Geomagnetic Method Research Articles

Subsurface Analysis of Sibayak Mountain Karo Regency Using Geomagnetic Method with 2D and 3D Modeling

Subsurface Analysis of Sibayak Mountain Karo Regency Using Geomagnetic Method with 2D and 3D Modeling

Investigation of the Extent of Hydrothermal Activities of the Sikidang Crater, Dieng Volcanic Complex (Central Java), Using Geomagnetic Method

Abstract The Sikidang Crater (± 2000 m asl) is one of the active craters in the Dieng Volcanic Complex (DVC). It is situated on the southeastern flank of Mt. Pangonan. The crater is significant for development of both tourism and energy sectors in Dieng. Thermal manifestations inside the crater which consist of boiling mud pools and pots, hot springs, fumaroles, gas vents, steaming and altered ground make the place a popular tourist attraction. They also serve as windows to the shallow subsurface processes and help better understand the dynamics of the Dieng geothermal system. However, the land use of the crater and its vicinity disregards the fact that the actual extent of the hydrothermal activity of the crater has not been figured out, and that the foci of the thermal fluid discharges in the crater often shift. Some agriculture plots, housing areas, as well as tourism and geothermal infrastructures are located within or near the morphological boundary of the crater. The inherent hydrothermal hazard of the crater therefore, must be well mitigated to minimize the negative impacts to the people, as well as their assets. Our research aims to delineate the lateral and vertical extent of the hydrothermal activity of the crater by geomagnetic method. Geomagnetic anomaly in geothermal field occurs due to the difference in the intensity of hydrothermal alteration of the rocks. The equipment used was a pair of Proton Precision Magnetometers GEOTRON G5. Our result shows that low geomagnetic anomaly (-2200 to -400 nT) correlated with demagnetized, hydrothermally altered andesitic rocks covers an area of ≥ 1.15 km2, i.e., more than seven times larger than the area outlined by morphological boundary of the crater. The anomalous zone extends N/NE - S/SW from beyond the areas of inter-volcanic plain between Pangonan and Igir Binem in the north, to the areas beyond Sikunang and Kendil cones in the south. Below the Sikidang mud pool the demagnetized rock mass reaches a maximum thickness of 2000 m. The supporting data, i.e., the fluctuations of the gas discharge, and the seismicity of the DVC indicate that the recent dynamics of the Sikidang Crater is mostly controlled by the internal processes within the crater.

Integration Of 3G Data (Geomagnetic, Gravity And Geology) To Identify Geothermal System Controlled By Geological Structure Of Telomoyo Plateau (Study Case Of Candi Umbul Area)

As the technology development, there are more and more new innovations that utilize existing resources to support the energy needs and to fulfill the consumer needs. The energy source that is being discussed at this time is geothermal energy. Geothermal energy sources are considered effective because they are renewable and environmentally friendly when compared to other energies such as fossil energy. In Indonesia itself, geologically, it has a complex series of volcanoes that can be used as a heat source in this new energy innovation. One area that thought to have geothermal potential is the telomoyo mountain area, which is indicated by the manifestation of hot springs on the surface, precisely around Candi Umbul. However, it is necessary to conduct subsurface studies to identify the presence of subsurface structures such as faults or intrusions as heat sources, where this can be overcome using geophysical methods. This research was conducted using the integration of two geophysical methods, namely the geomagnetic method to determine the direction of the fault continuity and the gravity method to determine the regional heat source, and in the other side geological data as a reference for interpretation. From geomagnetic measurements, 163 rock magnetism data were obtained which indicated the existence of a fault continuity with northeast-southwest orientation in the direction of the river flow and cut the manifestation of hot springs. Meanwhile, from 176 gravity topex data, a high complete boguer anomaly value was obtained as an indication of an intrusion in the northeast that was cut by the fault recorded in the geomagnetic data. Based on geophysical data analysis and correlation with geological data from previous studies, it can be assumed that there is a geothermal system in the study area with andesitic intrusion as the heat source, fault structure with northeast-southwest orientation as a weak zone for meteoric water migration, andesite lava as caprock, unit tuff rock as a reservoir and the telomoyo plateau as a recharge area to supply meteoric water from the geothermal system.

