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吕梁地区18亿年的后造山花岗岩:同位素年代和地球化学制约

耿元生1, 杨崇辉1, 宋彪1 2, 万渝生1 2   

  1. 1. 中国地质科学院地质研究所,北京100037; 2. 北京离子探针中心,北京100037
  • 收稿日期:2004-12-20 修回日期:2004-12-20 出版日期:2004-12-20 发布日期:2004-12-20

Post-Orogenic Granites with an Age of 1800Ma in Luliang Area, North China Craton: Constraints from Isotopic Geochronology and Geochemistry

GENG Yuan-sheng1, YANG Chong-hui1, SONG Biao1 2, WAN Yu-sheng1 2   

  1. 1. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China; 2. Beijing SHRIMP Centre, Beijing 100037, China
  • Received:2004-12-20 Revised:2004-12-20 Online:2004-12-20 Published:2004-12-20

摘要: 对吕梁地区的芦芽山辉石石英二长岩和云中山花岗岩进行了全岩主量和微量元素分析,锆石SHRIMP的U—Pb同位素年龄分析。结果表明,芦芽山辉石石英二长岩和云中山花岗岩在Y+Nb对Rb和Y对Nb图解中均位于板内花岗岩区,在花岗岩的R1—R2图解上,芦芽山含辉石石英二长岩位于后碰撞隆升(post-collision uplift)花岗岩区,云中山花岗岩位于晚造山(late orogenic)花岗岩区,它们都属于后造山花岗岩。芦芽山辉石石英二长岩的锆石SHRIMP U—Pb年龄为1794±13Ma,云中山花岗岩的年龄为1801±11Ma。18亿年后造山花岗岩的确定,为确定古元古代末造山运动结束的时间提供了直接的证据。

Abstract: Major trace element characteristics and zircon U-Pb SHRIMP dating of the Luyashan augite-monzonites and Yunzhongshan granites in Luliang area, Shanxi Province indicate that the Luyashan augitemonzonites and Yunzhongshan granites belong to the post-orogenic granite.Zircon grains from the Luyashan augite-diorite yield a SHRIMP U-Pb age of 1 794±13 Ma and zircon grains from the Yunzhong-shan granite a SHRIMP age of 1 801±llMa. Determination of post-orogenic granites at ca.1 800 Ma provides direct evidence for constraints on the ending time of the orogeny at the end of Paleoproterozoie.