Journal of Applied Geology
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THE USE OF FORAMINIFERA FOSSILS FOR RECONSTRUCTING THE YOGYAKARTA GRABEN, YOGYAKARTA, INDONESIA
Get PDFThe Yogyakarta region is located in the southeastern part of Central Java, Indonesia. The region forms an elongated northeast – southwest-trending central depression bordered by two parallel faults in the west and east. These major faults divided the area into three parts, including the western, central and eastern parts. Herein, we investigate the relative uplift rate of the each part by using planktonic and benthonic foraminiferas. The foraminifera will show the initial position/datum of each part before uplift. Over sixty samples (primarily limestones and marls) were taken for this research. The uplift rates of each part were different and created a depressed block control by way of parallel faults. Based on foraminifera fossil observations, each block was in the same depositional environment (inner neritic) during N9. The present positions indicate that the western part was uplifted higher than the others, with this part being uplifted more than 590 meters. The central part was uplifted less than 120 meters, and the eastern part was uplifted above an altitude of 170-300 meters.
Keywords: Foraminifera fossil, planktonic, benthonic, graben, uplif
Characteristics Of Hydrothermal Alteration In Cijulang Area, West Java, Indonesia
Get PDFCharacterization of hydrothermal alteration in theCijulang area (West Java, Indonesia) was carriedout using shortwave infrared spectroscopy. Hydrothermal alteration in the Cijulang area occurs in the calc-alkaline volcanic and volcaniclastic rocks. Shortwave infrared spectroscopic measurements of reflectance for altered rocks and minerals were carried out by ASD-FieldSpec and the laboratory spectra acquired were then analysed with “The Spectral Geologist” software program. Shortwave infrared spectroscopy is capable of detecting most finegrained alteration minerals from different hydrothermal alteration zones. Characteristic alteration minerals identified from the SWIR technique include pyrophyllite, alunite, kaolinite, dickite, illite, montmorillonite, polygorskite, gypsum, epidote, paragonite, and muscovite. Most of the spectra show mixture ofalteration minerals and only a few display pure spectra of single mineral. The crystallinity of kaolinite from the samples was also determined from the reflectance spectra and show moderately to high crystallinity. Alteration system of the Cijulang prospectis similar to others documented high-sulfidation epithermal deposits, such as Rodalquilar (Spain), Summitville (Colorado), and Lepanto (Philippines). A characteristic alteration sequence and zonation of advanced argillic, argillic and propylitic alterationoutward from the silica core has resulted from the progressive cooling and neutralization of hot acidic magmatic fluid with the host rocks.Keywords: Cijulang, High-sulfidation, Alteration minerals, Shortwave Infrared Spectroscop
Origin of the Late Paleozoic metamorphic rocks in East Johor, Peninsular Malaysia
Get PDFLow grade metamorphic rocks including slate, phyllite, metasandstone with subordinate schist and quartzite are widely distributed in the East Johor, Peninsular Malaysia. Regionally, this rock unit is extended northward up to northern Terengganu area. The protolith of this rocks unit were deposited in shallow marine depositional environment that subsequently metamorphosed during Carboniferous time. The very thick argillaceous and arenaceous rocks more than 5000 metres were produced by fast rate accommodation spaces due to global sea level rise during Early to Late Carboniferous against with high fine-grained sediment supply. Tectonic setting, basin formation and sedimentation processes were controlled by rifting of Indochina-East Malaya continental block from Gondwanaland during Devonian to Late Carboniferous. This rifting formed basins within a passive margin tectonic setting along the western margin of Indochina-East Malaya continental block.Keywords: Metamorphic rocks, shallow marine, Carboniferous, passive margi
DYNAMIC MORPHOLOGICAL CHANGES OF SPIT IN APRIL–MAY 2014 IN OPAK RIVER MOUTH, BANTUL, DAERAH ISTIMEWA YOGYAKARTA
Get PDFAs an oceanic coast, the beaches in the southern part of Java Island are predominantly influenced by ocean energy which is driven by periodical monsoon. This periodical process impacts the dynamic changes of spit in the river mouth system. Therefore, spit is a key to study the process in the southern coast of Java Island especially in Opak River Mouth. It needs a deep-root explanation about the morphological changes and the sedimentological mechanism. This research project was built by data such as spit geometry, aerial photographs and spontaneous wind direction. The supporting data included multitemporal IKONOS-Quickbird images from Google Earth and aerial photographs. These data were collected from field-work investigation and laboratorywork. The spit geometry was compiled by Global Positioning System handheld tracking along the edge of spit and crosschecked by aerial photograph using pole. The ultimate interpretation and periodic models were built by data reconstruction based on the geometry of spit and spontaneous wind direction. Spit changed weekly due to monsoon transition in April to May 2014. The morphological changes could be noted as the spit starting to be cut off by the highrate flow of Opak River. The process continued until the net drift moving westward. Keywords: April, coast, May, Opak river mouth, spit
PRELIMINARY EVALUATION OF LOCAL SITE CONDITON IN YOGYAKARTA BASIN
Get PDFThe Yogyakarta Basin can be defined as NE – SW elongated depression zone of 20 km in width and 45 km in length, trending from Yogyakarta City in north to the Indian Ocean in south. The local geologic and soil conditions have a great influence on the intensity of ground motion and earthquake damage. Local site effects play an important role in earthquake-resistant design and must be accounted for on a case by case basis. Local site conditions can profoundly influence all of the important characteristics such as amplitude (peak acceleration, velocity and displacement), frequency content and duration of strong ground motion. The extent of their influence depends on the geometry and material properties of subsurface materials. Therefore, subsurface investigation was carried out through nine boreholes throughout the basin. Based on drill-logs, collected samples and laboratory test results, the subsurface soil profiles of nine areas in the basin are simplified for future strong ground motion simulation. Five subsurface layers in Tampuran, Krajan areas and six subsurface soil layers in Watu, Jl. Parangtritis, Wijirejo areas and seven layers in Jl. Parangtritis, Karang Semut, Bambang Lipuro areas and eight layers in Pranti area, have been simplified and the geotechnical properties of each layer have been evaluated as well.
