CAJ | 학술논문

阿吾拉勒成矿带位于新疆西天山伊犁地块东北缘,是一条极其重要的铁、铜、金多金属成矿带。松湖铁矿床位于该成矿带西段,矿区出露的地层主要为一套钙碱性系列的火山岩,岩石类型有安山岩、安山质火山碎屑、少量英安岩、流纹岩及等质的火山碎屑岩。铁矿体赋存于安山岩及安山质火山碎屑岩中。安山岩中锆石U-Pb谐和年龄为(343.2±2) Ma,属早石炭世维宪期。该组火山岩具有相似的稀土元素及微量元素地球化学特征,暗示它们应为同源岩浆演化的产物。其微量元素组成具有富集大离子亲石元素(Rb、Ba、Th、K等)和轻稀土元素、亏损高场强元素(Nb、Ta和Ti)的特点,显示活动大陆边缘火山岩特征。矿区安山岩的Nd同位素组成具有亏损型特征(εNd(t)=+2.09~+3.39,平均值为+2.59),而Sr同位素组成为富集型((87Sr/86Sr)i=0.7056~0.7060),显示其岩浆源区应为莫霍面附近的岛弧型地壳根部。
아오랍륵성광대위우신강서천산이리지괴동북연,시일조겁기중요적철、동、금다금속성광대。송호철광상위우해성광대서단,광구출로적지층주요위일투개감성계렬적화산암,암석류형유안산암、안산질화산쇄설、소량영안암、류문암급등질적화산쇄설암。철광체부존우안산암급안산질화산쇄설암중。안산암중고석U-Pb해화년령위(343.2±2) Ma,속조석탄세유헌기。해조화산암구유상사적희토원소급미량원소지구화학특정,암시타문응위동원암장연화적산물。기미량원소조성구유부집대리자친석원소(Rb、Ba、Th、K등)화경희토원소、우손고장강원소(Nb、Ta화Ti)적특점,현시활동대륙변연화산암특정。광구안산암적Nd동위소조성구유우손형특정(εNd(t)=+2.09~+3.39,평균치위+2.59),이Sr동위소조성위부집형((87Sr/86Sr)i=0.7056~0.7060),현시기암장원구응위막곽면부근적도호형지각근부。
Located at the northwest edge of Yili plate in Western Tianshan Mountains, Xinjiang, the Awulale metallogenic belt is one of the significant polymetallic iron, copper and gold belts discovered in recent years. The Songhu iron deposit is one of the volcanic type iron deposits in the western part of the belt and is hosted in the 2nd member of the Carboniferous Dahalajunshan Group. This paper focused on the petrology, petrography, geochemistry and geochronology of the volcanic rocks exposed in the ore district and tried to constrain their tectonic settings and petrogenesis. Some conclusions have been reached: (1) These volcanic rocks mainly consist of andesite and dacite, with minor rhyolite and volcaniclastic rocks, and belong to the calc-alkaline series. (2) The U-Pb age of zircons in the andesite is (343.2±2) Ma (MSWD=1.8), suggesting the Visean Age. (3) Trace element patterns show enrichment of LILE (Rb, Ba, Th, K etc.) and LREE, and depletion of HFSE (Nb, Ta, Ti). These characteristics suggest that these volcanic rocks might have been formed in the active continental margin arc and produced by cognate magma. (4) These volcanic rocks are characterized by relatively highεNd(t) values (+2.09 ~ +3.39) and high initial87Sr/86Sr ratios (0.7056~0.7060). The Nd-Sr isotopic characteristics indicate that their magma source was the roof of continental arc crust near the Moho surface.