Deformed stromatolites in marbles of the Mesoproterozoic Wumishan Formation as evidence for synsedimentary seismic activity

作     者：A.J.(Tom) van Loon Su Dechen 

作者机构：Geological InstituteAdam Mickiewicz University Institute of GeologyChinese Academy of Geological Sciences State Key Laboratory of Continental Tectonics and Dynamics 

出 版 物：《Journal of Palaeogeography》 (古地理学报（英文版）)

年 卷 期：2013年第2卷第4期

页      面：390-401页

学科分类：0303[法学-社会学] 0710[理学-生物学] 070903[理学-古生物学与地层学(含：古人类学)] 0709[理学-地质学] 07[理学] 0708[理学-地球物理学] 0705[理学-地理学] 0815[工学-水利工程] 0813[工学-建筑学] 0833[工学-城乡规划学] 

主　　题：soft-sediment deformation stromatolites seismites Wumishan Formation Mesoproterozoic Changping District Beijing 

摘      要：The Mesoproterozoic Wumishan Formation consists mainly of dolomites that represent diagenetically transformed limestones deposited in a shallow peritidal environment.Although the environment was tectonically stable,the study area in the Changping District(north of the Beijing area) was affected by synsedimentary earthquakes.Later,the dolomites in the study area were intruded by a granite.This resulted in contact metamorphism of the dolomites,changing them in a halo around the intrusion into marble.This marble,which is exposed near Taoyukou Village,shows some levels with well-developed stromatolites.The stromatolites contain structures that point at deformation when the stromatolites had not yet been lithified,and thus represent soft-sediment deformation structures.The stromatolites apparently built up during a time-span when repeated deformational processes affected the still unlithified sediment,from the sedimentary surface down to maximally a few decimeters.The deformed stromatolites thus represent seismites,which feature is exceptionally rarely recognizable in marble.