海相优质烃源岩发育的主要影响因素及沉积环境

对海洋生物、现代海洋沉积和古代海相地层中有机质含量分布特征和实验室模拟实验的结果表明,水体中高生物生产率是海相环境形成富有机质沉积的关键因素;沉积和早期成岩作用期间水体的相对还原环境是有机质富集保存的有利条件;海底深部流体的活动是造成富有机质沉积的不可忽视的因素;沉积速率是影响海相沉积有机质富集的主要因素。现有研究表明,在海相盆地中最有利形成优质烃源岩的沉积环境主要有欠补偿浅水—深水盆地、台缘斜坡、半闭塞—闭塞欠补偿海湾和蒸发潟湖。

Main Sedimentary Environments and Influencing Factors for Development of Marine Organic-rich Source Rocks

The studies of distribution characteristics and the results of corresponding laboratory modelings have demonstrated that there may be several main factors influencing concentration of ocean organism and organic content in modern marine sediments and ancient marine rocks. High organism productivity in sea waters during deposition is the key for organic-rich sediments. Reduction environment of waters in depositional and eogenetic stages is a favorable condition for organic matter accumulation and preservation, and also hydrothermal fluid activities in ocean bottom are also not ignorable. Suitable depositional rates are significant for accumulation of marine organic matter. Available studies have shown that the best favorable environments for the development of organic-rich source rocks include undercompensated basins, mesa-marginal slopes (lime-mud mound), semi-blocked or blocked undercompensated bays and evaporated lagoons.