江西乐平塔前钼（钨）矿床成岩成矿时代及意义

摘要

探讨江西省乐平市塔前钼（钨）矿床成矿岩体的形成时代。通过对塔前钼（钨）矿床进行野外地质调查和 SIMS 锆石 U-Pb 测龄，结果表明其成矿母岩为花岗闪长斑岩，其加权平均年龄为160．9±2．5 Ma（MSWD＝0．69），代表矿区花岗闪长斑岩的结晶时间。这与矿区矽卡岩矿石中辉钼矿 Re-Os 同位素年龄（162±2 Ma）在误差范围内一致，说明此矿床形成于中侏罗世晚期。将其与钦杭成矿带东段塔前－赋春成矿带与乐华—德兴成矿带中同类矿床进行对比发现，前者成矿年龄集中于161 Ma±，控岩控矿构造皆以北东向为主；而后者成矿年龄集中于170 Ma±，控岩控矿构造以北西向为主，预示钦杭成矿带东段2个成矿阶段（170～161 Ma B.P.）区域构造应力方向可能发生了重大转变。%This paper discusses the formation age of the ore-related intrusion in the Taqian Mo (W) deposit in Leping,Jiangxi of China.Through the field survey and SIMS zircon U-Pb dating,the results show that the ore-related intrusion of this deposit is granodiorite porphyry.Its weighted average age is 160.9±2.5 Ma (MSWD=0.69).This age is the crystallizing age of the granodiorite porphyry.The age of the ore-related intrusion is consistent with the molybdenum Re-Os isotopic age (162±2 Ma)of the skarn ore in the range of error,indicating that this deposit formed in the late Jurassic.Comparing this deposit with the similar deposits in the Taqian-Fuchun metallogenic belt and the Lehua-Dexing metallogenic belt in the eastern segment of the Qinhang metallogenic belt,it can be found that the ore-forming age of the former focuses on the ±161 Ma and the rock-control and ore-control structural system is northeast-trending,while the ore-forming age of the latter focuses on ±170 Ma and the rock-control and ore-control structural system is northwest-trending.This indicates that the orientation of the regional tectonic stress of the two mineralogenetic stages (170~161 Ma B. P.)in the eastern segment of the Qinhang metallogenic belt might obviously change.This paper discusses the formation age of the ore-related intrusion in the Taqian Mo (W) deposit in Leping,Jiangxi of China.Through the field survey and SIMS zircon U-Pb dating,the results show that the ore-related intrusion of this deposit is granodiorite porphyry.Its weighted average age is 160.9±2.5 Ma (MSWD=0.69).This age is the crystallizing age of the granodiorite porphyry.The age of the ore-related intrusion is consistent with the molybdenum Re-Os isotopic age (162±2 Ma)of the skarn ore in the range of error,indicating that this deposit formed in the late Jurassic.Comparing this deposit with the similar deposits in the Taqian-Fuchun metallogenic belt and the Lehua-Dexing metallogenic belt in the eastern segment of the Qinhang metallogenic belt,it can be found that the ore-forming age of the former focuses on the ±161 Ma and the rock-control and ore-control structural system is northeast-trending,while the ore-forming age of the latter focuses on ±170 Ma and the rock-control and ore-control structural system is northwest-trending.This indicates that the orientation of the regional tectonic stress of the two mineralogenetic stages (170~161 Ma B. P.)in the eastern segment of the Qinhang metallogenic belt might obviously change.