云南马关尖晶石相二辉橄榄岩包体的平衡温压条件及其指示意义  

EQUILIBRIUM p-TCONDITIONS OFSPINEL-LHERZOLITE XENOLITHS AND THEIR SIGNIFICANCE IN THE MAGUAN AREA, YUNNAN PROVINCE

作　　者：魏启荣[1] 王江海[2] 

机构地区：[1]中国地质大学材化学院,湖北武汉430074 [2]中国科学院广州地球化学研究所,广东广州510640

出　　处：《矿物学报》2004年第3期278-284,共7页Acta Mineralogica Sinica

基　　金：国家重点基础研究发展规划项目(G1998040807);国家自然科学基金项目(49972026);中科院知识创新项目(KZCX2 SW 117);中国博士后科学基金资助项目

摘　　要：依据云南马关地区8个尖晶石二辉橄榄岩包体中22个单斜辉石 斜方辉石矿物对的电子探针成分,采用TBM85、TBK90二辉石温度计和TBK90Ca、TWS91en、TX93Ca单辉石温度计估算了其平衡温度,用PM80en、PM80di压力计估算了其平衡压力。温压估算表明,马关尖晶石相二辉橄榄岩包体的平衡温压分别为900～1150℃和1.29～2.20GPa(相当于地下深度45～71km)。由TM80en与PM80en、TM80di与PM80di的估算结果所分别构筑的马关地区上地幔地温曲线与大洋地温曲线非常吻合,显示马关地区上地幔具有很高的热流值,暗示青藏东缘及邻区于0～16Ma期间有热的软流圈地幔上涌,地幔上涌在构造上的响应即是青藏东缘乃至整个东亚地区区域性岩石圈的东 西向伸展。Based on electron microprobe analyses of 22mineral pairs from 8 spinel-lherzolite xenolithsin the Maguan area, Yunnan Province, equilibrium temperatures of the xenoliths were calculated by two-pyroxene geothermometers (T_(BM85)and T_(BK90)) and single-pyroxene geothermometers(T_(BK90Ca), T_(WS91en), and T_(X93Ca)), and equilibrium pressures by P_(M80en)and P_(M80di)geobarometers. The results showed that equilibrium temperatures and pressures ofthexenoliths werefrom 900 to 1105℃ and 1.29 to 2.20 GPa (equivalent to 45～71 km depth), respectively. A geothermal curve of the upper mantle in the Maguan areawasestablished according to the estimated p-Tconditions by T_(M80en)and P_(M80en), and T_(M80di) and P_(M80di), respectively, which is similar to the ocean-type upper-mantle geothermal curve. It is revealed the lithospheric mantle in the Maguan area has a high value of thermal flow, indicating hot asthenosphere upwelling in the period of 0～16 Ma in eastern Asia, which resulted inE-W lithospheric extension in eastern Tibetand the whole East Asia.

关 键 词：尖晶石相二辉橄榄岩包体 平衡温压条件 单斜辉石 电子探针 

分 类 号：P581[天文地球—岩石学] P588.12[天文地球—地质学]