广东西淋岗花岗岩原地重熔成因的地质地球化学证据  

Geological and geochemical evidences for in-situ melting origin of the Xilingang granite in Guangdong Province

作　　者：唐煜坤[1,2] 杨志军[1,2] 彭卓伦[1] 许冠军[1] 李宏卫[1] 娄峰[1] 

机构地区：[1]中山大学地球科学系,广东广州510275 [2]广东省地质过程与矿产资源探查重点实验室,广东广州510275

出　　处：《地学前缘》2011年第1期49-55,共7页Earth Science Frontiers

基　　金：广东省自然科学基金重点项目(10251027501000019)

摘　　要：广东西淋岗岩体出露的地质剖面为研究花岗岩成因提供了大量信息。对该岩体的野外地质调查发现:下白垩统白鹤洞组红层(K1bh)与下伏花岗岩体呈突变接触关系,接触界面之下的花岗岩中含大量红岩碎屑,且红岩碎屑往下逐渐减少。岩石地球化学及矿物学测试结果表明:西淋岗花岗岩的成岩物质,应来自盖层之下包括下白垩统白鹤洞组下部红层在内的岩石地层。岩石熔融和岩浆结晶过程中,分异作用导致元素分布具有明显分带性;花岗岩中的石英是在比较稳定的条件下结晶而成,且在石英结晶过程中,SiO2过饱和度逐渐降低。上述研究结果表明,西淋岗花岗岩应是上地壳岩石原地熔融固结形成,而不是远道而来的"侵入体"。Lots of information concerning granite genesis can be obtained from the geological sections of Xilingang granite body in Guangdong Province.The sections indicate that the Baihedong Formation（K1bh） formed in the Early Cretaceous acted as a residual cap over the Xilingang granite body with abrupt contact in between.The granite underlying the contact contains numerous red bed clastics that reduce gradually with increasing depth in the rock body.The results of geochemical and mineralogical analysis suggested that materials of granite were from the in-situ rock-strata including part of the red bed of Baihedong Formation.Differentiation during the melting-crystallizing process led different elements to be enriched in different depths of the rock body.Growth of quartz crystals of granite is found in a stable environment and during crystallization of quartz,SiO2 supersaturation of magma gradually decreases.All the above data indicate that the Xilingang granite was formed by in-situ melting of the crustal rocks,not the intrusion from a depth source.

关 键 词：西淋岗 下白垩统 红层 花岗岩成因 原地熔融 

分 类 号：P596[天文地球—地球化学]