K.T. Dewi1, P.Frenzel 2 , A. Muller3, D. van Harten4
1. Marine Geological Institute, Bandung, INDONESIA
2. Marine Biology Department, University of Rostock, Germany
3. UFZ Centre for Environmental Research, Magdeburg, Germany
4. Department of Geology, Free University, Amsterdam, The Netherlands
Abstract
Surface sediments from water depths between 100 and 3070m along a transect off Timor Island between the Banda and Timor Seas contain more than one hundred species of marine ostracods. Generally, the number of species in each samples ranges from 2 to 112 and reflects a high diversity. The numbers of specimen is between 2 and 4942 individuals per 100 cc of sediment sample. The distribution of ostracod species clearly correlates with water depth. The abundance and diversity of the ostracod fauna tend to decrease with increasing water depth, except for one anomaly in station that was collected in the deepest part (3070m) of the study area. The highest numbers of individuals (>1000) occur in stations with water depth less than 100 m, i.e. in shelf zone and dominated by Paracytheridea, Polycope, Foveoleberis, and various species of Bairdiidae. The bathyal zone is characterized by Cytheropteron, Saida, Bradleya, Pelecocythere, Henryhowella, Krithe and Parakrithe. The unusually high number of ostracode in the Lower Abyssal zone (deeper than 3000m) is mainly caused by the high occurrence of shallow water ostracods. The abundance of ostracods in deep-water are strongly influenced by bathymetry and water mass characteristic that cause downslope transport of shallow water ostracods into deeper environments.
The results of this study clearly show that ostracods are an important component of marine sediments regarding the identification of paleoenvironments, and particularly paleobathymetry. They provide a new and promising tool for future studies of paleobathymetry based on ostracod distribution at continental margins. The results of this study and additional study on two other transects from continental margin could be applied as a model to reconstruct the paleoenvironments in Indonesia.
From : The 33rd Annual Convention & Exhibition 2004 Indonesian Association of Geologist