The Characteristics And Tectonic Implications Of Seismites In The Lower Cretaceous Shandong Rushan Basin,Shandong Province,East China

Shandong Rushan Basin is located in the north of bohai bay basin.The strong earthquake activities were happen because of the impact of the Tan-Lu fault zone.Leading to develop various soft-sediment deformation structures(SSDS),It is the ideal natural laboratory for the study of seismite.Applying to the Zhi Feng Zhuang profile belonging to the Lower Cretaceous of The Shandong Rushan Basin.With the sedimentology,Mineralogy,Structural Geology,Sedimentary geochemistry as the guidance.which carry out the formation and seismites characteristics.By the measure of Detrital zircon dating,which limit the forming time of the seismites,Revealing the characteristics of Tan-Lu fault zone in the Late Jurassic to Early Cretaceous and it's record.As the bottom of the LaiYang group,Zhi Feng Zhuang group belonging to the Lower Cretaceous of The Shandong Rushan Basin is the one of the five group(Lin Si Shan group,Zhi Feng Zhuang group,Shui Nan group,Long Wang Zhuang group,Qu Ge Zhuang group).Integration of the contact by The Shui Nan group for the upper and Lin Si Shan group for the bottom.Developing the feldspar sandstone,conglomerate,siltstone,granitic conglomerate and so on pertain to alluvial fan facies and fluvial facies as the layers characteristics.A single layer thickness of the conglomerate is 2-4m,The diameter of gravels are not the common size(between 5cm and 20cm),some can be achive 50 cm.,the sorting and rounding are not fine,which is the leading of close carrying piled up quickly.A single layer thickness of the Conglomeratic sandstone is 5-10 m,and The sorting mill is less than the difference.The main structure of the layers is single-stratum which developing horizontal bedding,imbricated structure and some plant fossils.Recognizing five SSDS including liquefied structure of sand shale,liquefied formation structure,drain structure(fire structure),ball and pillow structure and the ladder micro-fault in the field.On the basis of causes of seismites,the former reacher and the characteristics of tectonic evolution.Carrying out the precept for the study area of seismites,that is two categories(Soft SSDS and Brittle SSDS),three classes(Liquedied formation structure,Diapirs and Brittle formation).In addition,classify the Liquedied formation into four types(rain structure(fire structure),ball and pillow structure,liquefied structure of sand shale and liquid-and-curved formation structure).Analyzing of detrital zircon dating by choosing the seismites which developing liquid-and-curved formation structure as(selecting 42 test points),The age range 107-123 ma,It is believed that the soft deposition occurred after 114.5 Ma.Seismites in the target strata in the study area of wavy anticlinal structure,extensive development of axis Angle from 65 degrees to 80 degrees,and the transformation of the liquefied sand mudstone affectionately body direction of research and its mechanism may be related to the late Jurassic and early cretaceous period(145.5 ~ 99.6 Ma),Tan-lu sinistral strike-slip fault taking place sinistral shear force.