Shell Bed Identification of Kaliwangu Formation and its Sedimentary Cycle Significance, Sumedang, West Java

Abstract

Kaliwangu Formation cropping out around Sumedang area contains mollusk fossils dominated by gastropods and bivalves. In terms of sequence stratigraphy, each sedimentary cycle generally consists of four shell bed types: Early Transgressive Systems Tract (Early TST) deposited above an erosional surface or sequence boundary, that is characterized by shell disarticulation, trace fossils, gravelly content, no fossil orientation direction, and concretion at the bottom; Late Transgressive Systems Tract (Late TST) identified by articulated (conjoined) specimen in its life position, that shows a low level abration and fragmentation, adult specimen with complete shells, and variation of taxa; Early Highstand Systems Tract (Early HST) characterized by adult taxa that was found locally in their life position with individual articulation, juvenile specimens frequently occured; Late Highstand Systems Tract (Late HST) determined as multiple-event concentrations, disarticulated shell domination, and some carbon or amber intercalation indicating terrestrial influence. Shell bed identification done on this rock unit identified nineteen sedimentary cycles.

Characteristics of Kedondong Trass and Bobos Trass as Cement Raw Material, Cirebon, West Java, Indonesia

“…Kaliwangu Formation is Pliocene marine sediments rich in molluscs, consist of shale intercalated with sand and gravel. On top of those, Plio-Pleistocene volcanic rocks are andesitic-tuffaceous Kromong Breccia, undifferentiated volcanic rocks, and andesite intrusions (Aswan et al, 2013;Djuri, 1995;Jambak et al, 2015).…”

Paleodepositional Environment of Kaliwangu Formation based on Mollusc Fossils Assemblage in Ciwaringin River, Leuwimunding Area, Majalengka, West Java, Indonesia

“…The purpose of this research is to investigate the paleodepositional environment changes in the Ciwaringin River and its tributaries in the Leuwimunding area based on the abundance of mollusc fossils. Studies on the depositional environment of the Kaliwangu Formation based on mollusc fossils have been conducted by several researchers [5], [6], [7]. [5] and [6] conducted research in the Sumedang area to the west of the study site, while [7] conducted research in the Cirebon area to the east of the research area.…”

“…Studies on the depositional environment of the Kaliwangu Formation based on mollusc fossils have been conducted by several researchers [5], [6], [7]. [5] and [6] conducted research in the Sumedang area to the west of the study site, while [7] conducted research in the Cirebon area to the east of the research area.…”

Depositional Environmental Evolution of Nyalindung Formation based on Paleontology Molluscan Study, Ciodeng Area, Sukabumi, West Java, Indonesia

“…Several genera of mollusk fossils can be used as indicators of depositional environment, and even some of them can be used as an age index fossil. The study of mollusk paleontology is quite important because in recent years, there have been only a few articles published on the results of molluscan paleontology studies in Java, including Sufiati (2012) in Banten, Prasetyo et al (2012) in several sites in West and Central Java, Sufiati (2013) in Bumiayu and Cirebon, Aswan et al (2013) in Sumedang, Aswan et al (2015) in the Bobotsari Basin, Purwokerto and its surroundings, Aswan et al (2017) which investigated the age of several mollusk fossil-containing deposits on the island of Java, Aswan et al (2018) in the Cisaat River in Bumiayu, and Sari et al (2019) in Bayah, Banten province. The research on molluscan paleontology is also significant because rocks that contain mollusk fossils generally lack foraminifera contain, whereas foraminifera are usually used to determine the depositional environment.…”