鄂尔多斯盆地煤成烃潜力与成气热模拟实验

鄂尔多斯盆地煤的Ｒｏｃｋ Ｅｖａｌ分析结果表明，在肥煤—焦煤阶段，Ｓ１＋Ｓ２达最大值，随后生烃潜力减弱。煤的Ｐｙ ＧＣ分析及热模拟成气实验结果证实煤成气具有３个生气高峰，分别相应于Ｒｏ，ｍ０５％～０７％、１０％～１４％及２５％，表明煤成气具多阶段性的特点。这一规律性的认识有助于煤成气的勘探和开发。同时，随煤级增高，煤成烃特征亦发生有规律的变化：异构烃减少，正构烃增加；类异戊二烯烷烃分布亦存在多变性或多阶段的演化特点；苯系化合物具波动性变化特征。

GEOCHEMISTRY AND GENESIS OF MINERALIZED SILICEOUS ROCKS, CHANGKENG GOLD SILVER DEPOSIT, GUANGDONG PROVINCE

Mineralization of gold and silver is most closely related to siliceous rocks in Changkeng deposit, and the occurrence of orebodies composed of breccia bearing siliceous rocks are strictly controlled by fractured zones of faults and strata. The SiO 2 contents of mineralized siliceous rocks are from 73 to 92 percent, the average value of which is similar to marine hydrothermal cherts, but the average contents of TiO 2, Al 2O 3, TFe, CaO and K 2O of siliceous gold ores, as well as the CaO and FeO contents of siliceous silver ores, are apparently higher than that of hydrothermal siliceous sediments. The compositions of siliceous ores are distributed in hydrothermal and hydrogeneous regions of Al Fe Mn ternary diagram. Although the REE compositions of mineralized siliceous rocks with low ΣREE content and negative Ce anomaly are somewhat similar to those of marine hydrothermal sediments, its REE patterns bear analogy to country rocks. Moreover, the siliceous ores relatively enrich Fe and are poor in Cu, Co, and Ni. Combined with evidence of geological occurrence of siliceous orebodies, age of mineralization and source of ore forming fluids, it is believed that the siliceous ores are mainly formed by hydrothermal replacement of country rocks and filling in fractured zone, and that the presence of some siliceous rocks of marine hydrothermal sedimentary origin can not be excluded.