新疆东准噶尔早志留世弧岩浆岩:来自姜格尔库都克石英二长闪长岩岩石地球化学、锆石U-Pb年龄和Hf同位素证据

发布时间：2018-05-12 01:18

本文选题：石英二长闪长岩 + 早志留世　；参考：《现代地质》2016年06期

【摘要】：新疆东准噶尔姜格尔库都克石英二长闪长岩体被下泥盆统卓木巴斯套组不整合覆盖,其形成时代一直缺乏精确的年代学约束。采用LA-ICP-MS锆石U-Pb同位素测年方法,获得石英二长闪长岩锆石U-Pb年龄为(432.8±1.2)Ma,表明侵位时限为早志留世。岩石地球化学显示,石英二长闪长岩具低硅(Si O2=55.64%~58.68%)、低钛(Ti O2=0.54%~0.71%)、高铝(Al2O3=16.99%~18.05%)的特征,属高钾钙碱性、准铝质(A/CNK=0.85~1.00)系列,富集轻稀土元素(LREE)(LREE/HREE=2.88~3.26)和大离子亲石元素(LILE,如K、Rb、Ba和Sr),亏损高场强元素(HFSE:Nb、Ta、Ti)及P,反映出明显的消减带岩浆岩的特征。锆石具正εHf(t)值,介于+10.8~+13.6之间,两阶段Hf模式年龄(TDM2)为726~560 Ma,大于其形成年龄,表明源区可能为新元古代晚期至早古生代早期的新生岛弧陆壳物质。结合区域地质背景,认为姜格尔库都克石英二长闪长岩可能由俯冲洋壳和沉积物的含水流体引起上覆地幔楔以新元古代晚期至早古生代早期的新生岛弧陆壳物质部分熔融形成的,代表了古亚洲洋在早志留世时期向南俯冲消减的陆缘弧岩浆产物。
[Abstract]:The Xinjiang East Junggar Jianggaer Kuduk quartz monzodiorite is covered by the unconformity of the Lower Devonian Zhuomubas formation, and its formation age has been short of precise chronological constraints. Using LA-ICP-MS zircon U-Pb isotopic dating method, the zircon U-Pb age of quartz monzodiorite is 432.8 卤1.2 Ma, indicating that the emplacement time is early Silurian. The petrochemistry shows that the quartz monzodiorite has the characteristics of low silica, SiO2, 55.64 and 58.68, low Ti, Ti, O, 0.54, 0.54, 0.71, and high alumina, Al _ 2O _ 3, 16.99, and 18.05), which belong to the high-potassium calc-alkaline, quasi-aluminous Ar / CNK 0.85 / 1.00 series. The enrichment of LREE / HREE (2.88 ~ 3.26) and the large ion lithophile elements such as K _ (RbN) Ba and Sr ~ (2 +), and the depletion of high field strength elements (HFSE: NB ~ (+) Tatii) and Pe) reflect the characteristics of subducted zone magmatic rocks. The zircon has a positive 蔚 HfT (10.8 ~ 13.6), and the two-stage HF model age (TDM2) is 726560Ma. it is larger than its age of formation, indicating that the source region may be a neoproterozoic to early Paleozoic Cenozoic island-arc continental crust material. Combined with the regional geological background, It is considered that the Jiangerkuduk quartz monzodiorite may have been formed by the partial melting of the overlying mantle wedge from subducted oceanic crust and water bearing fluid in sediments from the late Neoproterozoic to the early Paleozoic. It represents the continental margin arc magma that subducted southward during the early Silurian period in the Paleo-Asian Ocean.
【作者单位】：陕西区域地质矿产研究院;
【基金】：中国地质调查局项目“新疆滴水泉幅(L45C003004) 北塔山牧场幅(L46C003001)1∶25万区调修测”(1212011120500) 中央返还两权价款资金项目“新疆东准噶尔卡拉麦里金矿带控矿构造调查研究及靶区优选”(Y15-1-LQ02)
【分类号】：P588.122;P597

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