关键词: 东濮凹陷, 深地震反射剖面, 初至波层析成像, 地壳精细结构, 深浅构造特征

Abstract: A nearly EW-trending deep seismic reflection profile with 70 km long across the middle-southern segment of Liaocheng-Lankao fault zone (Lanliao fault zone) and its adjacent area was completed in 2018. This profile reveals the fine crustal structure image and the tectonic features of the faults in this tectonic zone. It provides new seismic evidence for the research on the deep reflection structure and seismogenic environment of the middle-southern segment of Lanliao fault zone. These results are of great significance for the discussion on the deep dynamic and evolutionary process of the Dongpu Depression. According to this study, the characteristics of deep and shallow structure and crustal reflection structures on both sides of the Lanliao fault zone are obviously different.The crust in this area is composed of brittle upper crust and ductile lower crust.There are rich reflective layers and clear tectonic framework in the upper crust. In the western area of Lanliao fault zone, there is a set of dense reflectors with strong energy, which reflects the sedimentary interface of different times since Mesozoicin the basin.The basement slope with gentle dip to the East is the bottom boundary of the "dustpan shaped" sedimentary depression. The reflected wave of the crystalline basement presents a group of strong reflection wave group with good continuity in the eastern area of Lanliao fault zone, which areparallel unconformity on the Ordovician strata of Paleozoic or older strata There are some secondary faults in the hanging wall of Lanliao fault, which together with the Lanliao fault zone control the tectonic frameworkof "dustpan shaped" sedimentary depression Dongpu sag. The reflection structure of the lower crust is relatively simple. On the whole, it is mainly arc reflection with strong energy and short duration. The Moho-surface is characterized by a strong reflection band with piecewise continuous in horizontal direction and lasing for a certain time in vertical direction. The energy of Moho reflection wave group below Lanliao fault is obviously weakened, which is quite different from the reflection characteristics on both sides of Lanliao fault. This profile reveals 2 deep faults offset the Moho surface (FD1and FD2), which extend down to the top of the upper mantle and create conditions for the upwelling of hot materials from asthenosphere and the energy exchange in this area. It may also be the cause of arc reflection in the lower crust.

Key words: Dongpu Depression, Deep seismic reflection profile, First-arrival tomography, Crustal fine structure, Deep and shallow tectonic features