赣北莲花山钨锡矿集区中细粒白云母花岗岩成因--来自锆石U-Pb同位素和元素地球化学的约束  

Petrogenesis of fine-grained muscovite granite in the Lianhuashan tungsten tin ore cluster area of northern Jiangxi province—Constraints from zircon U-Pb isotopes and elemental geochemistry.

作　　者：余振东 谭荣 曹慧青 周先军 杨治 邓丽军 李秀财[2] 丁杨 尹青青 YU Zhendong;TAN Rong;CAO Huiqing;ZHOU Xianjun;YANG Zhi;DENG Lijun;LI Xiucai;DING Yang;YIN Qingqing(The Third Geological Brigade of Jiangxi Geological Bureau,Jiujiang 322100,Jiangxi,China;Hefei University of Technology,Hefei 230036,Anhui,China;Xuancheng Natural Resources and Planning Bureau,Xuancheng 242000,Anhui,China;Faculty of Geosciences and Environmental Engineering,Southwest Jiaotong University,Chengdu 611756,Sichuan,China)

机构地区：[1]江西省地质局第三地质大队,江西九江322100 [2]合肥工业大学资源与环境工程学院,安徽合肥230036 [3]宣城市自然资源和规划局,安徽宣城242000 [4]西南交通大学地球科学与环境工程学院,四川成都611756

出　　处：《地质通报》2023年第12期2084-2095,共12页Geological Bulletin of China

基　　金：江西省科学技术厅国家科技奖后备培育项目《赣北巨量钨多金属富集成矿与关键勘查技术研究》(编号:20203AEI91004)。

摘　　要：赣北莲花山钨锡多金属矿集区位于扬子板块东南缘,是九岭-障公山钨锡铜金多金属成矿带的重要矿集区之一,分布有茅棚店、徐家尖、八字脑、棉花坞、莳山锡钨多金属矿床(点)十余处,以及潘村萤石矿、大洲高岭土矿等非金属矿产3~4处,但多为中小型矿床矿点,始终未有较大找矿突破,且对成矿期花岗岩缺乏精确的年代学及地球化学测试数据。对茅棚店锡钨矿床中细粒白云母花岗岩进行了岩相学、锆石U-Pb测年、地球化学特征研究,为区域成矿规律研究提供了直接证据。结果表明,白云母花岗岩锆石LA-ICP-MS U-Pb年龄为127.5±1.0 Ma,燕山期岩石单元由中粗粒似斑状黑云母花岗岩→中细粒似斑状黑云母花岗岩→中细粒—粗粒似斑状二云母花岗岩→中细粒白云母花岗岩→花岗斑岩组合。地球化学研究表明,该中细粒白云母花岗岩为高分异S型花岗岩,具有高硅(SiO_(2)=75.08%~75.40%)、富碱、过铝质的特征及较高的分异指数DI,轻、重稀土元素分馏明显,呈左高右低的深“V”形,Eu表现为强烈的亏损,具有稀土元素四分组效应,Rb/Sr、Rb/Ba平均值分别为53.92和60.30,指示岩浆经历了多阶段分离结晶作用,此高分异花岗岩是区内钨锡矿床最主要的成矿地质体。Lianhuashan tin-tungsten polymetallic ore concentration district in northern Jiangxi province is located on the southeast edge of the Yangtze plate.It is one of the important ore concentration districts of the Jiuling-Zhanggongshan tungsten-tin-copper-gold polymetallic metallogenic belt.It is determined as a class I metallogenic prospect,with more than 10 tin-tungsten deposits(occurrences),including Maopengdian,Xujiajian,Bazinao,Mianhuawu,Shishan and so on,there are several non-metallic mining occurrences,such as Pancun fluorite deposit and Dazhou kaolin deposit,but most of them are small and medium-sized mineral deposits,and there has never been a significant breakthrough in mineral exploration.In addition,there is a lack of accurate chronological and geochemical testing data for granite during the mineralization period.The petrography,zircon U-Pb chronology and whole-rock geochemistry of the medium and fine-grained muscovite granite in Maopengdian tin-tungsten deposit are studied in this paper,which provide direct evidence for the study of regional mineralization patterns.The results show that the zircon LA-ICP-MS U-Pb age of the muscovite granite is 126.7±1.2 Ma.The Yanshanian rock unit consists of medium-coarse-grained porphyritic biotite granite→medium-fine-grained porphyritic biotite granite→medium-fine-grained-coarse-grained porphyritic mica granite→medium-fine muscovite granite→granite porphyry,which is the result of crystallization differentiation of homologous magma evolution.Geochemical studies show that the medium and fine-grained muscovite granite is a highly differentiated S-type granite,which is characterized by high silicon(SiO_(2)=75.08%~75.40%)and rich in alkali and peraluminous and high differentiation index DI.The fractionation of light and heavy rare earth elements is obvious,showing a deep V-type with high left and low right.Eu shows a strong negative anomaly and has four grouping effect of rare earth elements.The average values of Rb/Sr and Rb/Ba are 53.92 and 60.30 respectively,in

关 键 词：茅棚店锡钨矿 白云母花岗岩 锆石U-PB年代学 地球化学 赣北莲花山 

分 类 号：P588.121[天文地球—岩石学] P618.2[天文地球—地质学] P597.3