【摘要】 在皖北新元古界四十里长山组滨海潮间或潮下高能动水陆棚,陆源碎屑岩相的粉砂-细砂岩沉积地层中,发育了一组同沉积变形构造。剖面上整体为丘状,可识别出涌流破碎砾石堆、下陷回填砾石堆和震裂砾石堆3部分,下垫层为液化均一层。在它的左侧及下分层发育液化卷曲变形,包括震褶层和液化角砾岩。根据这些发育特征可以确定这组同沉积变形构造为古地震成因。其形成机理是在古地震应力作用下该处发生饱水沙层液化,并形成局部范围的地震能、重力能、与液化能多能量叠加使液化沙层局部爆发,推动沙层流动喷涌与破碎,局部破碎物短暂涌至海底,又下陷回填至液化沙层的负压带,形成由涌流破碎砾石堆和回填砾石堆组成的砾石丘构造。其成因类似河流阶地富含水的砾石丘、沙丘及混杂堆积。更多还原

【Abstract】 A group of synsedimentary deformation structures has developed in the terrigenous clastic facies silt-fine sandstone sediments between coastal tide and subtidal high dynamic water continental shelf margin,at north of Anhui Province Neoproterozoic Sishilichangshan Formation.It displays characteristic of mound with liquefaction even layer underlayment,and can be divided into three parts,which is the gush broken gravel heap,the subsidence backfill gravel heap and the shatter gravel heap.In the left and lower layer developed the liquefaction deformation,including shock-fold and liquefied breccia.According to these characteristics it can confirm the group of synsedimentary deformation structures is paleoseismic genesis.The formation mechanism is that under the stress of ancient earthquake,the saturated sand liquefied and partly outbreak by the earthquake energy,gravitational energy and liquefaction energy interacted in local range.Then the energy promote sand gush and broken,some broken gravel swarm into seabed,then subsidence backfill into negative pressure zone of liquefied sands,and finaly formed the gravel mound structure by the gush broken gravel heap and the subsidence backfill gravel heap.This genesis is similar with gravel mound,sand mound and chaotic sediments at river terrace rich in water.The study on paleoseismic genesis of underwater gravel mound structures has positive significance on the study of marine seismic sequence.更多还原