Our new chronology reveals substantially faster sedimentation rates during the end of the last glacial cycle, the Last Glacial Maximum, and deglaciation than previously reported, thus implying a substantial re-interpretation of paleoceanographic reconstructions from this sector of the Arctic Ocean.

Recent technological advances allow researchers to obtain radiocarbon ages from smaller samples than previously possible. We investigate the reliability and precision of radiocarbon ages obtained from miniature (11–150 μg C) samples of terrestrial plant fragments taken from sediment cores from Lake Żabińskie, Poland. We further investigate how sampling density (the number of ages per 1000 years) and sample mass (which is related to age precision) influence the performance of age–depth models.

Here we review current progress in LA-ICP-MS U–Pb carbonate geochronology and present strategies for acquisition and interpretation of carbonate U–Pb dates. We cover topics from imaging techniques and U and Pb incorporation into calcite to potential limitations of the method – disequilibrium and isotope mobility. We demonstrate the incorporation of imaging and compositional data to help refine and interpret U–Pb dates. We expect this paper to become a go-to reference paper for years to come.

The current geochronological state of the art for applying the radiocarbon (¹⁴C) method to deep-sea sediment archives lacks key information on sediment bioturbation, which could affect palaeoclimate interpretations made from deep-sea sediment. We use a computer model that simulates the ¹⁴C activity and bioturbation history of millions of single foraminifera at the sea floor, allowing us to evaluate the current state of the art at the most fundamental level.