GEOCHEMISTRY AND TECTONIC ENVIRONMENT OF THE VOLCANIC ROCKS FROM ELASHAN FORMATION IN ZHONG JUH AREA, QINGHAI PROVINCE

Study on the volcanic rocks from Elashan Formation in Zhong Juh area, Qinghai Province, indicates that it belongs to acid-intermediate high-K and low-Ti calc-alkali series. The analysis results reveal that ∑REE varies from 139.45×10^-6 to 219.55×10^-6, with enrichment of LREEs (LREE/HREE of 7.695-13.46, averagely 9.09). The distribution patterns show gently right-dipping smooth curves with weak negative Eu anomaly(δEu=0.53-0.83). The general uniformity of trace element curve patterns reflects the homogeneity of volcanic rocks in this area. According to the analysis on tectonic environment, it is concluded that the volcanic rocks is the product of magmatic arc formed by compression and collision.