Study on Volcanic Facies of Yingcheng Formation in Yaoshen Area

Abstract

There are two classification including volcanic lava and volcanic clastic rock, totally 15 types in Yingcheng Formation, Yaoshen area. The lithology is mainly characterized as acid rhyolite, tuffs and volcanic breccia. By using logging data and seismic data, the authors come to the conclusion as follows: there existed five types of lithofacies of volcanic lava in this area, with eruption-overflow facies most widely developed. The section is characterized as eruption mixed with overflow, superposed eruption-overflow facies and volcanic sedimentary facies occurred far from the crater. There are frequent volcanic activities, multi-periodic activities of volcanic eruption developed, thus multi-periodic eruption modes were formed. This area is overlapped and connected in the plane, adjacent eruption facies are often connected, overflow facies are distributed on lave platform.