豫西骆驼山多金属硫铁矿床硫化物Rb_Sr等时线年龄及其地质意义  

Rb_Sr isochron age of sulfide minerals in Luotuoshan pyrite_polymetallic deposit of western Henan Province and its geological significance

作　　者：杨晨英 叶会寿[2] 向君峰[2] 陈小丹[2] 邢波[1] 李亮[3] 王赛[1] 

机构地区：[1]中国地质大学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]昆明理工大学国土资源工程学院,云南昆明650093

出　　处：《矿床地质》2016年第3期573-590,共18页Mineral Deposits

基　　金：国家科技支撑计划项目(编号:2011BAB04B06);国家自然科学基金(编号:41303233;41403041);国土资源部公益性行业基金(编号:200911007_08)联合资助

摘　　要：豫西骆驼山多金属硫铁矿床位于华北陆块南缘南泥湖矿田西北侧。为确定该矿床的形成时代,文章选取了8件硫化物矿物样品,采用Rb_Sr等时线定年方法测定成矿年龄。结果获得,闪锌矿+磁黄铁矿+方铅矿等时线年龄为(137.3±2.6)Ma,闪锌矿+方铅矿等时线年龄为(138.2±5.8)Ma,闪锌矿+磁黄铁矿等时线年龄为(137±3)Ma,磁黄铁矿+方铅矿等时线年龄为(137.1±2.7)Ma,方铅矿等时线年龄为(138.4±7.6)Ma,磁黄铁矿等时线年龄为(137.2±3.7)Ma。上述定年结果表明,骆驼山多金属硫铁矿床的成矿时代为137 Ma左右,属早白垩世。硫化物Sr同位素初始比值(^(87)Sr/^(86)Sr)i介于0.713 23~0.713 32,平均值为0.713 25,小于陆源硅酸盐Sr的初始值0.7190,而高于地幔Sr的初始值0.7040,表明成矿物质来源于壳幔混合。骆驼山多金属硫铁矿床与矿田内的南泥湖_三道庄斑岩_矽卡岩钼(钨)矿床、冷水北沟铅锌矿成矿时代基本一致,是同一构造_岩浆_流体成矿活动的产物。结合前人对华北陆块南缘中生代期间地球动力学背景研究成果,笔者认为骆驼山矿床是中国东部中生代构造体制大转折过程晚期的产物。The Luotuoshan pyrite-polymetallic deposit lies on the northwestern side of the Nannihu orefield which is located on the southern margin of the North China craton. In order to determine the metallogenic age of the de- posit, the authors chose eight sulfide mineral samples to determine the metallogenic age by using the Rb-Sr isochron dating method. The result shows that the isochron age of sphalerite ＋ pyrrhotite ＋ galena, sphalerite ＋galena, sphalerite ＋ pyrrhotite, pyrrhotite ＋ galena, sphalerite and pyrrhotite are （137.3 ± 2.6） Ma, （ 138.2 ± 5.8） Ma, （137 ± 3） Ma, （137.1 ± 2.7） Ma, （ 138.4 ± 7.6） Ma and （137.2 ± 3.7） Ma, respectively. These dating results indicate that the metallogenic age of the Luotuoshan pyrite-polymetallic deposit is about 137 Ma, suggesting Early Cretaceous. The （^87Sr/^86Sr）i Of sulfides range from 0.713 23 to 0.713 32, with an average of 0.713 25, lower than the （^87Sr/^86Sr）i ratio d the terrigenous silicates （0.7190） and higher than that of the mantle （0.7040）, implying that the ore-forming materials were derived from the crust-mantle mixture. The Luotuoshan pyrite-polymetallic deposit has basically the same metallogenic age as the Nannihu-Sandaozhuang porphyry-skarn molybdenum （tungsten） deposit and the Lengshuibeigou lead-zinc deposit. They are the products of the same structure-magma-ore-forming-fluid activities. Combined with the previous studies of the geodynamic settings of the East Qinling orogenic belt during the Mesozoic period, it is held that the Luotuoshan pyrite-polymetallic deposit is the product of great transition period of late Mesozoic tectonic regime in eastern China.

关 键 词：地球化学 Rb_Sr等时线年龄 成矿时代 闪锌矿 骆驼山多金属硫铁矿床 豫西 

分 类 号：P618.31[天文地球—矿床学]