CAJ | 학술논문

对山西代县洪塘矿区富含红色和黑色两种金红石的直闪岩进行岩相观察和矿物成分分析,并就其中锆石在阴极发光下的外部形态、内部结构及矿物包裹体进行研究.所分选出的锆石按其颗粒上的相对位置、形态、阴极发光图像、SHRIMP年龄值以及内部矿物包裹体划分为复杂锆石和单成因锆石,其中复杂锆石由核部、幔部和边部锆石三类锆石组成.第1类锆石无环带,部分边缘可见溶蚀痕迹,为继承锆石.内部包裹富锾矿物组合顽火辉石+金云母,与寄主岩石的组合明显不同,反映其可能是寄主岩石形成之前保留于锆石中的原岩矿物并源于地幔.第Ⅱ类锆石为半自形-自形晶,环带较宽且清晰,推测为高级变质锆石.其内矿物包裹体主要为直闪石,其次为钙铁辉石(?),反映其形成于角闪岩相,与寄主岩石的矿物组合可能一致.第Ⅲ类锆石主要位于增生边,阴极发光亮度高,推测为流体改造的变质锆石.第Ⅳ类单成因锆石多呈自形,阴极发光下较暗,生长环带规则且较窄.矿物包裹体有钠长石+石英+白云母,对应中压绿片岩相,其形成温度和压力低于寄主岩石,它与第Ⅲ类锆石可能是在同一期后期事件中形成.结合岩相学研究结果,认为该区金红石矿床之原岩可能是岩浆岩,后期经历了至少两期构造热事件,早期热事件可能导致了锆石内U-Th-Pb体系的重置.以上研究结果表明经历复杂变质作用的变质岩中锆石内部矿物包裹体的研究分析还是探讨寄主岩石成因及所经历地质事件的有效手段.
대산서대현홍당광구부함홍색화흑색량충금홍석적직섬암진행암상관찰화광물성분분석,병취기중고석재음겁발광하적외부형태、내부결구급광물포과체진행연구.소분선출적고석안기과립상적상대위치、형태、음겁발광도상、SHRIMP년령치이급내부광물포과체화분위복잡고석화단성인고석,기중복잡고석유핵부、만부화변부고석삼류고석조성.제1류고석무배대,부분변연가견용식흔적,위계승고석.내부포과부환광물조합완화휘석+금운모,여기주암석적조합명현불동,반영기가능시기주암석형성지전보류우고석중적원암광물병원우지만.제Ⅱ류고석위반자형-자형정,배대교관차청석,추측위고급변질고석.기내광물포과체주요위직섬석,기차위개철휘석(?),반영기형성우각섬암상,여기주암석적광물조합가능일치.제Ⅲ류고석주요위우증생변,음겁발광량도고,추측위류체개조적변질고석.제Ⅳ류단성인고석다정자형,음겁발광하교암,생장배대규칙차교착.광물포과체유납장석+석영+백운모,대응중압록편암상,기형성온도화압력저우기주암석,타여제Ⅲ류고석가능시재동일기후기사건중형성.결합암상학연구결과,인위해구금홍석광상지원암가능시암장암,후기경력료지소량기구조열사건,조기열사건가능도치료고석내U-Th-Pb체계적중치.이상연구결과표명경력복잡변질작용적변질암중고석내부광물포과체적연구분석환시탐토기주암석성인급소경력지질사건적유효수단.
Combined with petrographic observations and mineral compositions, morphologies, inner structures and mineral inclusions in zircons of ores from the Hongtang rutile deposit of Daixian, Shanxi. The zircons are subdivided into complicated zircons with core, mantle and rim and single zircons without overgrowth based on their relative locations, morphologies, CL images, SHRIMP ages and mineral inclusions. Type Ⅰ zircons are considered as inherited zircons, with rounded shape and no obvious zoning, which contain enstatite and phlogopite, showing different mineral association from that of its host rock. They are inferred to be previous minerals preserved in zircons before the formation of its host rock, and likely derived from mantle. Type Ⅱ zircons have broad and clear zoning, and contain anthophyllite and hedenbergite (?), in accordance with mineral associations of the host rock. They are speculated to be high grade metamorphic zircons. Type Ⅲ zircons are mainly rimed and speculated to be fluid-related zircons. Type Ⅳ zircons are mostly euhedral, with low-luminescence of CL and narrow growth zoning. They have albite, quartz and muscovite mineral inclusions, corresponding to middle-pressure green-schist facies. Type Ⅳ and type Ⅲ zircons might form in coeval thermal event. Combined with petrographic study results, it is inferred that the parent rock of this rutile ore deposit may be magmatic rock, and experience at least two thermal events, the earlier ones may result in the reset of system U-Th-Pb in zircons. The results of this investigation also show that study and analysis of mineral inclusions in zircons of high grade metamorphic rocks are an effective means of discussing the genesis and subsequent geological events of the host rock.