Integrative Geophysical Approach for Enhanced Iron Ore Detection: Optimizing Geoelectrical and Geomagnetic Methods

Integrative Geophysical Approach for Enhanced Iron Ore Detection: Optimizing Geoelectrical and Geomagnetic Methods

Three-dimensional Magnetotelluric Inversion and Magnetic for The Characterization of The Geothermal Field Reservoir Zone “X”

Geothermal as an alternative energy source that is renewable and environmentally friendly has an important role in providing domestic energy needs. Exploration is one of the most important stages in the development of geothermal energy because it can minimize the risk at the stage of exploitation and development. Geophysical methods such as geomagnet and magnetotelluric are one of the methods used in exploration. Magnetic method can provide information on the description of rock demagnetization due to the presence of heat source. However, the magnetotelluric method will provide information about rock type resistance on geothermal fields. The existence of heat source using the geomagnetic method is represented by a low anomaly value as an indication of demagnetized rocks. The results of 3D inversion processing show a low value of type resistance in the area and form an updome. The correlation of the two results of processing the data can be seen in the southern part of the "X" geothermal field research area. Based on 3D Inversion modeling it can be seen the depth of the "X" Base of Conductor (BOC) geothermal system ranges from 1000 m to -800 m with resistivity ≤ 10 Ωm which is suspected as volcanic rocks. Geothermal reservoir is at a depth of 1000 m to -2000 m with a moderate resistivity of 40 - 60 Ωm which is suspected as an andesite volcanic rock, with temperature estimates ranging from 218o C to 255o C.

Integrated geophysical methods used to explore geothermal potential areas in Siogung-Ogung, North Sumatra, Indonesia

The manifestations of some hot springs in Siogung-Ogung, North Sumatra, Indonesia have increased speculation of likely geothermal sources. Therefore, integrated geochemical and geophysical methods were employed to identify the geothermal prospect of the area. Two-dimensional electrical resistivity and geomagnetic methods were used for the geophysical survey. The geochemical survey used three concentration measurements: geothermometer silica (SiO2), geothermometer Na-K, and geothermometer Na-K-Ca. A Wenner Schlumberger array with a 5-meter electrode spacing was used to acquire the 2-D resistivity data, which was processed using Res2Dinv software. The geomagnetic method was performed with a proton precession magnetometer, and the data were processed using Surfer to produce the magnetic residual map. The 2-D electrical resistivity results show that the area has low resistivity values (1-700 Ωm). The resistivity values from 1 to 100 Ωm could be due to the presence of hot waters in alluvium, and the resistivity values > 400 indicate andesite rock, which can function as a hot water conductor from the source. The magnetic residual map shows geomagnetic values from 150 nT to 360 nT, which infer the potentiality of geothermal within the study area. The geochemical results show that the reservoir temperature is 572 °C. Based on the integrated results, the study area has promising geothermal potential.

3D inversion modelling of gravity and geomagnetic in the coastal aquifer of the Mandalika Lombok

Coastal aquifers are essential for coastal communities worldwide, one of which is in the Mandalika area (Lombok Island, Indonesia). This area is the tourism sector which requires an adequate supply of fresh water. Mandalika is a coastal area dominated by alluvial plains, an excellent rock as an aquifer. However, alluvial plains are also susceptible to seawater intrusion. This study uses a combination of gravity and geomagnetic methods to estimate bedrock potential as aquifers based on a 3D inversion model. Data collection was carried out at 151 measuring points using the loop method. Data processing was conducted using Oasis Montaj, Mag3D, and Grav3D. The data were combined to reduce ambiguity in interpreting rock-type estimates. The modelling results show that aquifer composition consists of sandstone, clay, and gravel with a density of about (1.3 - 2.4) g/cm3, susceptibility (0.00040 - 0.0045) SI at an average depth of 2 - 12 m with a percentage of 54.849% of the total 3D models. These rocks dominate the research location scattered around the coastal area of Kuta, around the Circuit to the Mertak area, and are concentrated in the flat morphology areas.

