摘要
错那洞淡色花岗岩与错那洞穹隆及周边的铅锌和钨锡铍矿床具有时空上的密切关系。含电气石淡色花岗岩是错那洞高分异淡色花岗岩的代表性岩石。岩相学研究表明.错那洞电气石可分为GT型和PT型两类。本次研究利用电子探针以及LA-ICP-MS分析两种类型电气石的化学组成。结果表明,GT型电气石中Fe/(Fe+Mg)原子比值为0.83〜0.87,Na/(Na+Ca)的原子比值为0.93〜0.95;PT型电气石中则分别为0.78〜0.95以及0.81〜0.95,表明二者均为碱性电气石和黑电气石。矿物地球化学特征表明GT型电气石来源于早期岩浆阶段的熔体,PT型电气石则来源于晚期岩浆热液流体。二者的成分变化分别符合低—中盐度流体对应的X_(-vac)-Al(NaR)_(-1)趋势和高Na及高盐度对应的AlO(R(OH))_(-1)趋势,表明从电气石花岗岩到花岗伟晶岩岩浆结晶环境中Na含量的增加,反映花岗伟晶岩结晶分异演化程度更高。与GT型电气石相比(Sn元素平均含量为23.15×10^(-6)),在PT型电气石中Sn元素明显富集(平均为193.57×10^(-6)),二者均表现出Sn成矿电气石的特征,并且PT型电气石特征更为显著。此外,PT型电气石中Sn-W-Be元素含量(193.57×10^(-6)〜0.13×10^(-6)〜8.41×10^(-6))较GT型电气石中(23.16〜0.02×10^(-6))显著富集:Pb+Zn含量(45.47〜2687.29×10^(-6),平均为787.55×10^(-6))也较GT型电气石中显著富集。这一特征指示了错那洞高分异花岗岩形成钨锡铍、铅锌等金属矿床的成矿潜力。
Cuonadong tourmaline-bearing leucogranite is a representative rock of highly differentiated igneous rock and it is closely related to Cuonadong dome and its surrounding lead-zinc and tungsten-tin beryllium deposits in time and space.Petrographic studies show that Cuonadong tourmaline can be divided into GT type and PT type.In this paper,electron probe and LA-ICP MS are used to analyze the chemical compositions of two types of tourmaline.The results show that the atomic ratios of Fe/(Fe+Mg)and Na/(Na+Ca)in GT tourmaline are 0.83-0.87 and 0.93-0.95,respectively,while PT tourmaline is 0.78-0.95 and 0.81-0.95 respectively,indicating that both of them are alkaline tourmaline and black tourmaline.The geochemical characteristics of tourmaline show that GT tourmaline is derived from early magmatic melt and PT tourmaline is derived from late magmatic hydrothermal fluid.The changes of composition of the two types of tourmaline accord with X_(-vac)-Al(NaR)_(-1) trend corresponding to low-medium salinity fluid and with AlO(R(OH))_(-1),trend corresponding to high Na and high salinity fluid respectively,indicating that the increase of Na content in the magmatic crystallization environment from tourmaline granite to granitic pegmatite reflects a higher degree of crystallization differentiation evolution of granitic pegmatite.Compared with GT tourmaline(the average content of Sn is 23.15×10^(-6)),Sn is enriched in PT tourmaline(193.57×10^(-6) on average).Both of them show the characteristics of Sn mineralization tourmaline,and PT tourmaline is more prominent.In addition,the content of Sn-W-Be elements in PT tourmaline(193.57×10^(-6)-0.13×10^(-6)-8.41×10^(-6))is significantly higher than that in GT tourmaline(23.16-0.02×10^(-6)).Pb+Zn content in PT tourmaline(45.47-2687.29×10^(-6),787.55×10^(-6) on average)is significantly enriched,compared with GT tourmaline.This feature indicates the metallogenic potential of Cuonadong highly differentiated granite to form tungsten,tin,beryllium,lead-zinc and other metal deposits.
作者
吴明锴
张刚阳
张丁川
陈曦
杨宾
Wu Mingkai;Zhang Gangyang;Zhang Dingchuan;Chen Xi;Yang Bin(College of Earth Science and Ministry of Natural Resources Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon Accumulation,Chengdu University of Technology,Chengdu,Sichuan 610059,China;College of Geosciences and Technology Southvoest Petroleum University,Chengdu,Sichuan 610500,China;Tibet Huayu Mining Co.,Ltd.,Lhasa 850032,China)
出处
《矿物岩石》
CAS
CSCD
北大核心
2021年第4期44-58,共15页
Mineralogy and Petrology
基金
国家重点研发计划项目(2017YFC0601505)
国家自然科学基金(41302066)
西藏华钰矿业股份有限公司博士后基金(80303-SHX070)
成都理工大学中青年骨干教师培养计划(KYGG201402)。
