scholarly journals Exploration of Iron Sand at The Eastern Coast Area of Binangun in Cilacap Regency Using Magnetic Survey

2017 ◽  
Vol 7 (2) ◽  
pp. 71 ◽  
Author(s):  
Sehah Allasimy ◽  
Sukmaji Anom Raharjo ◽  
Iska Andriyanto
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Anomaly ◽  
Data Interpretation ◽  
Research Area ◽  
Eastern Coast ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Magnetic Field Data ◽  
Geological Information ◽  
Geoelectric Data

<p class="AbstractText">Exploration of the spread of iron sand on the eastern coastal of Binangun District in Cilacap Regency has been conducted using the magnetic surveys. The magnetic data acquisition was conducted in April 2017. The total magnetic field data obtained is processed, so that can be obtained the local magnetic anomaly data. The modeling of the local magnetic anomaly data is performed on the trajectory of AB that extending from the position point of 109,274698° E and 7.686620° S to 109.2296195° E and 7.689099° S so that obtained various model of the subsurface anomalous objects. Interpretation on the subsurface anomalous objects is done to estimate the types of rocks and their formations based on the magnetic susceptibility value of each object which supported by the geological information of the research area. Based on the interpretation results to be obtained two layers of subsurface rocks that can be estimated as the iron sand that coexists with silt dan clay derived from the alluvium formation. The first rock has a length of 1238.2 meters, a depth of 1.709 – 20.513 meters, and a magnetic susceptibility value of 0.0183 cgs unit. The second rock has a length of 643.055 meters, a depth of 16.524 – 34.188 meters, and a magnetic susceptibility value of 0.0174 cgs unit. The results of this research are also supported by the results of geoelectric data interpretation, where the iron sand that coexists with silt and clay is found at a depth of 9.42 – 19.48 meters with a resistivity value of 52.99 Ωm at Geo-1 point; and a depth of 10.56 – 22.20 meters with resistivity value of 49,03 Ωm at Geo-2 point. Based on the results of of this research, the eastern coastal area of Binangun District is estimated to contain potentially iron ore and economically is a prospect for exploitation.</p>

scholarly journals Interpretation of Oil Seepage of Source Rock Based Magnetic Survey in Cipari Cilacap District

2015 ◽  
Vol 5 (02) ◽  
pp. 80 ◽  
Author(s):  
Sukmaji Anom Raharjo ◽  
Sehah S
Keyword(s):  
Magnetic Anomaly ◽  
Source Rock ◽  
Igneous Rock ◽  
Research Area ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Geological Information ◽  
Oil Seepage

<p class="AbstractText">The magnetic survey had been conducted in Village of Cipari, District of Cipari, Region of  Cilacap to interpret to the location of the oil seepage source rock. Boundary of the research area is 108.75675°E – 108.77611°E and 7.42319°S – 7.43761°S. The observed total magnetic data is corrected and reducted to obtain the local magnetic anomaly data. The local magnetic anomaly data is applied to model the subsurface bodies anomalies based on the Mag2DC for Windows software. With be supported the geological information, the some bodies anomalies are interpreted as the basaltic igneous rock (c = 0.0051), the alternately of sandstone and claystone and insert of marl from Halang Formation (c = 0.0014), the breccia from Kumbang Formation (c = 0.0035), the alternately of sandstones and claystone with insert of marl and breccia from Halang Formation (c = 0.0036), the claystone from Tapak Formation (c = 0.0015), the alternately of sandstones and claystone with insert of marl and compacted breccia from Halang Formation (c = 0.0030), and the alternately of sandstone and claystone from   Halang Formation (c = 0.0020). The plantonic foraminifer fossils as resources of oil seepage are estimated in the sedimentaries rocks, where the oil flows from those rocks into the         reservoir (source rock). Based on the interpretation results, the source rock is above basaltic igneous rock with the approximate position is 108.76164°W and 7.43089°S; and the depth is 132.09 meters below the average topographic.</p>

scholarly journals Estimasi Kedalaman Bitumen Batubara di Desa Banjaran Kecamatan Salem Kabupaten Brebes Berdasarkan Data Anomali Magnetik

2017 ◽  
Vol 4 (02) ◽  
pp. 171
Author(s):  
Sehah S ◽  
Sukmaji Anom Raharjo ◽  
Adi Chandra
Keyword(s):  
Magnetic Susceptibility ◽  
Data Processing ◽  
Data Acquisition ◽  
Magnetic Anomaly ◽  
Field Data ◽  
Magnetic Anomalies ◽  
Research Area ◽  
Magnetic Data ◽  
Geological Information ◽  
The Village