2D Surface Structure Modeling in Bengkulu City using Geomagnet Method

Research on 2D modeling of the subsurface structure of the Bengkulu city area was carried out using the geomagnetic method. In this study, we collected data from 130 measurement points using a set of Proton Procession Magnetometers (PPM) to obtain the total magnetic field value. The measurement data were processed by making corrections of daily variations and IGRF (International Geomagnetic Reference Field). We conducted data correction to contour the total magnetic field anomaly. After that, the contour of total magnetic field anomaly was used for the reduction to the poles. This research results from the total magnetic field anomaly show a pair of positive and negative closures. Cross-sections were made on the positive and negative closure pairs to determine the subsurface structure of the area by making a 2-dimensional (2D) model using Mag2DC software. The interpretation of the 2D modeling results shows that three rock layers are continuously arranged. The average susceptibility value of the first layer is 0.00001 cgs which is a sandstone layer at a depth of 0-400 meters; the second layer has an average susceptibility value of 0.002 cgs which is dominated by clay at a depth of 400-700 meters, and; the third layer has an average susceptibility value of 0.006 cgs which is a basalt rock layer at a depth of 700-1000 meters.

Results of Geomagnetic Studies on the Problem of Forecasting Strong Earthquakes in Uzbekistan

The article is devoted to the problem of forecasting strong earthquakes by the geomagnetic method. The geomagnetic method is widely used on this problem in seismically active regions of the world as one of the promising, informative and operational geophysical methods. The results of long-term geomagnetic studies on the problem of forecasting strong earthquakes in Uzbekistan are presented. Geomagnetic studies were carried out on the territories of the Tashkent, Ferghana, and Kyzylkum geodynamic polygons in the epicentral zones of strong earthquakes that occurred. Long-term, medium- and short-term precursors of earthquakes have been identified. Anomalous changes in the geomagnetic field associated with the decline in aftershock activity were also revealed. The dependence between the duration of the manifestation of long-term magnetic precursors and the magnitude of earthquakes is determined. Absolute proton magnetometers MMP-1, MV-01 (Russia), and G-856 (USA) were used to measure the geomagnetic field.

Identification of alteration zone and gold mineralization based on magnetic anomaly and 3D model of geomagnetic satellite data inversion of Mount Pongkor Area, West Java

Mount Pongkor is one of the areas in Indonesia with the largest gold mineralization potential in Java. One of the geophysical methods to identify the distribution of gold mineralization zones is the geomagnetic method that utilizes magnetic properties in the subsurface due to the influence of rock magnetization. Geomagnetic research has been conducted at Mount Pongkor, Bogor Regency, West Java with an area of 22 x 17 km as much as 793 magnetic satellite data from the National Oceanic and Atmospheric Administration (NOAA) website that has been corrected daily. This study aims to determine the distribution of alteration zones and mineralization of the study area. The results showed that the RTP map shows the distribution of magnetic anomalies ranging from -4.786 – 4.663 nT, with high anomalies in the north-south direction associated with mineralization zones with anomaly values ranging from 1.881 – 4.663 nT and low anomalies in the north-south direction associated with rock alteration zones with anomaly values ranging from -4,786 - (-2.174) nT. In the 3D inversion model, the alteration zone has an average depth of 350 - 2600 m from topography with susceptibility contrast values ranging from -0.35 - (- 0.25) SI and the mineralization zone has an average depth of 350 - 2800 m from topography with susceptibility contrast values of 0.25 - 0.35 SI.©2022 JNSMR UIN Walisongo. All rights reserved.

