CAJ | 학술논문

内蒙古苏-查萤石矿区是全球范围内最大的单一萤石矿区.萤石矿体大多呈似层状和透镜体状在下二叠统火山-沉积岩地层内产出,并且与显生宙花岗岩类侵入岩体具有密切时空分布关系,其中部分矿体直接出现在敖包吐花岗岩株中.本次研究主要对敖包吐岩株钾长花岗岩进行了锆石SHRIMP铀-铅同位素年龄测定,所获同位素年龄值为(138±4)Ma,MSWD值为2.3,属中生代燕山期.根据上述同位素年代学数值,同时结合其他地质与地球化学证据,可以推测,中生代时期,受古板块内部构造应力调整作用影响,苏-查萤石矿区及东西两侧曾发生过强烈构造-岩浆活动,并且形成有敖包吐花岗岩株及相关的萤石矿床.中生代燕山期花岗岩类岩浆活动不仅为萤石矿床的形成提供了物质、动力和热力来源,而且是成矿流体对流循环的"发动机".对比分析结果表明,敖包吐岩体的形成时间与华北陆台中东段许多含矿花岗岩体的成岩时代大体相似,它们很可能是地壳演化特定阶段混源(壳、幔源)岩浆活动的产物.
내몽고소-사형석광구시전구범위내최대적단일형석광구.형석광체대다정사층상화투경체상재하이첩통화산-침적암지층내산출,병차여현생주화강암류침입암체구유밀절시공분포관계,기중부분광체직접출현재오포토화강암주중.본차연구주요대오포토암주갑장화강암진행료고석SHRIMP유-연동위소년령측정,소획동위소년령치위(138±4)Ma,MSWD치위2.3,속중생대연산기.근거상술동위소년대학수치,동시결합기타지질여지구화학증거,가이추측,중생대시기,수고판괴내부구조응력조정작용영향,소-사형석광구급동서량측증발생과강렬구조-암장활동,병차형성유오포토화강암주급상관적형석광상.중생대연산기화강암류암장활동불부위형석광상적형성제공료물질、동력화열력래원,이차시성광류체대류순배적"발동궤".대비분석결과표명,오포토암체적형성시간여화북륙태중동단허다함광화강암체적성암시대대체상사,타문흔가능시지각연화특정계단혼원(각、만원)암장활동적산물.
Located on the northern margin of the North China continental massif, the Su-Cha (Sumoqagan Obo) fluorite ore district is the largest independent fluorite ore district in the world. Fluorite mineralization occurs in both Late Paleozoic volcano-sedimentary sequences of the Xilimiao Group and Mesozoic granitoid intrusions. Among these granitoid intrusions, the Aobaotu granitoid stock shows an intimate spatial relationship with the fluorite deposits. It intruded into Lower Permian volcano-sedimentary rocks of the Xilimiao Group, with an out-crop of 66 km2. The stock consists mainly of K-feldspar granite in the central facies and marginal facies porphyry-like granites. Petrology, geochemistry and isotopic geology of the Aobaota stock are similar to those of Paleozoic and Mesozoic granitoid intrusions, with positive Nd (t) values existent within the Da Hinggan Moun-tains-Mongolia orogenic belt. A fresh K feldspar granite sample from the Aobaotu granitoid stock was selected for SHRIMP U-Pb age dating. The zircon grains separated from the fresh K-feldspar granite sample give a weighted mean ~(206)pb/~(238)U age of 138±4 Ma, with a MSWD value of 3.2. Based on this zircon SHRIMP U-Pb age and com-bined with other geological evidence, it is suggested that the Aobaotu granitoid stock and its related fluorite de-posits were formed within a reformed rift basin located along the collision zone of the North China continental massif and Siberian platform. The Aobaotu granitoid stock was probably a product of Mesozoic Yanshanian tectonic-magmatic activities, and played an important role in the ore-forming process of the Su-Cha fluorite deposit. The rock-forming materials of the Aobaotu granitoid stock were derived from a mixed source composed of mantle- and crust-related components.