Tectono‐Volcanic Activity‐Driven Geomorphic Evolution of the Changling Fault Depression, Songliao Basin, China

ABSTRACT

The Changling fault depression is located in the Songliao Basin, northeast China. Deep volcanic rocks in the Cretaceous Yingcheng Formation are highly developed, resulting in complex underground structures and filling characteristics, which pose challenges to oil and gas exploration in the region. In this study, based on the comprehensive interpretation of extensive seismic, logging, and lithological data, the developmental characteristics of volcanic rocks in the Yingcheng Formation of the Changling fault depression were clarified. Additionally, the paleogeomorphic evolutionary characteristics of the basin under the background of intense faulting and volcanic activities were reconstructed, and the controlling effects of volcanic activities on geomorphic characteristics and sedimentary filling were discussed. The results indicate that the volcanic activities in the study area can be divided into three stages. During the first and second stages, volcanoes developed mainly with lava, forming sheet‐like and gently mound‐shaped volcanic ridges. In the third stage, they gradually evolved into high‐angle volcanic domes dominated by volcaniclastic rocks, with their distribution area gradually shifting from the bulge zone to the deep fault depression. A large number of rock masses generated by volcanic eruptions have modified the topographic structure of the lake basin. Together with fault activities, they control the multi‐fault depression landform divided by volcanic domes, which gradually transformed into a large shallow lake basin with progressively diminishing topographic differences. The transformation of the fault depression by volcanic activity affected the transport channels and unloading landforms of clastic sediments, thereby controlling the sedimentary processes.