闽西南新冲正长花岗岩LA-ICP-MS锆石U-Pb测年及其找矿意义
LA-ICP-MS Zircon U-Pb Dating of Xinchong Syenogranite in Southwestern Fujian and Its Prospecting Significance

作者: 肖爱芳 , 王治淇 , 黎敦朋 :福州大学紫金矿业学院,福建 福州;

关键词: 新冲正长花岗岩LA-ICP-MS锆石U-Pb测年晚三叠世找矿意义Xinchong Syenogranite LA-ICP-MS Zircon U-Pb Dating Late Triassic Prospecting Significance

摘要: 新冲正长花岗岩位于胡坊复式岩体东南缘,总体呈南西向展布,出露面积大于200 km2,岩性为肉红色斑状粗粒正长花岗岩。本文对新冲正长花岗岩样品进行了LA-ICP-MS锆石U-Pb测年,获得206U/236Pb加权平均年龄为222.0 ± 1.0 Ma (n = 24,MSWD = 0.53),表明新冲正长花岗岩侵位时代为晚三叠世,是印支运动晚期岩浆活动的产物。通过对比,新冲正长花岗岩的侵位时代晚于志留纪侵位的胡坊花岗岩,表明胡坊复式花岗岩为志留纪和三叠纪岩浆活动的产物。对新冲正长花岗岩稀土元素分析,显示新冲正长花岗岩稀土总量较高,富集轻稀土元素La、Ce,具有寻找离子吸附型稀土矿的良好找矿前景,这对闽西南地区岩浆演化和找矿提供了重要新资料。

Abstract: The Xinchong syenogranite is located at the southeastern portion of the Hufang Compound granite, which is mainly composed of meat red patchy, coarse-grained syenogranite, generally presents a southwestward distribution and covers an area of 200 km2. In this paper, the LA-ICP-MS zircon U-Pb dating results for the Xinchong syenogranite, revealed a weighted mean 206U/236Pb age of 222.0 ± 1.0 Ma (n = 24, MSWD = 0.53). The result shows that the emplacement age of Xinchong syenogranite is of late Triassic. By contrast, the emplacement age of Xinchong syenogranite is younger than that of the Hufang granite (Silurian), reflecting that the Hufang Compound granite is the product of magmatic activities of the Silurian and Triassic. The REE elements of the Xinchong syenogranite show that the total amount of REE elements is higher, and the LREE elements of La and Ce are enriched, has a good prospecting prospects of ion-adsorbed REE deposits, this provides important information for magmatic evolution and prospecting in the southwest of Fujian pro- vince.

文章引用: 肖爱芳 , 王治淇 , 黎敦朋 (2017) 闽西南新冲正长花岗岩LA-ICP-MS锆石U-Pb测年及其找矿意义。 地球科学前沿, 7, 349-355. doi: 10.12677/AG.2017.73038

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