Precise Th/U-dating of small and heavily coated samples of deep sea corals

被引：43

作者：

Lomitschka, M ^{[1
]}

Mangini, A ^{[1
]}

机构：

[1] Heidelberger Akad Wissensch, D-69120 Heidelberg, Germany

来源：

EARTH AND PLANETARY SCIENCE LETTERS | 1999年 / 170卷 / 04期

关键词：

deep-sea enviroment; scleractinia; uranium disequilibrium; absolute age;

D O I：

10.1016/S0012-821X(99)00117-X

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：

Marine carbonate skeletons Like deep-sea corals are frequently coated with iron and manganese oxides/hydroxides which adsorb additional thorium and uranium out of the sea water. A new cleaning procedure has been developed to reduce this contamination. In this further cleaning step a solution of Na(2)EDTA (Na2H2TB) and ascorbic acid is used which composition is optimised especially for samples of 20 mg of weight. It was first tested on aliquots of a reef-building coral which had been artificially contaminated with powdered ferromanganese nodule. Applied on heavily contaminated deep-sea corals (scleractinia), it reduced excess Th-230 by another order of magnitude in addition to usual cleaning procedures. The measurement of at least three fractions of different contamination, together with an additional standard correction for contaminated carbonates results in Th/U-ages corrected for the authigenic component. A good agreement between Th/U- and C-14-ages can be achieved even for extremely coated corals. (C) 1999 Elsevier Science B.V. All rights reserved.

引用

页码：391 / 401

页数：11

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