Paleogene Calcareous Nannofossil Chronostratigraphy At CB Well, South Makassar Basin
Cut Balqis Riva Alya, Rendy, Dewi Syavitri, Yarra Sutadiwiria, Andy Livsey*, Salsabila Reno

Study Program of Geological Engineering, Faculty of Earth Technology and Energy, Universitas Trisakti, Jakarta, Indonesia.
*PT. Horizon Consulting

Abstract

Well ^CB^ is located in the South Makassar Basin, where the lithological unit comprises of the Balangbaru and the Toraja Formation. The Paleogene calcareous nannofossils biostratigraphy of this area has not been studied yet and the chronostratigraphic framework is still arguable, So in this study, we discuss the detailed bio-chronostratigraphy of the South Makassar Basin, using calcareous nannofossil biostratigraphy. This study aims to identify the calcareous nannofossils assemblages, determine the age, calculate the sedimentation rate, and reconstruct Paleogene chronostratigraphy in the ^CB^ well in The South Makassar basin. This study analyzed high-resolution calcareous nannofossils of the well ^CB^ from a depth of 9 to 2288 m. The cutting samples and a few core samples were used for the biostratigraphic analysis and were processed using the smear slide method. There are 53 species of calcareous nannofossils belonging to 21 genera identified in the well ^CB^. Three calcareous nannofossils genera which dominate the assemblages are Cyclicargolithus, Reticulofenestra, and Sphenolithus. The age of the lithological unit is assigned to Maastrichtian Stage of Cretaceous to NP16-NP23 of middle Eocene to middle Oligocene. Unconformities detected in two horizons are correlated to the timing of well-known global climatic events such as ^K/Pg Meteor impact^, ^the Late Paleocene Thermal Maximum^ (66 to 55Ma) and ^Oi-1 glaciation^ (34 to 32Ma). This result reveals that the occurrence of unconformities of ^CB^ well in the South Makassar Basin is significantly related to eustatic changes caused by global climatic events. The implications of this study include that it could be a novel contribution to hydrocarbon exploration in Indonesia, as well as an important reference for further biostratigraphic studies in the South Makassar Basin.

Keywords: Biostratigraphy- Calcareous nannofossils- Chronostratigraphy- Paleogene- South Makassar Basin

Topic: Engineering