作　　者： ; ; ; ; ; ; ;

机构地区： 中国科学院广州地球化学研究所

出　　处： 《海洋地质与第四纪地质》 2006年第1期117-125,共9页

摘　　要： 利用气相色谱-质谱(GC-MS)对西成矿田泥盆系热水沉积岩和重庆城口震旦系正常沉积岩中的生物标志物进行了测定,并通过多元统计方法对两种环境中的多种生物标志物参数进行了聚类和判别分析。结果表明:(1)热水沉积岩和正常沉积岩中的有机质饱和烃/芳烃平均值分别为4.64和1.10,正构烷烃的碳优势指数CPI平均值分别为1.35和1.11,ΣnC22-/ΣnC22+为3.17和0.74,nC21+22/nC28+29平均值分别为4.29和1.61,Pr/Ph平均值分别为0.44和0.28,C29-/C30+平均值分别为7.41和0.98,C21/αβC30平均值分别为4.32和0.31。(2)热水沉积岩中的有机质具有高饱和烃、低芳烃,饱和烃馏分中低分子量生物标志物含量较高而高分子量生物标志物含量较低的特点。ΣnC22-/ΣnC22+和nC21+22/nC28+29可能反映西成矿田硅质岩形成时的特殊的热水沉积古环境,三环萜烷C21/αβC30藿烷值可能是热水沉积环境的一个较好的指标。(3)以ΣnC22-/ΣnC22+、nC21+22/nC28+29、Pr/Ph和C30αβ藿烷/ΣC29甾烷4个参数建立的两类判别函数可以定量判识热水沉积古环境。 By means of the computerized gas chromatography-mass spectrometry （GC-MS）, the characteristics and significance for hydrothermal sedimentary paleoenvironment of biomarkers from the typical hydrothermal siliceous rocks in the Xicheng Orefield of Qinling Mineralization Belt are studied preliminarily. Then a functional model based on biomarker parameters is established according to the result of multivariate statistic analysis. The results show： ① By comparison with the normal sedimentation, the organic matters from the hydrothermal rocks show the particular features： （a） the mean value of saturates/aromatics goes up to 4.64, indicating the characteristics of high saturates and low aromatics abundance; （b） the distribution of carbon-number varies confinedly with a single main peak, C17 or C18; （c） the mean value of carbon predominance index i. e. CPI is 1.35, which indicates an obvious odd-carbon predominance; （d） the mean values of ∑nC22^-/∑nC22^＋ and nC21＋22/nC28＋29 go up to 3.17 and 4.29, respectively; （e） the mean value of Pr/Ph is only 0.44, but C29^-/C30^＋ and C21 Tri/αβC30 go up to 7.41 and 4.32, respectively. These characteristics suggest that the hydrothermal rocks must have experienced an exceptional high-temperature environmental condition, and the depositional environment might be a high-temperature, hypersaline, anoxic, deep-water and close sea basin. ② The result of Q-type cluster analysis shows that the samples of hot-water rocks and normal sedimentary rocks can be classified correctly according to the biomarker parameters. And based on the four indicies i. e. ∑nC22^-/∑nC22^＋, nC21＋22/nC28＋29, Pr/Ph and αβC30-hopane/∑C29-sterane, a recovery model for discrimination of hydrothermal vs. normal aqueous sedimentary paleoenvironment is established by the stepwise discriminant analysis. The research results can provide evidences for recovery and reconstruction of ancient hydrothermal depositional environment, and supply a new approach for investiga

关 键 词： 热水沉积古环境 硅质岩 生物标志物 气相色谱 质谱 甘肃省

领　　域： [天文地球] [天文地球]