Dating diagenetic monazite in mudrocks: constraining the oil window?

被引：47

作者：

Evans, JA ^{[1
]}

Zalasiewicz, JA

Fletcher, I

Rasmussen, B

Pearce, NJG

机构：

[1] BGS, NERC, Isotope Geosci Lab, Nottingham NG12 5GG, England

[2] Univ Leicester, Dept Geol, Leicester LE1 7RH, Leics, England

[3] Univ Western Australia, Sch Earth & Geog Sci, Ctr Global Metallogeny, Crawley, WA 6009, Australia

[4] Univ Wales, Inst Geog & Earth Sci, Aberystwyth SY23 3DB, Dyfed, Wales

来源：

JOURNAL OF THE GEOLOGICAL SOCIETY | 2002年 / 159卷

关键词：

palaeozoic; Welsh Basin; oil window; monazite;

D O I：

10.1144/0016-764902-066

中图分类号：

P [天文学、地球科学];

学科分类号：

07 ;

摘要：

Authigenic monazite nodules, increasingly recognized in Pre-Mesozoic mudrock successions, provide a means for dating diagenesis by exploiting trace uranium within the monazite structure. But, dating is difficult in practice because of zonation and abundant host rock inclusions. We report here a refined technique that has yielded a date of 419 +/- 14 Ma 2sigma MSWD = 1.2 for a 17-point Pb-Pb regression age from a Telychian (Silurian: late Llandovery) mudrock from central Wales. SHRIMP analyses of monazite nodules from the same horizon are consistent with this, and additionally demonstrate concordance of the U-Pb and Th-Pb systems. These results open the door to providing robust dates for a phase of burial-related diagenesis which, in Wales, seems approximately coincident with, and perhaps was related to, hydrocarbon expulsion.

引用

页码：619 / 622

页数：4

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