云南兰坪盆地喜马拉雅期碱性岩^(40)Ar/^(39)Ar年龄及地质意义  

^(40)Ar/^(39)Ar ages of Himalayan alkaline rocks in Lanping basin, Yunnan Province, and their geological implications

作　　者：董方浏[1] 莫宣学[2] 侯增谦[1] 王勇[3] 毕先梅[2] 周肃[2] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037 [2]中国地质大学地球科学与资源学院,北京100083 [3]东华理工学院地球科学系,江西抚州344000

出　　处：《岩石矿物学杂志》2005年第2期103-109,共7页Acta Petrologica et Mineralogica

基　　金：国土资源大调查资助项目 (2 0 0 0 10 2 0 0 2 60 0 3 ) ;国家重点基础研究发展规划"973"资助项目 (2 0 0 2CB 412 60 0 )

摘　　要：对侵位于云南兰坪中新生代红层盆地中的碱性岩进行了Ar_Ar同位素定年 ,获得永平卓潘碱性杂岩体的侵入年龄为 36 .70Ma,巍山莲花山碱性石英二长斑岩的侵入年龄为 38.81Ma。兰坪盆地的构造演化受控于古特提斯的闭合及印度与亚洲大陆碰撞的造山作用 ,盆地经历了陆内裂谷、拗陷盆地和走滑盆地 3个阶段的发育过程。喜马拉雅期盆地处于走滑拉分阶段 ,可分为 4个构造幕 ,碱性岩主要在第 1构造幕期间侵入。盆地中的碱性岩体是青藏高原东缘总体呈NW走向的金沙江红河巨型富碱侵入岩带的组成部分。金沙江红河断裂带经历由转换压扭变形(42～ 2 4Ma)到转换张扭变形 (2 4～ 16Ma)、再到东西向伸展 (<16Ma)的过程 ,兰坪盆地的碱性岩发育于转换压扭变形期间。Alkaline intrusive rocks in Mesozoic-Cenozoic Lanping red bed basin of Yunnan Province were studied with the Ar-Ar isotope dating method. The results show that the Zhuopan alkaline intrusive complex in Yongping and the Lianhuashan alkaline beschtauite in Weishan have Ar-Ar plateau ages of 36.70 Ma and 38.81 Ma, respectively. Tectonic evolution of Lanping basin, controlled by closure of Palaeo-Tethys and collisional orogen between India plate and Asia continent, has undergone three evolutional stages, i.e., intracontinental rift, sag basin and strike-slip basin. The Himalayan basin at the strike-slip stage can be divided into four tectonic phases. The intrusion of alkaline complex is the first tectonic phase. Alkaline intrusive rocks in Lanping basin make up part of alkaline-enriched intrusive belt along the NW-striking Jinshajiang-Honghe fractured zone in the eastern margin of Qinghai-Tibet plateau. During the tectonic evolution of Jinshajiang-Honghe fractured zone from transitional compressional-shear deformation (42～24 Ma) and transitional extensional-shear deformation (24～16 Ma) to EW-striking extensional processes (<16 Ma), alkaline rocks in Lanping basin were developed in the transitional compressional-shear deformation phase. The intrusion of alkaline complex and the tectonic evolution in Himalayan period are controlled predominantly by mantle uplifting and partial melting generated by remnants of westward subducted Palaeo-Tethyan Yangtze block.

关 键 词：碱性岩体 喜马拉雅期 ^40AR/^39AR年龄 地质意义 兰坪盆地 云南 

分 类 号：P597.3[天文地球—地球化学] P588.15[天文地球—地质学]