Application of magnetic Method on Mapping the Geothermal Sources at Air Putih, Lebong, Bengkulu

Measurements have been made using the geomagnetic method in the Air Putih Tourism Area, Tambang Sawah Village, Pinang Belayar District, Lebong Regency with an area of 2000 m x 2500. Data collection was carried out using a Proton Procession Magnetometer (PPM) model G-856, which is a device with a proton sensor. which works based on the precess of the proton nucleus due to changes in the surrounding magnetic field and is equipped with other technical equipment, such as portable GPS (Global positioning system), types of navigation (maps of survey areas), such as talkies, umbrellas, pens, and recorded data. can be observed.. This research serves to map the potenTial for geothermal (geothermal), because this method is one of the geophysical methods that has advanTages in finding geothermal sources.Data processing is carried out using only Microsoft excel which can only plot magnetic anomalies and interpret qualitatively into initial research. To get the total animali, correction of IGRF (International Geomagnetics Reference Field) and correction of Daily Magnetic Value (diurnal). The results of this measurement obtained a magnetic field anomaly graph. This graph shows the high magnetic susceptibility value is found at poinT 43 which is suspected to be an area of economic value rock minerals and is in fracture zones and rocks with low susceptibility values are found at point 29 which can be suspected as a source area. hot water (hydrothermal). Keywords :Geomagnetic, Anomaly, and Hydothermal

Identification of Fault Structure in the Vicinity of Bukik Gadang Hot Spring Mount Talang Subdistrict Using Geomagnetic Method

Geological structures in the Bukit Gadang geothermal area have been identified using the geomagnetic method to determine the type of fault. Data was measured using a magnetometer in the area with dimensions of 1200 m × 1200 m consisting of 144 points at 12 tracks, and the spacing between points was 100 m. Magnetic anomaly data performed diurnal and IGRF (International Geomagnetic Reference Field) corrections. Furthermore, reduced to poles and continuous upwards processes were carried out to remove noise and separate local and regional anomalies. The magnetic field anomaly ​​in the study area ranges from -1771.8 nT to 1089.9 nT, dominated by negative values, indicating the presence of heat sources and the influence of demagnetization of subsurface rocks. The 2D modeling results show that two primary rocks dominate the study area; pyroclastic flow units and andesite lava rock, which come from the Jantan and Batino volcanic formations. The caprock rock layer was identified in the upper layer with a depth of 850 meters. The reservoir rock layer with low susceptibility values ​​was below the caprock layer. The 3D modeling results show a normal fault with a depth of 300-800 meters or at the border of the Jantan volcanic formation with the Batino volcanic formation. The fault line leads to the southeast-northwest (N160°E). The faults obtained from the 2D and 3D models are suspected to be the outflow of geothermal fluid from the reservoir rock layer and form a manifestation in the form of a hot spring at Bukik Gadang.

Identification of Earthquake Hazard Vulnerability in Bengkaung Village, West Lombok Using Geomagnetic Methods

An earthquake disaster is an event that causes various damage and loss of life. This study aims to determine the vulnerability of earthquake hazards in Bengkaung Village, West Lombok Regency. The method used in this research is the geomagnetic method. The results of this: study indicates the value of the magnetic field anomaly in the range of -1100 nT-1500 nT. 2D modeling with 4 paths shows that the study area is dominated by 5 rock layers with a susceptibility range between (0.013 - 6.21)×10^(-3) in SI, which consists of sandstone, clay, fractured andesite lava, fresh andesite lava. and granite. The highest vulnerability to earthquake hazards is in the southern part of Bengkaung Village, due to the presence of a cohesive soil type (like clay) on the surface of the study area, coupled with the presence of intrusions and faults. Meanwhile, the western part of Bengkaung Village and the northern part of the Bengkaung area have a relatively smaller earthquake hazard vulnerability than the southern part. This is because the western and northern parts have the main layer of non-cohesive soil (sandstone) which has high shear strength and becomes a damper in wave propagation when an earthquake occurs

