安哥拉地盾Quibala斑状花岗岩的年代学、地球化学特征:对Columbia超大陆演化的制约
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Geochronology and geochemistry of Quibala porphyritic granites in the Angolan shield: Implications for the evolution of the Columbia supercontinent
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    摘要:

    2. 1~1. 8 Ga发生了全球范围的Columbia超大陆汇聚事件,导致Congo克拉通与So Francisco克拉通沿Eburnean造山带发生汇聚。作为Congo克拉通的重要组成部分,安哥拉地盾记录了这一时期的构造- 岩浆事件。本文对安哥拉地盾Quibala地区的斑状花岗岩进行了岩石学、锆石U- Pb年代学和地球化学研究。Quibala斑状花岗岩LA- ICP- MS锆石U- Pb年龄为1987±20 Ma、1967±6 Ma和1956±12 Ma,限定斑状花岗岩其形成于1987~1956 Ma期间,为古元古代Eburnean期岩浆作用产物。岩石地球化学特征表明,Quibala斑状花岗岩具有典型的A型花岗岩地球化学特征,形成于后碰撞伸展环境,可能是受到壳幔相互作用影响的下地壳物质发生部分熔融而形成。综合年代学与地球化学研究结果,本文认为Congo克拉通与So Francisco克拉通的汇聚发生在Columbia超大陆开始形成阶段(2. 1 Ga左右),在1987~1956 Ma已转为碰撞后伸展环境。

    Abstract:

    Global Columbia supercontinent assemblage occurred between 2. 1 Ga and 1. 8 Ga. The collision between the Congo and So Francisco cratons formed the Eburnean orogenic belt. As an important part of the Congo craton, the Angolan shield has recorded tectono- magmatic events during this period. This study investigates the petrology, zircon U- Pb chronology, and geochemistry of porphyritic granites in the Quibala area of the Angolan shield. LA- ICP- MS zircon U- Pb dating yielded ages of 1987±20 Ma, 1967±6 Ma, and 1956±12 Ma, indicating that the porphyritic granite crystallized between 1987 Ma and 1956 Ma, coinciding with Paleoproterozoic Eburnean magmatism. Geochemical data classifies the Quibala porphyritic granite as A- type granite, suggesting formation in a post- collision extension setting.This granite may be formed by partial melting of lower crustal material influenced by crust- mantle interaction. Combining chronological and geochemical data, we propose that the Congo and So Francisco cratons, integral parts of the Columbia supercontinent, transitioned from a collisional to a post- collision extensional stage between 1987 Ma and 1956 Ma.

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靳立杰,张洪瑞,罗迪柯,贾鹏飞,刘伟,王子圣,李金镇,周永刚,江振国.2025.安哥拉地盾Quibala斑状花岗岩的年代学、地球化学特征:对Columbia超大陆演化的制约[J].地质学报,99(4):1209-1222.
JIN Lijie, ZHANG Hongrui, LUO Dike, JIA Pengfei, LIU Wei, WANG Zisheng, LI Jinzhen, ZHOU Yonggang, JIANG Zhenguo.2025. Geochronology and geochemistry of Quibala porphyritic granites in the Angolan shield: Implications for the evolution of the Columbia supercontinent[J]. Acta Geologica Sinica,99(4):1209-1222.

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  • 在线发布日期: 2025-04-27