河南信阳地区南湾组地球化学特征及其构造背景

GEOCHEMICAL CHARACTERISTIC AND TECTONIC SETTING OF THE NANWAN FORMATION IN XINYANG DISTRICT,HENAN PROVINCE

越来越多的研究结果表明华北与扬子板块碰撞缝合线位置位于北淮阳构造带内 ,其中 ,信阳地区南湾组构造的归属对确定华北与扬子板块碰撞缝合线位置的意义重大。南湾组的全岩及微量元素地球化学性质均揭示其具有活动陆缘沉积的特征 ;南湾组稀土元素地球化学特征表明其物源区来自上地壳。将南湾组稀土元素各特征值与华北、扬子两板块各圈层稀土元素特征值进行对比 ,发现其与华北板块上地壳的组成相似 ,与扬子板块各圈层的组成差异较大 ,因此可确定南湾组物源区主要为华北板块 ,南湾组是华北板块的组成部分 ,由此推断华北板块与扬子板块的碰撞缝合带位置应位于北淮阳构造带南湾组之南。同时 ,南湾组与邻区地层的地球化学特征对比揭示了信阳地区南湾组。

More and more research reveals that the position of collisional suture between North China and Yangtze plates is near the Beihuaiyang belt, in which the Nanwan Formation is a very important tectonic unit. Whole rock and trace elements data document that source area of the Nanwan Formation is from upper crust of active continent. Patterns of REE imply that the Nanwan Formation formed in the continental margin of North China Plate, so it can be deduced that the suture between the two plates locates on the south of Beihuaiyang belt. Geochemical feature of the Nanwan Formation is similar to those of the Fuziling Group in Anhui Province and the Liuling Group in the Qinling area, which suggests that they belong to same sedimental suit formed in different tectonic environments.