INTERPRETASI DATA GEOMAGNETIK UNTUK MENDETEKSI SEBARAN BATUAN MENGANDUNG MINERAL LOGAM DI AWANG BANGKAL, KABUPATEN BANJAR

Research has been carried out to detect the presence and distribution of rocks containing metallic minerals. Almost every object used every day contains metal elements, so the presence of metal is very important to support every human activity. The presence of metal minerals in nature is generally quite a lot, but the types of metallic minerals vary. The geomagnetic method is a geophysical method that can detect subsurface rocks containing metallic minerals based on the difference in the magnetic field between the rock and the surrounding rock. Processing of geomagnetic data obtained in the field begins with daily correction and correction of the earth's main magnetic field (IGRF). The correction results obtained are anomaly of the earth's magnetic field which is distributed horizontally on the surface. The results of the analysis in the form of local magnetic field anomalies (∆H) are divided into 3 (three) regions, the first having a value between -236.5 nT to -8 nT (nano tesla) as an area that has a high local magnetic field anomaly value. Second, the value of -377.2 nT to -236.4 nT as an area that has a moderate anomaly value. Third, the low anomaly values ranged from -778.4 nT to -377.1 nT. Areas that have high local magnetic field anomaly values are interpreted as ultramafic rocks, which are source rocks of nickel lateric deposits rich in ferromagnesian minerals, distributed in the southeastern part of the study area.

Natural disaster mitigation using geophysical methods

The research has been carried out about natural disasters (landslides, ground motion, drought) using geophysical methods. This research was conducted in several places, in East Java, i.e. land slides and ground motion occurred in Malang and Blitar areas and drought occurred in theTulungagung and Malang areas. This research uses resistivity and self-potential. The active method is resistivity, which means that an electric current is injected into the earth, after which the resulting potential difference is recorded, then processed. Self-potential and geomagnetic methods, are passive methods. In the self-potential method, the potential difference that occurs between two points, which have a certain distance, is recorded (the middle between those two points becomes a point measurement). The data of several points of measurement, that have been made within a certain distance, then is processed for determining underground river tracing. The equipment used is the OYO Mac Ohm resistivity meter. The results obtained are, an artesian well in the Tulungagung area, at a depth of 108 m, an indication of new faults in the Blitar area, and ground motion cracks in the Malang area.

Identification of Buried "Archeological" Objects in the Area around Kedulan Temple using Geomagnetic Methods

Temple is a religion place for ancient culture, Yogyakarta have many incridible temples one of the biggest is Prambanan temple. 2 Km to the north west direction from Perambanan temple located the Kedulans temple who still on renovation projects. Kedulan Temple is located in Tirtomartani Village, Kalasan District, Sleman, Yogyakarta Special Region, at coordinates 7° 44' 28" South Latitude and 110° 28' 5" East Longitude, with an altitude of 168, 45 meters above sea level. Kedulan Temple was found in a collapsed state and buried volcanic material from Mount Merapi. Based on the results of a stratigraphic study conducted by Pramumijoyo, et al., (2005) this temple is covered by 8 meters thick lava which is composed of 14 layers of sediment. To obtain information on the existence of archaeological objects that are still buried around the temple in this study, geophysical measurements were carried out using the geomagnetic method which aims to determine the potential for buried archaeological objects in this case assumed to be igneous rocks that have contrasting susceptibility. Based on the geomagnetic signal analytic map obtained, there is a magnetic anomaly which is suspected to be a hidden temple object which is bordered by a black line which is about 50 meters to the east of Kedulan Temple. This assumption is based on a high magnetic anomaly value >480 nT which is thought to originate from the temple rock object in the form of andesite rock.

