Publications of Research Center for Geotechnology, Indonesian Institute of Sciences
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CARBONATE DEPOSITIONAL ENVIRONMENT AND PLATFORM MORPHOLOGY OF THE WONOSARI FORMATION IN THE AREA EAST OF PACITAN
Get PDFPenelitian lapangan dan analisa di laboratorium telah dilakukan untuk menentukan sebaran fasies karbonat dan interpretasi lingkungan pengendapan serta morfologi platform dari batugamping Tersier Formasi Wonosari di sebelah timur Pacitan. Sampel batuan diklasifikasikan berdasarkan klasifikasi Jordan (1985) yang kemudian diinterpretasikan lingkungan pengedapannya. Formasi Wonosari di timur Pacitan terdiri atas fasies coral boundstone, foraminifera packstone-wackestone, larger foram packstone, coral-larger foram rudstone, dan fasies algal-foraminiferal packstone. Fasies-fasies tersebut mewakili lingkungan-lingkungan pengendapan reef zone atau outer-shelf, lingkungan basin-outer slope dan middle-upper slope yang terletak di utara reef zone, serta lingkungan back reef-inner shelf di sebelah selatan dan barat reef zone.
HYDROTHERMAL MINERALIZATION AT GOMBONG AREA KEBUMEN REGENCY - CENTRAL JAVA
Get PDFAktifitas magma dan sesar di daerah Gombong, Jawa Tengah yang diekspresikan dalam bentuk-bentuk melingkar (poligonal) dan kelurusan pada citra LANDSAT, diduga pembentukannya diikuti suatu proses mineralisasi yang diawali oleh aktifitas magmatik dan tektonik pada Kala Pliosen, ditunjukkan oleh adanya asosiasi yang erat antara zona mineralisasi dengan zona sesar. Mineralisasi di daerah penelitian dicirikan oleh asosiasi ubahan propilitik, pembentukan urat (terutama karbonat), dan butiran sangat halus Fe, Cu, Pb, dan Zn sulfida pada Formasi Gabon berumur Oligosen Akhir Boiling/lattice texture pada urat kuarsa yang tersingkap di Kali Lodeng mengindikasikan kondisi fluida hidrotermal dalam keadaan mendidih. Walaupun tak dijumpai kandungan inklusi fluida yang dapat dipergunakan untuk analisis mikrotermometri, asosiasi minral sulfida mengindikasi temperatur fluida hidrotermal daerah penelitian berkisar dari 300 – 350o C dan mengalami pendinginan hingga <300o C
UJI REGRESI LINIER BERGANDA UNTUK MENENTUKAN KONDISI DAN RELASI JUMLAH ARANG DENGAN TEMPERATUR DAN WAKTU PADA PROSES KARBONISASI GAMBUT
Get PDFPercobaan karbonisasi dengan menggunakan gambut yang berasal dari daerah Tulung Salapan, Sumatera Selatan telah dilakukan di laboratorium. Serangkaian data-data mengenai waktu; temperatur karbonisasi; dan jumlah arang/char-yield hasil karbonisasi gambut telah dikumpulkan. Untuk menelaah hubungan antara char-yield dengan temperatur dan waktu karbonisasi serta kondisi proses karbonisasi gambut tersebut suatu metoda uji regresi linier berganda digunakan dan diwakili oleh persamaan: Z = f(temp, waktu) = {99,310 – 0,113 *temperatur – 0,390*waktu}. Pengujian keberartian terhadap persamaan diatas dengan analisa variansi uji F memperlihatkan bahwa nilai F = 92,725 yang ternyata lebih besar dari nilai Ftabel dengan tarap signifikansi 5% atau F0,05 (2; 39) yang besarnya adalah 3,23. Hal ini berarti bahwa hipotesa nol/Ho ditolak dan menunjukkan bahwa pengaruh temperatur dan waktu karbonisasi terhadap char-yield memang ada dan diakui dalam proses, beserta pula persamaan diatas (model) memenuhi persyaratan yang diinginkan sehingga dapat digunakan. Pengujian keberartian dari masing-masing koefisien regresi dengan uji t menunjukkan nilai t untuk masing-masing koefisien adalah sebagai berikut: tbo = 21,454; tb1 = -10,394; dan tb2 = -8,799. Dengan tarap signifikansi a = 5% dan dengan derajat kebebasan v = (n-k); maka nilai ttabel atau t a,(n-k) atau t0,05,(39) adalah 1,679. Hal diatas mempunyai arti bahwa: ada pengaruh positip dari X atau Y terhadap Z; pengaruh negatip dari X terhadap Z dan pengaruh negatip dari Y terhadap Z. Selanjutnya hasil perhitungan menghasilkan nilai rxz,y = -0,857, yang menunjukkan besarnya sumbangan (share) kuatnya hubungan dari X terhadap Z dengan mengandaikan Y tetap/konstan. Nilai ryz,x = -0,816 menunjukkan besarnya share dari Y terhadap Z dengan X tetap. Nilai Koefisien Korelasi Pearson (r) atau Koefisien Moment Product (multiple R) adalah 0,909 yang menunjukkan besarnya derajat keeratan dari hubungan antara variabel char-yield terhadap waktu dan temperatur karbonisasi. Perhitungan juga memperlihatkan bahwa nilai Koefisien Determinasi (R square = r2) adalah 0.826, yang berarti bahwa 82,6% besarnya char-yield dipengaruhi oleh waktu dan