攀西红格层状岩体中辉绿岩脉成因及地质意义  

Origin and Geological Significance of Diabase Dikes from Hongge Layered Intrusion in Panxi Region

作　　者：王坤[1,2] 李奇维 秦颖 李祥波 董欢 Wang Kun;Li Qiwei;Qin Ying;Li Xiangbo;Dong Huan(Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process,Ministry of Education,China University of Mining and Technology,Xuzhou 221008,China;School of Resources and Geosciences,China University of Mining and Technology,Xuzhou 221116,China;School of Earth Sciences,China University of Geosciences,Wuhan 430074,China;Sun Yueqi Honors College,China University of Mining and Technology,Xuzhou 221116,China;School of Geosciences,Yangtze University,Wuhan 430100,China)

机构地区：[1]中国矿业大学煤层气资源与成藏过程教育部重点实验室,江苏徐州221008 [2]中国矿业大学资源与地球科学学院,江苏徐州221116 [3]中国地质大学地球科学学院,湖北武汉430074 [4]中国矿业大学孙越崎学院,江苏徐州221116 [5]长江大学地球科学学院,湖北武汉430100

出　　处：《地球科学》2022年第11期4294-4308,共15页Earth Science

基　　金：国家自然科学基金项目(No.41902082);江苏省双创博士项目(No.JSSCBS20211225);中国矿业大学大型仪器设备开放共享基金项目(No.DYGX-2021-095);中国博士后科学基金项目(No.2019M652733)。

摘　　要：为了了解峨眉山地幔柱岩浆系统的演化过程,对红格超大型钒钛磁铁矿矿床中辉绿岩脉进行了全岩主微量、矿物原位成分和同位素研究,并利用MELTS软件进行了岩浆过程模拟计算.研究发现,红格辉绿岩脉具有与峨眉山高钛玄武岩一致的稀土元素配分型式和Sr同位素组成,表明其起源于峨眉山地幔柱.辉绿岩含有斑晶和基质两个世代矿物,从斑晶核部到边部和基质,单斜辉石Mg^(#)值较为连续变化,而斜长石An值具有明显的间断.MELTS模拟表明,这种成分变化难以用简单的岩浆上升侵位解释,反映了辉绿岩脉在岩浆演化过程中可能还与同期的正长质岩浆发生了混合.我们的研究表明,峨眉山地幔柱岩浆作用具有穿地壳、多期次、多阶段演化的特点,并且同源岩浆混合也是一个不可忽视的方面.In order to understand the evolution of the magmatic system of the Emeishan mantle plume, whole-rock major and trace elements, in-situ mineral composition and isotope studies as well as MELTS simulation were carried out on the diabase dikes in the Hongge giant Fe-Ti-V oxide deposit. The study shows that the Hongge diabases have consistent REE patterns and Sr-isotope compositions with the Emeishan high-Ti basalts, indicating that the diabases were derived from the Emeishan mantle plume. The Hongge diabases contain two generations of minerals, i. e., phenocryst and matrix. It is found thatMg^(#)value of clinopyroxene varied continuously from the phenocryst core to rim and matrix, while the An values of plagioclase show an obvious discontinuity. The MELTS simulation results show that the composition variation could not be explained by a simple process of magma ascending, reflecting the basaltic magma may have mixed with the synchronous syenitic magma during the evolution process. Our research suggests that the Emeishan mantle plume magmatism is characterized by trans-crustal, polyphase and multi-stage evolution, and“self-mixing”between co-genetic magmas is also nonnegligible.

关 键 词：辉绿岩 层状岩体 攀西地区 峨眉山大火成岩 岩石学 

分 类 号：P581[天文地球—岩石学]