胶西北郭家岭花岗闪长岩侵位深度:来自角闪石温压计和流体包裹体的证据  

Emplacement depth of the Guojialing granodiorites from the northwestern Jiaodong Peninsula,eastern China:Evidences from hornblende thermobarometry and fluid inclusions

作　　者：陆丽娜[1] 范宏瑞[1] 胡芳芳[1] 杨奎锋[1] 蓝廷广[1] 

机构地区：[1]中国科学院地质与地球物理研究所矿产资源研究重点实验室,北京100029

出　　处：《岩石学报》2011年第5期1521-1532,共12页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(40625010);全国危机矿山接替资源找矿项目(20089930)联合资助

摘　　要：本文应用角闪石地质温压计和流体包裹体对胶东西北部与成矿关系密切的郭家岭花岗闪长岩结晶的温压条件、侵位深度进行了讨论。郭家岭花岗闪长岩的矿物组合为斜长石、角闪石、黑云母、石英、碱性长石、铁-钛氧化物、榍石和次生绿泥石,符合角闪石温压计的使用前提。应用角闪石-斜长石温度计和角闪石全铝压力计所获得的温压条件分别为,郭家岭岩体为694～733℃,1.3～2.4kbar,丛家岩体为702～719℃,2.4～3.9kbar,北截岩体为723～727℃,3.8～4.2kbar。未变形岩石的石英中含有5种类型包裹体,其中CO2-H2O-NaCl包裹体广泛分布,最具有代表性。由CO2-H2O-NaCl包裹体等容线相图计算的温压范围与岩石所获得的温压范围一致,表明角闪石温压计获得的结果是比较可信的。岩体的侵位深度变化较大,其中郭家岭岩体平均为6km,丛家岩体平均为10km,北截岩体平均为13km,显示从东到西侵位越来越深结晶温度越来越高的趋势。不同侵位深度的岩体同时出露到地表暗示了早白垩世以来胶东地区的剥蚀抬升速率可能是不均匀的,西部相对东部抬升更快剥蚀更多。Pressure and temperature（P-T）conditions of the crystallization of the Mesozoic（-130Ma）Guojialing granodiorites from the Jiaodong Peninsula（eastern China）have been investigated based on hornblende geothermobarometry and fluid inclusions.The calculated P-T conditions are,694-733℃ and 1.3-2.4kbar,702-719℃ and 2.4-3.9kbar,and 723-727℃ and 3.8-4.2kbar for the Guojialing,Congjia and Beijie plutons,respectively.There are 5 types of primary fluid inclusions,most of which belong to the CO2-H2O-NaCl type,in the quartz of the granodiorites.The P-T conditions measured for homogenization temperature and salinity of the primary CO2-H2O-NaCl inclusions are in agreement with that obtained from the hornblende geothermobarometry.It is concluded that the emplacement depths are 6km,10km and 13km for the Guojialing,Congjia and Beijie plutons,respectively,from east to west.This indicates that the denudation thickness for the western pluton is much bigger than that for the eastern one,and therefore the exhumation rates were probably not uniform within the Jiaodong Peninsula since the Early Cretaceous.

关 键 词：角闪石 地质温压计 流体包裹体 侵位深度 郭家岭 

分 类 号：P588.122[天文地球—岩石学]