Journal of Geoscience, Engineering, Environment, and Technology
Not a member yet
306 research outputs found
Sort by
Hydrogeochemistry of Natar and Cisarua Hot springs in South Lampung, Indonesia
Get PDFNatar Hot Spring is one of the geothermal manifestations that is located in Lampung Province, Indonesia. About 6 km to the east, another hot spring appears with temperature around 40°C with neutral pH called Cisarua Hot Spring. The Natar Hot Spring itself having temperature 47-54°C with 6.23 pH. Based on the geologic map, the appearance of these hot spring is caused by Lampung-Panjang Fault which trending northwest-southeast. Morphology of the research area is showing a flat terrain topography which composed of Quaternary volcanic rock and metamorphic rock in the basement. The nearest volcano that expected to be the heat source of the geothermal system is the Quaternary extinct volcano called Mt. Betung which is located about 15 km to the southwest. The aim of the study is to analyze the geochemistry of the manifestations and calculate the reservoir temperature. Geochemistry analysis result shows both manifestations are bicarbonate which is formed as a steam-heated water or steam condensates. Geothermometer calculation shows that the geothermal reservoir has temperature 150-160°C with approximately 300 m in depth. All manifestations are originated from meteoric water according to stable isotope analysis D and δ18O data and interacting with carbonate-metamorphic rock beneath the surface based on 13C isotope value. A further geophysics study is needed to determine where the heat comes from
The Weak Soil Investigation at the Slope Zone in the Hot Spring Area, Rokan Hulu, Indonesia
Get PDFThe slope failure can occur due to the soil on the slope area is relatively porous and the surface water is easily to move in the soil. The zone of the weak zone of the soil should be detected early to avoid the ground mass movement on the slope area. This study is to investigate the weak zone of the soil on the slope area of the hot spring tourism location using geoelectrical resistivity and soil property analysis methods. The Wenner configuration with a total of 40 electrodes has been employed at each four resistivity survey lines. The electrode spacing was adjusted to be 2 – 5 meter in order to get relatively higher resolution of the resistivity data. Soil samples were collected at several site to measure the soil characteristics of the study area. The soil analysis results show that the study area consist of gravel, sand, clay, silt and weathered methasediment. The geoelectrical resistivity model shows the relatively low resistivity value of about 30 ohm.m at the slope zone which is indicating that the soil has higher porosity. Generally only a few locations with the weak soil zone detected in the slope of the hot spring area, however, it is not potential for the ground mass movement due to the soil is relatively thin.  
The Use of Disintegration Ratio in Evaluating Rock Durability in Selected Mudrock Samples in Indonesia
Get PDFCharacterization of durability of mudrocks is important regarding its slaking behaviour within a short time when exposed to and or interact with water. Some relevant cases that occurred due to slaking are damage to roads and slope failures along the Cipularang and Cipali Toll Road. Current engineering activities related to the presence of mudrocks are being and will be held in several locations in Indonesia such as the construction of the Cisumdawu Toll Road in Ujungjaya District, Sumedang and building the National Observatory in Timau District, Kupang. This research is useful for providing engineering considerations related to those activities.
The methods used in this research included X-ray diffraction to obtain mineralogy of mudrock, laboratory testing of physical properties of rocks such as dry density, water content, porosity, absorption and mudrocks durability tests. Durability of rocks was determined by disintegration index test. Testing was carried out by wetting and drying of rock samples.
Test results showed that the average disintegration ratio of claystones, shales, mudstones and siltstones are 0.1035, 0.2183, 0.4942 and 0.9900. Slaking mode occurs to claystones, mudstones and shales is body slaking while dispersion slaking occurs to siltstones. Evaluation of the durability of mudrocks in this research indicates that siltstones have the highest durability characterized by very slow disintegration, followed by mudstones, shales and claystones at the lowest with very quick disintegration. Disintegration ratio from the disintegration index test characterizes the durability of mudrocks in more details. It can be concluded that porosity and absorption are incorporated into the main factors affecting the durability of mudrocks
Identification and Stratiraphic Position of Mollusk Type Locality at West Progo Stage
Get PDFThe location of the discovery of mollusk fossils on the island of Java is spread in various places. One location is in the Kulon Progo region known as West Progo beds. However, due to the lack of studies of mollusk fossils in the Kulon Progo region, this resulted in a lack of understanding of the location of the discovery. This study was intended to re-record the location of fossil molluscs discovery in the Kulon Progo region, with the aim of contributing to the stratigraphic arrangement in Kulon Progo. Research methods include literature studies, field investigations and laboratory analysis. The literature study includes libraries of the Dutch colonial era regarding the location of the discovery of mollusk fossils. Field studies in the form of stratigraphic measurements and sampling. Laboratory investigations include petrographic observations and identification of micro and macro fossils. The results of the investigation successfully re-identified the Kembang Sokkoh and Spolong locations which are two types of locations on the West Progo beds. Based on the lithological characteristics of the two locations included in the Jonggrangan Formation, with the Lower Miocene age based on an analysis of the fossil content of the molluscs
Correlation Between Fracture Azimuth, Surface Lineaments and Regional Tectonics: A case study from Belik District, Central Java, Indonesia
Get PDFTwo major strike-slip faults with northeast-southwest and northwest-southeast orientation have shifted the southern Central Java, including Belik District. Consequently, many smaller faults that have the same direction as the major faults and west-east direction folding systems were emerged. The orientation of these geologic structures could be observed from morphological features such as ridge and river. A quantitative approach was carried out to unravel the impacts of those geologic structures on the geomorphology of the study area, which is located between Slamet Mountain and Sindoro Mountain, Central Java province. The method used in this research was the structural geology analysis, including the interpretation of ridge and river lineament, the distribution of fractures, and statistical analysis. The research location is divided into four different segments based on its lineament and morphology. The lineament that has similar characteristics was tested using normality test of Kolmogorov-Smirnov. The Spearman test was used to obtain the correlation between surface lineament and fracture azimuth. All fracture azimuth, ridges and rivers tend to have northwest-southeast and northeast-southwest direction. These results show similar direction with strike-slip regional structural pattern. The statistical calculation and field observation indicate the influence of external factor on the change of the study area’s landform
The Geology and Lamongan Volcanic Rocks Case Study at Ranu Pakis, Klakah, Lumajang, East Java Province, Indonesia
No full textLamongan volcano is one of the unique volcanoes in the Sunda Volcano. This volcano has side eruption centers or on the slopes of the volcano. The morphology of parasitic eruptions in this volcanoes complex includes maars and boccas. There are about 64 parasitic eruption centers consisting of 37 volcanic cones (bocca) and 27 ranu (maar).