<p>The Estimation of coal bituminous depth in Village of Banjaran, District of Salem, Regency of Brebes based on magnetic anomaly data has been done. The Village of Banjaran is located in the geology basin which called as Bentarsari Basin. The activities stages that carried out in this research include of magnetic data acquisition in the field, data processing, and interpretation. The interpretation of the anomalies data is done through the modeling using the Mag2DC for Window software on the local magnetic anomalies data. Based on this modeling results, then obtained six anomalous objects that can be interpreted as the subsurface rocks in the research area, which consists of sediments of gravel, sand, clay, and silt ( = 0.0020 cgs units); tuff and tuffaceous sandstone ( = 0.0069cgs units); andesite breccia, tuff, and tuffaceous sandstone ( = 0.0085cgs units); solid andesite breccia which not layered ( = 0.0115 cgs units); coarse sandstones, limestones, and sandy marl ( = 0.0109cgs units); andesite sandstone that layered with claystone and thin insertions of new coal bituminous alternately ( = 0.0008cgs units). Based on the modeling results and the geological information of this research area, it can be estimated that the coal bituminous found in the Kaliglagah formation, with its depths ranging between 104.48 m – 505.97m, and the value of the magnetic susceptibility is 0.0008 cgs units.</p>

scholarly journals APPLICATION OF MAGNETIC SURVEY TO EXPLORE THE IRON ORE DEPOSITS IN THE NUSAWUNGU COASTAL REGENCY OF CILACAP CENTRAL JAVA

2017 ◽  
Vol 7 (2) ◽  
pp. 79 ◽  
Author(s):  
S Sehah ◽  
Sukmaji Anom Raharjo
Keyword(s):  
Magnetic Susceptibility ◽  
Iron Ore ◽  
Research Area ◽  
Ore Deposits ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Magnetic Minerals ◽  
The Third ◽  
Central Java ◽  
Iron Ore Deposits

The research aiming to explore the iron ore deposits in the Nusawungu coastal Regency of Cilacap has been conducted using the magnetic survey. The acquisition of magnetic data was conducted in April – Mei 2017, covering the area in the ranges of 109.314° – 109.345°E and 7.691° – 7.709°S. The obtained magnetic field strength data were corrected, reduced, and mapped to obtain the contour map of local magnetic anomaly. The modeling process was carried out along the path extending over the map from the positions of 109.314°E and 7.695°S to 109.335°E and 7.699°S, so that some subsurface anomalous objects are obtained. The lithological interpretation was performed to identify the types of subsurface rocks and their formations based on the magnetic susceptibility value of each anomalous objects and supported by the geological information of the research area. Based on the interpretation results, three rocks deposits of alluvium formations were obtained, which are estimated to contain iron ore. The first deposit has a length of 164.85 m, a depth of 0.57 – 8.43 m, and a magnetic susceptibility value of 0.0097 cgs. The second deposit has a length of 376.28 m, a depth of 2.56 – 19.66 m, and a magnetic susceptibility value of 0.0108 cgs. The third deposit has a length of 1,306.26 m, a depth of 3.70 – 58.69 m, and a magnetic susceptibility value of 0.0235 cgs. Out of the whole rocks deposits, the third rock deposit is interpreted to have the most prospective iron ore. This interpretation based on its high magnetic susceptibility value, which indicates the presence of many magnetic minerals (i.e. iron ores) in the rock.

An Augmented Iteratively Re-weighted and Refined Least Squares Method for lp Minimization Problem in Inverse Modeling of Potential Field Magnetic Data

2020 ◽  
Vol 1 (3) ◽  
Author(s):  
Maysam Abedi
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Least Squares ◽  
Minimization Problem ◽  
Potential Field ◽  
Field Data ◽  
Least Squares Method ◽  
Porphyry Copper ◽  
Magnetic Data ◽  
Magnetic Field Data

