摘要
苦水蛇绿混杂岩是近年来在苦水地区从老地层命名中解体而来,混杂岩中蚀变辉绿岩、玄武岩的主微量元素的测试结果显示,轻稀土LREE略富集,重稀土Yb、Lu略亏损,(La/Sm)_N值为0. 79~0. 92,(La/Yb)_N=1.45~1.73,具有洋中脊玄武岩的特征,在Ti-Zr图解判别中,为洋中脊玄武岩(MORB),综合认为区内玄武岩应形成于洋脊环境。辉长岩的LA-ICP-MS锆石U-Pb年龄测定结果为(336.3±2.3)Ma,谐和图密集,结合该区前人年代学和区域地质调查等资料,认为苦水蛇绿混杂岩的时代下限为石炭纪,与同一构造带中的鄯善县康古尔塔格蛇绿岩代表了同一个洋盆——康古尔洋,且洋盆存在的时限可能比较长,早古生代就发育有古洋盆。
Kushui ophiolitic melange is disintegrated from the old strata in Kushui area in recent years. The main micro-test results of basalt and altered diabase in the melange show that LREE is slightly enriched, Yb and Lu are slightly depleted,(La/Sm)_N is 0.79-0.92,(La/Yb)_N is 1.45-1.73, and it has the characteristics of mid-oceanic ridge basalt. In Ti-Zr diagram, it is distinguished as mid-oceanic ridge basalt. The LA-ICP-MS zircon U-Pb dating of gabbro is 336.3 ±2.3 Ma, which is dense in harmony map. Combined with the data of previous chronology and regional geological survey, it is considered that the lower age limit of Kushui ophiolitic melange is Carboniferous and Kangguertage ophiolite in the same tectonic belt. The Kangguertage ophiolite in Shanshanxian County represents the same ocean Basin-the Kanggultag Ocean, and the existence time of the ocean basin may be relatively long. The ancient ocean basin was developed in the Early Paleozoic.
引文
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