CAJ | 학술논문

近年,在安徽金寨银山地区,发现了钼-铅-锌多金属矿床,赋矿岩石为中酸性岩浆岩.岩浆岩中的黑云母和角闪石单矿物的~(40)Ar-~(39)Ar同位素地质年龄测定表明,矿区内的中粒二长花岗岩、细粒二长花岗岩和细晶闪长岩脉分别形成于(136.8±1.6)Ma、(130.4±1.2)Ma和(125.4±1.0)Ma,为燕山晚期早白垩世侵入岩.根据岩体产状和接触关系,赋矿石英正长(斑)岩和爆发角砾岩的形成晚于二长花岗岩和细晶闪长岩脉.矿区内,钼矿体和铅锌矿体主要呈脉状产于不同岩性的岩浆岩体中,钼矿体主要发育于爆发角砾岩中心附近的石英正长斑岩中,铅锌矿体则主要赋存在二长花岗岩体中.钼矿床中辉钼矿的Re-Os同位素模式年龄为(112.6±1.3)Ma和(113.5±1.3)Ma.根据矿体与岩浆岩的相互关系以及同位素地质年龄测定,矿区内的钼-铅-锌多金属矿床与石英正长斑岩的形成时间接近,成矿与浅成-超浅成偏碱性岩浆的侵入和相关的热液作用有关,属于斑岩-隐爆角砾岩型矿床.结合前人的研究成果,笔者认为:该区的岩浆岩和钼-多金属矿床形成于中国东部大规模岩石圈减薄、拆沉和热侵蚀的地球动力学背景,大别造山带应力场由挤压转化至伸展阶段以后;区内的钼-多金属矿床归属东秦岭-大别钼成矿带的东延部分,是中国东部EW向大规模成矿带的组成部分.
근년,재안휘금채은산지구,발현료목-연-자다금속광상,부광암석위중산성암장암.암장암중적흑운모화각섬석단광물적~(40)Ar-~(39)Ar동위소지질년령측정표명,광구내적중립이장화강암、세립이장화강암화세정섬장암맥분별형성우(136.8±1.6)Ma、(130.4±1.2)Ma화(125.4±1.0)Ma,위연산만기조백성세침입암.근거암체산상화접촉관계,부광석영정장(반)암화폭발각력암적형성만우이장화강암화세정섬장암맥.광구내,목광체화연자광체주요정맥상산우불동암성적암장암체중,목광체주요발육우폭발각력암중심부근적석영정장반암중,연자광체칙주요부존재이장화강암체중.목광상중휘목광적Re-Os동위소모식년령위(112.6±1.3)Ma화(113.5±1.3)Ma.근거광체여암장암적상호관계이급동위소지질년령측정,광구내적목-연-자다금속광상여석영정장반암적형성시간접근,성광여천성-초천성편감성암장적침입화상관적열액작용유관,속우반암-은폭각력암형광상.결합전인적연구성과,필자인위:해구적암장암화목-다금속광상형성우중국동부대규모암석권감박、탁침화열침식적지구동역학배경,대별조산대응력장유제압전화지신전계단이후;구내적목-다금속광상귀속동진령-대별목성광대적동연부분,시중국동부EW향대규모성광대적조성부분.
In recent years, molybdenum-lead-zinc polymetallic deposits were discovered in Yinshan area, Jinzhai, An-hui Province. The ore bodies are hosted mainly in Yanshanian rnagmatic rocks. Dating results of ~(40)Ar/~(39)Ar iso-topic ages of biotite and hornblende in magmatic rocks show that medium-grained adamellite, fine-grained adamellite and fine-granined diorite in the ore district were formed respectively in (136.8 ± 1.6) Ma, (130.4 ±1.2) Ma and (125.4 ± 1.0) Ma, suggesting that they are Early Cretaceous products formed during late Yansha-nian movement. According to their attitudes and relationship, quartz-syenite (porphyry) and explosion-breccia were formed later than adamellite and diorite. Regional magmatism evolved from high potassium calc-alkaline to alkaline. Molybdenum and lead-zinc deposits occur in the veined form in different lithologic magmatic rocks, and molybdenum deposits mainly occur in quartz syenite (porphyry) distributed in the center of explosion-breccia.The Re-Os isotopic model ages of motybdenite in molybdenum deposits are (112.6 ± 1.3) Ma and (113.5 ±1.3) Ma, which are considered to be the ages of regional molybdenum deposits. Geological characteristics and isotopic ages show that the molybdenum-lead-zinc polymetallic deposits may genetically related to the emplace-ment and hydrothermal activities of the late stage quartz syenite (porphyry). These deposits should thus belong to shallow-seated or ultra-shallow-seated porphyry-explosion-breccia deposits. In combination with the achieve-ments made by previous researchers, the authors hold that the molybdenum-lead-zinc polymetallic deposits and related magmatic rocks were formed in a geodynamic setting of regional large-scale lithospheric thinning, delami-nation and thermal erosion in East China, and also in a regional stress field formed during the conversion of the Dabie orogenic belt to the extension stage. The molybdenum polymetallic deposits are controlled by the EW-trending structures, and belong to the East Qinling-Dabie molybdenum belt, a part of the larger EW-trending metallogenic belt in eastern China.