豫西铁炉坪银铅矿床矿脉构造解析及近矿蚀变岩绢云母^(40)Ar-^(39)Ar年龄测定  

Vein Structure Analysis and ^(40)Ar/^(39)Ar Dating of Sericite from Sub-ore Altered Rocks in the Tieluping Large-size Ag-Pb Deposit of Western Henan Province

作　　者：高建京[1] 毛景文[2] 陈懋弘[2] 叶会寿[2] 张继军 李永峰 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室,地球科学与资源学院,北京100083 [2]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 [3]陕西省地质调查院,西安710065 [4]河南省有色金属矿产探测工程技术研究中心,郑州450016

出　　处：《地质学报》2011年第7期1172-1187,共16页Acta Geologica Sinica

基　　金：全国危机矿山接替资源找矿项目(编号20089949,200841019);公益性行业科研专项经费项目(编号K0801);豫西熊耳山西段银多金属成矿规律及深部找矿预测(编号2010-021)的研究成果

摘　　要：河南省洛宁县铁炉坪大型脉状银铅矿床地处华北陆块南缘熊耳山中生代变质核杂岩构造西部,由一组主要的NNE走向陡倾斜矿脉和一组次要的NW走向陡倾斜矿脉有规律地组成。矿脉以条带状、角砾状和晶洞-晶簇-梳状三种主要形式多阶段充填而成,按照主要矿脉的矿物共生序列可以分为四个阶段:铁镁碳酸盐阶段(Ⅰ)、烟灰色石英-贱金属硫化物-银矿物主矿化阶段(Ⅱ1)和白云石-白色石英-粗晶方铅矿-银矿物主矿化阶段(Ⅱ2)及主成矿后的玉髄-萤石-方解石阶段(Ⅲ)。在矿床尺度上,矿脉受成矿前的韧性剪切带制约;在露头尺度上,矿脉利用和切割成矿前剪切带。在各成矿阶段期间,矿脉表现出明显的张剪性和扩容脉(dilational vein)特征;从运动学观察可知,容矿构造的运动方向是基本上一致的,主要表现为NE走向容矿构造的左旋下滑运动和NW走向容矿构造的右旋下滑运动。本次研究在铁炉坪矿区的近矿蚀变岩中选取绢云母进行40Ar/39Ar年龄测定,获得坪年龄为(134.6±1.2)Ma,相应的等时线年龄为(135.3±2.4)Ma。这一数据与在同一矿田内蒿坪沟矿脉的绢云母40Ar-39Ar年龄(134.9±0.8)Ma和蒿坪沟花岗斑岩的锆石SHRIMP年龄(133.5±1.4)Ma极为相近,进一步显示出矿田内成岩与成矿的时空一致性。The large Tieluping vein-type Ag-Pb ore deposit,located in the western Xiongershan metamorphic core complex,the south margin of North China Craton,consists mainly of one set of NNE-trending steeply-dipping ore veins and one set of secondary NW-trending oblique ore veins.Ore veins occur as banded,breccia and drusy structures in the form of multiple-stage fillings.Based on mineral paragenesis in the main ore veins,four stages can be recognized： an early Fe-Mg carbonates stage（I） prior to polymetallic mineralization,a smoky gray quartz-base metal sulphide-silver minerals stage（II1）,a dolomite-white quartz-coarse grained galena-silver minerals stage（II2）,and a calcedony-fluorite-calcite stage（III） after the polymetallic mineralization.In the perspective of deposit,ore veins are controlld by pre-mineralization ductile shearing zones;in the perspective of outcrop,ore veins use and cut pre-existing shearing zones.The ore veins are characterized by distinct tensional shear and dilational veins at each mineralizing stage.Kinematic observations demonstrate that motion direction of ore-hosting structure is basically coherent,characterized by a sinistral slipping of the structure of NE-trending ore veins and dextral slipping of structure of NW-trending ore veins.40Ar/ 39Ar dating was performed on sericite from the subore altered rocks,which yielded a plateau ages of（134.6±1.2）Ma and an isochronal age of（135.3±2.4）Ma.The age data corresponds to the sericite 40Ar-39Ar plateau age of（134.9±0.8）Ma for the Haopinggou lead-silver veins and the zircon SHRIMP U-Pb age of（133.5±1.4）Ma for the Haopinggou granite porphyry in the same ore field,thus further indicating the spatial and temporal consistency of the mineralization and intrusion.

关 键 词：矿脉 运动学 40AR-39AR 绢云母 银铅矿 铁炉坪 熊耳山 

分 类 号：P618.5[天文地球—矿床学]