Research On Paleogeographic Environment Of Baoziwan Area In Ordos Basin

Ordos basin is one of the large inland basin of abundant energy and mineral source of Mesozoic in the east of our country. And it was preserved integrally. The Yanchang Formation of Triassic is not only researched early, but also the first obtain oil gas strata of the basin. For a number of years, it is the primary target of oil and gas exploration. By substantive field and indoor practice development work, this paper systemic researched the source, the sedimentary system, sedimentary facies, paleogeographic environment, under the guidance of sedimendary geology and petrolume geology theory.Based on the characateristic of the peripheral of the basin ,by using paleocurrent direction, clastic particles style and characteristic, heavy mineral combination, quartz cathode luminescence and rare earth element allocation model, we researched the source condition of basin.The sourse of the Chang 6 oil-bearing layer in the area came from Alashan palaeocontinental and was impacted by the Yinshan palaeocontinental.In the Chang 6 oil-bearing layer in the area four structure profile was identified. They are normal graded type, reverse graded type, homogeneous type, compound type. The normal graded type development mainly in microfacies of underwater distributary channel. The reverse graded type development mainly in microfacies of debouch bar or subaqueous crevasse splay, The homogeneous type development mainly in microfacies of distal bar, interdistributary bay, subsea natural barrier, prodelta et al. The compound type development mainly in microfacies of superposition underwater distributary, superposition debouch bar,and tne combination of underwater distributary channel and debouch bar.According to lithology combination, Sedimentary Fabric, depositional evolution sequence, by using drilling corns, logging, testing analysis, the type and the character of sedimentary microfacies was identified. On the basic of sedimentary microfacies and facies analysised, we discussed the paeogeographic environment character and evolution of every sequence. At the same time, homologous depositional model is erected.ordos basin developed from Mid-late Triassic to Early Cretaceous, then, underwent reformation. Especially, the climate fluctuation of the quatemary has been working on biology, sediment, physiognomy and environment. the quatemary climate evolution curve is given, the physiognomy evolutionary charecateristic of the quatemary is described.