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Batubara Formasi Warukin di daerah Sampit dan sekitarnya, Kalimantan Tengah Kusnama, Kusnama
Indonesian Journal on Geoscience Vol 3, No 1 (2008)
Publisher : Geological Agency

http://dx.doi.org/10.17014/ijog.vol3no1.20082The Warukin Formation in Sampit area, occupying the Barito Basin, was conformably deposited on top of the Berai Formation, but unconformably lies on the Tanjung Formation, Undifferentiated Metamorphic Rocks and Sepauk Granitic Rock. The formation consists of sandstone, interbedded claystone-mudstone, conglomerate and intercalations of coal, having Early-Late Miocene in age. Coal of the Warukin Formation at the Sampit area occurs within sandstone and interbedded claystone-mudstone facies. Two main seams, A and B, was deposited within sandstone and interbedded claystone-mudstone facies respectively. Generally, the coal is bright banded with partly dull lithotypes; brownish black in colour and it has a medium to light in weight. Physically, the coal recognized in two seams, is generally banded with brittle to friable in hardness; and has partings of claystone and mudstone. The thickness of the coal deposit ranges from 80 cm to 200 cm. On the basis of calorific value and lithotype, and also ash, moisture, and sulphur contents, the coal includes to subbituminous C - A rank. The coal was deposited in a wet-forest swamp occupied by high plants and shrubs. Â Â

Karakteristik Batubara dan Batuan Sedimen Pembawanya, Formasi Talangakar, di daerah Lampung Tengah Kusnama, Kusnama; Panggabean, Hermes
Indonesian Journal on Geoscience Vol 4, No 2 (2009)
Publisher : Geological Agency

http://dx.doi.org/10.17014/ijog.vol4no2.20095The rock succession of coal bearing formation, situated in Lampung Tengah, occupies the basinal margin or the western part of South Sumatra Basin. Physiographically, the rock succession lies in the Palembang Zone which directly contacts with the southernmost Barisan Mountain Zone. The rock facies consists of conglomerate, and conglomeratic and quartz sandstones in the lower part, whilst the upper part comprises shale, claystone, mudstone, siltstone, and coal with coally shale and shaly coal intercalations. The rock facies of coal bearing unit is strongly believed to be part of the Oligo - Miocene Talangakar Formation deposited in a fluvial â paralic environment which further up section, it turns to be a sub-littoral deposit. The depositional environment strongly affected the coal characteristics and type. Stratigraphically, the rock unit is conformably overlain by the Early - Middle Miocene limestone unit and is intruded by the Middle â Late Miocene granodiorite. The basement of the Tertiary rock succession is metamorphics of the Gunungkasih Complex and the Cretaceous granitic rock. The normal fault controlling the area studied has a northwest - southeast direction and it caused the dip of coal trending north - east direction of 15Âº - 23Âº. The coal of the research area was deposited in wet forest swamp environment within a high to medium subsidence level. The coal is grouped to a high to low volatile bituminuous rank, included to a mature category. Â Â

Fasies dan lingkungan pengendapan Formasi Bobong berumur Jura sebagai pembawa lapisan batubara di Taliabu, Kepulauan Sanana-Sula, Maluku Utara Kusnama, Kusnama
Indonesian Journal on Geoscience Vol 3, No 3 (2008)
Publisher : Geological Agency

http://dx.doi.org/10.17014/ijog.vol3no3.20085The Bobong Formation is a coarse clastic sedimentary rock succession. In the lower part, it consists of breccia and conglomerate facies, then followed by quartz sandstone with intercalations of claystone facies. Upwards, the rock succession is gradually changed to become alternating shale, claystone and mudstone. In the upper section the rock unit is well exposed in the western and northern parts of the Taliabu Island. The formation is Jurassic in age and it was deposited within a fluvial-transition to shallow marine environ- ment. The coal bed found within quartz sandstone and shale and claystone-mudstone facies ocupies the upper part succession of the Bobong Formation. The coal in the Taliabu Island has two seams having a thickness of 30 - 40 cm and 100 - 120 cm, respectively. The geochemical analysis result indicates that the calorific value ranges from 6,186 to 7,350 cal/g, the sulphur content is from 3% to 4.65% , fixed carbon ranges from 45.69 to 53,96%, and ash content from 7.86 - 16.37%. On the basis of those parameter, the coal within the Bobong Formation is categorized as subbituminous to high volatile bituminous rank. Â Â

