东马努斯盆地热液蚀变火山岩元素迁移特征及影响因素  

CHARACTERISTICS AND INFLUENCE FACTORS OF ELEMENT MIGRATION OF HYDROTHERMAL ALTERED ROCK IN EASTERN MANUS BASIN

作　　者：赵霞[1,2] 黄朋[1] 胡宁静[3] 孔娟娟[1,2] 廖仁强[1,2] 王雄[1,2] 

机构地区：[1]中国科学院海洋研究所海洋地质与环境重点实验室,青岛266071 [2]中国科学院大学,北京100049 [3]国家海洋局第一海洋研究所海洋沉积与环境地质重点实验室,青岛266061

出　　处：《海洋地质与第四纪地质》2017年第3期86-101,共16页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金项目(41576049;41666002);中国科学院前沿科学研究重点计划项目(QYZDB-SSW-SYS025)

摘　　要：本文选择东马努斯盆地的5个新鲜火山岩和1个蚀变火山岩作为研究对象,对样品进行全岩主微量及斜长石电子探针分析,并对蚀变岩石与新鲜火山岩之间的化学成分进行对比,深入探究了蚀变火山岩的元素迁移特征及影响因素。结果显示,蚀变火山岩的硫化物以黄铜矿、方铅矿和闪锌矿为主,为富Cu型热液硫化物。岩石蚀变区的SiO2含量极高,为硅化蚀变。蚀变岩石的化学成分约为同区玄武质安山岩和英安岩成分总含量的平均值,原岩可能为安山岩。在热液蚀变的过程中,蚀变岩石的质量增加了150%,其中元素Cu、Zn、Ga、Sr、Cd、Ba和Pb超强烈富集,Ti、V、Mn、Co、Ni、Mo和U强烈富集,Si和Fe中等富集;Sc、Cr、Nb、Ta、W和Bi轻微富集;Be和Ca超强烈亏损;Li、Na、Mg、K、Rb、REE和Y强烈亏损;Zr、Cs和Th轻微亏损;Al、P和Hf稳定不变。推测影响蚀变岩石元素迁移的因素有3种:成矿作用、交代作用(绿泥石化、硅化)和元素在流体中的活动性。Five fresh and one altered volcanic rock samples from Eastern Manus Basin were chosen as research materials in this study. The major and trace elements of the bulk samples and the in-situ plagioclase of these rocks are analyzed. Comparative studies of altered rock and fresh rocks are carried out to explore the characteristics and influence factors of element migration during the hydrothermal alteration. As results, the hydrothermal sulfide of altered rock is a sort of copper-rich sulfide which mainly composed of chalcopyrite, sphalerite and ilmenite. Silicified alteration is the main type of alteration as the SiO2 content is extremely high in the altered area. The contents of major and trace elements of the altered rock change around the average of the content of basaltic andesite and dacite. Andesite is believed the protolith of the altered rock. During the process of hydrothermal alteration, the mass of the altered rock is increased by 150%. The altered rock is most enriched by the elements of Cu, Zn , Ga, Sr, Cd, Ba and Pb, enriched by Ti, V, Mn, Co, Ni, Mo and U, less enriched by Si and Fe, and least enriched by Sc, Cr, Nb, Ta, W and Bi. The altered rock is most depleted by Be and Ca, more depleted by Li, Na, Mg, K, Rb, REE and Y, and least depleted by Zr, Cs and Th. Al, P and Hf are immobile elements. The influence factors of element migration of the hydrothermal altered rock may include mineralization, metasomatism （such as chlo- ritization and silicification） and the activity of elements in fluids.

关 键 词：东马努斯盆地 蚀变火山岩 热液硫化物 迁移特征 影响因素 

分 类 号：P736.4[天文地球—海洋地质]