南海北部第三纪钙质超微化石生物地层学研究  

TERTIARY CALCAREOUS NANNOFOSSIL BIOSTRATIGRAPHY IN THE NORTH PART OFTHE SOUTH CHINA SEA

作　　者：段威武[1] 黄永样[1] 

机构地区：[1]地质矿产部广州海洋地质调查局

出　　处：《地质学报》1991年第1期86-101,T002,共17页Acta Geologica Sinica

摘　　要：本文根据40口钻井剖面的钙质超微化石分析和研究成果,将南海北部海相第三系,划分出上渐新统至上新统18个超微化石带和始新统1个未命名组合。始新统未命名组合仅见于珠江口盆地东北缘。上渐新统至上新统18个超微化石带为连续沉积,但各带的发育程度不尽相同。其中相当于E.Martini(1971)划分的NN4—NN5带,NN11带和NN13—NN15带发育良好,横向稳定,分布广。它们是南海北部上第三系划分和对比的重要标志。结合部分有孔虫分带和岩性资料,探讨了全区海相第三系的沉积特征及沉积间断分布发育情况。文中还讨论了下、上第三系,第三系与第四系的超微化石划分标志以及再沉积超微化石的特点和地质意义。The marine tertiary sequences in the north part of the South China Sea (from the Beibu Gulf Basin through the Pearl Mouth Basin and S. E. Hainan Basin to the Tainan Basin) may be divided into 18 calcareous nannofossil zones of Late Oligocene to Pliocene age and 1 unnamed assemblage of Eocene age on the basis of the analyses of calcareous nannofossils from 40 offshore boreholes. The unnamed Eocene assemblage has been only found on the northeast margin of the studied region, which represents the oldest nannofossil-bearing sediments in this region. It is assumed that the sea water came from the northeast. Since the Late Oligocene, the distribution of marine sediments in the north part of the South China Sea has continuously extended. The marine Upper Oligocene, Miocene and Pliocene are characterized by continuous sedimentation in the whole area, but the development of the 18 nannofossil zones varies from basin to basin. Among the 18 nannofossil zones, those corresponding to Martini's NN4-NN5 zones, NN11 zone and NN13-NN15 zones are well developed and well preserved, which are relatively persistent laterally and also widespread. They are the important markers for both the stratigraphical subdivision and the correlation of the Upper Tertiary between various basins in the northern part of the South China Sea. Based on mainly the nannofossils and the sedidmentary features, with also reference of the foraminifera zonation in certain basins, the present paper approaches the boundaries between the Upper and Lower Tertiary and between the Quaternary and Tertiary as well as the boundary within the Upper Teriary. A preliminary statistics suggests that reworked calcareous nannofossils are relatively abundant at least in the Midle Miocene-Upper Miocene, the Upper Pliocene and Mid-Upper Eocene (?) in the Pearl River Mouth Basin. This has been thought to be related to the basement uplift or sea (lake) leve fall and to the enlargement of the erosion area during that depositional period.

关 键 词：钙质超微化石 生物地层学 第三纪 

分 类 号：Q911.661[天文地球—古生物学与地层学]