APPLICATION OF UPWARD CONTINUATION FILTER FOR GEOMAGNETIC DATA INTERPRETATION IN GONDANG, BOJONEGORO AREA

There are several manifestations of hot springs and mud pools in Gondang area, Bojonegoro, East Java, there were. This can be an indication of certain geological conditions. The description of these conditions can be done by measuring the geomagnetic method. A total geomagnetic anomaly has been generated through some geomagnetic values recorded in the region, which has been corrected using IGRF correction and diurnal correction. These steps were done to reduce external influences on the real value of the data. This research will use several variations of values in the Upward Continuation filter and one of them will be chosen to proceed as a model. Upward Continuation Filter is a process of transforming potential field data from a flat plane towards the higher plane. The purpose of this study is to compare the results of contour maps on several variations of the Upward Continuation value, to obtain the results of the separation of residual and regional anomalies using the Upward Continuation method, and to determine the value of the susceptibility distribution of inversion modeling in the Gondang region, Bojonegoro. Based on the results of data processing, it is known that the upward continuation value used is 100mdatum with a magnetic intensity value in the regional anomaly of 106.5 nT to 509.0. While the value of the residual anomaly is -232.1 nT to 159.4 nT. The 3D model was made using this residual anomaly which shows the low susceptibility distribution value in the range of -0.0298 to -0.0135 SI around the manifestation area, whereas the high susceptibility value has a value range of 0.0114 to 0.0466 SI interpreted as rock intrusion. Rock intrusion occurs within the area around the manifestation of mud pools.

Principal component analysis and K-means clustering as tools during exploration for Zn skarn deposits and industrial carbonates, Sala area, Sweden

This contribution presents an application of principal component analysis (PCA) and K-means clustering as tools for data dimension reduction and grouping of multivariate, whole-rock lithogeochemical data. The study dataset consists of 64 geochemical variables and measurements of spectrophotometric brightness determined from 181 dolomite marble samples, collected at various distance from two contrasting types of mineral deposits, 1) stratabound, dolomite marble- and skarn-hosted Zn-Pb-Ag sulphide deposits and 2) industrial dolomite deposits. Clustering and PCA outputs are assessed based on spatial distribution relative to known mineral deposits and interpretability using geological domain knowledge, to test if the methods can provide a non-biased classification of dolomite samples which is useful for exploration vectoring. The PCA illustrate that three principle components derived from centered log-ratio transformed data can account for 79.69% of the dataset variance. K-means clustering provide unsupervised division of samples into different groups reflecting relative contents of detrital (siliciclastic-volcaniclastic), biogenic and hydrothermal components in the marble protoliths. Spatial analysis of principal components and K-means clusters reveal systematic distribution patterns relative to known deposits, thus providing an exploration guide. The samples most prospective for Zn-Pb-Ag deposits are divided into groups of ‘halo dolomite’ exhibiting elevated Fe and Mn, and an ‘ore dolomite’ also showing elevated Zn, Pb, Ag, Sb, Hg. This can be reconciled with magnetite and Mn-bearing Mg-silicates and carbonates in hydrothermal alteration haloes, and proximal enrichment in hydrothermal sulphides (galena, pyrrhotite, pyrite, sphalerite). Samples in these groups returned low spectrophotometric brightness, resulting from sulphides and Fe oxides grinding to dark powders during sample preparation, significantly lowering the brightness of powdered dolomite marble, even when occurring in low concentrations. Conversely, a ‘clean dolomite’ group is characterized by low contents of the elements above, high contents of Ca, Mg, Sr and total carbon, low magnetic susceptibility and high spectrophotometric brightness, and spatially coincide with known industrial dolomite deposits. An additional group of ‘detrital-rich dolomite’ is distinct from the other groups in an elevated content of high field strength elements and Al, and intermediate spectrophotometric brightness. This variety represent samples containing a higher content of co-settled volcaniclastic-siliciclastic material in the marble precursor. Assessment of the clustered data in relation to magnetic susceptibility measurements from the same samples show that Halo and Ore dolomite can be differentiated from other dolomite types by geomagnetic methods, hence providing a proxy for their indirect detection during geophysical surveys.

