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Research about Indonesia

Source-linked reports with geographic coverage including Indonesia.

72 records · Page 4Linked to original sources
USGS2000

South Sumatra Basin Province, Indonesia; the Lahat/Talang Akar-Cenozoic total petroleum system

Oil and gas are produced from the onshore South Sumatra Basin Province. The province consists of Tertiary half-graben basins infilled with carbonate and clastic sedimentary rocks unconformably overlying pre-Tertiary metamorphic and igneous rocks. Eocene through lower Oligocene lacustrine shales and Oligocene through lower Miocene lacustrine and deltaic coaly shales are the mature source rocks. Reserves of 4.3 billion barrels of oil equivalent have been discovered in reservoirs that range from pre-Tertiary basement through upper Miocene sandstones and carbonates deposited as synrift strata and as marine shoreline, deltaic-fluvial, and deep-water strata. Carbonate and sandstone reservoirs produce oil and gas primarily from anticlinal traps of Plio-Pleistocene age. Stratigraphic trapping and faulting are important locally. Production is compartmentalized due to numerous intraformational seals. The regional marine shale seal, deposited by a maximum sea level highstand in early middle Miocene time, was faulted during post-depositional folding allowing migration of hydrocarbons to reservoirs above the seal. The province contains the Lahat/Talang Akar-Cenozoic total petroleum system with one assessment unit, South Sumatra.

Open-File Report↗
USGS1993

Differentiation of volcanic ash-fall and water-borne detrital layers in the Eocene Senakin coal bed, Tanjung Formation, Indonesia

The Sangsang deposit of the Eocene Senakin coal bed, Tanjung Formation, southeastern Kalimantan, Indonesia, contains 11 layers, which are thin (<5 cm) and high in ash (> 70%). These layers are characterized by their pelitic macroscopic texture. Examination of eight of the layers by scanning-electron microscopy, energy-dispersive X-ray, and X-ray diffraction analyses show that they are composed primarily of fairly well-crystallized kaolinite, much of which is vermicular. Accessory minerals include abundant Ti oxide, rare-earth element-rich Ca and A1 phosphates, quartz that luminescences in the blue color range, and euhedral to subhedral pyroxene, hornblende, zircon, and sanidine. Although this mineral suite is suggestive of volcanic ash-fall material, only the four pelitic layers in the middle of the bed are thought to be solely derived from volcanic ash-falls on the basis of diagnostic minerals, replaced glass shards, and lithostratigraphic relationships observed in core and outcrop. The three uppermost pelitic layers contain octahedral chromites, some quartz grains that luminesce in teh orange color range, and some quartz grains that contain two-phase fluid inclusions. These layers are interpreted to be derived from a combination of volcanic ash-fall material and hydrologic transport of volcaniclastic sediment. In contrast, the lowermost pelitic layer, which contains large, rounded FeMg-rich chromites, is thought to have been dominantly deposited by water. The source of the volcanic ash-fall material may have been middle Tertiary volcanism related to plate tectonic activity between Kalimantan and Sulawesi. The volcanic ash was deposited in sufficient amounts to be preserved as layers within the coal only in the northern portions of the Senakin region: the southern coal beds in the region do not contain pelitic layers.

southeastern Kalimantan↗
USGS1993

Scanning electron microscope observations of sublimates from Merapi Volcano, Indonesia

Sublimates were sampled from high-temperature (up to 800°C) fumaroles at Merapi volcano, Indonesia in January 1984. Sampling is accomplished by inserting silica tubes into high-temperature vents. Volcanic gas flows through the tubes and sublimates precipitate on the inner walls in response to the temperature gradient. With decreasing temperature (800–500°C) in the tubes, there are five sublimate zones: 1) cristobalite, magnetite, and halite; 2) halite, sylvite, K-Ca sulfate (K 2 Ca[SO 4 ] 2 ), acmite, wollastonite, and pyrite; 3) halite, sylvite, galena, Pb-Bi sulfide, aphthitalite, sphalerite, and Cs-K sulfate; 4) halite, sylvite, galena, PbKCl 3 , aphthitalite, and Na-K-Fe sulfate ([Na, K] 2 Fe[SO 4 ]Cl 2 ); and 5) halite, sylvite, galena, PbKCl 3 , and various sulfates of Pb, Cu, and Zn. Texturally, the sublimate phases grade from large, well-formed crystals at their highest-temperature occurrence to more numerous, smaller crystals that are less perfect at lower temperatures. These changes imply that the crystal nucleation and growth rates increase and decrease, respectively, as temperature decreases. Several of the sublimate phases also exhibit highly anisotropic morphologies (whiskers, platelets, spheres), especially below their highest temperature of deposition. Overall, the textural data suggest that the gas is saturated or slightly supersaturated with the phases at their hottest occurrence, but that the gas becomes increasingly supersaturated with the phases at lower temperatures. The anisotropic morphologies probably form because the crystals grow toward more supersaturated conditions in the center of the tube. The gas fails to maintain equilibrium with the precipitating sublimates because the high velocity of the carrier gas prevents complete mass transfer from the gas stream to the tube walls.

