渤海湾盆地渤南低凸起西段中—新生代构造演化及地貌恢复OA

Recent exploration in the west section of the Bonan low uplift within the Bohai Bay basin has revealed significant potential for medium-deep buried-hill type oil and gas traps,leading to the discovery of the large-scale Bozhong 26-6 oil and gas reservoir.Understanding the formation and evolution of these buried hills,the development of sedimentary systems,and the mechanisms of hydrocarbon generation,storage,and migration often requires tectonic analysis and tectonic geomorphological restoration.To elucidate the complete tectonic deformation and geomorphic evolution of the west section of the Bonan low uplift and provide theoretical support for oil and gas exploration,this paper utilizes seismic reflection and drilling data to analyze the stratigraphic distribution and tectonic deformation characteristics during the Mesozoic-Cenozoic periods.Using Move software,two-and three-dimensional tectonic restoration was conducted to accurately reconstruct the geomorphological features during key tectonic activity periods.Results reveal that:① During the early Mesozoic(Indosinian to early Yanshanian),the study area was subjected to strong compressional orogeny,which transitioned from a near S-N to a NE direction.This tectonic activity led to the development of numerous near E-W and NE-directed thrust faults,as well as several near S-N strike-slip faults.The region experienced intensive uplift,resulting in the absence of Jurassic sedimentation and extensive erosion of Paleozoic strata.Consequently,the Precambrian basement was exposed and flattened,forming a large-scale flattened mountain landform.② In the late Mesozoic(middle to late Yanshanian),the tectonic regime shifted to a strong NW-SE extensional environment.During this period,reverse faults in the Huanghekou depression,located on the southern side of the uplift,experienced intense negative inversion.This process allowed the depression to receive a large amount of Cretaceous volcaniclastic and muddy-sandy sediments.Meanwhile,the west section of the Bonan low uplift and part of the Bozhong depression to the north remained uplifted,acting as sediment source areas.③ The early Cenozoic(early to middle Himalayan)was characterized by strong NW-SE extension and rifting.During this phase,the study area experienced near S-N bidirectional detachment.The H uanghekou depression continued to fault southward,forming a basket-shaped and half-graben structure.Simultaneously,the Bozhong depression underwent northward faulting and detachment.The west section of the Bonan low uplift was affected by transtensional detachment,presenting a geomorphic feature described as"high and narrow in the west,low and wide in the east."This tectonic activity ultimately shaped the current"two depressions with one uplift"pattern,providing space for the deposition of Cenozoic Shahejie Formation source rocks and Dongying Formation cap rocks.