Southern Of Ordos Lower Paleozoic Erathem Sedimentary Facies

The study area of this thesis is located in the southern Ordos Basin, includes Han Cheng HuaZiShan, He Jin XiWeiKou, as well as its adjacency, and covers three tectonic zones, including Wei Bei uplift, Jin Xi fold belt, and Shan Bei slope, where the research formations belong to the lower Paleozoic erathem strata (Cambrian and Ordovician system), marine carbonate deposition. Based on sorting and access of previous research results, field geological prospecting, and actual measurement, a research in detail was made and concentrated in the petrological characteristics, strata characteristics, paleontology features, as well as the paleogeography features of sedimentary facies and lithofacies. Sampling was done in two typical profiles, Hua Zi Shan and Xi Wei Kou, which is in the research region, and the samples were analyzed using geochemical test method.The lower Paleozoic erathem strata in the study area were dominated by carbonate rocks-limestone and dolomite, and were rich in oolitic limestones, bioclastic limestone, wormkalk, as well as oolitic dolostone, with few mudstone layers and Gypsum halite. The sedimentary facies was mainly the upgrowth of open tableland facies, Ring lu Sandy shale, Ring lu Muddy dolostone, Dolomitic limestone, and so on. Those facies as well as evolution Characteristics of the deposition were discussed in this work.The result from the analysis on carbon and oxygen isotopes in Han Cheng Hua Zi Shan profile and He Jin Xi Wei Kou profile in Shanxi and Shaanxi province respectively, is:theδ18O andδ13C value in the carbonatite of Cambrian system in the former profile ranged from-l0.19‰to -5.65‰and -2.58%o to 0.69‰, respectively; The ratios in Cambrian and Ordovician system in the latter profile were -9.64‰--5.94‰and-4.84‰-0.41‰forδ18O andδ13C, respectively. A positive drift of oxygen isotopes was apparently observed at both the top and bottom of Zhang Xia Group in the Han Cheng Hua Zi profile, as well as at the border s between Mao Zhuang and Xu Zhuang Groups in Cambrian system, between the 1st and 2nd sections of Ma Jia Gou Group in Ordovician system, and in the 6th section.