Geochronology aims to establish the age of rocks, minerals, and geological events including fluid movement and mineralization, within a specific degree of uncertainty, using signatures inherent in the rocks themselves. Absolute dating is only accomplished through the use of naturally-occurring radioactive isotopes found within geological samples. The U–Th–Pb isotopic system is the benchmark for...

The deposits of Eocene Lake Gosiute that constitute the Green River Formation of Wyoming contain numerous tuff beds that represent isochronous, correlatable stratigraphic markers. Tuff beds selected for Ar/Ar analysis occur within laminated mudstone, are matrix supported, and lack evidence of reworking. These tuffs contain 2%–15% euhedral phenocrysts of quartz, plagioclase, sanidine, biotite, a...

Rocks from the Valhalla metamorphic core complex, British Columbia, Canada, have experienced granulite Jades metamorphism at conditions of 820±30°C, 8±1 kbar. Peak metamorphism was accompanied by dehydration melting of muscovite, but not biotite, followed by minor back reaction of garnet + K-feldspar + H20sillimanite + biotite+plagio close.' At conditions very near those of the peak, extensive ...

The deposits of Eocene Lake Gosiute that constitute the Green River Formation of Wyoming contain numerous tuff beds that represent isochronous, correlatable stratigraphic markers. Tuff beds selected for 40Ar/39Ar analysis occur within laminated mudstone, are matrix supported, and lack evidence of reworking. These tuffs contain 2%–15% euhedral phenocrysts of quartz, plagioclase, sanidine, biotit...

Introduction High precision in situ analysis of trace-element compositions and isotope ratios has revolutionised geochronology and geochemistry over the past decade. Most of the advances are due to the proliferation of laser-ablation microprobe inductively coupled plasma mass spectrometry (ICP-MS) and the rapid development of the multi-collector (MC-) ICP-MS. One of the main benefits of in situ...

Much attention has been given to sampling design, and the sampling method chosen directly affects the sampling accuracy. The development of spatial sampling theory has lead to the recognition of the importance of taking spatial dependency into account when sampling. This text uses the new Sandwich Spatial Sampling and Inference (SSSI) software as a tool to compare the relative error, coefficien...

Abstract Detrital zircon geochronology can help address stratigraphic- to lithospheric-scale geological questions. The approach is reliant on statistically robust, representative age distributions that fingerprint source areas. However, there a range of biases may influence any detrital signature. Despite being fundamental and controllable bias, handpicking grains has received surprisingly litt...