Coral Reef Development as an Indicator of Seal Level Fluctuation: A Preliminary Study on Pleistocene Reef in Bulukumba, South Sulawesi

Abstract

-Coral reef is one of the best archives of a climate change. The reefs record the condition of environment where they developed. Indonesia as a tropical country has abundant coral reefs from Tertiary to Recent. The ancient reefs are commonly found along the coast and they form terraces. This research is located at the Selayar limestone of Bulukumba Regency, South Sulawesi. The objective of this research is to define paleoclimate change based on the coral development and sea level fluctuation. Sample collection was done by applying five intersect lines perpendicular to the cliff. Petrographic analyses of fossils, and microfacies study as well as the sea level fluctuation were analyzed by studying organism, reef development, and morphology. This article is focused on the sea level fluctuation analysis.There are three stages of the reef development and sea level fluctuation. It was initiated within a protected shallow marine to a reef front slope unconformably overlying siliciclastic rock. The second period of the reef development is characterized by the growing of branching, delicate, robust, and massive corals associating giant Tridacna sp. The third period is the formation of bafflestone delicate branching coral and robust branching corals. Following the Pleistocene reef development three beach abrasions (notches) were identified indicating the sea level fluctuation. Beach abrasions occurred during the Pleistocene reef development as the first notch. The second notch occurred at the reef crest and back reef during the first sea level fall and finally the recent sea level as the third notch.

Pleistocene reef development in Bulukumba, South Sulawesi

“…Pleistocene reef unconformably overlies volcanic rock of the Walanae Formation [4] in Bira area. On the other hand the Walanae Volcanic does not expose in Pulau Liukangloe (small island closed to Bira).…”

“…They are a member of the Selayar Limestone, Walanae Formation [3], [4]. The rocks are exposed in several terraces indicating sea level fluctuations and/or tectonic activities during their development.…”