冀东太平村钼矿床辉钼矿Re-Os同位素测年及其地质意义

太平村钼矿床位于燕辽钼(铜)成矿带中段南部,马兰峪复背斜核部西段。矿体主要赋存于燕山期中酸性侵入体外接触带的变质岩及角砾岩中,深部主要表现为隐伏似斑状二长花岗岩中的稀疏浸染状辉钼矿化,表明区内钼矿化与侵入岩系统有关。对矿区深部矿体中的7件辉钼矿样品进行了Re-Os同位素测年,其模式年龄为(162.5±2.5)~(165.7±2.5)Ma,加权平均年龄为(164.11±0.92)Ma,MSWD=0.82,等时线年龄为(164.4±3.9)Ma,MSWD=1.7,表明太平村钼矿形成于中侏罗世晚期。辉钼矿中Re含量为18.79×10~(-6)~66.65×10~(-6),平均41.86×10~(-6),指示成矿物质可能为壳幔混合来源,与同属燕辽钼(铜)成矿带的辽宁肖家营子钼矿床、冀东唐杖子金(钼)矿床、峪耳崖金矿床及下营房金矿床辉钼矿成矿时代、成矿物质来源基本一致,同属燕辽钼(铜)成矿带第三期构造-岩浆岩-成矿事件的产物。

Re-Os isotopic dating of molybdenite from Taipingcun Mo deposit in eastern Hebei and its geological significance

Taipingcun Mo deposit is located in the western Malanyu anticlinorium core，and the southern cen- tral Yanshan- - Liaoning molybdenum (copper) metallogenic belt． The ore bodies are mainly hosted in metamorphic rocks and breccias along the exocontact zone of Yanshanian intermediate- acid intrusive bodies． Besides，sparsely disseminated molybdenite mineralization was found in concealed porphyritic monzonitic granite in deep． It indicates that molybdenum mineralization in the area is associated with the intrusive rocks． The Re - Os dating of seven mo- lybdenite samples collected from the deep ore bodies shows the model ages ranging from (162. 5 ± 2. 5) Ma to (165. 7 ±2. 5) Ma，the weighted mean age of (164. 11 ± 0. 92) Ma，MSWD = 0. 82 and the isochronal age of (164. 4 ±3. 9) Ma，MSWD =1. 7，which indicates the deposit formed in the late Middle Jurassic． The Re content of molybdenites is 18. 79 ×10 －6 ～66.65 ×10 －6 ，with an average value of 41. 86 ×10 －6 ，suggesting a mixing ori- gin of the materials from crust and mantle． The ore- forming age and materials of the Taipingcun Mo deposit are ba- sically consistent with those of the Xiaojiayingzi Mo deposit in Liaoning，the Tangzhangzi gold (molybdenum) de- posit，Yuerya- and Xiayingfang gold deposits in eastern Hebei． All belongs to the Yanshan- -Liaoning molybdenum (copper) metallogenic belt． These deposits are resulted from the third phase of the tectonic- magmatic- metallogenic events of Yanshan - - Liaoning molybdenum (copper) metallogenic belt．