Diagenesis with its responsivity of ore-forming on Triassic and Jurassic in Ordos basin
鄂尔多斯盆地三叠－侏罗系的成岩作用及其成藏成矿响应

The diagenesis of Triassic-Jurassic in Ordos Basin, revealed the characteristics of quasi-craton, which were influenced by the peripheral active belts of the basin. The volcanic material and ferromagnesian coming from the north ancient mountain, set out abundant Fe2+, Mg2+, Si4+,Al3+to pore water, and formed zeolite and silicoide in syndiagenetic and ealy diagenetic phases. The Bentonite interlayer in Upper Triassic was also formed at same time. The accumulation of riching Uranium clastics, and the pre-concentration of hydronium U caused by adsorption of hydrosyalites and brown coal, was also made in this period. In middle diagenetic phase, the hydrocarbon was created, and made its primary migration carried by the pore water, which was released from hydrosyalites. In this period, organic liquid entered into reservoirs and made the aluminumsilicate minerals dissolved to create secondary pore. Montmorillonite and illite catalysed the creation of oil-gas. All these appeared typical organic-inorganic agency of diagenesis and hydrocarbon accumulation. Hypergene diagenetic phase was important to oil-gas enrichment and minerogenesis in Ordos Baisn. Middle-late Yanshan movement was a tectothermal event, that not only caused the maturation of the oil in Triassic and the gas in palaeozoic, but also provided the dynamic conditions for the migration of oil-gas. On the other hand, strong reducing environment caused by the large-scale migration of gas to north-eastern and the gas's missing in Dongsheng area, contributed to enrichment of large uranium mine in Jurassic, where the hydrographic conditions were available to the accumulation of the uranium mine. So, the enrichment of the uranium mine of Jurassic in Dongsheng area was the result of typical organic-inorganic agency of diagenesis and metallogenesis.