Stratigraphic Sequence And Basin Properties Of The Lower Paleozoic In Aershan,Daxinganling

Based on the analysis in the research area,lower Paleozoic layer mainly developed around a set of shallow marine clastic sediments and carbonate rock sediments.Clastic particles are generally relatively small,mainly including metamorphic siltstone,metamorphic sandstone and slate.The Suzhong Formation in the group is mainly composed of crystalline limestone and shale,and occasionally a trilobite fossil fragments.The Tongshan Formation mainly to small sandstone,siltstone and slate combination.Special Duobaoshan lithological association,widely developed in a large number of acidic volcanic rocks.These volcanic rocks with a small amount of sedimentary rock such as slate,sandstone,and was the output of interbedded.Luohe Formation divided into two segments based on cycles and lithology.Luohe Formation,Sec microcrystalline limestone and sandstone was the output of interbedded.The upper micrite thickness of the lower part contains a layer of gray slate.The Luohe Formation is mainly composed by grain sandstone,fine-grained sandstone,argillite and silty slate.Luohe Formation is mainly composed of pebbly sandstone,coarse-grained sandstone and slate,occasionally brachiopod fossils.Specific analysis of sedimentary environment around the layer is as follows:the Formation of Suzhong,the Formation of Tongshan,the First section of Luohe Formation were in the tidal flat sedimentary environment.The Second section of Luohe Formation was in the restricted platform sedimentary environment.The Formation of Woduhe was in the fan-delta sedimentary environment.The Formation of Duobaoshan was in the island arc environment.Through comprehensive research and analysis,it can be deduced that the research area was a back-arc rift basin in the Paleozoic:in the Early Cambrian and the Early Ordovician it was rift basin arc near the mainland side of the sedimentary,sedimentary similar to the passive continental margin;in the Upper Ordovician the volcanic activity strengthened because of the north-west subduction of the Siberia.The Formation of Duobaoshan developed the volcanic sedimentary strata;in the Lower Ordovician and the Silurian,as the Eerguna subduction weakened,it was respectively the tidal-flat facies and fan delta facies sedimentary environment.