湘南新田岭大型钨钼矿床辉钼矿Re-Os同位素测年及其地质意义  

Re-Os dating of molybdenite from the Xintianling giant tungsten-molybdenum deposit in southern Hunan Province,China and its geological implications

作　　者：袁顺达[1,2] 张东亮[3] 双燕 杜安道[5] 屈文俊[5] 

机构地区：[1]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,北京100037 [2]中国地质大学地质过程与矿产资源国家重点实验室,北京100083 [3]中南大学地学与环境工程学院,长沙410083 [4]重庆地质矿产研究院,重庆400042 [5]国家地质测试中心,北京100037

出　　处：《岩石学报》2012年第1期27-38,共12页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(40903020、40930419、40434011);中央级公益性科研院所基本业务费专项资金(K1001、K2007-1-12);国土资源大调查项目(1212010634001);中国地质大学地质过程与矿产资源重点实验室基金(GPMR200839);中国博士后科学基金(20080430457)联合资助

摘　　要：新田岭矿床是湘南地区一大型矽卡岩-石英脉型钨钼多金属矿床,在成因上与骑田岭岩体早期侵位的角闪石黑云母二长花岗岩相关。分别对该矿床矽卡岩型和石英脉型矿石内的辉钼矿单矿物进行了Re-Os同位素测年,结果显示,矽卡岩型矿石中1件辉钼矿的187Re-187Os模式年龄为159.1±2.6Ma,6件石英脉型矿石中辉钼矿的187Re-187Os模式年龄为159.1～160.2Ma,加权平均值为159.4±1.3Ma,对应的等时线年龄为161.7±9.3Ma,与已有的矽卡岩内铁云母Ar-Ar年龄(157.1±0.3Ma)和石英脉内石英流体包裹体的Rb-Sr年龄(157.4±3.2Ma)在误差范围内相吻合,指示新田岭钨钼矿床的成矿时限大致可限定为157.1～161.7Ma,表明钨钼矿化与该区骑田岭岩体早期侵位的角闪石黑云母花岗岩(160～163Ma)具有密切的时间关系。结合已有的研究结果认为,新田岭大型钨钼矿床与骑田岭岩体早期侵位的角闪石黑云母二长花岗岩具有密切的时、空联系,而南部的芙蓉锡矿与晚期侵位的黑云母二长花岗岩更为密切,整个骑田岭A型花岗岩的侵位及相关的钨锡多金属成矿作用应为一个连续的演化过程,均为南岭地区150～160Ma钨锡多金属爆发式成矿作用的产物。该区在中-晚侏罗世(150～165Ma)岩石圈的伸展减薄背景下,软流圈地幔物质沿着深大断裂上涌,强烈的壳幔相互作用可能为大规模的花岗质岩浆活动及钨锡多金属的成矿大爆发提供了主要的热动力和部分物源。The Xintianling tungsten deposit is a large-sized skarn and vein-type tungsten-molybdenum polymetallic deposit located in southern Hunan Province,which is genetically associated with the early stage hornblende-biotite monzonitic granite of Qitianling pluton. Direct Re-Os dating on molybdenites collected from the skarn and quartz-vein type ore in the Xintianling deposit have been carried out, to better understand the age of mineralization.The results show that the Re-Os dating of one molybdenite sample collected from skarn-type ore yields a 187 Re-187 Os model age of 159.1±1.9Ma,and six molybdenite samples collected from quartz-vein-type ore yield 187 Re- 187 Os model ages ranging from 159.1±1.9Ma to 160.2±2.9Ma,with an average of 159.4±1.3Ma,and give an isochron age of 161.7±9.3Ma（2σ）,with an initial 187 Os of 0.6±2.3（MSWD=0.051）.Comparison of the Re-Os ages with published Ar-Ar date（157.1±0.3Ma）on iron mica and Rb-Sr date（157.4±3.2Ma）on quartz indicates that the timing of skarnization and tungsten-molybdenum mineralization are identical within error.Therefore,we can constrain the absolute age of tungsten-molybdenum mineralization in the Xintianling deposit at ca.161.7～157.1Ma.These ages are consistent with the SHRIMP zircon U-Pb ages（163～160Ma）of the early stage hornblende-biotite monzonitic granite.Based on previous studies,it is suggested that the mineralization of the Xintianling W-Mo deposit is spatially and temporally related to the early stage hornblende-biotite monzonitic granite of Qitianling pluton. While the Furong tin deposit located in southern part of Qitianling pluton may be closely related to the late stage biotite monzonitic granite.The emplacement of the Qitianling A-type granite and associated tungsten-tin polymetallic mineralization is a continuous evolution process,which are the products of large-scale mineralization of the Nanling in Middle-Late Jurassic（150～160Ma）.Under the tectonic setting of Mesozoic lithospheric extension,asthenosphere upwelling alo

关 键 词：辉钼矿Re-Os同位素定年 钨钼多金属矿床 新田岭 湘南 

分 类 号：P618.65[天文地球—矿床学] P618.67[天文地球—地质学]