福建河田高分异花岗岩的矿物和全岩地球化学找矿标志研究

发布时间：2018-06-07 02:29

本文选题：高分异花岗岩 + 石榴子石　；参考：《地质学报》2017年08期

【摘要】：我国的华南地区是一个钨、锡、钼、铋、铀、铌钽、铅锌、稀有、稀土多金属成矿区。近年来,高精度年代学数据表明上述矿产集中爆发形成于晚侏罗世的165~150Ma。野外和实验证据表明,花岗岩可以划分为高分异花岗岩、低分异花岗岩和未分异花岗岩。从目前的研究结果来看,钨、锡、铌钽、锂、铍等成矿作用都与高分异花岗岩密切相关。建立与这些矿产有关高分异花岗岩的普适性的矿物学、矿物地球化学和全岩地球化学的指标,有助于判断植被覆盖严重和风化严重地区、数据积累较少的岩体的成矿潜力。位于福建省长汀县境内的河田花岗岩体新鲜露头少,大部分岩体都掩盖在厚厚的风化层下,且植被覆盖严重,但是该岩体中已发现多处锡、钨、铅锌矿(化)点。本研究发现,该岩体的锆石U-Pb年龄、石榴子石和全岩地球化学特征与江西西华山第二期成矿花岗岩具有高度相似性,因此推断河田岩体可能具有成钨锡多金属(超)大型矿的成矿潜力。此外,当花岗岩向高分异阶段不断演化的过程中,某些元素比值(例如Rb/Sr、Zr/Hf和Nb/Ta)可以作为衡量岩浆的结晶分异程度的参数;西华山和河田花岗岩在达到熔体-流体相互作用阶段时,全岩Zr含量和Zr/Hf比值大概在Zr=50×10-6和Zr/Hf=15处发生转折。同时,与不成矿花岗岩中的石榴子石相比,成矿花岗岩中石榴子石的Sn、Y和Yb元素含量明显升高,可达2~10倍,因此,高分异花岗岩的石榴子石的微量元素特征可能是重要的找矿标志之一。
[Abstract]:South China is a tungsten, tin, molybdenum, bismuth, uranium, niobium, tantalum, lead zinc, rare, rare earth polymetallic mineralization. In recent years, the high accuracy geochronological data indicate that the concentrated eruption of the mineral deposits occurred in the late Jurassic at 165 ~ 150 Ma. The field and experimental results show that the granites can be classified into high differentiated granite, low differentiated granite and undifferentiated granite. The results show that the mineralization of tungsten, tin, niobium, tantalum, lithium and beryllium are closely related to high grade isomorphic granites. The establishment of universal mineralogy, mineral geochemistry and whole rock geochemistry indexes related to these minerals is helpful to judge the ore-forming potential of rock mass with low data accumulation and serious vegetation coverage and weathering. There are few fresh outcrops of the granite body in Changting County Fujian Province. Most of the rock masses are covered under the thick weathering layer and the vegetation is covered seriously. However many tin tungsten and lead-zinc ore sites have been found in this rock mass. It is found that the zircon U-Pb age, the geochemical characteristics of the garnet and the whole rock are highly similar to those of the second stage of Xihuashan metallogenic granite in Jiangxi Province. Therefore, it is inferred that the Hetian rock body may have the metallogenic potential of tungsten and tin polymetallic (superlarge) ore deposits. In addition, some element ratios (such as RB / Sr, Zr / HF and NB / Ta) can be used as parameters to measure the degree of crystallization differentiation of magma during the evolution of granites to high differentiation stage. When Xihuashan and Keda granites reach the stage of melt fluid interaction, the Zr content and Zr/Hf ratio of the whole rock turn at Zr=50 脳 10-6 and Zr/Hf=15. At the same time, compared with the garnet in non-metallogenic granite, the contents of Sno _ Y and Yb in the granites are significantly higher than those in the non-metallogenic granites, and the contents of Sno _ Y and Yb in the granites can reach 2 ~ 10 times. The trace element characteristics of pomegranate from high grade isomorphic granites may be one of the important prospecting indicators.
【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;中国地质科学院地质研究所国土资源部大陆构造与动力学重点实验室;中国地质大学;湖南柿竹园有色金属有限责任公司;
【基金】：国家自然科学面上基金项目(编号:41273043,41425010) 地质调查项目(编号:DD20160056) 国家重点研发计划课题(编号:2016YFC06002008)资助的成果
【分类号】：P588.121;P632

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