豫西骆驼山硫多金属矿床纹层状矿石硫化物Rb-Sr定年及S同位素组成对矿床成因的制约  

Rb-Sr isochron age of sulfides and sulfur isotopic composition from lamellar ores of the Luotuoshan sulfur polymetallic deposit in western Henan Province and its constraints on the ore genesis

作　　者：邢波[1,2,3] 向君峰[1] 叶会寿[1] 陈小丹[1] 张国苏 杨晨英 金雪[2] 

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(北京)地球科学与资源学院,北京100083 [3]内蒙古自治区地质调查院/内蒙古自治区岩浆活动与找矿重点实验室,内蒙古呼和浩特010020 [4]河南省栾川众鑫矿业有限公司,河南洛阳471542

出　　处：《地质通报》2016年第6期998-1014,共17页Geological Bulletin of China

基　　金：国家科技支撑计划项目(编号:2011BAB04B06)

摘　　要：已有研究在骆驼山硫多金属矿床成因方面存在较大争议,争论的焦点在于该矿床是否形成于中—新元古代的喷流沉积成矿作用。纹层状矿石曾被认为是喷流沉积成因矿床的重要证据之一,但也可能为热液交代成因。厘定骆驼山硫多金属矿床纹层状矿石的成矿时代和成矿物质来源是解决争议最为直接有效的途径。通过详细的野外地质观察,该型矿石在空间上主要产于矽卡岩与致密块状硫化物矿石之间,在透辉石长英角岩、矽卡岩及大理岩等围岩中也有分布,这种构造通常由不同金属矿物的纹层相间排列,以及金属矿物纹层与围岩纹层相间排列而成,地质特征表明纹层状矿石交代了矽卡岩。采用硫化物Rb-Sr同位素定年法对9件纹层状构造发育的硫化物样品(6件闪锌矿和3件磁黄铁矿)进行成矿年龄测定,获得闪锌矿和磁黄铁矿的等时线年龄为139.6±2.6Ma,表明骆驼山硫多金属矿床形成于早白垩世。纹层状矿石样品的S和Sr同位素测试结果表明,矿石的δ^(34)S值为+1.7‰^+3.3‰(平均值为+2.44‰),塔式分布特征明显;Sr同位素初始比值(^(87)Sr/^(86)Sr)i介于0.709704~0.709943之间,平均值为0.709823,二者均反映骆驼山硫多金属矿床的成矿物质主要来自下地壳的深源岩浆。综上分析,结合野外地质调查和室内显微镜下观察,认为纹层状矿石是中生代岩浆热液成因,而非中—新元古代喷流沉积成因,进而表明骆驼山硫多金属矿床应属岩浆热液交代成因的矽卡岩型矿床。该结果对于今后在该矿集区乃至整个豫西地区寻找类似的硫多金属矿床具有一定的理论指导意义。There are considerable debates about the genesis of the Luotuoshan sulfur polymetallic deposit in previous studies. The fo cus of controversy lies in whether it was formed from the Meso-Neoproterozoic exhalative sedimentary mineralization or not. The lamellar ores are considered as important evidence in sedimentary exhalative mineralization ,but the hydrothermal metasomatic genesis is also possible. Therefore,determining the metallogenic epoch and ore-forming material resources of the lamellar ores is the most direct and effective way to solve these debates. In the spatial distribution, we found that the lamellar ores mainly occur between skarns and dense massive sulfide ores and some distribute in wall rock such as diopside feldspar and quartz hornfels, skarns and marbles by detailed field geological observation. The structure formed by alternate arrangement of different metallic minerals laminas and metallic minerals laminas and wall rock laminas. The geological features suggest that the lamellar ores replace skarns. In this paper ,Rb-Sr dating was carried out for nine sulfides samples （comprising six sphalerite and three pyrrhotite samples） from lamellar ores of the Luotuoshan sulfur polymetallic deposit, which yielded an isochron age of 139.6±2.6Ma, suggesting that the metallogenic epoch of Luotuoshan deposit is Early Cretaceous. Sulfur and strontium isotopes of these sulfides show that δ34S values of the ores have a narrow range of＋1.7‰~＋3.3‰（averagely＋2.44‰）,with more obvious tower-shaped distributional features,and that the values of （87Sr/86Sr）i range from 0.709704 to 0.709943,with an average of 0.709823,which implies that ore-forming materials mainly originated from deep-seated magma of the lower crust. Based on the above analyses in combination with geological investigation in the field and microscope observation,the authors hold that the lamellar ores formed in Mesozoic and belonged to magmatic hydrothermal genesis, further indicating the Luotuoshan sulfur polymetallic deposit

关 键 词：硫化物Rb-Sr定年 S同位素组成 纹层状矿石 骆驼山硫多金属矿床 栾川矿集区 

分 类 号：P618.2[天文地球—矿床学]