小岩浆大流体成大矿与透岩浆流体成矿作用——以东秦岭-大别山成矿带钼矿床为例

发布时间：2018-03-01 08:02

本文关键词： 小岩浆大流体双层结构透岩浆流体钼矿东秦岭-大别山　出处：《岩石学报》2017年05期 　论文类型：期刊论文

【摘要】：岩浆活动与内生金属成矿作用关系密切,备受国内外矿床学家的关注。表现为它们在时空上具有广泛的一致性,成矿与岩浆岩有关,成矿物质由同源岩浆分异演化而来。这便是著名的岩浆热液成矿理论,也称岩浆期后热液成矿理论,该理论把内生金属成矿系统看作是一个理想系统。东秦岭-大别山地区的钼矿-花岗岩关系研究表明,钼成矿与小岩体(小岩浆)关系密切,而大岩体/基与钼矿没有成生联系;地质事实表明,大型-超大型矿床往往广泛发育了大规模的热液(流体)蚀变(大流体),具有大的流体/岩浆比,其矿化蚀变范围是小岩体的几十甚至几百倍,表明成矿过程中必有外来流体的广泛参与。由于小岩体往往没有经过强烈的分异结晶作用,质量平衡计算表明,小岩浆体不可能产生足够数量的含矿流体和成矿物质;因此,成岩与成矿有本质的区别,成矿系统应是一个非线性的复杂性动力学系统。研究表明,东秦岭-大别山小斑岩体来源较深(下地壳),成矿流体来源于地幔,二者呈双层结构;岩浆实际上是沟通深部和浅部的通道,这种非岩浆分异的外来成矿流体我们称之为透岩浆流体。小岩体不是成矿的必备的条件,只有出现大流体时才能成大矿。东秦岭-大别山地区有200多个小岩体,但大型、超大型钼矿矿床仅有10余个,只有小岩浆(小岩体)大流体(强蚀变)成大矿,其余众多小岩体由于没有流体(蚀变)或流体少(弱蚀变)而不成矿或成小矿。由此可见,岩浆成矿系统实际上是一种流体(挥发分)过饱和系统或熔体-流体流及流体对熔体的强相互作用。当岩浆系统被加入大量源自地幔的高温高压含矿流体之后,系统将具有极大的活动能力,从而深部含矿流体沿裂隙快速上升到地壳浅部卸载成矿。为解释上述成矿特征,作者引入并厘定了透岩浆流体的概念。透岩浆流体被重新定义为透过岩浆活动并导致岩浆系统行为发生非线性变化的外来流体。据此,输入了含矿流体的岩浆可成矿,未输入含矿流体的岩浆不成矿。这种认识可以解释东秦岭-大别山地区大多数小岩体不成矿或只形成小矿的现象。
[Abstract]:Magmatic activity is closely related to endogenetic metal metallogeny, which has attracted the attention of ore deposit scientists at home and abroad. It is shown that they have extensive consistency in time and space, and mineralization is related to magmatic rocks. This is the famous magmatic hydrothermal metallogenic theory, also known as post-magmatic hydrothermal metallogenic theory. The study on the relationship between molybdenum ore and granite in East Qinling and Dabie Mountains shows that molybdenum mineralization is closely related to small rock mass (small magma). The geological facts show that large-scale hydrothermal (fluid) alteration (large fluid) alteration (large fluid / magma ratio) is often widely developed in large and super-large ore deposits, and has a large fluid / magma ratio, while the large rock mass / base is not related to molybdenum deposits, and the geological facts show that large-scale and super-large deposits often develop large-scale hydrothermal (fluid) alteration. The range of mineralization alteration is tens or even hundreds of times of that of small rock mass, which indicates that there must be extensive participation of foreign fluids in the metallogenic process. Since the small rock mass often does not undergo strong differentiation and crystallization, the mass balance calculation shows that, It is impossible for small magmatic bodies to produce a sufficient number of ore-bearing fluids and ore-forming materials; therefore, there is an essential difference between diagenesis and metallogenesis, and the ore-forming system should be a nonlinear and complex dynamic system. The East Qinling-Dabie mountain Xiaobian rock body originated from the lower crust and the ore-forming fluid from the mantle, and the magma is actually a channel to connect the deep and shallow areas. This kind of non-magmatic differentiation of foreign ore-forming fluid is called permeable magmatic fluid. Small rock mass is not a necessary condition for metallogeny, and it can only be formed when large fluid occurs. There are more than 200 small rock masses in the East Qinling and Dabie Mountains area, but they are large. There are only more than 10 super-large molybdenum ore deposits, only small magma (small rock mass) and large fluid (strong alteration) are formed into large ore deposits, and many other small rock masses are not metallogenic or mineralized because they have no fluid (alteration) or less fluid (weak alteration). The magmatic ore-forming system is actually a fluid (volatile matter) supersaturation system or a melt-fluid flow and a strong interaction between the fluid and the melt. When the magmatic system is added to a large number of high-temperature and high-pressure ore-bearing fluids derived from the mantle, The system will have great mobility, so that the deep ore-bearing fluid rises rapidly along the fissure to the shallow part of the crust to unload the ore-forming. The author introduces and defines the concept of permeable magmatic fluid. Permeable magmatic fluid is redefined as a foreign fluid that passes through magmatic activity and causes nonlinear changes in the behavior of the magmatic system. This understanding can explain the phenomenon that most of the small rock masses in the East Qinling-Dabie Mountain area are not metallogenic or only form small ore deposits.
【作者单位】：河南省国土资源科学研究院河南省花岗岩与成矿作用重点实验室;中国地质大学地质过程与矿产资源国家重点实验室;国土资源部成矿作用与资源评价重点实验室中国地质科学院矿产资源研究所;河南省有色金属地质勘查总院;河南省地质调查院;
【基金】：国土资源部公益性行业专项基金(200811020) 河南省科技攻关项目((2006)2647) 国家自然科学基金项目(41402069)联合资助
【分类号】：P618.65

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