Keywords: Basin, Yogyakarta, depression, ground motion, earthquake
GEORADAR INVESTIGATION AT THE KEDULAN TEMPLE EXCAVATION SITE, KALASAN, YOGYAKARTA
Get PDFKedulan Site is the buried and ruined 9th century Mataram Hindu Kingdom temple, located in Tirtomartani Village, Kalasan District, Sleman Regency, Yogyakarta Special Province. This temple was incidentally discovered by sand diggers on 24 November 1993 under several meter thick of fluvio-volcanic deposit of the modern Merapi. Several technical studies were needed to carefully excavate the temple, including geology and geophysical approaches. One of the geophysical method have been applied was ground penetration radar (georadar). This method uses radar technology to obtain a continuous profile of the shallow sub-surface and thus allows scientists to image soil substratums based on differing dielectric constants. Georadar investigation by Department of Geological Engineering, Faculty of Engineering, Universitas Gadjah Mada, was conducted on 4 December 2007. The main purpose was to identify the location of the outer stone fence as an estimation to define the temple site area to be excavated. About one line was chosen to cross the site in north-south direction in a distance of 328 m. Two runs were completed on the same line but different courses, i.e. forward and backward, where one was checked with another. The result indicates the presence of the outer stone fence was possibly buried in a depth of 7 m. It was located about 40 m distance outside the inner stone fence. Assuming the fences were quadrangle relative to the main temple, hence it is estimated that the site area to be excavated is about 13.830 m² and total 96.808 m³ gravels and sands to be removed
Geochemical Fraction, Mobility And Bioavailability Of Lead In Unsaturated Soil Of Yogyakarta City, Indonesia
Get PDFLead (Pb) is one of common heavy metals found inthe soil of urban environment. In Yogyakarta City,Indonesia, lead content in the soil was already reported by some researchers, however all of the report were only reveals the distribution of lead concentration in the soil. Therefore, this research paper aims to understand the geochemical fraction leadin the soil of Yogyakarta City and assess the mobility and bioavailability of lead release to the environment. The soil sampling location is selected on Kotagede District, representing the oldest urban area of Yogyakarta city. A shallow bore hole was drill until about 7 m below the surface and soil/sediments weresampled for each 1 m depth started from the surface. Six steps of sequential extraction procedures were carried out to assess the geochemical fraction of Pb for each of soil samples. The sequential extraction shows that the highest amount of Pb in thesoil of Yogyakarta City is found in amorphous ironoxide, crystalline iron oxide and non residual fraction form of Pb. Based on the results of geochemical fraction, the mobility factor of lead can be calculated and reveals low mobility factor range from 0.4 to 3.3%. The mobility of lead is decreased from the surface to the deeper soil, on the other hand the bioavailability of Pb calculated from exchangeable and carbonate fraction is also show low risk of bioavailability. Therefore, it can be concluded that although Pb concentration is high in non-residual fraction, Pb isin low risk condition due to its poor mobility and bioavailability. But, concern on lead contamination should be considered because if the concentration of Pb is enriched over the adsorption capacity of ironoxide, it can easily release to the environment and can impact to human in the future.Keywords: Yogyakarta city, Lead, Sequential extraction, Geochemical fractio
The mineralogy of gold-copper skarn related porphyry at the Batu Hijau deposit, Sumbawa, Indonesia
Get PDFClacic gold-copper bearing skarn in the Batu Hijau porphyry deposit is located in the western part of Sumbawa Island, Indonesia. Skarn mineralizations were found at the deep level of the deposit (-450m to -1050mL) by drilling program 2003. No evidence around Batu Hijau has limestone although most skarn are metasomatiz ed from carbonate-rich rock as limestone or marble. Most skarn-type metasomatic alteration and mineralization occurs at the contact of andesitic volcanic rock and intermediate tonalite porphyry intrusion and within intermediate tonalite in some. Although both endoskarn and exoskarn can be developed, it has no clear minerals to known the endoskarn. Exoskarn is more principle skarn zone. The formation of skarn occurred two min stages: (1) prograde and (2) retrograde. The prograde stage is temporally and spatially divided into two sub-stages as early prograde (sub-stage I) and prograde metasomatic (sub-stage II). Sub-stage I begin