Area Research Of The Early Paleozoic Stratigraphic In Helan Mountain Region

Helan Mountain region is located in the western margin of Ordos, LowerPaleozoic Cambrian, Ordovician strata complete lack of early Cambrian and Silurianstrata, mainly deposition of a marine carbonate clastic rockssedimentary formations.This article first type of Helan Mountain region of Lower Paleozoic basin analysis, indenial Helan aulacogen proposed the characteristics of the Helan Mountain regionLower Paleozoic peripheral foreland basin on the basis of the study area formationlithology formation collage contactevidence of the relationship, stratigraphicthickness of Helan Mountain of Cambrian, Ordovician strata partition.（1）Clear the Helan Mountain region of Lower Paleozoic basin type, the HelanMountain region Zhuozishan, Helan Mountain, Niushoushan, Qinglongshan fieldgeological survey, combined with their predecessors in the region to do the LowerPaleozoic detrital zirconsdata of the Stone Age, Neoproterozoic magmatic record andpaleontological evidence that the Helan Mountain area early Mesozoic provenancefrom the North Qilian orogenic belt, Neoproterozoic provenance from the Alashanmicro plots,"Helan aulacogen" does not exist, Alashan in early Paleozoic stand-alone,the Alashan southward subduction form a peripheral foreland basin, a collision or puttogether in a certain period between the late Ordovician and Devonian period,NorthQilian island arc gradually close to the Alashan micro-plots, ocean basingradually disappear.（2）Cambrian strata of the Helan Mountain region is divided into threestratigraphic zones, namely the formation area in North China, peripheral forelandbasin formation area and Sabina formation area. Compared with divided strata withineach stratum, and compared with the strata of the North China headquarters todetermine the boundaries of the stratigraphic area. Qilian formation area and theperiphery of the dividing line of the foreland basin formation area Wonsan sub-Science Hill-the ancient city of sub--Niushoushan-Big, Ronaldinho Mountain area, south of the line development flysch clastic sedimentary formations, north of theboundary development of carbonate platform facies. Detrital zircon age data showthat the characteristics of table mountain region has been pro-North China Northstrata peripheral foreland basin formation zone dividing line should be between TableMountain and the Helan Mountain. At the same time, based on Su yukou any3wells-days deep a well Lee1well lithologic and stratigraphic thickness comparativeanalysis, indicating that the Cambrian ancient land uplift area is located east of Lee1well location near the ancient land uplift area is the periphery before foreland basinstrata area and northern formation area on the eastern side of the dividing line.（3）Helan Mountain region Ordovician formation area in North China,peripheral foreland basin strata area and Sabina formation of area is also divided intothree strata area. In contrast with the division on the basis of the study area strata, thethe study strata of collage contact relationship to determine the boundaries of thestratigraphic area.Qilian stratigraphic zone peripheral foreland basin strata area the Yi Yao Shan-South pool-Grand Cross of the groove-the Shek Kip groove-first cattle Hill-sizeRoshan as the dividing line, Table Mountain region remains peripheral foreland basinstrata areathe dividing line between North strata.