Editorial Board Herman Darman Chief Editor Shell International Exploration and Production B.V. P.O. Box 162, 2501 AN, The Hague – The Netherlands Fax: +31-70 377 4978 E-mail : [email protected] Minarwan Deputy Chief Editor Repsol Exploración SA Paseo de la Castellana, 278-280, Madrid 28046 Spain E-mail : [email protected] Fuad Ahmadin Nasution PT. Energi Mega Persada Tbk/EMP Tonga Bakrie 24th Floor, Rasuna Epicentrum, Jl. H.R Rasuna Said Jakarta 12960-Indonesia E-mail : [email protected] Fatrial Bahesti NAD-North Sumatra Assets Standard Chartered Building 23rd Floor, Jl Prof Dr Satrio No 164 Jakarta 12950 - Indonesia E-mail: [email protected] Wayan Ismara Heru Young University Link coordinator Legian Kaja, Kuta, Bali 80361, Indonesia E-mail : [email protected] Julianta Panjaitan Membership coordinator PT. Schlumberger Geophysics Nusantara, Data & Consulting Services, Jl. Mulawarman Km. 20, P.O.Box 117, Kelurahan Manggar, Balikpapan 76117, Kalimantan Timur, Indonesia, E-mail : [email protected] Advisory Board Prof. Yahdi Zaim—Quarternary Geology—Institute of Technology, Bandung Prof. R. P. Koesoemadinata—Emeritus Professor—Institute of Technology, Bandung Berita Sedimentologi • Published 3 times a year in February, June and October.by the Indonesian Sedimentologists Forum (Forum Sedimentologiwan Indonesia—FOSI), a commission of the Indonesian Association of Geologists (Ikatan Ahli Geologi Indonesia—IAGI). • Cover topics related to sedimentary geology, includes their depositional processes, deformation, minerals, basin fill, etc. Volume 20— February 2011 Page 2 Number 20 / February 2011 Berita Sedimentologi Sedimentological journal of the Indonesian Sedimentologists Forum (FOSI), a commission of the Indonesian Association of Geologist (IAGI) From the editors Last year, 2010, the Indonesian tologi will be published electroni- be geographical. For this edition, Association of Geologist (IAGI) cally in PDF format to reduce for example, we will focus on celebrate the 50th anniversary of cost and give higher flexibility in SUMATRA. the organization. This event give journal editing. Electronic journal As a ‘new’ publication we would a new momentum to the Indone- also give more freedom to pub- like to hear comments from our sian Sedimentologists Forum lish color figures with different readers, especially FOSI and (FOSI) to reactivate the bulletin. level of resolution. On top of IAGI members. If you like to that, the electronic journal will participate in the editorial team. also reach larger number of read- Please let us know. ers as it will be easier to access. We hope the 3000+ members of the Indonesian Geologists Asso- Herman Darman ciation (IAGI) who live in differ- ent part of the world can get the Editor in Chief benefit of this journal as well. The editorial board will pick a theme for each journal and it will The last ‘Berita Sedimentologi‘ journal was published in 2000 in Inside this issue: paper format. Thereafter many key people in the editorial board left Indonesia and we admitted Bird Foot Print 5 that the hand-over was not suc- cessful. Talang Akar Formation 7 A new editorial board was set with many new members. We Ombilin Basin 12 hope that the coming publication of Berita Sedimentologi will achieved the following goal: Andaman-Sumatra 18 Forearc • Publish technical journal regularly Langkat structures 22 • Facilitate discussions related to sedimentary geology in University news 285 Indonesia and Southeast Asias region 2 • Provide opportunities for knowledge transfers through generations The coming Berita Sedimen- Volume 20— February 2011 Page 3 About FOSI he forum was founded in 1995 sia. The forum was accepted as the sedi- at least two years relevant experience. as the Indonesian Sedimentolo- mentological commission of the Indone- FOSI has organized 2 international con- gists Forum (FOSI). This or- sian Association of Geologists (IAGI) in ferences in 1999 and 2001, attended by ganization is a communication 1996. About 300 members were regis- Tand discussion forum for geologists, es- more than 150 international participants. tered in 1999, including industrial and pecially for those deal with sedimentol- academic fellows, as well as students. Most of FOSI administrative work will ogy and sedimentary geology in Indone- be handled by the editorial team. IAGI FOSI has close international relations office in Jakarta will help if necessary. with the Society of Sedimentary Geology (SEPM) and the International Associa- The official website of FOSI is: http:// tion of Sedimentologists (IAS). www.iagi.or.id/fosi/ Fellowship is open to those holding a recognized degree in geology or a cog- nate subject and non-graduates who have FOSI Membership ny person who has a back- the ideal solution, and we may