李雅庄煤矿煤岩中C_(25)、C_(30)等无环类异戊二烯烷烃的检出及其地球化学意义

C_(25), C_ (30) and Other Acyclic Isoprenoid Alkanes in the Coal Rock of the Liyazhuang Coal Mine and Their Geochemical Significance

对沁水盆地李雅庄煤矿煤岩样品,进行了饱和烃生物标志化合物特征研究,检测到了丰富的无环类异戊二烯烷烃,特别是C25、C30及头—头连接的高碳数无环类异戊二烯烷烃,这些化合物被认为是甲烷菌的特征标志化合物。李雅庄煤矿煤岩沉积时为偏氧化的环境,原始环境不利于细菌发育,故检出的无环类异戊二烯烷烃应主要是成煤作用后期,煤层中甲烷菌发育的痕迹。认为李雅庄煤矿煤岩样品中丰富的、与古细菌,特别是甲烷菌有关的无环类异戊二烯烷烃化合物的检出,为该地区甲烷碳同位素组成在-56.3‰^-61.7‰煤层气的次生生物成因提供了地球化学依据。

In this paper, studies focus on the characteristics of biomarker compounds of saturated hydrocarbons of the coal rock sample of the Liyazhuang coal mine. Abundant acyclic isoprenoid alkanes, especially C25, C30 and the headto-head linked long chain acyclic isoprenoid alkanes have been identified, which are well known special biomarkers for methanogic bacteria. The primary depositional environment of coal rocks of the Liyazhuang coal mine is inclined to an oxidized one, which was against bacterial activity, therefore, the long chain acyclic isoprenoid alkanes identified in the coal sample of the Liyazhuang coal mine are traces for methanogenic bacteria developed in coal beds after coalification. It is proposd that the abundant acyclic isoprenoid alkanes related to archaebacteria, especially methanogenic bacteria in the coal sample of the Liyazhuang coal mine provide geochemical evidence for the secondary biogenic origin of the coalbed gas with carbon isotopic composition of methane ranging from - 56.3‰ to - 61.7‰ in this region.