The Northwestern Ordos Basin Ordovician Ancient Uplift On Both Sides Of The Ancient Karst Partition Difference And Main Controlling Factors

Ordos basin, the ordovician top due to long-term exposure to erosion and weathering crust is formed by caledonian period formed by geological effect. Central palaeohigh both belong to qilian sea and north sea, on both sides of the sedimentary characteristics have obvious difference, at the same time the central palaeohigh of peripheral ancient karst development and the influence of the reservoir has the control function. Based on ancient landform restoration and contrast, partition of ancient uplift on both sides of the ancient karst difference and main controlling factors for an analysis and discussion. Obtained the main results and understanding:1. Select the impression method combined with the residual thickness method is adopted to ordos basin ancient uplift the peripheral landscape restoration.2. is studied in detail the ancient uplift in northern karst development characteristics and differences on both sides, the karst area. Western ancient uplift in the study area, with thick bedded limestone is given priority to, attitude of stratum is steep, main form some caves, poor regularity, for karst development are not mature area. Ring depression basin day terrain is relatively low, has certain regularity, solution pores to mature in the karst area. Ancient uplift eastern gentle, uniform corrosion, karst slope development zone, is located in the high maturity of karst areas. Palaeohigh southeast slope, strata are relatively steep, dissolution pore development is relatively uniform, but development degree is not high, to mature in the karst area. Basin ancient karst area located in the eastern part of the ancient uplift, the most development days in ring depression for low and middle mature area.3. Tianhuan area ancient karst mainly limestone dissolution, is characterized by large karst cave development. In the vertical growth, in the upper portion of the kerry group in the cave, formed by the karstification is relatively easy to occur. Another set of karst cave development in the kerry group in the lower part, relatively easy to occur dissolution and formation of karst caves. Kerry group east of table mountain in the exposed area can lava stone for dolomite, dolomite showed uniform corrosion, could not form large water-eroded cave is characterized by development of solution pores, the fabric selective dissolution character of dissolution4. set up different parts of the ancient karst development pattern, discusses the karstification control factors, think of the ancient karst development characteristics and strength by climate, landforms, water dynamic conditions, sea level change and rock properties, sedimentary facies and tectonic factors such as control. Kerry group in the karst cave type and reservoir sedimentary facies (micro), karst landform and strata outcropped joint control, three composite area shall be the favorable development zone...