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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.
The differentiation process of granite magma is an important factor that restricts the metallogenesis of rare metals. The superimposition of multi-stage magmatism in orogenic process tends to lead to the massive accumulation of pegmatite melt. The Mufushan complex granite in South China is composed of multi- Sub-multistage granite intrusions formed in the continuous and frequent multi-stage magmatic activity in the region formed in southern China an important area of rare metal deposits on Mufushan complex granite edge of the mountain peaks containing niobium tantalum (40) Ar / ~ (39) Ar isotopic dating of muscovite albite feldspar and pegmatite from Daxing feldspathic muscovite albite in the central part of the rock mass. The muscovite ~ (40) Ar / ~ (39) ) Ar Ping ages are 127.7 ± 0.9 Ma and 130.5 ± 0.9Ma, respectively. Combined with the field observation base and the existing isotopic geochronological data, it is inferred that the area experienced multiple magmatic evolutions in the early to mid Yanshanian period, And the rare metal mineralization of pegmatite occurred in the Cretaceous at the end of the magmatic activity, reflecting the multi-stage differential evolution of regional magma leading to the gradual enrichment and mineralization of rare metals. These geological phenomena show that Mufushan area During the Indosinian period, it experienced a wide range of land-continent collision orogeny. After entering the Yanshanian period, the tectonic setting began to change from intracontinental collision to extension and thinning. Under the influence of basaltic magma underplating during lithosphere extension, Melting of the crust, multi-stage magmatic activity led to the final rare metal mineralization.