نتایج جستجو برای: geochronology

تعداد نتایج: 1891  

2002
Stephen J. Mojzsis Mark Harrison

A recurring challenge to ion microprobe U^Pb zircon geochronology has been to discriminate between preservation of original igneous zircon populations and inherited grains. This has proved particularly problematic in studying the polyphase metamorphic rocks that dominate Early Archean gneissic terranes. For example, differing interpretations exist for the origin of complex zircon populations in...

2012
CHARLES A. NITTROUER

Floodplain sedimentation removes particles from fluvial transport and constructs stratigraphic records of flooding, biogeochemical sequestration and other aspects of the environmental history of river basins—insight that is enhanced by accurate geochronology. The natural fallout radionuclide 210Pb, often employed to date lacustrine and marine sediments, has previously been used to determine flo...

2015
Cameron M. Mercer Kelsey E. Young John R. Weirich Kip V. Hodges Bradley L. Jolliff Jo-Anne Wartho Matthijs C. van Soest

Quantitative constraints on the ages of melt-forming impact events on the Moon are based primarily on isotope geochronology of returned samples. However, interpreting the results of such studies can often be difficult because the provenance region of any sample returned from the lunar surface may have experienced multiple impact events over the course of billions of years of bombardment. We ill...

2010
James M. McLelland Bruce W. Selleck

In recent years, a rapidly expanding database, especially in sensitive high-resolution ion microprobe (SHRIMP) geochronology, has led to signifi cant advances in understanding of the Precambrian tectonic evolution of the Grenville Province, including its Adirondack outlier, and the Mesoproterozoic inliers of the Appalachians. Based upon this information, we review the geochronology and tectonic...

2013
B. Demarchi K. Rogers D.A. Fa C.J. Finlayson N. Milner K.E.H. Penkman

This study successfully isolates a fraction of intra-crystalline proteins from shells of the marine gastropod Patella vulgata and assesses the suitability of these proteins for IcPD (Intra-crystalline Protein Diagenesis) geochronology. We discuss the mineralogical composition of this gastropod, investigated for the first time by X-ray diffraction mapping, and use the results to inform our sampl...

2006
J. W. Boyce K. V. Hodges W. J. Olszewski M. J. Jercinovic B. D. Carpenter P. W. Reiners

A new analytical method had been developed to enable high-spatial-resolution (U–Th)/He dating of accessory minerals. It involves the use of a focused ArF excimer to ablate pits in a polished grain surface, with the evolved gases spiked for isotope-dilution measurement of radiogenic He. These data are converted to concentrations by precise measurement of each pit using an optical interferometric...

Journal: :Science 1974
C Emiliani N J Shackleton

Oxygent isotopic analysis of a long piston core from the western equatorial Pacific has produced a record for the entire Brunhes epoch. This record can be correlated point by point with the isotopic records of previously analyzed Atlantic and Caribbean cores, leading to the construction of a generalized temperature curve for the entire Brunhes epoch.

2009
M. A. Tamers

Note References below that are in red italics indicate published methodology works by M.A. Tamers Ph.D., D.Sc. and J.J. Stipp Ph.D., owners of BETA Analytic Inc., who were among the originators of the Benzene Method of Radiocarbon Dating. Between the two of them they have published well over 100 articles on geochronology and research related to the Benzene Method of Radiocarbon dating. An addit...

2014
Wei Lin Karim Benzerara Damien Faivre Yongxin Pan

1 Biogeomagnetism Group, Paleomagnetism and Geochronology Laboratory, Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China 2 France-China Bio-Mineralization and Nano-Structures Laboratory, Chinese Academy of Sciences, Beijing, China 3 Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Université Pierre...

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