Stratigraphy and Tectonics of the Sengkang Basin, South Sulawesi Suyono, Suyono; Kusnama, Kusnama
Indonesian Journal on Geoscience Vol 5, No 1 (2010)
Publisher : Geological Agency

DOI:Â 10.17014/ijog.v5i1.89Sulawesi was formed during the Oligocene - Miocene collision between the Eurasian Plate and micro-continental fragments detached from the Indian-Australian Plate. The Sengkang Basin situated on the South Sulawesi Province, was formed by a major north northwest - south southeast trending fault system of the Walanae Fault Zone, which was followed by the formation of Late Neogene foreland basin and syn-orogenic deposition. The fault system separated the eastern and western parts of South Sulawesi and influenced the deposition during the Late Miocene to Quaternary. The lower part of the deposition unit consists of small carbonate reefs of the Tacipi Member occupying the East Sengkang Basin, where this shallow marine facies is intercalated within or overlies marine claystones representing the base of the Walanae Formation. The middle sequence is interpreted as a delta foreset consisting of the Samaoling and Beru Members. During the deposition of these two members, the northern part of the Sengkang Basin gradually changed from a tidal and deltaic to fluvial environments. Furthermore, the upper sequence of this sedimentary unit is dominated by fluvial deposits.

PERKEMBANGAN GEOLOGI DAN TEKTONIK PRATERSIER PADA MINTAKAT KUANTAN PEGUNUNGAN DUA BELAS DAN MINTAKAT GUMAI-GARBA, SUMATERA BAGIAN SELATAN Kusnama, Kusnama; Andi Mangga, Syahrir
Jurnal Geologi dan Sumberdaya Mineral Vol 17, No 6 (2007): Jurnal Sumber Daya Geologi
Publisher : Pusat Survei Geologi

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The configuration of the pre-Tertiary tectonic and stratigraphic developments of the Southern Sumatera has been an interesting problem for many years. Many geologists have used various concepts in solving the geological problem in order to reconstruct the geological setting of Sumatera and the related surrounding areas.The pre-Tertiary basement in Sumatera comprise allochtonous rocks consisting of many terrains which are composed of various lithologies of different age sand historical backgrounds and they are separated each other by tectonic sutures.The Kuantan-Duabelas Mountain Terrain is occupied by metamorphic, sedimentary and volcanic rocks of Paleozoic-Mesozoic (Carboniferous - Triassic) age and are intruded by the Mesozoic granitoid rocks. The terrain occurred in the western part of Sumatera. Meanwhile, the Gumai-Garba Terrain which is occupied by the tectonite/ melanee, metasediment, carbonate and volcanic rocks of Mesozoic (Jurassic - Cretaceous) age are intruded by the Late Cretaceous granitoid rocks. Keywords: pre-tertiary, tectonic, terrain, Southern Sumatera

STRATIGRAFI DAERAH TIMIKA DAN SEKITARNYA, PAPUA Kusnama, Kusnama
Jurnal Geologi dan Sumberdaya Mineral Vol 18, No 4 (2008): Jurnal Sumber Daya Geologi
Publisher : Pusat Survei Geologi

