鄂尔多斯盆地上三叠统延长组负载构造类型及特征OA北大核心CSTPCD

Load structures are known as an important type of soft sediment deformation structure,and are characterized by gravity(density difference)as the main driving force and deformation occurring at the lithologic interface with inverted density.According to whether the deformation structures are separa-ted from the parent body,load structures can be divided into three categories including,non-separated load structures,separated load structures,and composite load structures.The non-separated load struc-tures include heavy load(mold)structures,flame structures,water drop structures and diapir(extru-sion)structures,and the separated load structures includes sand ball(false nodule),ball pillow layer and mud ball.A large number of load structures were recognized in the cores and outcrops of the Yanchang Formation of the Late Triassic in the Ordos Basin.Through the analysis of the characteristics,formation conditions and triggering mechanisms of different types of load structures,it is believed that the load struc-tures were the result of the dual mechanisms of earthquakes and gravity.In addition to gravity,seismic disturbance was also the main reason for the formation of various deformation structures.It reflects the characteristics of strong tectonic activity in the Ordos basin during the Middle Indosinian Movement.