摘要
对保存有多细胞藻类原植体、细菌和疑原类化石的贵州瓮安陡山沱组磷块岩所作的地球化学分析表明，磷块岩有机质演化程度较高，最高热解温度ｔｍａｘ达５９７℃。岩石抽提物中以非烃化合物和沥青质为主要成分，烃类含量不足２０％。色谱质谱（ＧＣＭＳ）分析图谱显示正烷烃的碳数范围很宽，有显著的高碳数正烷烃峰群（Ｃ１９—Ｃ３１），奇偶优势明显，烃类有机组分中除正烷烃外还包含有萜烷、甾烷、芳香烃和类异戊二烯烃等。其中生物标记化合物及其组成特征指示了有机物的主要来源是当时生存的真核的多细胞藻类、细菌和古细菌，这与所观察到的磷块岩中保存的古生物化石组成相吻合。某些特征有机物和生物标记物还指示了磷块岩沉积环境特征：强还原性、高盐度、低陆源输入以及与水热活动相关的局部高温。这与沉积学和岩石学的观察相符。
The Neoproterozoic Doushantuo phosphorite has been well known for its well pres erved multicellular thallophytes,animal embryos,acritarchs,bacteria and other o rganism's remains.An organic geochemical analysis of the fossil bearing phospho rite samples has been carried out and yielded the following results:(1) the extr acted organic matters show relatively high maturity,the maximum pyrolitic temper ature ( t max ) is 597℃;(2) the extracted organic fractions are composed mainly of non hydrocarbons and asphaltenes,and the content of hydrocarbons les s than 20%;(3) GC MS analysis of the extracts shows a normal alkane distributio n pattern with a wide range of carbon atom numbers,distinct peaks that represent the n alkanes between n C 19 and n C 31 can be seen in the mass spectrum,an odd even predominance of the alkanes is also distinct;(4) in addition to the alkanes,the hydrocarbons fractions contain terpane,steranes,aro matics and isoprenoids.The composition of the organic compounds,specially the bi omarkers from the extracts of the phosphorite samples,indicate that the main sou rces of the organic matters are the non vascular plants,protists,bacteria and a rchaeobacteria;these organisms lived in the basin during Neoproterozoic time,and their remains were preserved in the phosphate deposit.Some of the biomarkers in dicate the depositional environment of the phosphorites:strong reduced condition ,high salinity and low terrigenous input.Some aromatics,such as benzo fluoranth renes,methyl phenathrene,pyrene and benzo pyrene,were possibly formed and tran sported from local hydrothermal or volcanic activities of nearby region.These ma tch well with the sedimentological observation.
出处
《北京大学学报（自然科学版）》
CAS
CSCD
北大核心
1999年第4期509-517,共9页
Acta Scientiarum Naturalium Universitatis Pekinensis
基金
国家自然科学基金