The presented work examines application of an Augmented Iteratively Re-weighted and Refined Least Squares method (AIRRLS) to construct a 3D magnetic susceptibility property from potential field magnetic anomalies. This algorithm replaces an lp minimization problem by a sequence of weighted linear systems in which the retrieved magnetic susceptibility model is successively converged to an optimum solution, while the regularization parameter is the stopping iteration numbers. To avoid the natural tendency of causative magnetic sources to concentrate at shallow depth, a prior depth weighting function is incorporated in the original formulation of the objective function. The speed of lp minimization problem is increased by inserting a pre-conditioner conjugate gradient method (PCCG) to solve the central system of equation in cases of large scale magnetic field data. It is assumed that there is no remanent magnetization since this study focuses on inversion of a geological structure with low magnetic susceptibility property. The method is applied on a multi-source noise-corrupted synthetic magnetic field data to demonstrate its suitability for 3D inversion, and then is applied to a real data pertaining to a geologically plausible porphyry copper unit.  The real case study located in  Semnan province of  Iran  consists  of  an arc-shaped  porphyry  andesite  covered  by  sedimentary  units  which  may  have  potential  of  mineral  occurrences, especially  porphyry copper. It is demonstrated that such structure extends down at depth, and consequently exploratory drilling is highly recommended for acquiring more pieces of information about its potential for ore-bearing mineralization.

scholarly journals Two Dimensional Modeling of Basaltic Rocks Intrusion Based on The Local Magnetic Anomalies Data in Jatilawang District Banyumas Regency

2020 ◽  
Vol 10 (2) ◽  
pp. 171
Author(s):  
Sehah Sehah ◽  
Sukmaji Anom Raharjo ◽  
Urip Nurwijayanto Prabowo
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Anomalies ◽  
Basaltic Rock ◽  
Research Area ◽  
Magnetic Data ◽  
Two Dimensional ◽  
Basaltic Rocks ◽  
Dimensional Modeling ◽  
Susceptibility Contrast ◽  
Lateral Length

Two dimensional modeling to basaltic rocks intrusion in Pekuncen and Karanglewas Villages Jatilawang District, Banyumas Regency, Central Java based on the local magnetic anomalies data has been carried out in March – June 2020. The amount of magnetic data obtained from the acquisition in the field was 239 data stretching in position of 109.107222° – 109.134944°E and 7.561361° – 7.577306°S, with the local magnetic anomalies values ranging of -2,961.11 – 1,516.31 nT. To model anomalous sources in the subsurface in two dimensions, then the local magnetic anomalies data is transformed into pseudogravity anomalies data, so that anomalous value can be obtained as -27.815 – 41.087 mGal. Based on the pseudogravity anomalous map, the basaltic rock intrusion is interpreted to be located in the eastern part of the research area, so modeling of anomalous sources is conducted in this area. The results of 2D-modeling to local magnetic anomalies data indicate the presence of anomalous object interpreted as basaltic rock intrusion with magnetic susceptibility contrast value of 0.0223 cgs, located at depth of 52.61 – 505.97 m and a lateral length of 1777.94 m. This rock intrudes sediment rock from the Halang Formation and is connected to other basaltic rock near the surface with magnetic susceptibility contrast value of 0.0165 cgs, located at depth of 1.94 – 80.90 m and lateral length of 751.83 m. The results of lithological interpretation are in accordance with the geological information of the research area.

scholarly journals APPLICATION OF UNMANNED AERIAL VEHICLE AS A BASE MAP LAYER IN NEAR-SURFACE GEOPHYSICS

2021 ◽  
Vol 13 (1) ◽  
pp. 26
Author(s):  
Muhammad Yanis ◽  
Aprilla Hasibuan Anggini ◽  
Faisal Abdullah ◽  
Muzakir Zainal ◽  
Marwan Abubakar
Keyword(s):  
Data Analysis ◽  
High Resolution ◽  
Good Condition ◽  
Data Interpretation ◽  
Research Area ◽  
Magnetic Data ◽  
Physical Parameters ◽  
Large Area ◽  
Near Surface ◽  
Near Surface Geophysics

