青藏高原东缘保山地块沧源新生代中酸性侵入岩年代学、岩石成因与地块挤出

发布时间：2018-05-01 16:39

本文选题：保山地块 + 新生代　；参考：《矿物岩石地球化学通报》2017年02期

【摘要】：为探讨保山地块新生代岩浆侵位时代,揭示其成因和形成动力学机制,重建保山地块新生代演化历史,对保山地块东南缘沧源新生代岩浆岩中部分中酸性岩体和岩墙开展了岩石学、锆石U-Pb年代学和地球化学研究。结果表明,沧源地区新生代中酸性岩体和岩墙均侵位于40~41Ma,与澜沧新生代花岗质侵入岩年龄相当,为保山地块新生代早期岩浆活动的重要组成。沧源和澜沧新生代岩浆岩总体具有较强的轻-重稀土、特别是中-重稀土分馏,无明显Sr、Eu负异常,具高的Sr/Y、La/Yb、Gd/Yb值,与C型埃达克岩类似。样品的86Sri/87Sri为0.7065~0.7103,εNd(t)为-3.6~-5.6。沧源新生代岩浆岩很可能来自石榴斜长角闪岩源区在30~40km深度的部分熔融。通过岩相学和地球化学分析,首次在沧源新生代岩浆岩中识别出~41Ma的A型花岗岩。结合区域构造-岩浆研究成果,认为沧源-澜沧新生代岩浆带与青藏高原碰撞导致的东部岩石圈块体南东向挤出作用存在密切联系。
[Abstract]:In order to probe into the Cenozoic magmatic emplacement age of Baoshan block, reveal its origin and dynamic mechanism, and reconstruct the Cenozoic evolution history of Baoshan block, The petrology, zircon U-Pb chronology and geochemistry of some intermediate-acid rock bodies and rock walls in the Cangyuan Cenozoic magmatic rocks in the southeastern margin of the Baoshan block have been studied in this paper. The results show that both the Cenozoic intermediate-acid rock mass and the rock wall in Cangyuan area are located at 4041Ma, which is the same age as the granitic intrusive rocks of Lancang Cenozoic, and is an important component of the early Cenozoic magmatic activities in the Baoshan block. Cangyuan and Lancang Cenozoic magmatic rocks generally have strong light-heavy rare earths, especially medium-heavy rare earths fractionation, no obvious negative Sr-EU anomalies, and high Sr-Y / Y / La / Yb / Yb value, which is similar to C type adakite. The 86Sri/87Sri of the sample is 0.7065 (0.7065) and the 蔚 -Ndct) is -3.6 ~ (-5.6). The Cenozoic magmatic rocks in Cangyuan probably originated from the partial melting of the amphibolite source in the 30~40km depth. Based on petrographic and geochemical analysis, A-type granites of 41 Ma were first identified from Cenozoic magmatic rocks in Cangyuan. Based on the regional tectonic-magmatic research results, it is considered that the Cangyuan-Lancang Cenozoic magmatic belt is closely related to the south-east extrusion of the eastern lithospheric blocks caused by the collision of the Qinghai-Tibet Plateau.
【作者单位】：中国地质调查中心成都地质矿产研究所;四川省地质调查院;中国科学院紫金山天文台;
【基金】：江苏省自然科学基金(BK20151609,BK20161098) 国家自然科学基金项目(41202048,41302157,41302170) 中国地质调查局项目(1212011085119,1212011220412)
【分类号】：P597.3;P588.12

【参考文献】