QUATERNARY GEOCHRONOLOGY USING THE U-TH-PB METHOD

被引：33

作者：

GETTY, SR

DEPAOLO, DJ

机构：

[1] Berkeley Center for Isotope Geochemistry, Department of Geology and Geophysics, University of California, Berkeley

来源：

GEOCHIMICA ET COSMOCHIMICA ACTA | 1995年 / 59卷 / 15期

基金：

美国国家科学基金会;

关键词：

D O I：

10.1016/0016-7037(95)00197-8

中图分类号：

P3 [地球物理学]; P59 [地球化学];

学科分类号：

0708 ; 070902 ;

摘要：

We describe a method of uranium-thorium-lead (U-Th-Pb) isotopic age dating for Quaternary rocks. The approach uses an instrumental mass discrimination correction for lead isotope ratios, which allows small enrichments of radiogenic Pb-206 and Pb-208 to be detected at the level of 0.001%. Igneous rocks hosting minerals with a range in U-238/Pb-204 values of 100 can be dated with uncertainties of approximately +/- 15-20 kyr. A Quatemary rhyolite dated at 1.19 Ma by K-Ar yields a U-238-Pb-206 age of 1.03 +/- 0.10 Ma. A Holocene dacite (9.5 ka) has uniform Pb-206/Pb-207 to within +/- 0.0015% in groundmass phases, but 1 mm plagioclase phenocrysts have lower Pb-206/Pb-207 by 0.105 +/- 0.002% indicating contamination of the magma after plagioclase crystallization. High precision Pb-206/Pb-207 ratios may be a useful new tool for petrogenetic studies.

引用

页码：3267 / 3272

页数：6

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