IDENTIFIKASI FOSIL FORAMINIFERA BESAR DI BATUPASIR EKUIVALEN ANGGOTA GREBE, FORMASI JOHNSTON, RAIJUA

Abstract

Raijua Island is an island formed by accretion of the Australian Passive Margin sequence that collided with the Banda Arc. The lithology in this study area is generally sedimentary complexes such as sandstone, siltstone, claystone, limestone, conglomerate and tuff. The scope of this research study focuses on identifying the characteristics of fossils in sandstones at Bukit Wata Dagi, Raijua Island, East Nusa Tenggara to determine the relative age and depositional environment. The methods used in this analysis are statigraphic cross section and petrographic analysis. Microscopically, this rock is a type of Allochemic sandstone (Mount, 1985). There are 7 types of Large Bentic Foram fossil species namely Discocyclina.sp, Nummulites, Opercunella, Operculina, Heterostegina.sp, Eulepydina.sp, Alveolina.sp and Spiroclypeus. Based on the analysis that has been done, the sandstones in Bukit Wata Dagi are Paleocene - Eocene in age (Adam, 1970). These sandstones were deposited in a shoreline environment, which is closely related to the shallow marine environment - offshore transition. The sandstones in Bukit Wata Dagi are equivalent to the Jhonston Formation, Australia in terms of age characteristics and the same depositional environment.