摘要
陆内环境斑岩型矿床的成矿金属与硫等物质主要来源于富原生硫化物且呈相对还原状态的角闪岩相下地壳的部分熔融,岩浆的高氧逸度和富水是成矿的关键,但还原性下地壳的熔融产物如何变成高氧逸度岩浆尚不十分明确。为此,本文对哀牢山-红河富碱斑岩带内与陆内成矿斑岩同时代的莴莊粗面玄武岩与谷装箐云煌岩开展了成岩物理化学条件研究。结果显示,这类钾质-超钾质岩的岩浆具有较高的ΔFMQ值(+0.8^+4.3),这一特征很可能继承于经历古大洋俯冲改造的岩石圈地幔。幔源高氧逸度岩浆具备调节与改造下地壳熔融产物氧逸度的潜力。因此,源于古俯冲改造的岩石圈地幔且具有较高ΔFMQ(+2.7^+4.3)的钾质-超钾质岩浆,可能是导致陆内斑岩成矿系统中斑岩岩浆具较高氧逸度的原因,这类钾质-超钾质岩浆与富硫化物的新生的下地壳来源的熔体的混合,可能是导致陆内斑岩成矿的关键。
At present,ore-forming metals and sulfur for the intracontinental porphyry deposits are thought to be mainly sourced from the magma derived from partial melting of the amphibolite facies lower crust which is rich in primary sulfides under relatively reduced condition.However,it remains unclear how the melting products of such a reduced lower crust could become the magma with relatively high oxygen fugacity(fO2).Therefore,petrogenetic physicochemical conditions of the Wozhuang trachybasalt and Guzhuangqing minette which are spatially coexisted with the coeval ore-bearing porphyries in the Ailaoshan-Red River intracontinental alkali-rich porphyry belt have been studied in this paper.The results show that magmas of these potassic-ultrapotassic rocks have relatively high oxygen fugacitiesΔFMQ(+0.8^+4.3),which could be inherited from characteristics of the lithospheric mantle modified by the subduction of the ancient oceanic plate.The mantle-derived high-fO2 potassic-ultrapotassic magmas have potential to adjust and modify oxygen fugacity conditions of the lower crust melting products.Therefore,the highΔFMQ(+2.7^+4.3)potassic-ultrapotassic magmas,derived from the lithospheric mantle modified by ancient subduction,could result in the relatively high fO2-of the porphyry magma in the intracontinental porphyry mineralization system.The mixing between these high-fO2 potassic-ultrapotassic magmas and the melts derived from partial melting of the sulfide-rich juvenile lower crust could be the key factor resulting in the intracontinental porphyry mineralization.
作者
马瑞
黄明亮
胥磊落
毕献武
刘龚
MA Rui;HUANG Ming-liang;XU Lei-luo;BI Xian-wu;LIU Gong(State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《矿物岩石地球化学通报》
CAS
CSCD
北大核心
2020年第4期794-809,共16页
Bulletin of Mineralogy, Petrology and Geochemistry
基金
国家自然科学基金重大研究计划项目(91955209)
国家自然科学基金项目(41873052)
中国科学院B类先导专项(XDB18000000)
西部之光“一带一路”团队项目。
关键词
扬子克拉通
钾质-超钾质岩石
岩浆氧逸度
陆内斑岩矿床
Yangtze craton
potassic-ultrapotassic rocks
magmatic oxygen fugacity
intracontinental porphyry deposits
