攀西地区镁铁质岩浆成矿系统的流体动力学模型  

Fluid dynamics model of mafic magma metallogenic system in Panxi Area

作　　者：黑慧欣 罗照华[1] 程金华[1] 邱一冉 邓俊峰[1] 李解[1] I.V.Vikentyev 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室,北京100083 [2]Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry of Russian Academy of Sciences (IGEM RAS), Moscow 119017, Russia

出　　处：《地学前缘》2015年第3期333-347,共15页Earth Science Frontiers

基　　金：国家重点基础研究发展计划“973”项目(2011CB808901);中俄国际合作项目(RFBR 14-05-91162-NSFC);中国地质调查局地质调查项目(1212011220921,1212011121266,12120113094100,1212011121075)

摘　　要：尽管镁铁质侵入体及其与成矿作用的关系得到了特别关注,但有许多科学问题迄今仍模糊不清。基于新的野外观察和理论分析,文中提出一个复杂性流体动力学模型,试图整合解释矿床地质学、矿相学和矿物学特征。假定岩浆成矿系统的行为取决于熔体和流体两个子系统的强相互作用,系统演化过程中子系统物理性质的连续改变可以导致多种非线性变化:(1)熔体子系统未发生明显结晶作用之前,含矿流体弥漫式透过熔体向上迁移,产生具有隐性火成层理的致矿侵入体和浸染状整合矿体。在这种条件下,高速运动的含矿流体可以导致岩浆侵入体全岩矿化;较低速上升的含矿流体也可以导致强烈的岩浆分异作用,但岩浆侵入体的边缘部分将没有成矿金属的富集。(2)岩浆侵入体部分固结(如半固结)时,含矿流体只能大规模输入到岩体中心尚未固结的部分,并导致强烈的双扩散对流,产生明显的韵律性层理和整合型块状矿体。(3)岩浆侵入体接近完全固结时,巨大的流体超压或远场应力场可导致板状侵入体沿补给通道方向破裂,含矿流体上升导致了不整合矿体的产生。(4)岩浆侵入体完全固结之后,后续含矿流体只能沿着层状侵入体与底板围岩的接触带迁移,形成新型板状矿体或巢状矿体,甚至夕卡岩型矿体。(5)富氧化物流体之后还可以有富硫化物流体上升,有利于产生硫化物矿体。这种分析大致符合攀西地区的客观实际,因而可以得出结论:(1)岩浆侵入体是否成为致矿侵入体取决于含矿流体的输入,而不是岩浆分异作用;(2)致矿侵入体的分异特征是含矿流体输入的结果,而不是相反;(3)镁铁质岩浆成矿系统是一种复杂性动力系统,含矿流体的输入是其行为发生非线性变化的根本原因;(4)攀西地区的镁铁质岩浆成矿系统包括整合型(包括块状和浸染状两种亚型)、不整合型和夕卡�Despite of special attentions drawn to mafic intrusions and their relations to mineralization, many scientific issues related to them remain in ambiguity till now. Based on the new field observations and the theoretical analysis, a complexity fluid dynamic model is proposed to attempt an integrated interpretation of ore deposit geology, petrography, and mineralogy of the magmatic iron deposit. Given the behavior of a magmatie mineral system Being decided by strong interactions between the melt- and fluid-subsystem, the successive changes of physical properties of the system would induce a variety of non-linear modification in the system. （1） Before that there is not significant crystallization in the melt-subsystem, the ore-bearing fluid migrates up through the pervasive percolation, and induces ore-induced intrusion with hidden igneous layering and concordant ore bodies with disseminated structure. In such a condition, the ore-bearing fluid migrating up in a high speed could result in mineralization in the whole magmatic intrusion. The ore-bearing fluid migrating up with a lower speed could also lead to intense differentiation of a magmatic body, but the ore-forming metals will not be concentrated to the marginal parts of the intrusion. （2） If the intrusion is consolidated partly （for instance, a half）, the ore-bearing fluid may be transported on large scale only to the unconsolidated centre of the intrusion, in which the double-diffuse convection is caused, and obvious rhythmic sequences and concordant massive ore bodies are produced. （3） When the magmatic intrusion is cooled to complete consolidation, if the fluid overpressure is high enough or the far-field stress field is in action, the consolidating intrusion will be ruptured near the previous conduits. Under such circumstances, the ore-bearing fluid ascend to form the discordant ore body. （4） After complete consolidation of magma intrusion, subsequent invasion ore fluid can migrate along the contact zone between the layered intrusions

关 键 词：层状侵入体 岩浆铁矿床 成矿系统 透岩浆流体 流体动力学 四川攀枝花 

分 类 号：P611.11[天文地球—矿床学]