早寒武世初期沂沭断裂带地震效应

早寒武世初期,随着从古沂沭海峡向西海侵的发展,鲁西地区沉积了厚度不等的主要由砂岩、泥岩和碳酸盐岩组成的滨海、潟湖及浅海相沉积,其层位属下寒武统底部的李官组和朱砂洞组.在它们沉积过程中,沂沭断裂带正发生着伴有频繁海底地震的构造裂陷活动,使海底沉积物在自沂沭断裂带向西200 km范围内产生了不同的地震效应,形成了各种地震成...

Seismic effects from Yishu Fault Zone during the earlier Early Cambrian

In the earlier Early Cambrian，with the proceeding of the marine invasion from the Paleo-Yishu Strait to west，uneven thick deposits of sandstone，mudstone and carbonate rock of littoral，lagoon and neritic facies were deposited in western Shandong Province.The horizon of these layers belongs to the bottom part of Lower Cambrian consisting of the Liguan and Zhushadong Formations.Together with the depositional and formation processes，tectonic rift-depression was taking place in the Yishu Fault Zone，characterized by frequent submarine earthquakes with different seismic effects within 200km range from the Yishu Fault Zone to west.Various seismogenetic syndepositional deformation structures are formed in the seismicrecords.Seismic effect records developed in the Zhushadong Formation are mainly soft-sediment deformations such as diapir structure，carbonate lime-mud volcano，liquefied vein，liquefied breccia，seismic fold，graded-fault，siliceous vein etc.，besides a few brittle deformation of semi-consolidated sediments.Those preserved in the Liguan Formation are not only slump fold，load structure and ball-and-pillow structure，but also some seismo-turbidite.Magnitude reflected by submarine seismic effects might be Richater magnitude of 5.0～8.9.These evidences indicate that strong tectonic activities occurred along the Yishu Fault Zone in the Early Cambrian.Analyses from the viewpoint of marine engineering geology show that seismic effects mentioned above are destructive forms of sediment layers caused by earthquake at the sea-bottom.This paper has provided intuitive materials for understanding earthquake destruction to rock-soil layers of seafloor-engineering foundation.