大别山北麓钼矿找矿重大进展及其矿床地质特征研究

摘要

The Dabie orogen of east-central China marks the division between the North China and Yangtze Cra-tons, and is characterized by juxtaposition of the ~ 400 Ma Tongbai metamorphic belt and the ~ 220 Ma South Qin-ling-Dabie metamorphic belt. It comprises a Late Archean crystalline basement which is composed of gneiss, granu-lite and migmatite of the Dabie Formation. The Mesoproterozoic metasedimentary rocks overlies the Archean crystalline basement and is overlain by lower Paleozoic Devonian clastic rocks. The Triassic collision between the North China and Yangtze Cratons which generated numerous granitoid intrusions such as the Shangcheng, Xinxian and Lingshan intrusions, and other small syenite stocks, such as Tangjiaping, Dayinjian, Mushan and so on. The shallow-emplaced granite porphyries are closely related to porphyry-skarn Mo and Mo-W deposites, forming the Dabie molybdenum metallogenic belt. The belt is one of China's important regions where several large molybdenum deposits are distributed. Molybdenum deposits generally accur nearly E-W direction along the tectonic lineament and are mostly concentrated in a zone stretching from the Lingshan area of Xinyang in Henan Province to the Shapinggou area of Jinzhai in western Anhui Province. They occur in the endo- and exocontact zones of the porphyries. The major types of molybdenum deposits are porphyry, less porphyry-skarn and quartz vein-type. The ore-forming ages of the molybdenum deposits in the Dabie area are mainly cluster between (122. 7 ±1.9) ～ (113.1 ±7.9) Ma. The pulse is the result of the transition of the tectonic regime from NS- to nearly EW-directions in East China.%在总结近年来钼矿勘查成果的基础上,综合论述了大别山钼矿床的基本特征和成矿规律.钼矿带呈北西向狭长带状展布,钼矿床的形成与燕山期中酸性浅成-超浅成小花岗岩斑岩体有关,钼矿床直接产于岩体内外接触带及其附近；矿床类型主要为斑岩型,少量矽卡岩型、热液脉型.结合Re-Os同位素精测年龄数据,确定了大别山钼矿床的成矿时代主要集中在(122.7±1.9)～(113.1±7.9) Ma时限之间.根据成矿地质环境和化探异常特征,评价了该区钼矿床勘查前景,认为该区钼矿成矿条件优越,找矿潜力仍然非常巨大,初步提出7个找矿远景区.