look for ground in geoscience and/or other alternative in the near future. Hav- is engaged in the practising ing said that, for the current situation, A or teaching of geoscience or Linked is fit for purpose. its related business may apply for general International members and students are Total registered members: membership. As the organization has just welcome to join the organization. been restarted, we use Linked-in 119 (www.linkedin.com ) as the main data- February 2011 base platform. We realize that it is not Volume 20— February 2011 Page 4 First Evidence of Miocene Avian Tracks from Sumatra Short Announcement Yahdi Zaim*), Rizal Yan*), Gregg F. Gunnell+), Thomas A. Stidham+), Russell L. Ciochon**) and Aswan*) * Department of Geology, Institut Teknologi Bandung – Indonesia + Laboratory Paleontology, University of Michigan – USA ** Department of Anthropology, University of Iowa – USA he islands of oceanic southern Asia (Indonesia, Malaysia, and New Guinea) have played an influential role in the development of evolu- Ttionary thought, initially because of the his- toric studies by Alfred Russel Wallace and later by the discovery of Pleistocene human remains on Java by Eugene Dubois. Unlike the majority of Sunda Islands, much of the central core of Sumatra was emergent from the early Eocene through the early Miocene. Freshwater lacustrine sediments of the early Eocene Sangkarewang Formation have yielded an abundant diversity of fishes and a single bird skeleton but no other evidence of terrestrial vertebrates is known until the Pleis- tocene. In the summer of 2007 a reconnais- sance survey of Cenozoic sediments were initiated in the Ombilin Basin located in the Barisan Mountains of central Sumatra (Figure 1).The outcrop are well exposed in Sa- Figure 1: Ombilin Basin located in the Barisan Mountains of central Sumatra. On the left is Sing- wahlunto and Ombilin Coal Mining areas karak Lake (Picture from Google Earth,2009) consists of alternating conglomerates, quartz sandstones and shale. In addition to exploring the Sangkarewang Formation we examined sediments of the Sawahlunto and overlying Sawahtambang formations which span the Figure 2: General Stratigraphy of early part of the Miocene. In the Sawahlunto the bird foot print location Formation we discovered two series of avian tracks representing two different shorebirds (Figure 2). These tracks were found at the base of a thinly laminated, coarsening upward sandstone overlain by a relatively thin layer (0.5 meter) of coaly shale, followed by a quartz-sand conglomerate at the top of the local section (12 meters total thickness). The sandstone contains carbonaceous debris and small to medium, parallel ripples are formed (Figures 3). One set of tracks has an angle of 90 degrees between digits one and three and is of relatively small size and probably repre- sents a gruiform (rail). The second set of tracks has a 120 degree angle between digits one and three and was likely made by a cha- radriid (plover) or scolopacid (sandpiper) shorebird (Figures 4 and 5). In addition to the bird tracks, small, circular traces (Skolithos ichnofacies) are present probably representing Volume 20— February 2011 Page 5 tubes of suspension feeding invertebrates such as clams or worms (Figure 6). The presence of these traces suggests that the bird trcks were formed on an intertidal beach and the birds may well have been feeding on these invertebrates. The presence of these track ways suggest that further explo- ration of Tertiary sediments in Sumatra is warranted. The avian tracks from the Sawahlunto Formation are as the first discovery of the Bird Foot- print Fossils in Indonesia. Figure 3 : Outcrop shows the sandstone contains carbonaceous debris Figure 4 : First discovery of avian tracks, the Bird Footprint Fossils and small to medium, parallel ripples. The avian tracks are found at the in Indonesia from Sawahlunto Formation of Early to Middle Mio- base of this outcrop. cene in age. Figure 6 : Small, circular traces (Skolithos ichnofacies) are proba- Figure 5 : One set of tracks has an angle of 90 degrees between digits bly representing tubes of suspension feeding invertebrates. one and three,probably represents a gruiform (rail), and the second set of tracks has a 120 degree angle between digits. Volume 20— February 2011 Page 6 Outcrops Conservation of Tanjung Baru or Lower Talang Akar Formation, Baturaja City of Palembang Area - South Sumatra Basin: How important? Premonowati*), * Department of Geology, Faculty of Mineral Technology, UPN “Veteran” Yogyakarta ABSTRACT of channel plug was deposited in a very low weathered basement granite and quartzite, are energy environment before the channel was effective reservoirs in ten fields in South Tanjung Baru Formation