Pliocene - Quaternary biostratigraphy in the east of Vietnam continental shelf based on the calcareous nannofossil and foraminifera documents

Abstract

Foraminifera and calcareous nannofossil are widely used
in the marine biostratigraphy study due to their rapid
evolution and wide distribution. Through many years of
studying Pliocene - Quaternary in the east of the Vietnam
continental shelf via oil and gas exploration wells, the
authors found that these two fossil groups were really
effective tools for dividing details these sediments. The
A, B, C, D, E, and F wells were chosen as a presentative
for the study area. Following the standard zonal schemes
of planktonic foraminifera “N” Blow, “PL” & “PT”
Wade, et al.; the standard zonal schemes of calcareous
nannofossil “NN” Martini and “CNPL” Backman, et al.,
the Pliocene - Quaternary biostratigraphic framework
in the studied area were established. In this study, the
early Pliocene sediments were limited to the foraminifera
zone PL1-PL3/upper N18-N19, corresponding to the
nannofossil zone CNPL1-CNPL3/NN12-NN15. The late
Pliocene sediments consisted of the foraminifera zone
PL4-PL6/N20-N21, corresponding to the nannofossil
zone CNPL4-CNPL6/NN16-NN18. The early Pleistocene
sediments were characterised by foraminifera subzone
PT1a/the lower N22, approximate to the nannofossil zone
CNPL7-CNPL10/NN19. The late Pleistocene sediments
include the foraminifera subzone PT1b/the upper N22
and nannofossil zone CNPL11/NN20-NN21. The results
exhibited that the suitability of stratigraphic division in
the studied area with the standard zonal schemes in the
Pliocene - Quaternary period in Pacific and low - latitude
oceans. This is a premise to apply for the stratigraphic
study and correlation in the Vietnam continental shelf
and adjacent areas.