Pemetaan batuan penyusun candi di bawah permukaan berdasarkan metode geomagnetik studi kasus: cagar budaya candi Songgiriti desa Songgokerto kecamatan Batu kota Batu

The geomagnetic method is often used in petroleum, geothermal and mineral exploration and can be applied to searching prospect archaeological objects (Siahaan, 2009). Several studies has been used the geomagnetic method to seek for archaeological objects by Ariani (2012) in Losari Temples and Sismanto et al (1997) in Kedulan Temple. In Batu City there is one of the cultural heritage that have not been intact called Songgoriti Temple. So, in this research we expected the existence of temple’s rocks using geomagnetic method. The de sign of the research using geomagnetic methods begins with the study of litera ture. This research was conducted with two methods there is calculating the val ue of the magnetic susceptibility of samples Temple’s rock using Bartington Susceptibility Meter MS2B and retrieving data field using the Proton magneto meter type ENVI SCINTREX. In the end of this research, we accepted the re sults of the two methods were compared to find out the site rock of temple. In magnetometer data analysis, data is processed using Magpick software, surfer 9.0 software and Mag2dc software. The results of the research show that a local magnetic field patterns of rocks in the area of cultural heritage Songgoriti Tem ple is divided into three parts namely high local magnetic field (yellow to red), the moderate local magnetic field (green to yellow) and low local magnetic field (blue). Furthermore based on five cross-sectional modeling using Mag2dc, we obtained the prediction the site of temple Songgoriti that is the sample number 1 found on the 2 position i.e at coordinates 49S 664547.5m 9130115m and coor dinate 49S 664585m 9130105m; sample number 3 found on the 2 position i.e at coordinates 49S 664583m 9130100m and coordinate 49S 664585m 9130100m; sample number 4 found on the 2 position i.e. at coordinates 49S 664577.5m 9130115m and coordinate 49S 664577.5m 9130110m; sample number 5 found on the 3 position i.e. at coordinates 49S 664566m 9130095m, coordinates 49S 664573m 9130095m and coordinate 49S 664582.5 m 9130095m; sample num ber 6 is found in 5 position i.e. at coordinates 49S 664545.5 m 9130110m, coordinates 49S 664550m 9130110m, coordinates 49S 664546m 9130105m, coordinates 49S 664565m 9130105m and coordinates 49S 664562.5 m 9130100m. For sample number 2 that is not found at all in the five models cross section. This may be caused by the value of the magnetic susceptibility sample number 2 is minor when compared to another samples that is 0.86 x 10-6 m3/kg

Review of the distribution of granite using geomagnetic methods at Bukit Nunggal Air Mesu Village, Pangkalan Baru Sub-District, Bangka Tengah District

Exploration is activities happens before the mining activity. It has purposes to know, predict and obtain the dimension in quality and quantity from a reserve that has economic value. From surveying at bukit Nunggal, Mesu Village, Pangkalan Baru Sub-district, Bangka Tengah District showed that there are outcrops indicating the potential for becoming a reserve for granite. Measurement is conducted to know the resource estimation and it is done by an approach of geomagnetic method that is environment friendly. Geomagnetic is passive method to measure the magnetism level or susceptibility from the measuring point. The total of the line to know the dispersion pattern and the depth of the resource is 13 lines with the space between measurement is 10m. From the geomagnetic measurement obtained IGRF value is 42969, inclined degree 0.424 declined degree – 21.157, susceptibility value in between -54.2nT to 56.1 nT, and the granite susceptibility value is in between 21 nT to 50nT. The anomalies map showed that there is a resource potential, and the dispersion is from east to west. Viewed from the topography and the residential areas, mining activity is recommended to be done in the west area.