Sites 1146 and 1148 of Ocean Drilling Program Leg 184, in the South China Sea (SCS), comprise long sediment sections with a time span from the early Oligocene to the Pleistocene. Calcareous nannofossils from these two sites were biostratigraphically studied.
We recognized 53 early Oligocene to Pleistocene events that are commonly found in open sea areas and can therefore be correlated within a large geographic range. This study also revealed that a few conventionally used nannofossil events are not suitable for the SCS, and further evaluation is needed.
The lower Oligocene to Pleistocene sequences recovered at Sites 1146 and 1148 were subdivided into the 4 Paleogene zones and 21 Neogene to Quaternary zones of Martini, in correlation with the Paleogene to Quaternary zones of Okada and Bukry. This provided a lower Oligocene through Pleistocene nannofossil biostratigraphic framework.
A significant unconformity was recognized in the Oligocene–Miocene transition, in which the upper part of Oligocene Zone NP25 and lower part of Miocene Zone NN1 were missing. The time span of the unconformity was estimated to be ~1 m.y.
Very high sedimentation rates were seen in the Oligocene, relative low values were seen in the Miocene, and the highest values were seen in the Pleistocene, which was believed to be the result of tectonic and sedimentation history of the SCS.
1Su, X., Xu, Y., and Tu, Q., 2004. Early Oligocene–Pleistocene calcareous nannofossil biostratigraphy of the northern South China Sea (Leg 184, Sites 1146–1148). In Prell, W.L., Wang, P., Blum, P., Rea, D.K., and Clemens, S.C. (Eds.), Proc. ODP, Sci. Results, 184 [Online]. Available from World Wide Web: <http://www-odp.tamu.edu/publications/184_SR/224/224.htm>. [Cited YYYY-MM-DD]
2China University of Geosciences (Beijing), Xueyuan Road 29, Beijing, 100083, People's Republic of China. xsu@cugb.edu.cn
Initial receipt: 30 January 2004
Acceptance: 9 August 2004
Web publication:
19 November 2004
Ms 184SR-224