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且干布拉克杂岩体位于库鲁克塔格地块的西南缘,是构造运移到陆壳中的大陆岩石圈地幔顶部的岩块。在862±12Ma期间,该岩体在地幔内经历了复杂的交代作用首先是透辉石交代蛇纹岩;然后是金云母交代蛇纹岩和透辉岩,这些金云母经近地表地质作用后形成了我国规模最大的蛭石矿床;最后是含金云母的碳酸岩岩脉贯入并交代先期形成的各种岩石。研究证明,交代剂应当是碳酸质的碱性硅酸盐熔体或流体,并分异成共轭的两部分这些交代剂普遍具有Ta、Nb、Ti、Zr和Hf的贫化;而且,Nd、Sr、Pb、O、C、H同位素组成普遍具EMⅠ、EMⅡ地幔端元和地壳岩石的特征。由此而证明交代剂主要源自于消减板块中的深海沉积物和在海沟中裹挟的陆源浊积岩。
The dry Brak Complex is located on the southwestern margin of the Kuluke Tagu Block and constitutes the top of the continental lithospheric mantle that migrates into continental crust. During the period of 862 ± 12Ma, the rock subjected to complicated metasomatism within the mantle is dominated by diopside to account for serpentinite, then phlogopite to serpentinite and diopside, and these phlogopites are characterized by near-surface geology Forming the vermiculite deposit of the largest scale in our country. Finally, carbonate rock veins containing phlogopite mica penetrate into and confront various pre-formed rocks. Studies have shown that the replacement agent should be an alkaline silicate melt or fluid of carbonates and differentially conjugated to two parts. These agents generally have the depletion of Ta, Nb, Ti, Zr and Hf; and Nd The isotopic compositions of Sr, Pb, O, C and H are generally characterized by EM Ⅰ, EM Ⅱ mantle plume and crustal rocks. This proves that the agent mainly comes from the deep sea sediments in the subducting plate and the terrigenous turbidites that are trapped in the trench.