FRACTIONATION OF RUTHENIUM FROM IRIDIUM AT THE CRETACEOUS-TERTIARY BOUNDARY

被引：28

作者：

EVANS, NJ

AHRENS, TJ

GREGOIRE, DC

机构：

[1] CALTECH,LINDHURST LAB EXPTL GEOPHYS,SEISMOL LAB 25221,PASADENA,CA 91125

[2] GEOL SURVEY CANADA,OTTAWA,ON K1A 0E8,CANADA

来源：

EARTH AND PLANETARY SCIENCE LETTERS | 1995年 / 134卷 / 1-2期

基金：

加拿大自然科学与工程研究理事会; 美国国家航空航天局;

关键词：

D O I：

10.1016/0012-821X(95)00117-U

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：

New data on Ru/Ir abundance ratios are presented for nonmarine (Hell Creek, Montana; Frenchman River, Saskatchewan) and marine Cretaceous-Tertiary boundary sites (Brazos River, Texas; Beloc, Haiti; DSDP 577 and DSDP 596). The Ru/Ir ratio varies from 0.5 to 1 within 4000 km of Chicxulub and increases to 2-3 at paleodistances (65 Ma) of up to 12,000 km from the impact site. For CI chondrites, Ru/Ir = 1.5. A ballistic model of ejecta cloud cooling and expansion, which employs the available vapor-pressure versus temperature data for Ru and Ir, predicts qualitatively similar global variation in the Ru/Ir ratio but by only a factor of 1.5. We infer that several other factors, such as remobilization of PGE during diagenesis, preferential oxidation of Ru, condensation kinetics and atmospheric chemical and circulation processes, may account for the observed larger Ru/Ir variation.

引用

页码：141 / 153

页数：13

共 63 条

[1] THERMODYNAMICS OF THE GASEOUS OXIDES OF THE PLATINUM-GROUP METALS [J].