东昆仑格尔木南部纳赤台群和万宝沟群基质系统与外来系统地球化学差异

Geochemical divergence between the matrix system and exotic block system in the Naij Tal and Wanbaogou groups in the East Kunlun Mountains

东昆仑造山带的纳赤台群和万宝沟群为沉积-构造混杂堆积,2个群可分为基质系统和外来系统截然不同的2部分。除了古生物的差别外,从所做地球化学分析来看,两系统的常量元素、微量元素、稳定同位素、稀土元素和Si同位素等分析数据显示两者之间的明显差异,表明它们分别来自不同的沉积环境。基质系统的地球化学指标指示了半深水—深水的外陆棚—斜坡相沉积环境,而外来系统的地球化学指标指示浅水台地相的沉积环境。

The Naij Tal and Wanbaogou groups in the East Kunlun orogenic belt are sedimentary-tectonic mélanges. The two groups are divided into two utterly different parts, i.e. the matrix system and exotic block system. Besides the difference in fossils, there is also appreciable difference in geochemical characteristics. Major element, trace element, REE and isotope analyses of the two systems indicate that they were derived from different sedimentary environments. The geochemical indices of the matrix system reflect a bathyal-abyssal, outer shelf-slope facies sedimentary environment, while those of the exotic block system indicate a neritic platform facies environment.