The Last 14 Million Years (Miocene) of Paleoclimate Changes
Dr. Ir. Vijaya Isnaniawardhani, MT.1 , Dr. Ir. Rubiyanto Kapid2 , and Mohammad Rivaldy, S.T.1 ,
1Geosciences Department Universitas Padjadjaran
2Geology Departement, Bandung Technology Institute
e-mail: vijaya.isnania[at]unpad.ac.id
Abstract
Planktic marine microfossil and sedimentary analysis were performed on Miocene (14 million years ago) to recent sections in south part of West Java Basin to determine paleoclimate changes. The composite sections reveal that since Miocene, a bathyal to inner neritic setting (20 - 500 m sea level depth) was being filled by the fine silisiclastic, dominantly sediment in fluctuative of warm to medium temprature sea surface water. In older part, fine sediments contain Globorotalia tumida, Sphaeroidinella dehiscens, Globigerinoides trilobus sacculiferus and Orbulina universa- planktic foraminifera marine fauna as well as Discoaster quinqueramus, D. asymetricus, D. surculus, D. pentaradiatus, Gephyrocapsa omega and G.oceanica- planktic nannofossil marine flora remains indicated deposition in warm climate at Early Miocene (14-9 Ma). Meanwhile, Globorotalia truncatulinoides-foraminifera, Discoaster variabilis and Calcidiscus leptoporus-nannofossils as taxa characteristic of slight warm condition are locally abundant. In contrast, the younger part of deposited section at Late Miocene (5 Ma) is dominated by marker species of medium temprature climate, particularly Discoaster challengeri, Gephyrocapsa mediterrania, G. carribeanica and Coccolithus pelagicusnannofossils. The relative abundance of warm temprature marker species decrease as a consequence of temperature drop. This level is considered correlate with global glaciation period.
Keywords: Keywords : Miocene, paleoclimate, temprature, microfossil, sedimentary analysis
Topic: Climate Change