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本文研究了《海洋四号》87—88两个航次CC—48和CC(c)—9两岩心的钙质超微化石。共鉴定出7属13种。CC—48岩心自上而下可分为3个钙质超微化石组合,其中组合3和2分别相当于NN2和NN3带;CC(c)—9孔722cm以下的钙质超微化石属于一个组合,大致相当于NN3—4带。两孔所见最老沉积皆为早中新世。同时根据CC(c)—9孔NN3—4带中广泛见有Discoaster exilis化石,认为在该区其地史分布可下延至NN3带(最迟不晚于NN4带)。并结合CaCO_3含量、溶解指数及丰度变化,在早中新世钙质软泥沉积中识别出两个较强的溶蚀期,认为是南极底层水强烈活动所致。
In this paper, calcareous nannofossils of two cores CC-48 and CC (c) -9 of “Ocean IV” 87-88 were studied. A total of 7 genera and 13 species were identified. CC-48 core can be divided into three calcareous nannofossil assemblages from top to bottom, of which three and two correspond to NN2 and NN3 belts, respectively; CC (c) -9 calcareous nanofossils below 722 cm belong to one Combination, roughly equivalent to NN3-4 belt. The oldest deposits in both boreholes were all Early Miocene. In the meantime, Discoaster exilis fossils are widely found in the NN3-4 zone of CC (c) -9. It is believed that the historical distribution of this area can be extended to NN3 zone (no later than NN4 zone). Combined with the change of CaCO_3 content, dissolved oxygen index and abundance, two strong dissolution periods were identified in the sediments of calcareous slime in the Early Miocene, which are thought to be due to the strong activity of the Antarctic bottom water.