The purpose of this research is to study the characteristics of lithology and petrogenesis of this volcano complex, especially in Ranu Pakis and surrounding areas. The analytical method used is to do geological mapping and petrographic analysis.
The lithology found in this research area consists of magmatic and phreatomagmatic eruption deposits. Genetically this lithology includes pyroclastic flow, pyroclastic fall (scoria fall and phreatomagmatic scoria fall/accretionary lapili), tuff (phreatic) and basaltic lava. In some pyroclastic deposits, especially in maar there are fragments of accretionary lapilli, while in bocca there are basaltic lavas. Other fragments present in pyroclastic deposits are basalt scoria blocks and bombs embedded in the groundmass of volcanic ash. The results of petrographic analysis indicate that the volcanic rocks in the study area are calc alkaline affinity consisting of pyroxene andesite, basalt and pyroxene basalt lava. The pyroxene basalt lava is composed by plagioclase, clinopyroxene and little olivine embedded in the volcanic glass. Lavas are structured scoria and textured porphyritic, intersertal, trachytic, aphyric and pilotaxitic. Trachytic texture is found in the basalt fragments of pyroxene from the pyroclastic fall deposits in Ranu Pakis and Ranu Wurung. While pyroxene andesite lavas composed by plagioclase, clinopyroxene embedded in the volcanic glass. Lavas are structured scoria and textured porphyritic, intergranular, pilotaxitic and aphyric
Rock Formation Acid Mine Drainage in Epithermal Gold Mineralization, Pandeglang, Banten Province
No full textMine acid water is acidic water and contains iron and sulfate, which is formed under natural conditions when geological strata containing pyrites are exposed to an oxidizing atmosphere or environment. One of the impacts of the mineralization zone where there is a mining process is the potential for the formation of acid mine drainage, especially in the Cibaliung gold mineralization area and its surroundings, Pandeglang Regency, Banten Province. Acid-forming sulfide minerals include pyrite (FeS2), headquarters (FeS2), picoliters (FexSx), calcocytes (CuS), covellite (CuS), chalcopyrite (CuFeS2), molybdenite (MoS), mulenite (NiS), chalocytes (CuS), covellite (CuS), chalcopyrite (CuFeS2), molybdenite (MoS), mulenite (NiS), chalocytes (CuS), covellite (CuS), chalcopyrite (CuFeS2), molybdenite (MoS), mulenite (NiS), galena (PbS) ) and sphalerite (ZnS). Of all these minerals, pyrite is the most dominant sulfide in acid formation.
Alkaline mine water (alkaline mine drainage) is mine water that has an acidity level (pH) of 6 or more, containing alkalinity but still containing dissolved metals that can produce acids. The quality of mine water, acid or alkali, depends on the presence or absence of acid mineral content (sulfides) and alkaline materials in the geological strata.
Acid water formation tends to be more intensive in mining areas. This can be prevented by avoiding exposure to sulfide-containing materials in the free air. Acid-forming sulfide minerals include pyrite (FeS2), headquarters (FeS2), picoliters (FexSx), calcocytes (CuS), covellite (CuS), chalcopyrite (CuFeS2), molybdenite (MoS), mulenite (NiS), chalocytes (CuS), covellite (CuS), chalcopyrite (CuFeS2), molybdenite (MoS), mulenite (NiS), chalocytes (CuS), covellite (CuS), chalcopyrite (CuFeS2), molybdenite (MoS), mulenite (NiS), galena (PbS) ) and sphalerite (ZnS). Of all these minerals, pyrite is the most dominant sulfide in acid formation. Formation of potential acidic water also occurs in tailings which are residues/processing residues containing sulfide minerals. The formation of acid mine drainage does not always develop in every sulfide-ore mining. In certain types of ore deposits, there are neutralizing agents which prevent the formation of acid mine drainage