Pre-Tertiary Nannoplankton Biostratigraphy of Bobong, Buya and Tanamu Formations, Banggai-Sula Basin (2011)



The Banggai-Sula Microcontinent is interpreted as a fragment of the Australia РNew Guinea that became detached during Late Mesozoic and collided with the Eurasian Plate during the Middle Miocene to Pliocene. Until now, the stratigraphy and its importance to the petroleum industry are poorly understood due to lack of precisely biostratigraphic data, especially for Pre-Tertiary periods. This study is conducted to fulfill the mentioned need. The stratigraphical traverse investigating was undertaken throughout Teluk Manaf-Waigoya (Babong Formation), Mahigo (Buya Formation) and Parigi (Tanamu Formation) in Sula Island group. The quatitative nannoplankton analysis on the selected samples of measured section reveals that nannoplankton was developed from few and rare into multiple diverse and abundant. It is strong indication that Middle Jurassic to Late Cretaceous sediments were deposited in a major transgressive cycle. The biostratigraphy result indicates that 1 sample of Babong Formation is included zone NJ9 (Bajocian or Late Jurassic) which is characterized by the occurrence of Watznaueria brittanica and Diductius constans. 4 samples of Buya Formation are belonging to zone NJ17 (Tithonian/Late Jurassic) that is marked by the occurrence of Zeugrhabdotus embergeri at the bootom and Stepanolithion bigotii at the top, whereas 11 samples of Tanamu Formation are implied in zones CC13-CC17 (Coniacian to Campanian or Late Cretaceous) which are bounded by the occurrences of Marthasterites furcatus at the bottom and Quadrum gartneri at the top. The Jurassic assemblages are dominated by Genera Watznaueria and Zeugrhabdotus, whilst Cretaceous assemblages are dominated by Genera Watznaueria, Biscutum, Retecapsa, Predicosphaera, Placozygus, Eiffellithus, Cribrosphaerella and Zeugrhabdotus. Results of this study can be reference for the next detailed nannoplankton studies and hopefully, it can be very useful for the stratigraphical problem solving in Pre-Tertiary play hydrocarbon exploration.

Keywords: Nannoplankton, Biostratigraphy, Zonation, Jurassic, Cretaceous, Banggai Sula Basin.


Author : Panuju