矿床地质2011，Vol.30Issue(5)：828-836,9.
黑龙江岔路口钼多金属矿床辉钼矿铼-锇同位素年龄及地质意义
Re-Os isotopic dating of molybdenite separates from Chalukou porphyry Mo polymetallic deposit in Heilongjiang Province
摘要
Abstract
Located at the northernmost corner of the Deerbugan metallogenic belt and in the northeastern part of the Mongolian-Hinggan amalgamated massif, the newly found Chalukou ore deposit is the largest molybdenum poly-metallic deposit ever discovered in China. It contains 1.34 Mt of Mo (metal), 0.37 Mt of Pb-Zn and 4 200 t of Ag. As a part of the evaluation project of the molybdenum deposit, mineral exploration around Chalukou is still underway. During the Mesozoic Yanshanian orogeny, intense extensional tectonic and igneous activities resulted in the formation of large-scale acid volcanic rocks and granitoid intrusions at Chalukou and its neighboring areas. The Chalukou granite porphyry and quartz porphyry stocks were emplaced in the Jurassic volcano-sedimentary sequence controlled by NE-and NW-trending fault zones. Rock-forming minerals of the two porphyry stocks are mainly quartz, microcline, microperthite and plagioclase associated with minor biotite and sericite. Accessoryminerals include magnetite, apatite, zircon, sphene, and allanite. Molybdenum mineralization occurs within the Chalukou porphyry stocks and volcanic rocks as stockworks, veins, veinlets and disseminated blocks. The molybdenum ore consists of pyrite, chalcopyrite, molybdenite, sphalerite, galena, magnetite, pyrrhotite, K-feldspar, fluorite, quartz, sericite and chlorite. As the most important economic molybdenum mineral, molybdenite occurs in the impregnation, radioflake, thin film, aggregated flake and veinlet forms. Re-Os isotopic dating of eight molybdenite separates from the main ore body yielded an isochron age of (146.96 ± 0.79) Ma and model ages ranging from 146.2 Ma to 149.1 Ma with an average value of 147.4 Ma. The Re-Os isochron age is in agreement with field geological evidence, and the molybdenite is coexistent with chalcopyrite and pyrite, suggesting that the Re-Os isochron age represents the ore-forming time of the porphyry Mo mineralization in the Chalukou ore deposit and its neighboring areas. Combined with field geological observations and petrological evidence, the authors hold that the ore-forming materials might have been derived from a mixed source of depleted mantle-and crustal-derived magma or fluids. The Re-Os isochron age of the molybdenite separates at Chalukou indicates that late Jurassic intraplate granitoid magmatism and relevant molybdenum polymetallic mineralization in the northernmost part of the Da Hinggan Mountains were active after the latest Paleozoic collision between the Siberian plate and the Mongolian-Hinggan amalgamated massif. Therefore, the Chalukou district and its neighboring areas have a great potential for Mesozoic Yanshanian granitoid porphyry molybdenum polymetallic deposits.关键词
地球化学/铼-锇同位素年龄/辉钼矿/成矿时代/斑岩型钼多金属矿床/岔路口/大兴安岭Key words
geochemistry Re-Os isotopic age/molybdenite/ore-forming age/porphyry molybdenum polymetallic deposit/Chalukou/Da Hinggan Mountains分类
天文与地球科学引用本文复制引用
聂凤军,孙振江,李超,刘翼飞,吕克鹏,张可,刘勇..黑龙江岔路口钼多金属矿床辉钼矿铼-锇同位素年龄及地质意义[J].矿床地质,2011,30(5):828-836,9.基金项目
本文为国家重点自然科学基金项目(编号:41030421)和地质调查项目(编号:1212010911029)的成果 （编号:41030421）