The Geophysical method is operated by using physical parameters above the surface to estimate the subsurface structures. In data interpretation, all 3D surveys, i.e., magnetic, gravity, magnetotelluric, and airborne, are required for geographical conditions in the research area. In a large area, global DEM data is used to explain the field condition, but for local measurement, the data is not efficient due to low resolution (15-30 m/px). This research uses UAV technology to produce a high-resolution topography in local Geophysical measurement (500 x 600 m). The survey was conducted to map the coal structure in the subsurface. UAV data were also compared to SRTM (30 m/px) and DEMNAS (8 m/px) as global topography. Based on data processing, the UAV topographic was have a high resolution of 2.5 cm/px. Comparison of UAV and magnetic data are able to explain a good condition of field measurement than a global DEM data, even in a relatively small area; outcrops of the coal (50x50 m) can show a good differences contrast of topography. Based on data analysis, we can conclude that UAV technology can interpret the geophysical data measured in a local area.Keywords: UAV, SRTM, Topography, Geophysical Interpretation.Metode Geofisika bekerja dengan memanfaatkan parameter fisis diatas permukaan untuk pendugaan struktur bawah permukaan. Dalam tahapan interpretasi data, semua pengukuran 3D Geofisika; magnetic, gravity, magnetotelluric, dan airbone sangat membutuhkan keadaan geografis lapangan. Pada area yang luas, data DEM global digunakan untuk menjelaskan deskripsi lapangan, namun untuk pengukuran dekat permukaan yang bersifat lokal, data ini tidaklah efesien, karena resolusi yang relative rendah (15 – 30 m/px). Kami menggunakan teknologi UAV untuk menghasilkan topografi resolusi tinggi pada area pengukuran Geofisika dengan luas 500 x 600 m, yang disurvei untuk pemetaan batubara dibawah permukaan. Data UAV juga dibandingkan dengan topografi global SRTM (30 m/px) dan DEMNAS (8 m/px). Hasil pengolahan data menunjukkan data UAV menghasilkan topografi dengan resolusi 2.5 cm/px. Hasil overlay UAV dengan Geofisika magnetik mampu menjelaskan deskripsi lapangan dengan sangat baik dibandingkan DEM global, bahkan pada area yang relative kecil seperti singkapan batuabara (50x50 m) dapat menunjukkan keadaan perbedaan topografi dengan kontras. Berdasarkan data analysis, topografi UAV sangat potensial digunakan untuk interpretasi data Geofisika dekat permukaan yang diukur pada area yang relative lokal.Kata kunci: UAV, SRTM, Topografi, Interpretasi Geofisika.

Kimberlites and exploration geophysics

Geophysics ◽  
1979 ◽  
Vol 44 (8) ◽  
pp. 1395-1416 ◽  
Author(s):  
James C. Macnae
Keyword(s):  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Emplacement Mechanism ◽  
Geophysical Technique ◽  
Geologic Model ◽  
Main Factors ◽  
Original Size ◽  
Large Survey

This paper discusses geophysical prospecting techniques for kimberlite pipes, a major source of diamonds. A simple geologic model based on descriptions by Hawthorne (1975) and Nixon (1973) is given, and the varied geophysical responses obtained over kimberlite pipes are interpreted in terms of this model. The three main factors controlling these responses are the original size and inhomogeneity of the pipe, the depth of erosion, and the degree of weathering. Kimberlite pipes are roughly elliptical in surface exposure in most cases, with a “carrot shaped” extension at depth. The unweathered portion of the pipe generally contains a few percent magnetite, and this in most cases produces a clearly detectable magnetic anomaly. The presence of deep weathering may alter the magnetite in the top of the pipe to nonmagnetic oxides of iron, thus resulting in an increased depth to the magnetic source. If this depth is large, the magnetic response may not be large enough to detect the kimberlite in the presence of noise and the effect of other structures. In addition, if little erosion has taken place since emplacement, kimberlitic sediments known as epiclastic kimberlite will be present to considerable depths in the pipe, and this may also lead to the absence of a clear magnetic anomaly. In one large survey in South Africa, electromagnetic (EM) techniques have proven to be remarkably effective in detecting the presence of weathered clays or epiclastic kimberlite contained within the pipes. All pipes discovered during this survey had unmistakable EM signatures, while five out of eight had very small magnetic anomalies which would not likely have been selected as potential targets on the basis of magnetic data alone. These examples would indicate that in any area where deep weathering is expected, an EM survey is essential in combination with a magnetic survey if reconnaissance is to be based on airborne geophysical techniques. Due to the emplacement mechanism of kimberlite, considerable inhomogeneity within a pipe may be present, leading to significant variation in the response of any geophysical technique to one pipe, with resultant interpretation difficulties. Although this is not a limitation in the discovery of new pipes, it does make their geophysical delimitation difficult.

scholarly journals IDENTIFIKASI STRUKTUR PADA PROFIL MAGNET TOTAL DAN SEISMIK DANGKAL DI PERAIRAN TANJUNG SELOR KALIMANTAN TIMUR

2016 ◽  
Vol 2 (3) ◽  
Author(s):  
Delyuzar Ilahude ◽  
Lukman Arifin
Keyword(s):  
Magnetic Anomaly ◽  
Seismic Data ◽  
Single Channel ◽  
Data Interpretation ◽  
Research Area ◽  
Systematic Mapping ◽  
East Kalimantan ◽  
Magnetic Basement ◽  
The Many

