DEPOSITIONAL ENVIRONMENT STUDY OF THE CITALANG FORMATION BASED ON TAPHONOMY ANALYSIS OF VERTEBRATES FOSSILS AND MOLLUSKS FOSSILS AS WELL AS LITHOFACIES IN JEMBARWANGI VILLAGE AND THE SURROUNDING AREAS, SUMEDANG, WEST JAVA

• Main Author: Athira, Yasmine
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69705
• Institution: Institut Teknologi Bandung

Multiple fossil-bearing localities found in West Java are still understudied, one of those places is Jembarwangi village in Sumedang Regency, where abundant fossils with many potentials for further research remain. The Citalang Formation that can be found on the study area was sediments that was deposited in a fluvial environment. The purpose of this study is to analyze that fluvial environment in detail. To achieve that, fossil samples from vertebrates and mollusks, as well as several detailed stratigraphic columns of the Citalang Formation were analyzed. Vertebrate fossils are analyzed based on environment association as well as the abrasion present on the bone breakage and the mollusks fossils based on the condition of the shells and their long axis orientation to the rock bedding. Results of the study show that the Citalang Formation was deposited in a braided river system that consists of channel, natural levee, and floodplain. Terrestrial and semiaquatic animals have experienced minimal transportation based on their still well-preserved condition. In the channel deposits there are few semiaquatic vertebrate fossils such as Crocodylidae and Gavialidae. Meanwhile, there are a couple of terrestrial vertebrate fossils like Bovidae found on the natural levee deposits, with minimal abrasion, indicating minimal transportation. No mollusk fossils were found in the natural levee deposits. There are many terrestrial vertebrate fossils such as Stegodonidae, Suidae, and Cervidae among others that were found with almost no abrasion on the bone breakage showing minimal or no transportation in the floodplain deposits. Mollusk fossils in the floodplain deposits was found to have undergone transportation by slow moving water, washed by medium to high energy flood, and also found in their living position. The mollusks can be affected by different energy in water current based on their position in the floodplain relative to the channel, where its stronger near the channel and decreases as it gets farther away. There are four lithofacies found on the study area, namely; Conglomerate Facies, Siltstone-Tuffaceous Sandstone Facies, Claystone-Tuffaceous Sandstone Facies, and Claystone Facies. Based on the characteristics of each lithofacies in the Citalang Formation of the study area, it can be interpreted that the Conglomerate Facies was a part of the channel, Siltstone-Tuffaceous iv Sandstone Facies as the natural levee, also Claystone- Tuffaceous Sandstone Facies and Claystone Facies as the floodplain.