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本文通过对甘肃武山县鸳鸯镇蛇绿岩构造年代学的深入研究,结合野外实测地质剖面对鸳鸯镇蛇绿岩的形成,其代表的构造意义进行了探讨,该带蛇绿岩中采集的蛇纹石Sm-Nd同位素等时线年龄为473±23Ma;在该带硅化碳酸盐化变玄武岩中采用锆石U-Pb法测年,测得模式年龄值为546Ma。研究认为武山蛇绿岩其岩石组合中与显生宙的蛇绿岩大致相近,所不同的是组合中含深水碳酸盐岩;蛇绿岩中基性岩类的REE球粒陨石标准化配分模式接近平坦型及微量元素的环境判别图式都表明该蛇绿岩的生成环境很可能是初始洋盆;武山蛇绿岩代表古生代大陆裂解的产物,两组年龄值基本代表了本次大陆裂解成海盆的时代。
In this paper, through deep research on the tectonic chronology of the Yuanyangzhen ophiolite in Wushan County, Gansu Province, and the formation of the Yuanyangzhen ophiolite in the field with the measured geologic profile in the field, the paper discusses the tectonic significance of its representation. The snake collected from the ophiolite The Sm-Nd isotopic isochron age is 473 ± 23Ma. Zircon U-Pb dating is used for the silicified carbonate basalts, and the model age is 546Ma. The study shows that the rock assemblage of Wushan ophiolite is roughly similar to that of Phanerozoic ophiolite, except that the combination contains deep-water carbonate rocks; REE chondrite normalized patterns of basic rocks in ophiolite The results show that the formation environment of the ophiolite is likely to be the original oceanic basin. The Wushan ophiolite represents the product of the Paleozoic continental cleavage, and the age values of the two groups essentially represent the continental cleavage into Sea basin era.