INTERPRETATION OF DEPOSITIONAL ENVIRONMENT AND AGE DETERMINATION OF TAPAK AND KALIBIUK FORMATIONS BASED ON FOSSILS EVIDENCE IN BENTARSARI AREA, BREBES, CENTRAL JAVA PROVINCE

• Main Authors: Pratama, Muhammad Firman, Millayanti, Anis, Husna, Dzaka Ali Syaiful, Asupyani, Hilyan
• Format: Conference Object
• Language: English
• Published: 2019
• Subjects: Geology; Planktonic foraminifera
• Online Access: https://repository.ugm.ac.id/275728/; https://repository.ugm.ac.id/275728/1/B011UNO.pdf

The research is located in Bentarsari Village, Salem, Brebes District, Central Java Province. The regional stratigraphy in this region has devided into four part those are from old to young Kumbang, Tapak, Kalibiuk and Linggopodo Formations. The aim of this research is to reinterpret of Tapak and Kalibiuk Formations age, with the condition of depostional environment both of it, from fossils evidence. Methodology of this research it can be divided into two, first field orientation geological mapping with 1:12500 scale. Each points of location which has been found of outcrop should be plotted on base map, and describe all of features must be recorded. After that, it was reconstructed to be geological map. Then it was conducted in laboratory of paleontology to describe microfossils. The results were found several macrofossils that could be well or not described. In Claystone Unit (SBl) has been found molluscs which are Turitella djadjariensis as a gastropod and Pecten sp as a pelecypod, they found at different points of location. During observation it was found in Sandstone Carbonate Brownish Unit (SBkk) pelecypod fossil namely Paphia sp. The microfossils were found in SBkk Unit are planktonic foraminifera such as Globigerinoides ruber, Globigerinoides immaturus, Hastigerina aequilateralis, Globorotalia multicamerata, and Globigerinoides trilobus. Also, has been found bentonic foraminifera such as Valvulineria minuta and Pannellaina earlandi. Meanwhile, in Claystone Unit bentonic foraminfera both are same before,unless there was a different one namely Aphelophragmina pygmaea. According to the fossils data it can be interpreted the age of SBkk Unit Late Miocene – Middle Pliocene and the condition of depositional environment was Intertidal – Middle Neritic. While, the age of SBl unit was Middle Pliocene – Late Pliocene and the depositional environment was Middle Neritic – Transition through to be terrestrial.