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一、概况海底松散沉积物以及下伏地层的研究,对探讨边缘海的形成历史和油气资源的预测与勘探起着重要的作用.一九八一年七月中国科学院海洋研究所的地球物理调查船“科学一号”,于冲绳海槽南段西陡坡海底水深250米处(图1),发现了含有早中新世瓣鳃类和腹足类化石的岩石.由底层拖网收集到较多的棱角状碎石(图2).其成分为灰黑—黑色板状页岩和灰色砂岩,均为钙质胶结.碎石最大直径约为5公分,一般为3公分左右,因受海水长期腐蚀,表面有坑洼和现在底栖生物固着.其次,在碎石当中还混掺少量的磨圆很好的椭圆状砾石(图3).其岩性又全部为暗灰色中基性火成岩,大小在3公分左右.
I. Overview The study of unconsolidated sediments and underlying strata plays an important role in exploring the formation history of the marginal sea and in the prediction and exploration of oil and gas resources. Geophysical Survey of the Institute of Oceanology, Chinese Academy of Sciences, July 1981 The ship Scientific 1 has been found to contain rocks of the Early Miocene Valulaceae and Gastropod fossils at a depth of 250 meters at the seabed of the steep slopes in the southern section of the Okinawa Trough (Figure 1) (Figure 2) .Its composition is gray-black - black plate shale and gray sandstone, are calcareous cementation.The maximum diameter of the gravel is about 5 cm, usually about 3 cm, due to long-term seawater Corrosion, surface potholes and now benthic organisms fixed.Secondly, in the gravel mixed with a small amount of well rounded oval gravel (Figure 3) .Their lithology and all of the dark gray basement igneous rock, About 3 cm in size.