幕阜山复式花岗岩体多期次演化与白垩纪稀有金属成矿高峰:年代学依据

发布时间：2018-03-16 06:05

本文选题：Ar/Ar定年　切入点：稀有金属　出处：《地球科学》2017年10期 　论文类型：期刊论文

【摘要】：花岗岩浆的分异过程是制约稀有金属成矿的重要因素,造山过程中多期次岩浆活动的叠加作用易导致伟晶岩熔体的大量聚集成矿.华南幕阜山复式花岗岩体由多期次多阶段的花岗岩侵入体构成,在区域持续而频繁的多期次岩浆活动作用下形成了华南地区重要的稀有金属矿集区.对幕阜山复式花岗岩体边部的断峰山含铌钽铁矿白云母钠长石伟晶岩以及岩体中部大兴含绿柱石白云母钠长石伟晶岩进行了~(40)Ar/~(39)Ar同位素定年研究,其白云母~(40)Ar/~(39)Ar坪年龄分别为127.7±0.9 Ma和130.5±0.9Ma.结合野外观察基础及区域已有的同位素年代学数据,推断出在燕山早期至中期该地区经历了多期岩浆演化,且持续时间较长,而伟晶岩的稀有金属矿化发生在岩浆活动末期的白垩纪,体现了区域岩浆多期次的分异演化作用导致稀有金属逐渐富集成矿的过程.这些地质现象说明,幕阜山区域在印支期经历了广泛的陆陆碰撞造山作用,进入燕山期后构造背景开始由陆内碰撞挤压向伸展减薄转变,在岩石圈伸展过程中经由玄武质岩浆底侵作用的影响,下地壳发生熔融,多期次岩浆活动导致了最终的稀有金属成矿.
[Abstract]:The differentiation process of granitic magma is an important factor restricting the mineralization of rare metals. The superposition of multi-stage magmatic activity during orogenic process may lead to the accumulation and mineralization of pegmatite melts. The complex granite body of Mufu Mountain in South China is composed of multi-stage and multi-stage granite intrusions. An important rare metal ore concentration area in southern China was formed by the continuous and frequent multistage magmatic activity in the region. The Muscovite albite pegmatite and its rock in the edge of the complex granite body of Mufu Mountain are studied in this paper. Daxing Muscovite albite pegmatite in the central part of the body has been studied for its ar isotopic dating. The age of the Muscovite 40 ~ (th / /) ~ (39) ar plateau is 127.7 卤0.9 Ma and 130.5 卤0.9 Ma respectively. Combined with the field observation basis and the regional isotopic geochronology data, it is inferred that the early to middle Yanshanian magma evolution in this area has experienced many periods and the duration is longer. The rare metal mineralization of pegmatite occurred in the Cretaceous at the end of magmatic activity, which reflected the process of regional magmatic differentiation and evolution, which resulted in the gradual enrichment and mineralization of rare metals. During the Indosinian period, the Mufu Mountain area experienced extensive continental collision orogeny. After entering the Yanshanian epoch, the tectonic setting began to change from intracontinental collision to extensional thinning. During the lithospheric extensional process, it was influenced by Black Tortoise magmatic underplating. The melting of the lower crust and the multistage magmatic activity resulted in the final metallogeny of rare metals.
【作者单位】：中国地质科学院矿产资源研究所国土资源部成矿作用与资源评价重点实验室;湖北省地质调查院;湖南省核工业地质局311大队;湖南省地质调查院;
【基金】：中国地质调查局项目(No.DD20160056) 自然科学基金项目(No.41372088) 湖南省国土资源厅地质勘查项目(No.20170331) 深部探测项目(No.2017YFC0602701)
【分类号】：P588.121;P618.6

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