Genetic & Architectural Characteristics of Non-marine Depositional Sequence

Key words: 
• autocycle /
• environment factor /
• loWstand Wedge /
• faulted-steps break /
• equilibrium profile /
• sequence architecture

Abstract: Based on the geological and geophysical data,the authors summarized the applied seCuence strati graphy of non- marine basins in China. the controls on non- mari ne seCuences included both allocyclic and autocyclic processes. the most important factors Were tectonics and climate,but the environmental factor Would also be taken into account. the accommodation changed periodically With changing base level,resulting in the for mation of a series of genetically and spatially related depositional seCuences. Basically,base level of inner continent Was not controlled by changes of relative sea level. there Would be some relations bet Ween changes in relative sea level and continental base level during eustacy floodi ng,hoWever,a time lag existed betWeen the changes from marine basin to inner continent basin. the lake basin Was smaller than marine basin and the velocity of sedimentary supply Was higher, so the numbers of non- marine seCuences Were much more than those for med in marine facies during the same period. We have to pay attention to recognizing the systems tracts f or t he st udy of hi gh precision or hi gh-resolution seCuence strati graphy,especially to analyze t he loWstand systems tract Wit h its depositional systems. The genetic characteristics of seCuence boundary Were subaerial exposure,strati graphic truncation and subaCuatic erosion. According to the depositional feat ures of Zhanhua Depression,5 seCuence architect ures have been provi ded in this paper,Which are alluvial-fluvial/lacustri ne architecture，transitional architecture formed betWeen brackish lake and fresh lake,marine duration- deep lacustrine architecture，ramp architecture and fluvial-alluvial plain architecture. During the major development of non- marine basin，the step faulting breaks controlled depositional systems.Usually,loWstand complex fan,progradi ng Wedge and highstand turbidity f an Were located close to the third stepping break,it Was bypass of incised valley in loWstand period and then filled With adj acent sandy bar by the second stepping break,and at the first stepping break the sedi ments Were bypass Which could form favorable subtle or complex traps as the basin floor fan,and their economic significance Would be proved by boreholes in Bohai Bay Basin.