北昆仑德拉脱郭勒辉长岩地球化学特征及锆石U-Pb年龄
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摘要
通过1:5万区域地质矿产调查,在青海格尔木市北昆仑雪山峰地区构造岩浆岩亚带中发现一套晚二叠世侵入岩,主要岩性为一套钙碱性辉长岩。对其进行锆石U-Pb年龄和地球化学研究,测得锆石的206Pb/238U年龄为263.3±2.0Ma,地质时代属晚二叠世。全岩地球化学数据显示辉长岩为钙碱性岩系列岩石,岩石富Al2O3、CaO。Na2O、K2O、Fe2O3、MnO、P2O5、MgO含量均较低。在稀土元素球粒陨石标准化分配型式图中,曲线右倾,异常不明显,轻稀土曲线陡倾,重稀土相对平缓,轻稀土分馏较强,曲线平滑。微量元素N-MORB标准化蛛网图,强不相容元素Ba、Rb、Th富集,中等不相容元素Ta、Nb、Ce、Sm富集一般。曲线上Nb、Ti异常不明显,其分布型式与火山弧型玄武岩相似。通过该发现及研究以期望能为研究北昆仑造山带构造演化提供新的证据。
A set of late Permian intrusive rocks was found in the subzone of tectonic magma in northern Kunlun Xueshan area of Geermu city Qinghai province by 1: 50 000 regional geological and mineral survey. The main lithology is a set of calc-alkaline gabbro. Zircon U-Pb age and geochemistry were studied. The206 Pb/238 U age of zircon measured by LA-ICP-MS is 263.3 ±2.0 Ma.The geological age belongs to the late Permian. The geochemical data of the whole rock show that the gabbro is a calc-alkaline rock series, which is rich in Al2 O3,CaO.Na2 O,K2 O,Fe2 O3,MnO,P2 O5,MgO. In the normalized distribution pattern diagram of rare earth elements chondrite, the curve is inclined to the right, the anomaly is not obvious, the curve of light rare earth is steep, the heavy rare earth is relatively flat, the fractionation of light rare earth is stronger, and the curve is smooth. Trace element N-MORB standardized cobweb map, strong incompatible element Ba, Rb, Th enrichment, moderate incompatible element Ta, Nb, Ce, Sm enrichment is common. The abnormal Nb, Ti on the curve was not obvious. Its distribution pattern is similar to volcanic arc basalt. Through this discovery and study, the expected energy can provide new evidence for studying the tectonic evolution of the North Kunlun orogenic belt.
A set of late Permian intrusive rocks was found in the subzone of tectonic magma in northern Kunlun Xueshan area of Geermu city Qinghai province by 1: 50 000 regional geological and mineral survey. The main lithology is a set of calc-alkaline gabbro. Zircon U-Pb age and geochemistry were studied. The206 Pb/238 U age of zircon measured by LA-ICP-MS is 263.3 ±2.0 Ma.The geological age belongs to the late Permian. The geochemical data of the whole rock show that the gabbro is a calc-alkaline rock series, which is rich in Al2 O3,CaO.Na2 O,K2 O,Fe2 O3,MnO,P2 O5,MgO. In the normalized distribution pattern diagram of rare earth elements chondrite, the curve is inclined to the right, the anomaly is not obvious, the curve of light rare earth is steep, the heavy rare earth is relatively flat, the fractionation of light rare earth is stronger, and the curve is smooth. Trace element N-MORB standardized cobweb map, strong incompatible element Ba, Rb, Th enrichment, moderate incompatible element Ta, Nb, Ce, Sm enrichment is common. The abnormal Nb, Ti on the curve was not obvious. Its distribution pattern is similar to volcanic arc basalt. Through this discovery and study, the expected energy can provide new evidence for studying the tectonic evolution of the North Kunlun orogenic belt.
引文
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