The Mid Miocene Climatic Optimum (MMCO) indication at low latitude sediment case study: The Miocene Cibulakan Formation, Bogor Basin, Indonesia

Abstract

Middle Miocene Climatic Optimum (MMCO) is widely distributed and associated with increasing temperature and CO 2 content in the atmosphere. The effects of MMCO are identified in the mid-latitude region, with lack of examples from the low latitude areas. In this study, we aim to determine the effect of MMCO at Cibulakan Formation of Bogor Basin, Indonesia, which is situated in lower latitude. We took 58 samples from the Cibulakan Formation, which is exposed along Cileungsi River, for quantitative nannoplankton (the abundance of Helicosphaera carteri) analysis to mark increasing and decreasing salinity event, as they are sensitive to temperature. Temperature relates to the salinity of the seawater due to evaporation. From our analysis, we identified sea surface temperature change in Early Miocene which was presumably due to small scale Early Miocene glaciation and active tectonic during the period. The warmer temperature took place on Middle Miocene as the effect of a warm and open sea environment during Mid Miocene Climatic Optimum. Afterward, the temperature continued to rise until the late Miocene, as it had been triggered by the increasing global temperature at the Pacific Ocean and widely distributed clean water at North West Java Basin during the depositional period.