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对南海北部陆坡神狐海域4口钻孔(BY1、BY2、BY3、BY4)岩心沉积物中微体古生物的研究表明晚中新世以来该区沉积物中硅质和钙质生物组分丰度具有较大时间和空间变化。从时间上看,硅质生物在晚中新世—上新世几乎缺失,中更新世以来约40万年(0～24m)才较多出现,18万年以后繁盛,大于0.15mm粗粒级有孔虫在晚中新世期间丰度很低,而在更新世—上新世丰度很高;空间上的差异表现在不同的钻井岩心中生物丰度变化范围较大。根据硅质生物丰度变化可推测晚中新世—上新世—早更新世时海水表层古生产力极低,而中更新世以来古生产力相对较高。南海北部钙质生物丰度的变化主要受控于陆源物质的输入量,在钻探区可识别2个可能具有不同物质来源的小区块,如BY1、BY2孔晚中新世—上新世陆源物质的输入量高于更新世,BY3和BY4孔更新世陆源物质的输入量高于上新世。2007年本区钻探结果揭示的一个令人惊奇和十分独特的现象,水合物以高达20%～49%饱和度状态分散在细粒沉积物(黏土粉砂)孔隙中,本研究发现这些矿层富含钙质生物组分(钙质超微化石和有孔虫),而硅质组分贫乏。由此初步推测,大量钙质生物组分的存在可能增加了黏土粉砂沉积物的孔隙空间,从而为大量水合物的赋存提供了有利的沉积孔隙空间。
The study on the microfacies paleontologists in the core sediments of 4 wells (BY1, BY2, BY3, BY4) in Shenhu area on the northern slope of the South China Sea shows that the abundances of siliceous and calcareous biochemical components in the sediments of the area since the Late Miocene Has greater time and space changes. From the time point of view, the siliceous organisms were almost missing in the late Miocene-Pliocene, with more than 400,000 years (0 ~ 24m) occurring since the middle Pleistocene, flourishing after 180,000 years and coarse grains larger than 0.15mm The abundance of foraminifera during the Late Miocene was very low, while it was high during the Pleistocene-Pliocene spatially. The difference in space was manifested in a wide range of bio-abundance in different drilling cores. According to the change of the abundance of siliceous organisms, it can be inferred that the paleoproductivity was very low at the surface of the sea during the late Miocene-Pliocene-Early Pleistocene, whereas the paleoproductivity was relatively high since the middle Pleistocene. The change of calcareous bio-abundance in the northern South China Sea is mainly controlled by the input of terrestrial materials. Two blocks possibly with different material sources can be identified in the drilling area, such as Late Miocene-Pliocene terrestrial material in BY1 and BY2 Higher than the Pleistocene, the inputs of BY3 and BY4 Pleistocene terrigenous sources are higher than that of the Pleistocene. A surprising and unique phenomenon revealed by the 2007 drilling results in this area is that hydrates are dispersed in the pores of fine-grained sediments (clay silt) up to 20% to 49% Calcareous bio-components (calcareous fossils and foraminifera), while the siliceous components are poor. It is preliminarily speculated that the presence of a large amount of calcareous biological components may increase the pore space of clay silt sediments, thus providing a favorable depositional pore space for the abundance of hydrates.