Earth Sciences, Palaeontology; Mid Miocene Climatic Optimum (MMCO); nannoplankton; temperature changes; Cibulakan Formation
Global climatic event on Middle Miocene triggered by geology activity is called by Mid- Miocene Climatic Optimum (MMCO). This event was widely distributed and associated with increasing temperature and CO2 content in the atmosphere. The effect of MMCO was widely known the mid-latitude region, but still limited information in low latitude sediments. This study try to perform the effect of MMCO at Cibulakan Formation in which deposited in the low latitude basin, Bogor Basin.
Fifty eights samples from Cileungsi River were taken at Cibulakan Formation and quantitative nannoplankton analysis was carried out for this study. Nannoplankton shows the sensitive response with sea surface temperature changes. Increasing of total population nannoplankton indicates the rising of temperature and dropping temperature is marked by decreasing population. The effect of sea surface temperature changes relates with salinity changes as the effect of evaporation. Helicosphaera carteri and Umbilicosphaera jafari were counted to know the salinity trend at Cibulakan Formation.
Sea surfaces temperature changes was observed on Early Miocene which was influenced by small scale Early Miocene glaciation and active tectonic during this period. Warming temperature taken place on Middle Miocene as the effect of warm and open sea during Mid Miocene Climatic Optimum. Afterwards, hot temperature continued on Late Miocene triggered by global increasing temperature at Pacific Ocean and widely distribution of clean water at North West Java Basin.