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Outcrops, drilling profiles and comprehensive study of the well logs and the indoor map compilation based on comprehensive geological background, lithological, sedimentary structures, and paleontological features, that: research on Cretaceous Luohe Formation - Huanhe Huachi groups are classified as lakes, rivers, red (Hung) alluvial fan delta and wind into the deposition of sedimentary facies types. And further identified 15 kinds subfacies: littoral and shallow lake, semi-deep lake, alluvial fan, delta plain, delta front, meandering river, braided river channel, floodplain, fan top fan fan end, dunes, desert lake, gravel desert wadis. The Ordos Basin Cretaceous Luohe - Huanhe HUACHI have significantly different main sedimentary facies and sand body distribution significantly controlled by sedimentary facies. With the following paragraph in the southern part of the basin, northwest and southeast edge of the Luohe Formation, sedimentary bodies belonging to relatives of the impulse (Hung) sediments, landslides and weathered residual sediments; Luohe Formation mainly developed aeolian deposition, red (Hung) plot the fan braided fluvial deposition; into the ring the River HUACHI basin range narrow deposition relative to the overall basin edge punch (Hung) alluvial fan, braided river basin interior lakes, Delta. Luohe Formation wide distribution area of ??sandstone thickness, sandstone components, quartz characterization, sedimentary structures and sedimentary structures, to further clarify the presence of eolian sandstone, to determine the distribution of aeolian deposits. Sandstone distribution phase control of the Luohe Formation eolian sandstone, large sediment thickness, and horizontal thickness variation; Huanhe group stratigraphic thickness, but the sandstone is not developed, mainly mudstone deposited mainly the sandstone East thin thick in the west, northeast to southwest thickening of sedimentary characteristics. Ordos basin in the Yanshan movement so that the region occurred a third depression since the Triassic and Jurassic, subsidence center constantly shifted westward to the formation of an East Wing relief, the West Wing steep narrow asymmetric giant Taiwan syncline. By basin tectonics and climate impacts, Luohe group or eolian sedimentary strata in the Central River the Huachi group lake basin subsidence further transgressive expand the area, the formation of the inshore river deltas and lake sedimentary strata of sedimentary facies variation in the plane also strong, by the edge of the basin's alluvial fan facies (debris flow) - rivers lakes and rivers within the basin conglomerates gradually phase (the desert phase) transition evolution.
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