immediately after the intrusion of the tonalite stock into the calcium rich volcanic rocks. Then, sub-stage II originated with segregation and evolution of a fluid phase in the pluton and its invasion into fractures and micro-fractures of host rocks developed during sub-stage I. The introduction of considerable amount of Fe, Si and Mg led to the large amounts of medium- to coarse-grained anhydrous calc-silicates. From the texture and mineralogy, the retrograde metasomatic stage can be divided into two sub-stages: (a) early retrograde and (sub-stage III) and (b) late retrograde (sub-stage IV). During sub-stage III, the previously formed skarn zones were affected by intense multiple hydro-fracturing phases in the gold-copper bearing stocks. Therefore, the considerable amounts of hydrous calc-silicates (epidote), sulfides (pyrite, chalcopyrite, sphalerite), oxides (magnetite, hematite) and carbonates (calcite) replaced the anhydrous calc-silicates. Sub-stage IV was coexisting with the intrusion of relatively low temperature, more highly oxidizing fluids into skarn system, bringing about partial alteration of the early-formed calc-silicates and developing a series of very fine-grained aggregrates of chlorite, clay, hematite and calcite
Ground movement prediction due to block caving mining geometry using GIS
Get PDFLarge scale block cave mining has been operated for over 30 years in the Erstberg Mining District in the province of Papua, Indonesia. The ore body is divided into four vertically stacked ore bodies: Gunung Bijih Timur (GBT), Intermediate Ore Zone (IOZ), Deep Ore Zone (DOZ), and Deep Mill Level Zone (DMLZ). The GBT and IOZ mines were closed on 1993 and 2003, DOZ mine is in its peak production performance 80 ktpd, and DMLZ mine is still in the development stage to prepare mine infrastructures. This situation generates gradual downward settling of the surface or subsidence. Significant deformation changes at the surface by block caving subsidence could damage the mine’s infrastructures in surface and underground and also affect geological structures overlying the mining areas which may result in surface impacts on the natural geomorphology and land use.
In this paper, integrated system based on Geographic Information System (GIS) platform applied to predict ground movements due to underground mining. Deep Ore Zone (DOZ) block cave mine is studied for subsidence prediction. The mining extraction thickness model is obtained from height of draw (HOD) observed data. Subsidence Engineering Handbook (SEH) of empirical model and measured data from mining fields is used for subsidence calculation parameters. The calculations were performed in GIS. The maximum vertical displacement has been predicted about 12m by means of full caving mining method.
Keywords: Ground movements, block caving, GIS, underground mining, and subsidenc
Batch Studies On Arsenic Adsorption Onto Lignite, Bentonite, Shale And Iron Sand: Effects Of Ph, Time, Particle Size And Sulfate Concentration
Get PDFArsenic (As) is a toxic element found in both natural and anthropogenic sources. High concentration of this element was recently uncovered in the groundwater of Sumbawa Island, Indonesia. To mitigate this problem, As adsorption potential of natural geological materials like lignite, bentonite, shale, and iron sand obtained in Indonesia were evaluated by batch experiments. Arsenic adsorption onto these materials was investigated as a function of solution pH, particle sizes of adsorbents and coexisting sulfate concentration. In addition, batch leaching experiments were performed to elucidate the stability of geogenic As present in all adsorbents at different pHs. The results showed that among these natural materials tested, lignite was the most effective adsorbent of As(V) followed by bentonite, shale and then iron sand, and that the amounts of As(III) adsorbed onto all adsorbents were lower than those of As(V).This indicates that As(III) is more mobile in comparison to As(V). The adsorption isotherms of As(III) and As(V) conformed to nonlinear types, either Langmuir or Freundlich. It was found that adsorption of As onto these natural adsorbents was pH-dependent. This could be attributed to the changes in the surface charges of the adsorbents with pH. With respect to the adsorbent particle size, the amount adsorbed somewhat increased with decreasing particle size, which could be explained by the larger surface area of the smaller particles. Acidic (pH 10) conditions destabilized the geogenic As content of the adsorbents, indicating that the effectiveness of these natural materials as adsorbents is greatly limited by the pH of the contaminated system. Keywords: Adsorption, arsenic, natural geological materials, particle size, p