SOME OBSERVATIONS ON THE USE OF ZIRCON U-PB GEOCHRONOLOGY IN THE STUDY OF GRANITIC-ROCKS

被引：178

作者：

WILLIAMS, IS

机构：

[1] Research School of Earth Sciences, The Australian National University, Canberra City, ACT 2601

来源：

TRANSACTIONS OF THE ROYAL SOCIETY OF EDINBURGH-EARTH SCIENCES | 1992年 / 83卷

关键词：

DALGETY; DISCORDANCE; INHERITANCE; ION PROBE; KAMERUKA; MONAZITE; MOUNT SONES; RADIOGENIC PB; WATERGUMS; WATERSMEET;

D O I：

10.1017/S0263593300008129

中图分类号：

P [天文学、地球科学];

学科分类号：

07 ;

摘要：

In situ, microscale, U-Pb isotopic analyses of zircon using the SHRIMP ion microprobe demonstrate both the potential and the limitations of zircon U-Pb geochronology. Most zircons, whether from igneous or metamorphic rocks, need to be considered as mixed isotopic systems. In simple, young igneous rocks the mixing is principally between isotopically disturbed and undisturbed zircon. In polymetamorphic rocks, several generations of zircon growth can coexist, each with a different pattern of discordance. A similar situation exists for igneous rocks rich in inherited zircon, as these contain both melt-precipitated zircon and inherited components of several different ages. Microscale analysis by ion probe makes it possible to sample the record of provenance, age and metamorphic history commonly preserved within a single zircon population. It also indicates how the interpretation of conventionally-measured bulk zircon isotopic compositions might be improved.

引用

页码：447 / 458

页数：12

共 71 条

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