SHRIMP Zircon U-Pb Chronology of the Babu Ophiolite in Southeastern Yunnan Province
详细信息
- 责任者：Zhang Binhui (Chengdu Center ; China Geological Survey ; Chengdu 610082 ; China) ; Ding Jun
- 刊名：Acta Geologica Sinica
- 出版年：2013
- 卷期：87(10)
- 关键词：蛇绿岩 ; ophiolite ; 铀—铅计时 ; U-Pb dating ; 云南 ; Yunnan Province
- 页码：p.1498-1509
- 图表：7 illus., 2 tables, 56 refs.
- 分类号：0801
- issnNo：ISSN0001-5717
- isbnNo：CN11-1951/P
摘要
The southeastern Yunnan area is the convergent plaace of Yantze,Cathaysia,Indo-China blocks.The Babu opholite is considered a remnant of the Youjiang oceanic crust,one branch of Paleo-Tethys.This study conducted an investigation using geological mapping,rock association,geochemistry and geochronology.Results shows that the Babu ophiolite has a relatively complete association:mantle peridotite,cumulate gabbro,diabase wall groups,pillow lava and radiolarian silicalite.But the Babu ophiolite is an allochthonousnappe superimposed onto Triassic turbidite deposit.Mantle peridotites consist mainly of harzburgite,and lavas and dikes are low-K tholeiitic basaltic rocks,with REE and trace elements similar to N-MORB.The typical trace element ratios such as Ti/V=20~50,Nb/Yb-Th/Yb show that they were likely derived from DMM source.The observations suggest a MOR-type ophiolite.SHRIMP UPb age of zircons from amphibolites is 272±8Ma(n=11,MSWD =0.54),indicating a late Early Permian epoch.Considering late Paleozoic basic magmatism and sedimentary evolution of southwest Yangtze block,we proposed that the Babu ophiolite represents the residual oceanic crust of Youjiang basin during strong spreading in early Permian.
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