Chronostratigraphic Framework based on Micro-paleontological Data from Drilling LS33a in Deep Water Area of Northern South China Sea

Key words: 
• planktonic foraminifera /
• calcareous nannofossils /
• fossil events /
• biochronostratigraphy /
• deep water area /
• Qiongdongnan Basin

Abstract: Since the Oligocene, thousands of meters of marine strata have been deposited in the deep water area of the Qiongdongnan Basin in the northern South China Sea, in which micro-fossils are enriched. Twenty-one planktonic foraminiferal fossil zones (N22 zone-P19 zone) and twelve calcareous nannofossil zones (NN19 zone-NP24 zone) were recognized by fossil identification of the cored samples from drilling LS33a in deep water area. Combined with previous results of the ODP184 Leg implemented in the South China Sea and the Geologic Time Scale 2012, the geological ages of the fossil events were discussed, and the chronostratigraphic framework based on micro-paleontological data from drilling LS33a was constructed. On this basis, this paper discusses the position of the stratigraphic boundary between the Pleistocene and the Pliocene, the Upper Pliocene and the Lower Pliocene, the Pliocene and the Miocene, the Upper Miocene and the Middle Miocene, the Middle Miocene and the Lower Miocene, the Miocene and the Oligocene, the Upper Oligocene and the Lower Oligocene, defines the age assignment of Yacheng Formation, Lingshui Formation, Sanya Formation, Meishan Formation, Huangliu Formation, Yinggehai Formation and Ledong Formation, and finally establishes a high-resolution comprehensive chronostratigraphic framework suitable for the deep water area of the northern South China Sea.