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对鄂尔多斯盆地上古生界存在幔源成因无机气以及盆地的构造特征有利于幔源气上涌的观点进行置疑。鄂尔多斯盆地构造稳定，断裂主要集中在周缘，而且以挤压性质为主，并不利于幔源气的上涌；通过对天然气地球化学特征的分析，上古生界的天然气主要是上古生界石炭—二叠系煤系为烃源岩的煤成气组成：大部分甲烷的δ13C₁＜－30‰，显示有机成因，而部分δ13C₁＞－30‰是由于高成熟或者过成熟煤成气甲烷较重的结果；烷烃气虽发生单项碳同位素倒转，属于煤系不同源气或同源不同期煤成气的混合结果，烷烃气均为有机成因；部分二氧化碳气藏具有δ13C_CO2≥－8‰，为无机成因，是碳酸盐岩水解或者酸溶作用的结果；对盆地中氦的分析结果表明主要为壳源成因

WHETHER THERE ARE MENTLE SOURCE GASES IN UPPER PALEOZOIC NATURAL GAS IN E’ERDUOSI BASIN

The authors doubt about the opinions that there exist mantle origin abiogenic gases in Upper Paleozoic in E’erduosi Basin and the tectonic characteristics of the basin are favourable to the upward migration of mantle source gases. E’erduosi Basin is a structurally stable basin and most of the faults (mainly belonging in compressional type) concentrate around its periphery, so that it is unfavourable for the upward migration of mantle source gases; Through the analysis of gas geochemical characteristics, it is pointed out in the paper that the Upper Paleozoic natural gas is mainly composed of coal formaed gas by taking the Carboniferous—Permian coal measures as its source rocks; most of the δ13C1 ratios show its organic origin, the ratios being less than -30‰; partial samples’ δ13C1  ratios of more than -30‰ result from the heavier methane in high matured or over matured coal formed gas; although the single carbon isotope sequence reversal occurred in alkane gases, which resulted from the mixture of the coal formed gases originated from different source rocks or from the same source rock with different muturities. the alkane gases were organic origin also; Some CO2 reservoirs’ δ13CCO2 ratios show their abiogenic origin, these ratios being ≥-8‰, which was caused by the hydrolysis and acid solution of carbonate rocks; and the helium in the basin is also earth crust origin according to its analysis results.