Influence of volcanic eruptions on the sedimentary filling of a continental rift basin: a case study of the Yingcheng Formation in the Changling faulted depression in the Songliao Basin, China

The impact of volcanic eruptions on the sedimentary filling process of a rift basin is not only the premise for reasonably explaining the binary filling characteristics of volcanic and sedimentary rocks in a rift basin, but also the key geological basis for hydrocarbon reservoir prediction. Based on a large amount of three-dimensional seismic, logging and lithology data, we estimated the volcanic eruption period, volcano distribution and sedimentary facies distribution in the Changling faulted depression in the Songliao Basin. Then we assessed the influence of volcanic eruptions on the type of sedimentary fill, the distribution of sedimentary facies and the spatial stacking of sedimentary strata. This study revealed that during the rapid rifting stage, the Changling faulted depression experienced four phases of volcanic eruptions. The lithology, scale and spatial distribution of volcanoes were directly related to the activity and location of the basement faults in this area, reflecting the control that basement fault activity had on the volcanic eruptions. The stacking form and eruption scale of volcanic rocks played a substantial role in the paleogeomorphology of the basin, which in turn affected the form of the source channel in the basin, causing changes in the sedimentary facies type, spatial distribution and changes in spatial overlapping patterns of sediments. Moreover, the differences in location and delivery methods of volcanic debris complicate the structure and reservoir properties of the sandstone.