Characteristics of seismic wave groups and tectono-stratigraphic sequences of the Mesoproterozoic in depth layers,Ordos Basin
Based on the latest logging and seismic data,this paper makes and compares the synthetic records of 20 wells,studies the characteristics of the Middle Proterozoic seismic wave set in the Ordos Basin,and identifies 7 reflection interfaces.Among them,the interface T0,T1 and T3 are characterized by high amplitude,good continuity,and have stable waveform characteristics,thus are the main regional unconformities of the Middle Proterozoic,and thus can be used as marker layers for comparison.Based on that,the seismic wave group characters of each seismic stratum among the seven interfaces were summarized,and combined with field outcrop data,the Mesoproterozoic in the study area is divided into 7 sets of structural layers,namely the terrigenous clastic sedimentary layer Pt2-1(Dagushi Formation)above the bottom Paleoproterozoic or Archean gneiss,intermediate basic volcanic layer Pt2-2(Xushan Formation),acid volcanic rock layer Pt2-3(Jidanping Formation),andesite mixed with pyroclastic rocks layer Pt2-4(Majiahe Formation),clastic rock layer Pt2-5(Ruyang Group),mudstone-siltstone layer Pt2-6(Luoyu Group)and carbonate layer Pt2-7(Jixianian System).It is found that there were several stages of rifting from the Late Paleoproterozoic to Neoproterozoic in Ordos Basin,which influenced the development of Mesoproterozoic strata and unconformity.Xiong'er Group is the first set of cap layer deposited on the crystalline basement in the early stage of the development of the North China Craton rift.The basal Dagushi Formation receives terrigenous clastic deposits,the volcanic activity between then and the late Xiong'er Group formed andesite.In the late rifting period,the coarse clastic rocks of the Ruyang Group were angularly unconformable above the Xiong'er Group.Later,the transgression effect was the greatest,and the mudstones of the Luoyu Group were parallel unintegrated on Ruyang Group.By the end of the Mesoproterozoic period,the sea water circulation was good,and the Jixianian System carbonate rocks were formed,which were parallel unintegrated in the overlying Changcheng System strata.
Character of seismic wave groupTectono-stratigraphic sequenceOrdos BasinMiddle ProterozoicXiong'er Group
万方数据
维普
