CAJ | 학술논문

提木哈塔依蛇绿混杂岩位于新疆西准噶尔达拉布特蛇绿岩带北东端，蛇绿岩组合包括蛇纹石化及石英菱镁岩化方辉橄榄岩、玄武岩和硅质岩，蛇绿岩中侵入有辉长岩脉。对蛇绿岩开展了详细的岩相学、岩石地球化学、锆石U-Pb年代学和Hf同位素研究。玄武岩和辉长岩均为低钾拉斑玄武岩系列，两者同时具有轻稀土富集和弱亏损的E-MORB和N-MORB的配分曲线，微量元素具有Ba、U、K、La、Ce等LILE相对富集，Nb、Ta、Th等HFSE相对亏损的特征，结合玄武岩中相对稳定的微量元素和氧化物构造判别图解，认为蛇绿岩形成于弧后盆地。玄武岩LA-ICP-MS锆石U-Pb同位素年龄为（392.5）±2.9 Ma（n=26，MSWD=1.3），代表蛇绿岩形成年龄。玄武岩锆石εHf (t)值为+12.2~+15.1，Hf同位素地幔模式年龄t(DM)（407~543 Ma）与锆石形成年龄相近，指示玄武岩直接来源于亏损地幔，且没有遭受地壳物质的明显混染。地幔岩铬尖晶石化学成分和玄武岩Dy/Yb-La/Yb图解表明，地幔橄榄岩可能为亏损的尖晶石二辉橄榄岩发生25%~30%部分熔融的残余，而熔出的基性熔体为玄武岩和辉长岩的母岩浆。综合研究认为，达拉布特蛇绿岩所代表的西准噶尔洋盆为准噶尔洋北西俯冲形成的弧后盆地，洋盆在中志留世就已经存在并开始扩张，直到早石炭世洋盆依然存在，晚石炭世洋盆进入俯冲消减和闭合阶段。
제목합탑의사록혼잡암위우신강서준갈이체랍포특사록암대북동단，사록암조합포괄사문석화급석영릉미암화방휘감람암、현무암화규질암，사록암중침입유휘장암맥。대사록암개전료상세적암상학、암석지구화학、고석U-Pb년대학화Hf동위소연구。현무암화휘장암균위저갑랍반현무암계렬，량자동시구유경희토부집화약우손적E-MORB화N-MORB적배분곡선，미량원소구유Ba、U、K、La、Ce등LILE상대부집，Nb、Ta、Th등HFSE상대우손적특정，결합현무암중상대은정적미량원소화양화물구조판별도해，인위사록암형성우호후분지。현무암LA-ICP-MS고석U-Pb동위소년령위（392.5）±2.9 Ma（n=26，MSWD=1.3），대표사록암형성년령。현무암고석εHf (t)치위+12.2~+15.1，Hf동위소지만모식년령t(DM)（407~543 Ma）여고석형성년령상근，지시현무암직접래원우우손지만，차몰유조수지각물질적명현혼염。지만암락첨정석화학성분화현무암Dy/Yb-La/Yb도해표명，지만감람암가능위우손적첨정석이휘감람암발생25%~30%부분용융적잔여，이용출적기성용체위현무암화휘장암적모암장。종합연구인위，체랍포특사록암소대표적서준갈이양분위준갈이양북서부충형성적호후분지，양분재중지류세취이경존재병개시확장，직도조석탄세양분의연존재，만석탄세양분진입부충소감화폐합계단。
Located in the northeast Darbute ophiolitic mélange, West Junggar, Xinjiang, the Muhatayi ophiolitic mélange consists mainly of harzburgite with serpentinization and silica-carbonate alteration, basalt and chert, together with some intrusive gabbro veins. In this study, petrographic and geochemical analysis, U-Pb dating and Hf isotope study were conducted for ophiolitic mélange. Both of basalt and gabbro in ophiolitic mélange belong to low-potassium tholeiitic series, display typical characteristics of E-MORB and N-MORB, and are enriched in LILE (Ba, U, K, La, Ce) and depleted in HFSE(Nb, Ta,Th). In combination with the discrimination diagrams of immobile trace elements and oxides, the authors hold that the Muhatayi ophiolitic mélange was produced in an arc-basin setting. The LA-ICP-MS U-Pb isotope dating of zircons from basalt yielded an age of (392.5 ± 2.9) Ma(n=26, MSWD=1.3), which represents the age of ophiolitic mélange.εHf (t) values of zircons range from+12.2 to+15.1 and t(DM)(407-543 Ma)values are close to the ages of zircons, which indicates that the basaltic magmas were derived from depleted mantle without crustal contamination. The chemical composition of Cr-spinel of harzburgite and the Dy/Yb versus La/Yb of basalt reveal that the harzburgite was the residual after the 25%-30% partial melting of depleted spinel-lherzolite, the mafic melt was the parental magmas of basalt and gabbro. It is thus considered that the west Junggar Basin represented by Darbute ophiolitic mélange was developed in an arc-basin setting resulting from the northwestward subduction of Junggar Ocean,the west Junggar Ocean was spread before Middle Silurian and remained existent in early Carboniferous, and then the oceanic basin experienced the stage of subdution and closure.