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水洞峡蛇绿岩主要由辉石岩、辉长岩和玄武岩组成。玄武岩的Sm-Nd年龄值为492.9±22.6Ma,表明为早奥陶世岩浆产物。玄武岩具有较高的SiO2和TiO2含量,LREE富集,基本无铕异常,具有较低的Th/Ta比值,和较高的Ta/Hf的值,主要地球化学特征与WPB相似,与OIB有区别,在构造环境判别图解中,玄武岩均投入WPB区域。根据上述特征并结合区域地质构造特征,认为可能形成于板内拉张环境。
The Shuidongxia ophiolite is mainly composed of pyroxene, gabbro and basalt. The Sm-Nd age value of basalts is 492.9 ± 22.6Ma, indicating that the Early Ordovician magma products. The basalts have high content of SiO2 and TiO2, LREE enrichment, little Eu anomaly, low Th / Ta ratio and high value of Ta / Hf. The main geochemical characteristics are similar to WPB and different from OIB In the tectonic setting diagram, basalt is put into WPB area. According to the above characteristics and combined with the geological structure of the region, it is considered that it may form in the plate tension environment.