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在东准噶尔卡拉麦里蛇绿岩带南侧30~40 km的滴水泉地区新发现了一套蛇绿岩.该蛇绿岩由蛇纹石化地幔橄榄岩、辉石岩、辉长岩、斜长岩、玄武岩以及少量的硅质岩片组成,本研究获得辉长岩的LA-ICP-MS锆石U-Pb年龄为416.8±3.2 Ma,时代为早泥盆世早期.这套蛇绿岩构造侵位于一套年龄为405.7±5.8 Ma的岛弧火山-沉积地层中,或在早石炭世的后碰撞花岗岩中呈顶垂体产出.主量元素上,该蛇绿岩中的玄武岩具有与洋中脊拉斑玄武岩一致的低Al2O3,TiO2,P2O5,K2O,高MgO,CaO特征;稀土元素上,辉石岩、辉长岩、玄武岩均为LREE明显亏损的配分型式;微量元素蛛网图中,除Rb,Ba,U,Sr等活泼元素有异常波动外,总体上表现为平坦型的分布特征,其中玄武岩中的各元素的丰度与N-MORB十分一致,辉长岩和辉石岩中各元素的丰度则相对N-MORB明显亏损,具堆晶超镁铁-镁铁质岩的特点.通过区域地质背景分析,结合Hf/3-Th-Ta,TiO2-FeO/MgO,Ti/1000-V,Zr/Y-Zr等构造判别图解结果,认为该蛇绿岩应形成于洋中脊环境,是哈萨克斯坦-准噶尔古板块和西伯利亚板块之间的古洋盆岩石圈残片,该洋盆打开于中志留世之前,在晚泥盆世之前闭合,随后进入后碰撞-陆内演化阶段.滴水泉洋中脊型蛇绿岩带的发现给我们提供了一个重要的启示,即在时代和成因认识上存在较大分歧的卡拉麦里蛇绿岩带中的蛇绿岩可能并非单一成因,而是本次发现的洋中脊型蛇绿岩和其北侧的俯冲带型蛇绿岩因后期构造混杂的产物.
A new set of ophiolites has been discovered in the area of Dripuquan, 30 ~ 40 km to the south of the Kalamaili ophiolite belt in East Junggar, which is composed of serpentinized mantle peridotite, pyroxene rock, gabbro, Long rock, basalt and a small amount of chert, the LA-ICP-MS zircon U-Pb age of the obtained gabbro was 416.8 ± 3.2 Ma, dating from early Early Devonian.The ophiolite structure The intrusion is located in a set of island arc volcano-sedimentary formations with an age of 405.7 ± 5.8 Ma or in the late Carboniferous post-collisional granite as a top pituitary.The main elements of this ophiolite are the The middle ridge spinel basalt is consistent with low Al2O3, TiO2, P2O5, K2O, high MgO and CaO characteristics. On the rare earth elements, the pyroxenite, gabbro and basalts are all characterized by obvious depletion of LREE. In addition to the abnormal fluctuations of the active elements such as Rb, Ba, U, Sr and so on, there are generally flat distributions, in which the abundance of each element in the basalt is in good agreement with the N-MORB. In the gabbro and pyroxene The abundance of each element is obviously depleted relative to that of N-MORB, and is characterized by the accumulation of ultramafic-mafic rocks. By analyzing the regional geological background , The results of the discrimination of structures such as Hf / 3-Th-Ta, TiO2-FeO / MgO, Ti / 1000-V and Zr / Y-Zr indicate that the ophiolite should be formed in the mid-ocean ridge environment and be a Kazakhstan-Junggar Paleo-oceanic lithosphere fragments between the old plate and the Siberian plate, which closed before the Late Devonian and then entered the post-collisional-intracontinental evolution stage before the Middle Silurian. The discovery of the ophiolite belt provides us with an important revelation that the ophiolite in the Kalamaili ophiolite belt, which has a long history of divergence in age and genesis, may not be the single cause, but the discovery of this time Mid-oceanic ridge ophiolite and its subduction-type ophiolite on the north of the late tectonic confluence of products.