High Iridium concentration of alkaline rocks of Deccan and implications to K/T boundary

Journal of Earth system science

J S Ray1¹  Anirban Das1¹  N Bhandari1¹  A D Shukla1¹  P N Shukla1¹ 

[1] Physical Research Laboratory, Ahmedabad 380 009, India.$$

关键词: Carbonatite;    Deccan;    iridium;    alkaline rocks;    K/T boundary;    Anjar;    Amba Dongar;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

We report here an unusually high concentration of iridium in some alkali basalts and alkaline rocks of Deccan region having an age of about 65Ma, similar to the age of the Cretaceous-Tertiary boundary. The alkali basalts of Anjar, in the western periphery of Deccan province, have irid-ium concentration as high as 178pg/g whereas the alkaline rocks and basalts associated with the Amba Dongar carbonatite complex have concentrations ranging between 8 and 80 pg/g. Some of these values are more than an order of magnitude higher than the concentration in the tholeiiticbasalts of Deccan, indicating the significance of alkaline magmatism in the iridium inventory at the Cretaceous-Tertiary boundary. Despite higher concentration, their contribution to the global inventory of iridium in the Cretaceous-Tertiary boundary clays remains small. The concentration of iridium in uorites from Amba Dongar was found to be < 30 pg/g indicating that iridium is not incorporated during their formation in hydrothermal activity.

【 授权许可】

Unknown