南秦岭地区存在两种不同构造属性的耀岭河群

The existence of two different tectonic attributes in Yaolinghe Group in South Qinling region

广泛分布于南秦岭构造带的耀岭河群变质火山岩对南秦岭构造带的属性，乃至整个秦岭造山带的演化起着十分重要的作用。通过对湖北两郧、陕西商南、镇安和安康凤凰山等地区耀岭河群变质岩石组合、原岩组合、岩石化学和稀土、微量元素等方面的研究表明，在不同地区耀岭河群具有不同的岩石组合、岩石化学和地球化学特征，安康-武当地区中部的耀岭河群为板内拉斑玄武岩-偏碱性玄武岩组合，形成于板内拉张-裂谷环境，而商南耀岭河、镇安和安康凤凰山等地区的耀岭河群则为钙碱性玄武岩-岛弧拉斑玄武岩组合，形成于会聚板块边缘-岛弧构造背景，进一步证实南秦岭地区在6．5～8亿年期间存在两种不同的构造体制。

The study of metamorphic volcanic rocks of Yaolinghe Group widely distributed in South Qinling tectonic belt is very important in determining the attribute of South Qinling tectonic belt and even the evolution process of the whole Qinling orogenic belt. Results of this study show that Yaolinghe Group possesses different rock assemblages. This conclusion is based on petrochemical and geochemical characteristics in different areas obtained from exploration of metamorphite assemblages and initial rocks as well as analyses of petrochemical components, rare earth and trace elements in Yunxian-Yunxi （Hubei）, Shangnan （Shaanxi）, Zhen＇ an, Fenghuangshan, Ankang and other areas. Studies of metavolcanite obviously show that Yaolinghe Group in the center of Ankang-Wudang area is an intraplate tholeiite-partial alkali basalt group formed in a pull-apart intraplate （rift basin） tectonic setting, whereas Yaolinghe Group in Shangnan, Zhen＇an and Fenghuangshan areas are of calcalkali basalt-island arc tholeiite series formed on the edge of the convergent plate-island are. There must have existed two tectonic regimes in South Qinling region in the period of 650--800 Ma.