Year

1993

Degree Name

Master of Science (Hons.)

Department

Department of Geology

Abstract

Ostracod faunas from surface and core sediment samples from west of Bawean Island, Java Sea, Indonesia have been studied- quantitatively. A total of 113 species including seven new species, 1 new subspecies and 16 species which remain in open nomenclature were recorded. The following new species and subspecies were erected: Polycope baweaniensis sp. nov., Cytherella javaseaense sp. nov., lAglaiocypris susilohadii sp. nov., Loxoconcha wrighti sp. nov., Loxoconcha ismailusnai sp. nov., Keijia tjokrosapoetroi sp. nov., Keijella carriei sp. nov. and Foveoleberis cypraeoides baweani ssp. nov.

Ostracod faunas from surface and core sediment samples from west of Bawean Island, Java Sea, Indonesia have been studied- quantitatively. A total of 113 species including seven new species, 1 new subspecies and 16 species which remain in open nomenclature were recorded. The following new species and subspecies were erected: Polycope baweaniensis sp. nov., Cytherella javaseaense sp. nov., lAglaiocypris susilohadii sp. nov., Loxoconcha wrighti sp. nov., Loxoconcha ismailusnai sp. nov., Keijia tjokrosapoetroi sp. nov., Keijella carriei sp. nov. and Foveoleberis cypraeoides baweani ssp. nov.

The species spectra of the study area show a close biogeographical relationship with other assemblages from the Malacca Strait and the southern part of South China Sea. A moderate affinity with eastern part of Indonesia including Gulf of Carpentaria, the Solomon Islands and Arafura Sea is probably due to the presence of shelf break in the Banda Sea which has more than 5000 m depth.

Changes in ostracod diversity and density from core samples of the study area were documented. The ostracod faunas on the upper part (at interval 0-60 cm) were more abundant and diverse than on the lower parts. This change and also variation in sedimentoiogical and geochemical data (such as texrural changes, abundance of calcareous ooliths, very low phosphorus and organic contents in some intervals of the cores), it is inferred that a stadia! period occurred in the study area. In certain areas during this period, this was indicated by the present of a oligohaline and less agitated environment On the basis of radiocarbon data from surrounding areas, it is suggested that this period was at about 10 ka ago.

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