Niuyingzi—Guojiadian Basin Sedimentary Filling Evolution And Its Relation With Tectonic Deformation In Western Liaoning Province

Yanshan orogenic belt is an intraplate orogenic belt in the northeastern part of North China Plate,west of Baotou in Mongolia,east of the Bohai Bay,east-west direction of the overall structure,the east part of orogenic belt end of the NENNE.In this paper,the Niuyingzi- Guojiadian basin is located in the eastern section of the Yanshan orogenic belt, it is a small basin which has been intense tectonic transformation lately. For characteristics of sedimentary and structural features of the formation in the basin, we get the following understanding:Dengzhangzi famation consists of a set of poor sorting and roundness carbonate conglomerate composition.Composition and maturity structure of conglomerates indicate that it is closely related to an intense tectonic activity, it is a sedimentary record of strong tectonic movements during the Late Triassic.And its underlying strata Shuiquangou formation was conformable contact. It is a homocline with tops to the east. This paper confirm the variation of conglomerate component of Dengzhangzi formation in Niuyingzi-Guojiadian basin, and according to different gravels Dengzhangzi group was divided into 3 sections. Dengzhangzi Group 1 segments are andesite gravel-based, along the cross-section the andesite conglomerate reduced and limestone gravel part rising into the upper gravels dominated by limestone gravel, gravels are mainly from Shuiquangou group and Cambrian-Ordovician strata; Dengzhangzi group 2 conglomerate segment contains gray, thin- thick layer of micritic calcite dolomite gravel, gray and black siliceous shales, glauconitic quartzarenite and gray-green diabase, they are mainly from Qingbaikou system; Dengzhangzi group 3 segments with gray flint zebra dolomite, dolomitic limestone, with a small amount of brown and red,containing Mn dolomite, gray-green diabase, silicified shale and quartz sandstone, these gravel mainly from Jixian system. Dengzhangzi formation conglomerate with a clear descending stratigraphic features in profile,reflecting the provenance normal sequence stratigraphy.Combined with the basin surrounding stratigraphy, structural features, Dengzhangzi formation conglomerate’s possible source areas were analyzed and discussed in Niuyingzi- Guojiadian basin. This paper pointed out that Niuyingzi- Guojiadian basin’s source area is the west part of the basin. The two subvertical faults Daqizi fault and Zhuzhangzi fault hace a complex deformation history, in the Late Triassic, Proterozoic strata thrust from NW to SE over Dengzhangzi group,then both deformed again due to anther tectonic movement, therefore, currently seen NiuyingziGuojiadian basin a residual basin which had experienced a strong post-tectonic transformation and erosion,rather than a prototype basin.