西秦岭南缘康县-留坝一带白水江群碎屑岩的地球化学特征及构造背景

Geochemical characteristics and tectonic setting of clastic rocks of the Baishuijiang Group in the Kangxian-Liuba area on the southern margin of the West Qinling,China

西秦岭南缘白水江群主要由碎屑岩基质和不同性质的岩块组成,碎屑岩为一套深水浊流沉积。碎屑岩的稀土元素球粒陨石标准化曲线以轻稀土元素富集、Eu负异常和重稀土元素平坦为特征;主量元素和微量元素的特征指示白水江群碎屑岩的物质来源具有多源性,但主要以岛弧环境为主。这表明白水江群的构造环境为活动大陆边缘,而非被动大陆边缘。

The Baishuijiang Group on the southem margin of the West Qinfing is composed of clastic matrix and blocks of different origins. The clastic rocks are marked by a sequence of deep-water turbidite current deposits. The chondrite-normalized REE distribution patterns for the clastic rocks are LREE-enriched with flat HREE and negative Eu anomalies and the characteristics of the major elements and trace elements indicate that the clastic rocks were derived from multiple provenances but mainly from an island arc. This suggests that the tectonic setting of the Baishuijiang Group is the active continental margin rather than the active continental margin.