伊通地堑下第三系的有机相组合及其与盆地沉积环境和构造演化的关系

ORGANIC FACIES ASSOCIATIONS IN RELATION TO SEDIMENTARY ENVIRONMENTS AND TECTONIC EVOLUTION IN THE YITONG GRABEN,NORTHEASTERN CHINA

一、引言近年来,由于各种先进仪器的应用,有机地化的基础研究取得了长足的进展,如何与其它学科结合,使有机地化在地学领域发挥更大的作用,成为各国有机地化工作者普遍关心的问题;同时,作为盆地充填物质重要组成部分的有机质的组成和性质,不仅是决定盆地油气潜能的最重要因素并与一些重要层控矿床的形成和分布密切相关,而且是沉积盆地的背景特征和发展演化的综合反映。因此,有机地化分析不仅是油气资源评价的重要手段,亦可成为盆地分析的有用工具。本文试图将有机与无机分析结合起来,在确定源岩的生烃潜能的同时,通过有机相反映盆地的沉积环境和构造演化。

Organic fades is defined in this paper as a mappable stratigraphic unit containing a specific genetic organic matter type in certain abundances. The three-dimensional morphology, paragenetic relationship and association pattern of genetically related organic facies types in a given chronostratic or lithostratic unit are referred to as the organic facies associatio(OFA). Four organic facies types namely Organic Facies B,C,D and E have been recognized in the Yitong Graben with the aid of combined sedimentological and organic geochemical studies. Although sedimentary environmental analysis indicates that the depositional fill features of different subunits in this graben are similar, the organic basin-fill sequences and organic facies associations of different subunits are quite different in various depressions. Organic facies and its association studies have remedied the defect of sedimentary environmental analysis which takes framework sandstones as its major object, and thus revealved the tectonic subsidence and depositional fill history of the basin more effectively.