Field trip Guide Book: Paleogene Sedimens of Bayah Area
Instructor: Awang H. Satyana
Years: 2015
Instructor: Awang H. Satyana
Years: 2015
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Regional GeologyJava island is a part of Eurasia Plate forming the edge of the plate as Sunda shield which is overidding the northerly moving Indian Oceanic Plate. This plate interaction form complex tectonic setting in the present-day Java which includes back-arc, inter-arc, and fore-are basins.
West Java may be subdivided into some tectonic provinces:
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Stratigraphy
The early Tertiary sediments are generally dominated by coarse clastics rich in quartzose material derived from the basement of the Sunda Shield to the north. The environment of deposition, however, appears to vary markedly from locality to locality. At Gunung Walat (PasirBongkok) the sequence is of fluvial original, while near Bayah environments are more deltaic to shallow marine. Further west at Cihara the same sequence becomes dominated by shallow marine facies. In the Valley of Cimandiri and further to the south in the Ciletuh area, the coarse clastics are associated with what is now believed to be a submarine fan sequence, but in the southern part of Ciletuh area the sediment is characterized by fluvial deposits. These outcrops are considered to be some of the best and most continuous in Java.
This field trip focuses on the Eocene Bayah Formation and Oligo-Miocene limestone of Citarate or rajamandala Formation. Koolhoven(1933)first described the Bayah Formation from the vicinity of Bayah, SW Java, as consisting of two facies, Northern and Southern. The Bayah cropping out north of Cimandiri Village is dominated by black clays, concoidal, with rare limestone intercalations (Northern Facies). The clays are devoid of fossils, except that they contain large, thin Oppreculina in the lowermost part.
This field trip focuses on the Eocene Bayah Formation and Oligo-Miocene limestone of Citarate or rajamandala Formation. Koolhoven(1933)first described the Bayah Formation from the vicinity of Bayah, SW Java, as consisting of two facies, Northern and Southern. The Bayah cropping out north of Cimandiri Village is dominated by black clays, concoidal, with rare limestone intercalations (Northern Facies). The clays are devoid of fossils, except that they contain large, thin Oppreculina in the lowermost part.
Stop Site and Outcrops
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Intercalated breccia – sandstone which its strike can be traced continously. These rocks were deposited in the slope with turbidite mechanism.
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Intercalated sandstone, siltstone, claystone, and conglomeratic sandstone. Some outcrops were deposited in ideal system tracts pattern sequence from lowstand, transgressive, dan highstand; and the repreated from lowstand, transgressive, and highstand.
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Massive to thick bedded conglomeratic quartz sandstone of Walat/Bayah Formation at Pasir Bongkok area.
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Coal and thin bedded silty sandstones of Walat/Bayah Formation at Pasir Bongkok
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