From the total magnetic anomaly and single channel seismic data interpretation on the systematic mapping in the Tanjung Selor waters, east Kalimantan, are shows correlation almost similar between magnetic anomaly with the seismic data records. The magnetic anomaly value and seismic data profiles are show that the many fault and fold structures identification in the research area. The total magnetic anomaly result which are presented of the magnetic basement. Dari Anomali magnet total dan data seismik dangkal saluran tunggal pada pemetaan sistematik di perairan Tanjung Selor, Kalimantan timur, menunjukkan hubungan yang hampir mirip antara nilai anomali magnet total dengan data seismik. Profil anomali magnet dan data seismik dangkal menunjukkan banyaknya struktur sesar dan perlipatan teridentifikasi di daerah penelitian. Anomali magnet total hasil penelitian ini lebih cenderung menggambarkan intensitas magnet batuan dasar.

scholarly journals Distribution of Iron Sand in The Widarapayung Coast Area at Regency of Cilacap Based on Magnetic Anomaly Data

2017 ◽  
Vol 6 (02) ◽  
pp. 97
Author(s):  
Sehah Allasimy ◽  
Sukmaji Anom Raharjo ◽  
Muhammad Andi Kurniawan
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Research Area ◽  
Object Model ◽  
Intensity Data ◽  
Magnetic Intensity ◽  
A Value ◽  
Proton Precession Magnetometer ◽  
Sand And Gravel

Interpretation on the magnetic anomalies data has been done in the Widarapayung coast area, District of Binangun, Regency of Cilacap to identify distribution of iron sand. The acquisition of magnetic intensity data in this area has been done in December 2015 and May 2016 using Proton Precession Magnetometer (PPM) with type of GSM-19T. The research area extends on the geographic positions of 109.2501°BT – 109.2702°E and 7.6781°LS – 7.6986°S. Magnetic anomalies data modeling is done with using Mag2DC for Windows software so obtained some subsurface anomalous objects model. The anomaly object model having a value of magnetic susceptibility of 0.0093cgs unit is interpreted as iron sand interspersed with silt, clay, sand, and gravel from the alluvium formation. This formation is lain at a depth of 1.709 to 11.966m and a length of 1576.7m. The iron sand contained in this formation is estimated prospects for exploitation. Based on the interpretation results, alluvium formation is also found at a depth of 1.140 to 30.769m, which expected be composed of silt, clay, sand, and gravel with a magnetic susceptibility value of 0.0051cgs unit. The content of iron sand in this 2<sup>nd</sup> alluvium formation is expected to be relatively small.

scholarly journals Enhancing the quality of interpretation magnetic data at low latitudes

2017 ◽  
Vol 1 (T4) ◽  
pp. 105-114
Author(s):  
Hai Hong Nguyen ◽  
Nhan Thanh Nhan ◽  
Liet Van Dang ◽  
Thu Ngoc Nguyen
Keyword(s):  
Magnetic Anomaly ◽  
Hilbert Transform ◽  
Amplitude Spectrum ◽  
Data Interpretation ◽  
Analytic Signal ◽  
Magnetic Data ◽  
Low Latitudes ◽  
Reduction To The Pole ◽  
Signal Method

Magnetic anomalies are antisymmetrical and often skewed to the location of the sources, because both of the magnetization and ambient field are not directed vertically, so it’s difficult to interpret. For reducing the magnetic anomaly to a symmetrical one – this located on the source of the anomaly – people often use the reduction to the pole (RTP) where the magnetization and ambient field are both directed vertically. However, at low latitudes (an absolute inclination less than 16o30’), the amplitude spectrum of the RTP’s operator was amplified at higher frequencies (short wavelengths) can form a narrow pie-shaped; so it produces artifacts elongated along the direction of the magnetic declination. Therefore, many methods of RTP at low latitudes are given to solve this problem, but most of them are not efficiency. In this paper, we performed enhancing the quality of interpretation of magnetic data at low latitudes by some RTP methods for magnetic data at low latitudes and the analytic signal method using gradient operator and Hilbert transform. This method is applied to a model and to a real magnetic anomaly to find out the best method. Then this method was applied to enhance the quality of magnetic data interpretation in the Southern Vietnam. The result showed that the analytic signal method using Hilbert transform allowed enhancing the quality of interpretatio of magnetic data n at low latitudes is the best.

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