Merapi Volcano↗
USGS1992

Placer and lode platinum-group minerals in south Kalimantan, Indonesia: Evidence for derivation from Alaskan-type ultramafic intrusions

Platinum‐group element minerals (PGM) occur in significant proportions in placer deposits in several localities in South Kalimantan. They consist of Pt‐Fe alloy that may be intergrown with or contain inclusions of Ir‐Os‐Ru alloy, laurite and chromite. Alluvial PGM found along Sungai Tambanio are in part derived from chromitite schlieren in dunitic bodies intruded into clinopyroxene cumulates that may be part of an Alaskan‐type ultramafic complex. A chromitite schlieren in serpentinite from one of these dunitic bodies is anomalous in PGE (Pt: 580 ppb; Pd: 3.4 ppb; Rh: 1 ppb; Ru: 9 ppb; Ir: 21 ppb; and Os: 3.9 ppb). The chondrite‐normalized PGE pattern for this rock, pan concentrates from this area, and PGM concentrates from diamond‐Au‐PGM placer deposits have an ‘M'‐shaped pattern enriched in Ir and Pt that is typical of PGE‐mineralization associated with Alaskan‐type ultramafic complexes.

South Kalimantan↗
USGS1991

Studies of a peatified angiosperm log cross section from Indonesia by nuclear magnetic resonance spectroscopy and analytical pyrolysis

Samples from a 10 cm cross-sectional radius of a peatified angiosperm log from Sumatra, Indonesia, were examined by 13 C nuclear magnetic resonance and pyrolysis-gas chromatography in order to understand chemical changes due to the peatification process. NMR results show degradation by selective loss of carbohydrates in all parts of the log section compared with fresh wood; however, the degree of degradation is less near the center of the log section. The degree of ring substitution of aromatic lignin monomeric units, as measured by dipolar dephasing NMR methods, appears to be less at the center of the log section than at the periphery. The methoxyl carbon content of lignin in the log is lower than in unaltered angiospermous lignin but does not appear to change as a function of either radial position or the degree of aromatic ring substitution. Pyrolysis-gas chromatography indicates higher yields of catechols in the outer areas relative to the heartwood. Other than the variations in catechol contents and in the yields of carbohydrate-derived pyrolysis products (e.g. levoglucosan, angelicalactones), the pyrolysis results do not show significant changes related to radial position, indicating that the lignin is not significantly altered across the log section.

Organic Geochemistry↗
USGS1990

Volcano hazard mitigation program in Indonesia

Volcanological investigations in Indonesia were started in the 18th century, when Valentijn in 1726 prepared a chronological report of the eruption of Banda Api volcno, Maluku. Modern and intensive volcanological studies did not begin until the catastrophic eruption of Kelut volcano, East Java, in 1919. The eruption took 5,011 lives and destroyed thousands of acres of coffee plantation. An eruption lahar generated by the crater lake water mixed with volcanic eruptions products was the cause of death for a high number of victims. An effort to mitigate the danger from volcanic eruption was first initiated in 1921 by constructing a tunnel to drain the crater lake water of Kelut volcano. At the same time a Volcanological Survey was established by the government with the responsibility of seeking every means for minimizing the hazard caused by volcanic eruption.

Earthquakes & Volcanoes (USGS)↗
USGS1984

Volcanic hazards in Indonesia: The 1982-83 eruption of Galunggung

Indonesia faces a perpetual volcanic-hazards problem of enormous proportions, exemplified by the 1982-83 eruption of Galunggung in West Java. Though moderate in size, this caused widespread destruction and a marked socio-economic impact on more than half a million people. The prolonged activity provided and opportunity for the Volcanological Survey of Indonesia to conduct systematic monitoring studies for the first time. The lessons learned from this study will be useful in developing mobile, rapid-response monitoring teams to meet future volcanic crises.

Galunggung↗
USGS1983

Krakatau 1883

This year marks the 100th anniversary of the eruption of Krakatau, perhaps the most famous volcanic event in recorded history. During a 23-hour period on August 26 and 17, 1883, more than 4 cubic miles of volcanic debris exploded upward from Krakatau, resulting in the death of more than 36,000 people and producing catastrophic devastation. The 1883 events at Krakatau caused phenomena that were recorded around the world that lingered for several years after the main eruption.

