关键词: 松辽盆地, 营城组, 流纹岩, 岩石构造, 火山岩地层分析, 地层学

Abstract:

The vocanlic strata in deep of Songliao basin has been an important target for oil/gas exploration, study of vocanlic rocks is of some significance for strata analysis. In this paper, we focus on the rhyolite of Yingcheng Formation on outcrops in Jiutai, southeast margin of the Songliao basin. According to primary structure of rock, rhyolite is divided into four basic types:rhyolitic structure rhyolites, vesicular rhyolites, lithophysa rhyolites, and massive rhyolites. Each type has specific forming mechanism and can be identified at the scale of outcrops, hand specimens and thin sections. Rhyolite is constituent element of a cooling unit, and the ideal rhyolite sequence is vesicular rhyolites-lithophysa rhyolites-rhyolitic structure rhyolites-massive rhyolites-rhyolitic structure rhyolites-lithophysa rhyolites-visicular rhyolites, which is often incomplete in actual study. The cooling unit defined by the rhyolite sequence can be an elementary unit for volcanic strata analysis.