Cover and Front Matter

Cover and Front Matter of Berita Sedimentologi Vol. 47 No. 3, 2021

Isotopic reconstruction of Proboscidean habitats and diets on enigmatic island of Sulawesi

Sulawesi is known for its complex geological and biogeographic history, which is reflected in their extinct and extant faunal assemblage. Evidence of oldest terrestrial fauna in Sulawesi was found in the Early Pleistocene sediment and evolved since then. Despite being mostly isolated from the mainland Southeast Asia; four successive Proboscidean taxa have been found from the southern part of the island. The four taxa are: Stegoloxodon celebensis, Stegodon sompoensis, Stegodon sp. B, and cf. Palaeoloxodon namadicus, in which respective taxa are included in successive faunal stages. The aim of this research is to reconstruct the diet and palaeoenvironment of these Proboscidean taxa by incorporating stable isotope analysis with the fossil faunal record, geology, and stratigraphy. Stable carbon (δ13C) and oxygen (δ18O) isotope analysis were especially used in this study. Our result suggests that Stegoloxodon celebensis and Stegodon sompoensis were flexible feeders and were able to adapt to different niches, from closed canopy forest to open vegetation, while the diets of Stegodon sp. B, Celebochoerus heekereni and cf. Palaeoloxodon namadicus suggest that they were more specialized.

Tenggar Cave, Tulungagung: preliminary study and its paleontological potentials

Goa Tenggar or Tenggar Cave is situated in the karstic physiography of southern Tulungagung, East Java that made up of prehistoric caves. These include the Wajak complex (minimum age of 37.4 to 28.5 thousand years ago) and the Song Gentong (around 7000 BP). The formation of Tenggar Cave is influenced by the subterranean river that penetrates the limestone unit. This cave has a front width of ± 10 m and a roof height of ± 8 m. The east side of the cave floor is a layer of soil, and the western side is the river. The inside of the cave composed by very compact conglomerate deposits and paleosoil that contains faunal remains, including Cervus sp., Bos sp., Bubalus sp., and Bibos sp., which may have occurred during the Pleistocene. The fossilized faunal remains from Tenggar Cave show that there was a relatively open environment during that time, such as a savannah with large trees and flowing rivers around the cave. The paleoenvironment indicates late Pleistocene to early Holocene period, similar to paleoenvironment in the Sewu Mountains that stretch along the southern part Java from central to the eastern tip of the island includes the coastal towns of Gunung Kidul, Pacitan and Tulungagung. The situation is certainly a point of interest when associating the findings with the surrounding sites, starting from Wajak, Song Gentong, Pacitan, Ponorogo, and Gunung Kidul. However, absolute dating test is necessary to be more certain of the lifetime of the fossilized fauna. If the fossils were from the Late Pleistocene, it could be an important information for the fields of paleontology, paleoanthropology, and prehistoric archaeology given that the occurrence of sites with such antiquity are limited in Southeast Asia. It is essential to conduct intensive research in Tenggar Cave in the future.

Geological stories from the journey of mollusks fossils in Java

The journey began in the Eocene with the presence of mollusk fossil in the Nanggulan Formation (near Yogyakarta) in Central Java. Many experts believe this was the early part of the Tethys system which might still be connected to the Tethys system in Europe.The oldest mollusk fossils type locality after Nanggulan is the Early Miocene Jonggrangan Formation in Kulon Progo near the city of Yogyakarta, which is dominated by the gastropod Haustator specimen. Molluscan paleontological studies of this type of locality reflect a restricted environment with less influence of the Tethyan system. Haustator are considered as the ancestor of the Turritellidae group, which is found mostly on Java Island, during the younger Tertiary to Quaternary Periods.The story continued to the Middle Miocene where the Tethyan realms indication was clearly observed by the presence of some typical Tethys species such as Volema and Babylonia from Nyalindung Formation, West Java. The regional sea level rise in this epoch (around 12 Ma) that was indicated by the presence of Vicarya as an index fossil, which occurrence was due to land submerging to become mangroves area. The fossil then quickly become extinct when the sea level dropped back.Late Miocene to Pliocene was like the transition period from the Tethyan realm to the Pacific realm, where the Tethyan fauna was no longer present. Only evolutional traces of the Middle Miocene mollusk fossils were observed. This continuous evolution is most clearly seen in Turritella cramatensis (late Miocene), Turritella acuticarinata (early Pliocene) and Turritella cikumpaiensis (late Pliocene) which was interpreted to have originated from Turritella angulata as their ancestors.Earth cooling environment that happened in the late Pliocene/early Pleistocene has led the diversity and evolution of a new group of mollusks, most clearly observed from the abundance of Turritella bantamensis in the Bojong Formation, Banten. The new Turritella group has a curved whorl that different from its predecessor with an angled whorl shape.Plio-Pleistocene tectonics event has ended the period of Java marine mollusks domination, then only freshwater mollusk fossils can be found in almost all Quaternary mollusks-bearing deposits.