Earthquake Information Bulletin (USGS)↗
USGS1976

Pre-Eocene rocks of Java, Indonesia

The exposed pre-Eocene rocks of Java can be divided into two compound units for purposes of reconnaissance mapping and structural interpretation: a sedimentary sequence and melange. The sedimentary sequence consists of moderately deformed and little-metamorphosed conglomerate, sandstone, mudstone, claystone, chert, and limestone. The melange consists of a chaotic mechanical mixture of rocks identical to those of the sedimentary sequence and their metamorphic equivalents, such as schist, phyllite, quartzite, and marble. In addition, it contains a large proportion of quartz porphyry and smaller amounts of granite, basalt, gabbro, peridotite, pyroxenite, and serpentinite. The sedimentary sequence is at least partly of Early Cretaceous age and the melange is of Early Cretaceous to very early Paleocene age. They are overlain unconformably by Eocene rocks. The presence in the melange of blocks of quartz porphyry and granite is not easily reconcilable with current plate tectonic concepts in which the sites of formation of melange and plutonic rocks should be hundreds of kilometres apart.

Java↗
USGS1974

Preliminary report on the geology of the Solok Quadrangle, West Sumatra

This report is a brief description of the geology of the Solok quadrangle in West Sumatra. It is based on work done by the writer from April 27 to October 14, 1971, as part of the U. S. Geological Survey (USGS) Cooperative Project with the Geological Survey of Indonesia (GSI). The project is sponsored by the Government of Indonesia and the Agency for International Development, U. S. Department of State, and staffed by personnel of the USGS and counterparts of GSI.

Solok Quadrangle, West Sumatra↗
USGS1970

Tectonic map of Indonesia: A progress report

Orogeny, volcanism, and seismicity are now intensely active in Indonesia. Many Dutch tectonists--Brouwer, Umbgrove, van Bemifielen, Smit4Sibinga, Vening Meinesz, Westerveld, and others--recognized that this complex cluster of islands represents an early stage in the evolution of orogenic belts. Not until Indonesia is understood can we comprehend the Alps. This report summarizes some aspects of work to date on the Tectonic Map of Indonesia. The preparation of this map is a joint project of the Geological Survey of Indonesia and the United States Geological Survey, sponsored by the Government of Indonesia and the United States Agency for International Development. The Tectonic Map of Indonesia will be published at a scale of 1:5,000,000. Adjacent regions in other countries will be included to provide a broader context. The map limits presently envisaged are the parallels of 12° N. and 15° S., and the meridians of 91° and 148° E. Tectonic features will be shown in many colors and patterns. Bathymetry is being newly compiled, and will be shown with contours and shades of blue. Figure 1 shows the islands of Indonesia.

Open-File Report↗
USGS1970

Geothermal potential of the Dieng Mountains, Central Java, Indonesia

This report summarizes results of a 2-week (Feb. 23-Mar. 10, 1970) study of the geothermal resources of the Dieng Mountains, Java; the work was done as part of a cooperative program of the Ministry of Mines and the U. S. Geological Survey under the auspices of the Government of Indonesia and the Agency for International Development, U. S. Department of State. The Dieng Mountains were chosen as the subject for investigation and appraisal for two reasons: 1) the Dieng Plateau was cited as a promising geothermal target by a UNESCO Volcanological Mission in 1964 (Tazieff, Marinelli, and Gorshkov, 1966); 2) the Dieng Mountains lie in a region of no electrical power, and are between the two power distribution systems of Central Java.

Central Java, Dieng Mountains↗
USGS1965

Geologic map of Indonesia - Peta geologi Indonesia

The geology, compiled by Th. H. F. Klompe in 1954 from published and unpublished maps of the Direktorat Geologi, has been brought up to date on the basis of investigations carried out to 1962 (Ref. Sigit, Soetarjo, "I. A brief outline of the geology of the Indonesian Archipelago, and II. Geological map of Indonesia;" Direktorat Geologi publication, 1962.) Base compiled by Th. H. F. Klompe and printed on a Mercator projection. Geographic names are as of 1962 and in general follows the system of United States Board on Geographic Names.

IMAP↗
USGS1944

Halmahera (Molukkas): terrain intelligence

This folio was rushed to completion on urgent request from the Strategic Intelligence Branch, Office of Chief of Engineers. The geologists, soils scientists, and ground-water hydrologists had completed their studies in manu- script form, but time was not available for editing the folio, coordinating its different parts, or checking it for inconsistencies. Parts of the text have not even been proof-read for typing mistakes.

Strategic Engineering Study↗