CAJ | 학술논문

北天山温泉群长期以来被认为是古元古代的变质岩。最新的野外调查和锆石SHRIMP U-Pb测年结果表明，温泉群可以划分为三个岩石构造单元：（1）前早新元古代变质火山岩和变质沉积岩，主要包括斜长角闪岩、云母片岩、石英片岩、黑云母片麻岩、大理岩等；（2）早新元古代混合岩和正片麻岩；（3）早古生代未变质变形的辉长岩和闪长岩。上述三种岩石组合类型均被后期二云母花岗岩（脉）所侵入。温泉县以南的混合岩和花岗片麻岩中锆石的SHRIMP U-Pb年龄分别为926±12 Ma和907±11 Ma，与天山地区出露的新元古代花岗岩类的时代基本一致。结合前人对花岗片麻岩Nd同位素组成的研究，花岗片麻岩应为古老地壳物质部分熔融的产物，而同期的混合岩化作用则是新元古代地壳加厚和部分熔融的直接地质证据。辉长岩和闪长岩侵入到温泉群花岗片麻岩和斜长角闪岩中，其中闪长岩的锆石SHRIMP U-Pb年龄为452±7 Ma，并含有1.1 Ga和1.4 Ga的继承锆石。根据前人的研究成果，本区早古生代辉长岩和闪长岩具有岛弧岩浆岩的地球化学特征，可能与准噶尔-巴尔喀什洋的俯冲作用有关，这一俯冲增生作用最终导致伊犁北部与哈萨克斯坦陆块在志留纪拼贴造山，并使温泉群前寒武纪变质岩与侵入岩发生变质变形作用。
북천산온천군장기이래피인위시고원고대적변질암。최신적야외조사화고석SHRIMP U-Pb측년결과표명，온천군가이화분위삼개암석구조단원：（1）전조신원고대변질화산암화변질침적암，주요포괄사장각섬암、운모편암、석영편암、흑운모편마암、대리암등；（2）조신원고대혼합암화정편마암；（3）조고생대미변질변형적휘장암화섬장암。상술삼충암석조합류형균피후기이운모화강암（맥）소침입。온천현이남적혼합암화화강편마암중고석적SHRIMP U-Pb년령분별위926±12 Ma화907±11 Ma，여천산지구출로적신원고대화강암류적시대기본일치。결합전인대화강편마암Nd동위소조성적연구，화강편마암응위고로지각물질부분용융적산물，이동기적혼합암화작용칙시신원고대지각가후화부분용융적직접지질증거。휘장암화섬장암침입도온천군화강편마암화사장각섬암중，기중섬장암적고석SHRIMP U-Pb년령위452±7 Ma，병함유1.1 Ga화1.4 Ga적계승고석。근거전인적연구성과，본구조고생대휘장암화섬장암구유도호암장암적지구화학특정，가능여준갈이-파이객십양적부충작용유관，저일부충증생작용최종도치이리북부여합살극사탄륙괴재지류기병첩조산，병사온천군전한무기변질암여침입암발생변질변형작용。
The metamorphic rocks of the Wenquan Group in the Northern Chinese Tianshan have been regarded as Paleoproterozoic in age. According to our field observations and zircon SHRIMP U-Pb dating, the Wenquan Group can be subdivided into three lithotectonic units: (1) pre-Early Neoproterozoic meta-volcanic and meta-sedimentary rocks, including amphibolite, micaschist, quartz schist, biotite gneiss and marble;(2) Early Neoproterozoic migmatite and orthogneiss;and (3) undeformed Early Paleozoic gabbro and diorite. All these three units were intruded by two-mica granite or dykes. Migmatite and granitic gneiss collected from the south of Wenquan City yielded zircon SHRIMP U-Pb ages of 926±12 Ma and 907±11 Ma, respectively. These ages are close to those of Neoproterozoic granitoids occurring in the Chinese Tianshan. Previous results of a Nd isotopic study on orthogneiss indicate an origin of partial melting of continental crust, and the occurrences of synchronous migmatite support a thickening and partial melting of continental crust. Gabbro and diorite intruded in the granitc gneiss and amphibolite of the Wenquan Group. A diorite yields a zircon SHRIMP U-Pb age of 452±7 Ma, and contains inherited zircons with older ages of 1.1 Ga and 1.4 Ga. According to the previous studies, the gabbro and diorite have geochemical features of arc-related magmatism, the early Paleozoic arc-type magmatic rocks of the study area were likely formed during subduction of the Junggar-Balkhash Oceanic lithosphere, and the subsequent accretion between the Northern Yili block and the Kazakhstan continent that induced the metamorphism and deformation of the Precambrian metamorphic and magmatic rocks of the Wenquan Group.