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The rocks succession exposed in the Timika area, Papua, have an age ranging from Precambrian to Quaternary. The oldest rock is the Nerewip Formation consisting of pillow lava and basalt intercalated with foliated meta-sedimentary rocks and overlies unconformably and paraconformably by the Otomona Formation which is dominated by slate and sandstone and also metamorphosed of Precambrian-Cambrian in age. On top of the Otomona Formation is overlain unconformably the Tuaba Formation which consists mainly of sandstone, and red mudstone in the upper part. The age of this formation is not younger than Ordovician. The Siluro-Devonian Modio Formation comprises predominantly dolomite and minor clastic sediments lying disconformably on the Tuaba Formation. The overlying coarser upward sequence Aiduna Formation with a shallow marine to deltaic environment, overlies unconformably the Modio Formation consisting of alternating of sandstone and carbonaceous mudstone, intercalated by bio-calcarenite and coal beds, probably of Permian in age. On top of this formation was conformably deposited the red beds Tipuma Formation of a terrestrial origin. The age of the formation is thought to be Triassic to Early Jurassic. The Kembelangan Group of Middle Jurassic to Late Cretaceous comprises of intercalating of quartz sandstone and mudstone which are rich in ammonite fossils overlies unconformably the Tipuma Formation. The Tertiary sequence which is dominated by carbonate platform having rich in large foraminifera of the New Guinea Limestone Group lying conformably on the Kembelangan Group. The age of this group is Paleocene to Early Miocene. The Late Miocene to Pliocene Buru Formation consist of alternating of sandstone and mudstone overlying conformably the Nugini Limestone Group. The Diorite intrusion in this unit in Late Tertiary resulted a favourable Au/Cu mineralization in the formation, in north of Timika (the Central Range of Papua). The Quaternary deposits are widespread in the southern part of south Timika area. Keywords : Papua, Timika, Stratigraphy, Diorite intrusion, Precambrium,Paleozoic, Mesozoic, and Tertiary

Stratigraphy and Tectonic Development of Mentawai Islands, West Sumatera, Based on Plate Tectonic Theory Mangga, S Andi; Kusnama, Kusnama; Suyono, Suyono
Jurnal Geologi dan Sumberdaya Mineral Vol 16, No 3 (2006): Jurnal Sumber Daya Geologi
Publisher : Pusat Survei Geologi

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The Mentawai Islands are situated on the Indian Ocean westwards of West Sumatera Province forming a non-volcanic island arc. Stratigraphic and tectonic development of the islands are strongly related to the subduction between the Indian Ocean and Eurasian Continental Plate. Tectonic activities have occurred since Early Tertiary - Late Pliocene. It has happened simultaneously with the Indian Ocean Plates collision moving northwards and subducted below the Sunda/Eurasian Continental Plate. The Ophiolite and Melange Complexes were exposed and overlain unconformably by the acceleration prism of sedimentary rocks (Mentawai Group) formed as a pond sedimentation deposited within a small basin situated between active thrust fault fragments. Based on the age determination gained from paleontological analysis, tectonic configuration, basin development, and sedimentation rate, the Mentawai Islands are believed to be formed by mélange complexes comprising part of an uplifted accretionary complex of a non-volcanic island arc. Keywords: stratigraphy, tectonic, mélange, Mentawai Islands

HUBUNGAN LINGKUNGAN PENGENDAPAN FORMASI MALAWA DAN KETERDAPATAN BATUBARA DI DAERAH SOPPENG, SULAWESI SELATAN Kusnama, Kusnama; Andi Mangga, Syahrir
Jurnal Geologi dan Sumberdaya Mineral Vol 17, No 4 (2007): Jurnal Sumber Daya Geologi
Publisher : Pusat Survei Geologi

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Lithologically, the Malawa Formation comprises medium to coarse-grained quartz sandstone, shale and claystone in the lower part; and mudstone and carbonaceous fine- grained sandstone in the upper part. The thickness of the Malawa Formation in the Gatareng area is about 100 metres. The lower part of the Malawa Formation was deposited in a fluvial environment occupied by terrestrial vegetation such as land algae, fungus, ferns and mangroves, while the upper part of the formation was indicated by fluviatile close to the beach and sand dunes. On the basis of fossil content, the age of the formation is within the range of Middle Eocene -Oligocene.Several coal intercalations which are characteristically black in colour with good luster of sub-bituminous, were found in the formation with the thickness from 50 cm to 120 cm. Based on the lithology succession and the river stream where the coal deposits were found, coal occurred in the Malawa Formation can be divided into two blocks, Bakeko and Kandangsapi Blocks. Each block has some coal seams with different various rock succession. Keywords: Malawa Formation, Gatareng Area, sub-bituminous, beach environment

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