鲁西枣庄-临沂地区新元古界震碛岩的主要特征

鲁西枣庄—临沂地区新元古界碳酸盐岩系中,发育有由地震造成的同沉积构造现象,如微晶方解石脉、层内变形褶曲、层内微断层和内碎屑碳酸盐岩堆积等。野外实地观察、地质剖面测量和室内分析研究认为它们是由地震产生的强震动,使距震中一定范围的未固结沉积物经震动液化,震动变形形成的震积岩组合。根据其发育规律与组合特征,该地区震碛岩的形成应与古郯庐断裂在新元古代的活动密切相关。可初步确定为含有A、B和C3个震积岩单元的震动液化地震序列。

MAIN CHARACTERS OF THE NEOPROTEROZOIC SEISMITES IN ZAOZHUANG-LINYI AREA, WESTERN SHANDONG

The synsedimentary structures which was created by earthquakes, such as the crystallitic calcite veins, intraformational folds, intrastratal micro-faults, intraclast carbonate rocks and so on, were well developed in the Neoproterozoic carbonate rock series in Zaozhuang-Linyi area, western Shandong. Based on field observation, geological section survey and laboratory study, these phenomena of synsedimentary structures were thought to be results of strong vibration resulted from the earthquakes, and the combinations of vibration and accumulation rocks were formed in adjacent area of the epicenter by vibration liquefaction and vibration distortion in unconsolidated rocks. In the light of this mechanism, seven types of seismites were described and the seismic succession by vibrational liquefaction including three vibration and accumulation units (A, B and C) was set up. The formation of vibration and accumulation rocks should be closely related to activities of the paleo-Tan-Lu fault.