temperatur karbonisasi, sedangkan sisanya sebesar 17,4% ditentukan oleh faktor atau variabel lainnya. Nilai r2 yang disesuaikan (adjusted R square) adalah 0,817 yang berarti besarnya pengaruh waktu dan temperatur terhadap char-yield yang sesungguhnya adalah sebesar 81,7%. Hasil interpretasi juga memperlihatkan bahwa proses karbonisasi gambut terbaik adalah proses karbonisasi pada temperatur 350oC dengan waktu karbonisasi selama 25 menit. Hal ini didasarkan pada hasil perhitungan yang menunjukkan bahwa pada percobaan tersebut besarnya char-yield prediksi adalah 50,01% dibandingkan dengan 50,14% char-yield percobaan yang berarti bahwa nilai residualnya adalah sebesar 0,13%
RAPID EX SITU COLLECTION AND THERMAL BEHAVIOR ANALYSIS OF VOLATILE ORGANIC MATTERS BY THERMAL EXTRACTION CONE CHAMBER FOR HIGH UN-BURNT CARBON COAL FLY ASH
Get PDFA thermal extraction cone chamber system has been modified to measure differential thermal functions and products where overall volatile organic matters are lost to the environment during heating. The aims of the research are to analyze and measure the thermal behavior of high un-burnt carbon coal fly ash derived from textile industrial power in Bandung. Efforts are being made to find the solution in large-scale utilization for alternative energy based on their by product. The sample analysis show that volatile organics matter exceed 30%, which means that others oxides element content are independently favorable. The modified cone chamber can collect the sample up to the total volumes of 30% of the chamber. In contrast to traditional chamber sample collectors, the modified cone extracts volatile organics matter from high un-burnt carbon coal ash divided in two treatments. Results show that the energy of pyrolisis, direct combustion or simple carbonization can be recovered (20%-42%) from wet or dry sample, with extraction efficiency compound-specific. During the direct combustion experimentation, resulted to the embedded energy is pushing up to 2790C for the average of volatile organic matters of 34% and for pyrolisis experimentation is 3300C for average volatile organic matters of 30%. The maximum thermal productivity values of 80 minutes for the direct combustion is 10220C and for pyrolisis is 10310C, and the contrary of 10 minutes, for the direct combustion is 7430C and for pyrolisis is 7010
OUTLINE OF QUATERNARY TECTONICS OF INDONESIA
Get PDFQuaternary teetonics in fndonesia is conveniently grouped into four types comprising ( 1) uplift and subsidence, Q)warping and folding, (3) horizontal displacements, and (4) volcanotectonic deformations. Quaternary age of the various deformations is mostly inferred from horizontal to subhorizontal attitudes of strata or erosion surfaces, percentage of living mollusc and/or coral species in fossil assemblages, mammalian fauna, imglements, incomplete recrystallization or compaction of sediments, and incomplete devellopment of post Glacial "Daly levels". Radiometric dates for fndonesian Quaternary deposits are rare. Uplift is generally intermittentas is indicated by the presence of multfple coral reef terraces and other types of marine phenomena. The maximum uplift has exceeded 750 meter during the Quaternary. Subsidence implies similar rates of displacement but results in greater depths through absence of denudation. Quaternary folding has raised the land to about 300 meter elevation. Warping has even affected the "stable" regions like e.g. the Sunda Shelf. Horizontal displacements are important along transcurrent faults; e.g. the Lembang Fault near Bandurg, Java, displays a mean horizontal shift of L40 m in the last 6,000 years or even shorter. Vertical displacement through volcanotectonic collapse of the volcanoes and resulting folding through gravity tectonics of the bases are common features and has continued into subhistorical time. Contemporary tectonic diastrophism such as uplift and faulting is especially apparent in the Moluccas.
THE STATE OF ANAK KRAKATAU IN SEPTEMBER 1968
Get PDFAn fndonesian-.Tapanese volcanological team pald a five days visit to the Krakatau Complex in Strait Sunda between September 27 and October 2, 1968. Though no increased activity was recorded in the crater area of Anak Krakatau, morphological changes were observed in the top region of the volcano. These changes must be due to a minor phreatic eruption which is supposed to take place some time between March 1963 and September 1968.
