太平洋海山磷酸盐的锶同位素成分及形成年代  

Sr Isotopic Compositions and Age Dating of Marine Phosphates from Pacific Seamounts

作　　者：潘家华[1] 刘淑琴[1] 杨忆[2] 刘学清[3] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037 [2]中国科学院研究生院,北京100039 [3]北京市地质矿产勘探开发局,北京100050

出　　处：《矿床地质》2002年第4期350-355,共6页Mineral Deposits

基　　金：中国大洋矿产资源研究开发协会项目 (DY95_0 8)资助

摘　　要：作者首次对太平洋不同海山上与富钴结壳伴生的各种产状的磷酸盐的锶同位素成分及其形成年代进行了深入研究。研究表明 ,我国调查区磷酸盐的87Sr/ 86Sr比值变化于 0 .70 76 6至 0 .70 84 2之间 ,形成年代相当于距今 2 1Ma至 39.5Ma。磷酸盐化作用主要发生在晚始新世_早渐新世及晚渐新世_早中新世期间。西、中太平洋磷酸盐形成年代的一致性揭示 ,自晚始新世至早中新世 ,在太平洋水下海山上曾发生过广泛的磷酸盐化作用 。The aim of this study is to provide for the first time Sr isotopic compositions and age dating of different modes of phosphates dredged from different Pacific submarine guyots. Studies show that the 87 Sr/ 86 Sr ratios of phosphate samples vary from 0.70766 to 0.70842, corresponding to apparent ages of 21 to 39.5 Ma. Two major episodes of phosphatization have been detected, namely late Eocene/early Oligocene and late Oligocene /early Miocene. The similarity of age dating between phosphates from Western Pacific and those from Central Pacific submarine guyots seems to confirm the conclusion that the phosphatization occurred extensively on the guyots in Pacific through late Eocene to early Miocene and can serve as an important indicator of paleoenvironmental change.

关 键 词：地球化学 大洋磷酸盐 锶同位素 形成年代 太平洋 富钴结壳 古海洋环境 

分 类 号：P736.3[天文地球—海洋地质] P736.[天文地球—海洋科学]