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鲁西蒙山新太古代末闪长岩体的区域构造意义?-SHRIMP锆石U-Pb年代学证据

侯贵廷,王传成,王延欣,肖芳锋,李 乐   

  1. 北京大学 地球与空间科学学院;教育部重点实验室造山带与地壳演化实验室,北京 100871
  • 收稿日期:2008-03-20 修回日期:2008-03-20 出版日期:2008-03-20 发布日期:2008-03-20

SHRIMP Zircon U-Pb Chronology and Tectonic Significance of the Latest Neoarchean Mengshan Diorite, Western Shandong Province

HOU Gui-ting   

  1. The Key Laboratory of Orogenic Belts and Crustal Evolution,Earth and Space Sciences School, Peking University, Beijing 100871, China
  • Received:2008-03-20 Revised:2008-03-20 Online:2008-03-20 Published:2008-03-20

摘要: 华北克拉通东部陆块的鲁西地区,太古宙结晶基底主要分两个单元:西部的TTG(tonalitic英云闪长质-trondhjemitic奥长花岗质-granodioritic花岗闪长质)岩石单元和东部的片麻状二长花岗岩单元。鲁西的两个岩石单元沿北北西向古构造带拼贴,沿古构造带侵位一些深成闪长岩体。在该古构造带的南部发育的深成闪长岩体的SHRIMP锆石 U-Pb定年结果给出了上交点年龄2534±77Ma,近谐和点年龄为2536±26Ma,代表在晚太古代末(~2.5Ga)沿古构造带拼贴过程中的深成岩浆活动,是鲁西地区前寒武纪完成克拉通化的陆壳固结作用。从地质年代学和区域地质上,本文确定了沿北西走向的泰山-蒙山古构造带分布的南部蒙山闪长岩体与北部的泰山闪长岩体处于同一条深成岩浆活动带,这表明鲁西地区新太古代末TTG岩区与二长花岗岩区两个单元沿古构造带拼贴是华北克拉通东部陆块在新太古代末发生的重要大地构造事件。

Abstract: The TTG(tonalite-trondhjemite-granodiorite)in the western area and gneissoid adamellite unit in the eastern area of the Western Shandong Province were identified in the eastern block of the North China Craton. These two areas were amalgamated together at the latest Neoarchean along the NNW-trending paleo-structural belt with intrusion of some plutonic diorite bodies.The U-Pb SHRIMP results of zircons from the Mengshan diorite pluton in the southern segment of the paleo-structural belt give the upper interception age of 2 534±77 Ma based on the fine discordant line and give the close concordia age of 2 536±26 Ma that represents the age of diorite pluton emplacement. The diorites along the NNW-trending paleo-structural belt represent the plutonic magmatic activity and the cratonization during the juxtaposion of two Archean microblocks in the Western Shandong.