摘要
陆内碰撞和流体作用都是当前地球科学的前沿领域，但陆内碰撞体制流体作用以及有关成矿作用的研究仍很薄弱。文章以陆内碰撞成岩成矿模式为基础，通过理论分析，建立了陆内碰撞体制流体作用的模式，即在陆内俯冲体制中，随板片俯冲深度的增加，依次产生改造流体、变质流体和岩浆流体，所产生的流体在空间上具有分带性，并造成岩石、元素、矿化蚀变的成带规律分布；陆内俯冲的早期挤压阶段的流体作用以深部物质分泌的上升流体（改造、变质和部分熔融）为主，晚期伸展阶段以浅层下渗流体（来自大气降水）循环为主，中期由挤压向伸展的转变阶段为深分泌上升流体与浅层下渗流体的混合作用。为检验模式的科学性，选择典型的陆内碰撞带——东秦岭作为实例解剖，发现该区的陆内碰撞作用与金矿床等的成矿作用在时间、空间、地质地球化学特征等方面都十分吻合，且与理论推导的陆内俯冲体制的流体作用规律一致。对若干典型矿床成矿流体的氢同位素研究表明，成矿流体的性质、来源和演变特征等与理论推导的陆内碰撞体制流体作用规律完全符合。
Intracontinental collision and fluidization remain to be well studied although they have become the forward research fields since 1980′s. In the light of metallogenic and petrogenic model for collisional orogenesis proposed by Chen (1991, 1992), this paper, through theoretical deduction, advances a fluidization model for intracontinental collision. During intracontinental subduction, fluids were produced by reworking, metamorphism and magmatism in turn as the subducting slab descending. The fluids showed clear spatial zonation, which results in regular zonations in element distribution, petrogenesis, mineralization and alteration. At the early compressing stage of the intracontinental subduction, fluids were derived mainly from deep secretion (reworking, metamorphism and magmatism), whereas at the late extension stage, fluids were characterized as shallow down going meteoric water; consequently, at the middle compression to extension transition stage, fluids should be the mixed deep secreted and shallow meteoric ones. To testify the rationality of this fluid evolution model for intracontinental collision, the author takes the eastern Qinling mountains, a typical intracontinental collisional orogenic belt, as an example because the metallogenic geology, geochemistry, space and time of gold deposits have been verified consistent with the intracontinental collision occurred most intensively in Mesozoic. The oxygen and hydrogen isotopic analyses and the thermometric data for ore forming fluids of several representative gold deposits show that the feature, source and evolution of the ore forming fluids extremely agree with the theoretical model for fluidization in intracontinental collision.
出处
《地学前缘》
EI
CAS
CSCD
1996年第4期282-289,共8页
Earth Science Frontiers
基金
全国博士后基金
国家305项目
关键词
陆内碰撞
流体作用
成矿作用
金矿床
intracontinental collision, fluidization, mineralization, the eastern Qinling mountains, gold deposits
