Seismic volcanostratigraphy of Yingcheng formation in the Songliao basin, Cretaceous, NE China

Volcanic edifices in the Songliao Basin were subdivided into central, proximal and distal facies according to their architectures and fades associations. Six kinds of seismic volcanic fades units are identified in the volcanic edifice of the Yingcheng Formation. They are named after their outlooks and called mound-, lens-, dome-, pond-, wedge- and sheet-shaped seismic facies, respectively. The former three are the central facies associations and composed predominantly of explosive, effusive and extrusive facies, respectively. Pond- and wedge-shaped ones belong to the proximal facies associations and composed predominantly of effusive braided lava flow and interbedded explosive pyroclastics and effusive lavas. The sheeted one is mainly of distal facies characterized by volcanic sedimentary facies. Lithology and lithofacies change rapidly in the center of volcanic edifice and their seismic responses are complex. The key controlling factors for that include eruptive conditions, contemporaneous collapse, post-volcanism faulting, porosity and fluid. The central parts of the volcanoes are the most favorable for creating volcanic reservoirs.