辽东地区古元古代花岗岩SHRIMP UPb年龄、Hf同位素组成及构造意义
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沈阳地质调查中心,沈阳地质调查中心,沈阳地质调查中心,沈阳地质调查中心,沈阳地质调查中心

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SHRIMP UPb Ages and Hf Isotopic Compositions of Paleoproterozoic Granites from the Eastern Part of Liaoning Province and Their Tectonic Significance
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Shenyang Institute of Geology and Mineral Resources, China Geological Survey,Shenyang Institute of Geology and Mineral Resources, China Geological Survey,Shenyang Institute of Geology and Mineral Resources, China Geological Survey,Shenyang Institute of Geology and Mineral Resources, China Geological Survey,Shenyang Institute of Geology and Mineral Resources, China Geological Survey

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    摘要:

    位于华北克拉通东部的辽东地区广泛出露古元古代花岗岩,为更准确地认识辽东地区古元古代构造演化过程,本文选取大顶子二长花岗岩、五磊山似斑状花岗岩、四门子二长花岗岩和顾家堡正长花岗岩进行了系统研究。锆石SHRIMP U-Pb年代学研究表明,大顶子岩体年龄为1869±16Ma,五磊山岩体年龄为1830.5±5.9Ma,四门子岩体年龄为2157±14Ma,顾家堡岩体年龄为2169±11Ma。大顶子岩体富硅,低钾,高镁,表现为钙碱性特征的S型花岗岩;五磊山和四门子岩体富硅,低钾,高镁,表现为钙碱性特征的I型花岗岩;顾家堡岩体富硅,高钾,高镁,表现为高钾钙碱性特征的I型花岗岩。大顶子、五磊山、四门子岩体富集K、Rb、Sr、Ba等大离子亲石元素,亏损Nb、Ta、Zr、P、Ti等高场强元素;顾家堡岩体亏损Sr、Ba等大离子亲石元素,亏损Nb、Ta、P、Ti等高场强元素。四个岩体锆石εHf(t)值为-36~79,对应的单阶段Hf模式年龄tDM为2115~2548Ma,集中于古元古代,两阶段Hf模式年龄tDMC为2323~3084Ma,集中于中太古代。综上,大顶子、五磊山、四门子和顾家堡岩体可能与岩石圈拆沉、地幔热上涌使新生地壳熔融有关。四门子和顾家堡岩体可能处于活动大陆边缘构造背景,大顶子和五磊山岩体可能是地块拼合或者裂谷闭合后区域由挤压转为伸展构造背景。本次获得的辽东古元古代岩浆构造活动与华北板块东西陆块的拼合时代基本吻合,也是我国华北东部对全球“Columbia”超大陆拼合作用的响应。

    Abstract:

    Paleoproterozoic granites are widespread in the eastern part of Liaoning province (ELP),which is located in the eastern North China Craton. In order to clarify the Paleoproterozoic tectonic evolution of the ELP, this paper presents a systemic study on the Dadingzi monzogranites, Wuleishan porphyritic granites, Simenzi monzogranites and Gujiapu syenogranites. The Dadingzi monzogranites, Wuleishan porphyritic granites, Simenzi monzogranites and Gujiapu syenogranite have SHRIMP zircon UPb ages of 1869±16 Ma、1830.5±5.9 Ma、2157±14 Ma and 2169±11 Ma, respectively. The above four granites are characterized by high SiO2, high MgO and low K2O, and Dadingzi is geochemically calcalkaline Stype granites, whereas Wuleishan and Simenzi granites belongs to calcalkaline Itype granite series,and Gujiapu granite is high SiO2, high MgO and high K2O, and is geochemically highK, calcalkaline Itype granites. Dadingzi、Wuleishan and Simenzi granites are enriched in large ion lithophile elements (LILE), such as K, Rb, Sr and Ba, but depleted in high field strength elements (HFSE), such as Nb, Ta, Zr, P and Ti. Gujiapu granites show depletions both in LILE (such as Sr and Ba) and HFSE (such as Nb, Ta, Zr, P and Ti). The above four granites have zircon εHf(t) values ranging from -3.6 to 7.9, with Paleoproterozoic Hf model ages (tDM) of 2115 to 2548 Ma and Mesoproterozoic twostage Hf crustal model ages (tDMC) of 2323 to 3084 Ma. We conclude that Dadingzi、Wuleishan、Simenzi and Gujiapu granites are formed by partial melting of neonatal crust induced by asthenospheric mantle upwelling, which is related to lithosphere delamination. The Simenzi and Gujiapu granites indicate an active continental margin setting. The Dadingzi and Wuleishan granites maybe an extensional environment transformed from a compressional environment after continentcontinent collision or closure of rift. The ELP orogeny coeval with collision between the Eastern and Western blocks of the North China Craton is corresponding to the amalgamation of the Columbia supercontinent.

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宋运红,杨凤超,闫国磊,魏明辉,石绍山.2016.辽东地区古元古代花岗岩SHRIMP UPb年龄、Hf同位素组成及构造意义[J].地质学报,90(10):2620-2636.
SONG Yunhong, YANG Fengchao, YAN Guolei, WEI Minghui, SHI Shaoshan.2016. SHRIMP UPb Ages and Hf Isotopic Compositions of Paleoproterozoic Granites from the Eastern Part of Liaoning Province and Their Tectonic Significance[J]. Acta Geologica Sinica,90(10):2620-2636.

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  • 收稿日期:2016-03-11
  • 最后修改日期:2016-04-29
  • 录用日期:2016-05-03
  • 在线发布日期: 2016-10-25
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