安徽宣城更新世红土正构烷烃分布特征及其古植被意义

利用气相色谱一质谱联用仪(GC-MS)在安徽宣城更新世红土中检测出了微量的分子化石，包括正构烷烃、一元正脂肪酸、一元正脂肪醇以及α-正构脂肪酮等．正构烷烃的分布型式表明其来源于低等菌藻类生物和陆生高等植物，其中高碳数正构烷烃主要以C29为主峰，显示流域中的植被类型以木本植物为主；(C27 C29)／(C31 C33)比值的变化反映出，在以木本植物占优势的背景下，流域中草本植物的相对比例也发生了多次变化．这一比值在本剖面上表现出多阶段的变化．而且这种变化与岩性、粒度变化密切相关，反映出这些参数可能还蕴涵着古气候信息．

Distribution of n-Alkanes as Indicative of Paleovegetation Change in Pleistocene Red Earth in Xuancheng, Anhui

Using GC/MS analysis, a series of molecular fossils, including n-alkanes, n-alkanoic acids, n-alkanols, and n-alkan-2-ones, have been identified from the Pleistocene red earth in Xuancheng, Anhui Province. The n-alkanes are proposed to be of mixed origin, derived from microorganisms and higher plants. The dominance of C_(29) homologue in the n-alkane distribution in most samples suggests the occurrence of trees in the region studied here. The parameter of (C_(27)+C_(29))/(C_(31)+C_(33)) n-alkanes, representative of the abundance of grassy plants relative to woody plants, infers a varied grassy density spanning the last 1 Ma. Profiles of this ratio of n-alkanes display a varied trend comparable with the lithology, an indirect inference of paleoclimate which merits further investigation.