太平洋东部ES0103柱状样品中可溶有机质的组成变化及其早期成岩作用

The composition changes and diagenesis of soluble organic matter from the core ES0103 in the East Pacific

利用2001年采自太平洋东部ES0103站位的多管沉积物柱状样品，采用GC／MS对沉积物中的可溶有机质（氯仿沥青“A”）及其族组成（饱和烃、芳烃、非烃和沥青质）、正构烷烃、类异戊二烯烃和萜类化合物进行了定量分析，结果表明：（1）氯仿沥青“A”中的非烃较饱和烃和芳烃的含量高，反映出该海区沉积物中有机质的演化程度较低。（2）正构烷烃的碳分子数范围多为nC14～nC34,CPI值略显奇偶优势，轻重烃比值（nC23^-／nC34^＋）较低；类异戊二烯烃的Pr／Ph值较低，显示出该海区沉积物中的烃类是在较强的还原环境下形成的低成熟烃类，其母质来源主要为大型低等水生生物。（3）总有机碳与显晶蜡产率、氯仿沥青“A”均呈明显正相关关系，表明有机质相对富集层位所处的沉积环境也有利于高蜡烃的形成，成烃演化与成岩作用阶段有较好的对应关系。而萜类化合物的Ts／Tm值在表层和深部差别不大，显示出典型的低成熟烃类的特征。由此可见，ES0103柱状样品所处海区的沉积物为在较强还原环境中形成的，其有机质演化程度较低，为早期成岩作用阶段的产物。

Core ES0103 was sampled in 2001 with a multi-tube sampler at the site of 8°22′08＂N and 145°21′56＂ W at 5 530 m water depth. The gas chromatography-mass spectrometry method has been applied to the quanti- ty analysis on the contents of chloroform bitumen ＂A＂ and its group components （saturated hydrocarbons,aromatic hydrocarbons,resin and asphalt）,n alkanes,isoprenoids and terpenoids from the deep-sea core ES0103 located in the East Pacific. The results showed that： （1）the proportion of resin（40.14%- 49.73%）in total chloroform bitumen ＂A＂ is more than that of saturated-hydrocarbon and aromatic hydrocarbon;Besides,resin plus asphalt has a dominant quantity（51.38% -69. 35% ）in the total content of soluble organic matter; the ra rio of saturated hydrocarbon to aromatic hydrocarbon,0. 52-1.17 in the core,is an important index indicating the envolution level,these above indexes suggested organic substances in sediment were premature. （2）The nalkanes in sediments from the East Pacific is in range of nC14 - nC34; with slight odd-even preference（CPI： 0. 937-1. 224） ,and CPI showing a decrease tendency with the depth increase. The gas chromatographies of nalkanes are single mode with high carbon range for nCes. Additionally, the low ratios of light hydrocarbon to weight hydrocarbon （nC23^- / C24 ^-）and Pr/Ph showed that these hydrocarbons formed in reducing environments and were just in an early matured stage. Moreover,it can be inferred from the molecular assemblace features of organic matters in sediments that the matrixes of these biomarkers mainly derived from large inferior hydrobios, the material source affect the molecular assemblace features. （3）During early diagenesis, the organic molecular is in an active state,a series of chemical reactions will take place by the effects of microorganism and redox environments,some molecules were changed and others formed. As consequence,any changes in composition of organic matters can be used to mirror the processes of diagenesis. The noticeable and good positive correlations between total organic carbon （TOC）and the productivity of macrocrystolline wax or the content of chloroform bitumen ＂A＂ indicated that depositional environment of horizons which rich in organic matters is good for producing of macrocrystolline wax, and exiting a better coincidence relation between hydrocarbon generation evolution and diagenesis. The ratio of Ts/Tm of terpenoids which nearly has no difference between the surface and the deep layers of the core implies a typical immature hydrocarbons characteristic, in other words,sediments were just in an early diagenesis stage. In this paper,the research shows that sediments of the sea area where core ES0103 located formed in an intensive reducing environment,and the organic matters which were the products of the early diagenesis stage in these sediments also has a low level of evolution.