Osmium isotope of the Co-rich crust from seamount Allison, central Pacific and its use for determination of growth hiatus and growth age

作     者：MENG XianWei LIU YanGuang QU WenJun SHI XueFa 

作者机构：Key Laboratory of Marine Sedimentology&Environmental GeologyFirst Institute of OceanographyState Oceanic AdministrationQingdao 266061China National Research Center for GeoanalysisBeijing 100037China 

出 版 物：《Science China Earth Sciences》 (中国科学（地球科学英文版）)

年 卷 期：2008年第51卷第10期

页      面：1446-1451页

核心收录：

学科分类：070704[理学-海洋地质] 0709[理学-地质学] 07[理学] 0707[理学-海洋科学] 

基　　金：the Ministry of Science and Technology and the China Oceanic Min-eral Resource Research and Development Association (COMRA) (Grant Nos. 2006DFB21620 and DY105-01-01-09) 

主　　题：seamount Allison Co-rich crust Os isotope growth hiatus 

摘      要：Based on its microstructure, Co-rich crust A1-1 from seamount Allison, central Pacific, was scraped at averaged interval of 1.3 mm to measure osmium isotopic composition, and subsequently to establish the 187Os/188Os profile of scraping section of the crust. By observing the variation of 187Os/188Os under 10Be chronology and matching it to the well-known seawater Os isotope evolution of the past 40 Ma, two growth hiatuses (H1 and H2) occurring in the periods respectively between 13.6 and 29.6 Ma and between 8 and 9.8 Ma in the crust were recognized. According to the two hiatuses, the dating scheme for each scraped layer of the crust was suggested. For the upper layers younger than 6.8Ma, their growth ages were calibrated under 10Be chronology; for the lower layers older than 6.8Ma, their growth ages were obtained from 187Os/188Os evaluation curve by linear interpolation. Hereby, the age for the most inner layer of the crust was determined to be 39.5 Ma. H1 and H2 exactly correspond to the boundary between phosphatization and non-phosphatization and volcanic ash layer in the crust, respectively.