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    王丹阳, 李猛兴, 王权, 王丽娟. 华北克拉通减薄的岩浆浅表响应——来自大青山岩体的证据[J]. 华东地质, 2024, 45(2): 173-186. DOI: 10.16788/j.hddz.32-1865/P.2024.02.003
    引用本文: 王丹阳, 李猛兴, 王权, 王丽娟. 华北克拉通减薄的岩浆浅表响应——来自大青山岩体的证据[J]. 华东地质, 2024, 45(2): 173-186. DOI: 10.16788/j.hddz.32-1865/P.2024.02.003
    WANG Danyang, LI Mengxing, WANG Quan, WANG Lijuan. Magmatic response to lithospheric thinning of the North China Craton—evidence from the Daqingshan granite[J]. East China Geology, 2024, 45(2): 173-186. DOI: 10.16788/j.hddz.32-1865/P.2024.02.003
    Citation: WANG Danyang, LI Mengxing, WANG Quan, WANG Lijuan. Magmatic response to lithospheric thinning of the North China Craton—evidence from the Daqingshan granite[J]. East China Geology, 2024, 45(2): 173-186. DOI: 10.16788/j.hddz.32-1865/P.2024.02.003

    华北克拉通减薄的岩浆浅表响应——来自大青山岩体的证据

    Magmatic response to lithospheric thinning of the North China Craton—evidence from the Daqingshan granite

    • 摘要: 华北克拉通燕山期岩浆作用是研究克拉通破坏机理的理想载体。文章选择大青山岩体进行了LA-ICP-MS锆石U-Pb定年及岩石地球化学研究,探讨了岩石成因及其对华北克拉通中部北缘中生代构造-岩浆演化的启示。研究表明,该岩体为似斑状二长花岗岩,锆石U-Pb年龄为(139±1)Ma,为早白垩世早期岩浆活动的产物。岩石地球化学特征显示:岩体明显高硅、富碱且相对富钾,过铝质,贫镁钛磷铁钙;NK/A、全岩锆石饱和温度、P2O5含量、Zr值、FeOT值等指标说明,岩体为过铝质、高钾钙碱性系列高分异I型花岗岩,且富集大离子亲石元素Rb、Th、K,亏损高场强元素Ba、Sr、P、Ti;稀土元素总量偏低,轻稀土元素相对重稀土元素分馏较强,负铕异常明显(δEu=0.08~0.56),具有稀土元素四分组特征;岩体具有明显地壳浅源特征,侵位时代与华北克拉通岩浆作用峰期一致,是克拉通减薄的岩浆浅表响应,与古太平洋板片后撤密切相关。

       

      Abstract: The magmatic activities of the Yanshan period in North China Craton are an ideal carrier for studying the mechanism of craton destruction. In this paper, the Daqingshan granite was selected for LA-ICP-MS zircon U-Pb dating and geochemical analysis to investigate the rock genesis and its implications for the Mesozoic tectonic-magmatic evolution in the northern margin of the central North China Craton. The results show that the granite consists mainly of phenocryst adamellite, with a zircon U-Pb age of (139±1) Ma (MSWD=0.28, N=12), indicating an early Cretaceous magmatic event. The geochemistry of the genesis indicates that it is highly silicic, alkali-rich, relatively potassium-rich, peraluminous, and magnesium-titanium-phosphorus-calcium poor. The genesis was classified as a highly differentiated type I granite of peraluminous for the results of NK/A, saturation temperature of zircon and the value of P2O5, Zr and FeOT. The granite is enriched in large ion lithophile elements (Rb, Th, K) and depleted in high field-strength elements (Ba, Sr, P, Ti). The total rare earth element contents are low (ΣREE ranges from 84.5×10-6 to 216.0×10-6), with a strong fractionation between light and heavy rare earth elements and significant negative Eu anomalies (δEu=0.08~0.56), showing a four-group pattern. The genesis exhibits obvious characteristics of crustal source and intrusion age coincides with the peak period of magmatic activity in the North China Craton, representing a shallow magma response to craton thinning, closely related to the retreat of the ancient Pacific plate.

       

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