GEOLOGICAL AND GEOPHYSICAL INVESTIGATIONS OF THE KLIRIPAN MANGANESE FIELD, CENTRAL JAVA
No full textItttining activities in the Ifliripan manganese field are historically compiled since the first excavation in 1912. The geology of the Krengseng manganese mine in the Kliripan field is described, together with the manganese ores. A magnetic survey for measuring the anomaly of the vertical intensity was carried out in the Krengseng mine. The anomalies observed are as a whole small, but towards the west the effect of the andesitic rocks are conspicuous. While, the whole distribution of the anomalies seems to be explained by the assumption that the geological bodies are magnetized by the earth's field in a low geomagnetic latitude of the Southern hernisphere. The widely part of the zorte of positive anomalies seems to coincide with the area ascertained by bore-holes to reserve a manganese layer. However, it is questionable whether the coincidenee shows a logical relation between the anomalies and the manganese layer.
MAGNETIC PROSPECTING AT THE TJIKOTOK GOLD MINE, WEST JAVA
No full textFrom November to December 1967 at Tjiparaj in the area of the Tjikotok gold mine, the magnetic survey was carried out with a Ruska vertical field balance, the scale value of which was adjusted 3.54 v/s.d- The number of observation polnts amounts to 309 with a spacing of 10 m. To eliminate the diurnal variation of the earttr,'s magnetic field and the change of the instrumental condirion, a loop measu'rement for repeating at the base point was completed within nearly one hour. From the magnetic anomalies obtained, has been found a peculiar feature, which is considered to charact erizn the anomalies of vertical intensity in the equatorial region. As to the gold bearing quartz vein, the southern part in the surveyed area may be considered more promising than the norlhern part
COASTAL ACCRETION IN WESTERN INDONESIA
No full textCoastal accretion has been found to be important for Sutnatra's East coast and Java's North coast, rcspectively amounting to 60-50O m/yr and 55 - Zl4 m/yr near the mouths of large streams. Elsewhere on the same coasts the yearly accretion rates are respectively 15 m and less than 30 m. The annual accretion in the vicinity of Padang (Sumatra's West coast) is less than 10 m. In the Landak region of West Kalimantana rate of 110 m/yr is known. Data are wanting for other coasts of Indonesia but it seems hardly probable that higher accretion rates are present, except presumably for the Mahakam river, East Kalimantan. Comparing accretion rates on Java's North coast from maps surveyed in the period around 1850 till 1946 (aerial photographs), it was found that aggradation rates most commonly have been accelerating since 1920- This rise is undoubtedly due to an increase in denudation rate through vast. deforestations by the growing population and the partial clearance of estates during the Pacific War and the ensuing armed revolution It may also indicate an absolute lowering of sea level and/or tectonic uplift of the land. Positively favourable for coastal growth are thefollowing factors : High denudation rate in the drainage basins through scanty vegetation, high relief, heavy rainfall and the presence of easily erodible rock like marl; tectonic uplift; clastic volcanic activity; rhizophora growth in the coastal swamps; low springtides; quiet and shallow sea. In studying the beach ridges of the Tjiasem Bay area (West Java) it was found that the older generation of beach ridges is invariably of larger s:ze and was formed before the turn of the century, while since then only smaller-sized ridges have been developed. The same relations are alsovalid for other beach ridge series in Java, i.e. the older ones are larger than the younger ridges. The latter were probabl.v formed because of an important climatic change around 1900 - if the age - data inferred from accretion rates in the Tjiasem Bay area are right - and,/or a eustatic lorvering of sea level
Permian Volcanism and Its Relation to The Tectonic Development of Sumatra
No full textThe Permian volcanic deposits col'ering an extensive area southeast of Lake Singkarak, Central Sumalra, have been mapped in detail and studied in relation to the structural development of the pre-Tertiary Sumatra orogene. During the Permian time, Central Sumatra was occupied by aa elongated sea basin in which thick sequences of bathyal and neritic sediments were deposited. Pelitic sediments dominated, but at the same time volcanic activity started in this area. The volcanic products comprise mainly ftows of hornblende and augite andesites whit their tuffs. In some parts of southern sumatra the volcanic activity lasted till cretaceous ume. The main phase of foiding took place about 120 m'y. ago accompanied by an emplacement of granitic rocks. After an uplift in younger Cretaceous time, the area was strongly attacked by erosion. The regional geologic history of Sumatra revealed clearly a divergent behaviour from the classical concept of magmatic evolution in an orogenic belt as demonstrated by the dominantly andesitic charebter of the geosynlinal volcanism Other examples of volcanism associated with geosynclinal subsidence, possessing an andesitic rather than a basaltic character. could also be observed in the Tertiary Sunda mountain system of Sumatra. The Indonesian examples and similar occurrences of andesitic volcanism during a geo-sysnclinal subsidence in other parts of the world, show that much work still will have to be done in order to gain a better understanding regarding the relationship between volcanism and orogenesis.