Dinoflagellate biostratigraphy of Eastern Indonesia stratigraphy: key of petroleum exploration success

Several major discoveries in the eastern part of Indonesia (e.g. Tangguh and Abadi) have increased more petroleum exploration interest in the area. These sizeable discoveries encountered gas in the Jurassic sandstone, which is a key reservoir target in the Northwest Shelf of Australia. The Mesozoic sandstone provenance is located in the Australian Continental Plate or also known as the Sahul Shelf. Thousands of wells were drilled in the Sahul Shelf and the stratigraphy in this area is well understood. The extension of the Mesozoic sandstone towards Indonesian territory, with much less well information, is one of the keys of success for petroleum exploration. Refinement of the stratigraphy of the eastern part of Indonesia is crucial to understand the extension.To refine the stratigraphy of Eastern Indonesia, especially for the Mesozoic interval, dinoflagellates play a significant role. Several types of this marine biota have been used by Australian stratigraphers as markers. In the case where stratigraphic tie to Northwest Shelf Australia discoveries, key wells or standard chronostratigraphy, dinoflagellate understanding is critical.Dinoflagellate markers are used to mark several subdivisions of Plover Sandstone. Norvick (2001) used W. indotata and D. caddaensis Maximum Flooding Surfaces to subdivide the reservoir target into upper, middle and lower Plover Formation. These surfaces are named after dinoflagellates. More markers were identified to mark the source rock and seal in the petroleum system. To have a detail correlation from Indonesia to the NW Shelf, understanding of dinoflagellates is crucial.

Fossil-bearing Citalang Formation, Sumedang-Majalengka, West Java

The Citalang Formation in Sumedang-Majalengka area comprises of various lithological units, including coarse-grained sandstones to conglomerates, greenish grey to dark grey claystone with sandstone and tuff interbeds, and pumice-bearing tuffaceous sandstones and tuff. All these units occur in the lower part of the formation and the contacts with older, underlying rock units are unconformable in several places.Vertebrate fossil fragments are frequently found in the lowermost part of the formation, especially within the coarse-grained sandstones to conglomerates unit. This unit also holds stone tools artefacts, which were made from different kind of stones and show quite simple or primitive shape. The age of Citalang Formation is not yet resolved and still needs to be researched. Some published literatures suggest Pleistocene while there are others that suggest Pliocene.

On the 91/17 pattern in the brackish ichnofabric

From previous research, I have identified what ichnotaxa dominate each ichnofabric unit and how many ichnotaxa are taking up a share of the total observed ichnofabric units. The contribution of this paper is the 91/17 pattern. The point of this pattern is that only 17% ichnotaxa (6 of 34 ichnotaxa) had 91% of the total ichnofabric units that were observed. In addition, the six ichnotaxa tend to be more monospecific. These are the most effective strategies for the animal to survive by constructing the most essential structures. These strategies are common in brackish paleoecology in the fluvial-marine transition zone.

The Palaeo-Kambaniru river mouth, Sumba, East Nusa Tenggara, Indonesia: A record of strongly seasonal catastrophic flow in a monsoon-controlled deltaic complex

The Kambaniru River valley near the city of Waingapu preserves a thick succession of coarse-grained fluvial-deltaic sediment deposited during the Late Pleistocene. This succession incises through a thick uplifted coral reef terrace succession and records intervals of highly episodic flow events during the last glacial interval. The occurrence of intraclastic, coarse sand/gravel matrix olistostromes in several areas attests to the occasionally catastrophic nature of flow in the ancestral Kambaniru River. Small to moderate-sized coral-rich reefs and laterally restricted reef terraces occur on delta-front conglomerate successions at multiple horizons through the study interval. These reefs record both intervals of low flow as well as periodic river-mouth avulsion episodes. Comparison of radiometric dates obtained from pelecypod and coral material from both deltaic successions and laterally adjacent coral reef terrace intervals indicates that uplift/subsidence history of the terraces differs from that of the valley and that correlation between the two should be taken with care.

Archaeology of disaster in Indonesia: where are we now?

Natural disasters are a phenomenon that shaped the Indonesian Archipelago. Earthquakes and volcanic activities have become periodic experiences in the lives of people in this region. The geographical characteristics of Indonesia which are located at the confluence of active plates and part of the global volcanic chain are natural factors that make these islands vulnerable to disasters. Cultural historical studies have recorded various phenomena of past natural disasters in the archipelago. Some have had minimal impact, but others have resulted in the loss of civilization. Although the issue has become the important part of the civilization and profile of Indonesia, the archaeological study of disasters has not well developed. The existing studies so far are still very partial with the fragmentary results. Characterized with this complex character, the study of archaeological disaster requires a multidisciplinary approach. This paper attempts to discuss the archaeology of disasters in Indonesia including the background, current conditions and the prospects of future development. Particularly in discussing the role of local wisdoms in dealing with disasters as part of the civilization of the archipelago.

Quaternary nannoplankton in the Northeast Java Basin

In Indonesia, nannofosils are commonly used for age estimation on Miocene marine sediment, but they are rarely performed on Quaternary sediment. This paper introduces two nannofossil biozones, Martini (1971) and Backman et al. (2012) and the comparison between the two biozones. An uninterrupted interval of marine sediments was described and picked for quantitative nannoplankton analysis. The samples were taken from Ledok Formation to Lidah Formation in Pati Region, Northeast Java Basin. The samples were prepared by quick smear slides method and and analyzed by quantitative field of view method. Martini (1971) biozone can be used to subdivide the Late Miocene–Pleistocene sediments into 5 biozones, but Backman et al. (2012) can be used to classify the same sediments into 8 biozones. The biozone subdivision from Backman et al. (2012) is more detailed than that of Martini (1971) because an updated dating and biozone in the three new dating zone data.