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清水泉辉长岩体位于东昆仑中缝合带清水泉蛇绿岩北侧,主要岩性为角闪辉长岩。该岩体的LA-ICP-MS锆石U-Pb测年结果为452.1±5Ma,形成时代为晚奥陶世。辉长岩体样品SiO_2含量为43.89%~45.99%,Na_2O含量为1.30%~2.32%,K_2O含量为0.68%~1.39%,P_2O_5含量为0.26%~0.40%,TiO_2含量较低,为0.74%~0.95%,MgO含量为5.72%~6.54%,Mg~#值较低,为53~54。岩石地球化学特征显示,该岩体属于拉斑玄武岩系列,稀土元素表现出轻稀土元素富集、重稀土元素亏损的特点,微量元素以富集大离子亲石元素(Cs、Rb、Ba等,尤其以Ba的正异常最为突出)、亏损高场强元素(Nb、Ta、Ti、Zr、Hf)为特征。微量元素构造判别显示,其形成于活动陆缘岛弧构造环境。结合区域地质资料研究表明,清水泉辉长岩体可能形成于以清水泉蛇绿岩为代表的东昆仑中弧后有限洋盆向北俯冲的初始阶段。
Qingshuiquan gabbro body is located in the east Kunlun seam suture Qingshuishan ophiolite north, the main lithology hornburn gabbro. LA-ICP-MS zircon U-Pb dating of this rock mass is 452.1 ± 5Ma and the formation age is Late Ordovician. The contents of SiO_2 in gabbro samples are 43.89% -45.99%, Na 2 O content is 1.30% -2.32%, K 2 O content is 0.68% -1.39%, P 2 O 5 content is 0.26% -0.40%, TiO 2 content is low, 0.74% 0.95%, the content of MgO is 5.72% ~ 6.54%, the value of Mg ~ # is low, which is 53 ~ 54. The geochemical characteristics of the rocks show that the rock belongs to the series of tholeiite basalts. The rare earth elements are characterized by enrichment of light rare earth elements and depletion of heavy rare earth elements. Trace elements enrichment of large ion lithophile elements (Cs, Rb, Ba, Especially the positive anomalies of Ba are the most prominent), depleted high field strength elements (Nb, Ta, Ti, Zr, Hf). The trace element structure discrimination shows that it is formed in the active land marginal island arc tectonic environment. According to the study of regional geological data, the Qingshuiquan gabbro body may be formed at the initial stage of the northward subduction of the finite oceanic basin after the middle arc of East Kunlun, represented by Qingshuiquan ophiolite.