Geological mapping of Jharia Coalfield, India using GRACE EGM2008 gravity data: a vertical derivative approach

Research has been carried out related to subsurface structures in the Tejakula Buleleng Bali area and its surroundings using the gravity method. This study aims to identify the local Tejakula fault. The data used in this study is gravity anomaly data obtained from observations of Geodetic Satellite (GEOSAT). The method used in interpreting the type of disturbance uses the Second Vertical Derivative method, which then produces two-dimensional (2D) and three-dimensional (3D) fault model interpretations. Based on the results obtained in the study, the condition of the bouguer gravity anomaly value in the Tejakula area and its surroundings at the research location is in the range of 65 mGal to 185 mGal. Meanwhile, based on the Second Vertical Derivative method in determining the type of fault, the Tejakula Fault can be categorized as a mandatory fault with an upward trend.

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Efficient Use of Satellite Gravity Anomalies for mapping the Great Sumatran Fault in Aceh Province

INDONESIAN JOURNAL OF APPLIED PHYSICS ◽

10.13057/ijap.v9i2.34479 ◽

2019 ◽

Vol 9 (02) ◽

pp. 61

Author(s):

Muhammad Yanis ◽

Marwan Marwan ◽

Nazli Ismail

Keyword(s):

Gravity Data ◽

Gravity Anomalies ◽

Geological Structure ◽

Geological Mapping ◽

Capital City ◽

Satellite Gravity ◽

Alluvial Deposits ◽

The North ◽

Aceh Province ◽

Tilt Derivative

<p>Gravity Satellite has been widely used in tectonic studies and regional of geological mapping. The Satellite Gravity data are provided free by Scripps Institution of Oceanography, University of California San Diego. The data are acquired by GEOSAT and ERS-1 satellites with a 1.5 km resolution for one pixel. For a further application, the tilt derivative analytic technique was used in order to enhance linear trends of the geological structure revealed by the Bouguer anomalies. The method is represented by the value of an angle between the total horizontal and vertical derivative from the gravity data. The results show that the tilt derivative calculation has been able to map clearly some geological structures on the north of Sumatra i.e., the Aceh and the Seulimeuem segments, as well as some local faults around them. On the other hand, Banda Aceh as the capital city of Aceh Province and Pidie District is dominated by positive values of the tilt derivative anomalies. The data coincide with geological maps of both areas where they are covered by alluvial deposits. Based on the result, it can be concluded that the tilt derivative method is potentially used for quick interpretation of the satellite gravity data.</p>

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Predictive Geological Mapping from Geophysical Data Using Self-Organizing Maps: A Case Study from Baie Verte, NL, Canada

Geophysics ◽

10.1190/geo2020-0756.1 ◽

2021 ◽

pp. 1-55

Author(s):

Angela Carter-McAuslan ◽

Colin Farquharson

Keyword(s):

Gravity Data ◽

Geological Mapping ◽

Magnetic Data ◽

Self Organizing Maps ◽

Predictive Mapping ◽

Legacy Data ◽

Geological Units ◽

Radiometric Data ◽

Self Organizing

Self-organizing maps (SOMs) are a type of unsupervised artificial neural networks clustering tool. SOMs are used to cluster large multi-variate datasets. They can identify patterns and trends in the geophysical maps of an area and generate proxy geology maps, known as remote predictive mapping. We applied SOMs to magnetic, radiometric and gravity datasets compiled from multiple modern and legacy data sources over the Baie Verte Peninsula, Newfoundland, Canada. The regional and local geological maps available for this area and the knowledge from numerous geological studies allowed for assessing the accuracy of the SOM-based predictive mapping. Proxy geology maps generated by primary clustering directly from the SOMs and secondary clustering using a k-means approach reproduced many geological units identified by previous traditional geological mapping. Of the combinations of datasets tested, the combination of magnetic data, primary radiometric data and their ratios, and Bouguer gravity data gave the best results. We found that using reduced-to-the-pole residual intensity or analytic signal as the magnetic data were equally useful. The SOM process was unaffected by gaps in the coverage of some of the datasets. The SOM results could be used as input into k-means clustering as k-means clustering requires no gaps in the data. The subsequent k-means clustering resulted in more meaningful proxy geology maps than were created by the SOM alone. In regions where the geology is poorly known, these proxy maps can be useful in targeting where traditional, on-the-ground geological mapping would be most beneficial which can be especially useful in parts of the world where access is difficult and expensive.

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Geological significance of high-resolution magnetic data in the Quesnel terrane, Central British Columbia1This article is one of a series of papers published in this Special Issue on the theme of New insights in Cordilleran Intermontane geoscience: reducing exploration risk in the mountain pine beetle-affected area, British Columbia.2Geological Survey of Canada Contribution No. 20100225.

Canadian Journal of Earth Sciences ◽

10.1139/e10-109 ◽

2011 ◽

Vol 48 (6) ◽

pp. 1065-1089 ◽

Cited By ~ 1

Author(s):

M.D. Thomas ◽

M. Pilkington ◽

R.G. Anderson

Keyword(s):

British Columbia ◽

High Resolution ◽

Mountain Pine Beetle ◽

Gravity Data ◽

Sedimentary Cover ◽

Volcanic Rocks ◽

Geological Mapping ◽

Magnetic Data ◽

Structural Variations ◽

High Resolution Data

The ability of airborne sensors to image the magnetic signatures of prospective Quesnel terrane rocks through ubiquitous Quaternary glacial sedimentary cover in central British Columbia helps target new areas for mineral exploration. Newly acquired high-resolution data provide new perspectives on the nature and probable areal distribution of many geological units, revealing detail and information unattainable by conventional geological mapping. In combination with gravity data, these magnetic data indicate the presence of a granitic intrusion and a development of Nicola Group volcanic rocks, both potential hosts for porphyry- and (or) vein-type mineralization, under younger Tertiary volcanic cover. At a finer scale, magnetic patterns and fabrics permit discrimination between volcanic rocks of the Tertiary Chilcotin and Kamloops groups, and detection of subtle compositional and (or) structural variations within the groups. Contacts between volcanic cover and basement rocks and between basement units are more accurately defined, significantly reducing locally the areal extent of volcanic cover and opening up more ground for exploration. The high resolution of features in images of magnetic vertical derivatives reveals the Naver pluton to be more complex than currently mapped, comprising several integral elements, one of which may be a large roof pendant. Internal subdivisions of the Thuya batholith are defined, and annular marginal phases are proposed within two large granodioritic intrusions. Several new intrusions are proposed within the extensive, mainly sedimentary Devonian–Triassic terrain northeast of Kamloops, internal composition variation is suggested for some larger mapped intrusions, and areas underlain by some intrusions are enlarged.

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Gravity observation of field camp geophysics in Karangsambung using Data Acquisition 2005-2019

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/873/1/012049 ◽

2021 ◽

Vol 873 (1) ◽

pp. 012049

Author(s):

E J Wahyudi ◽

A Laesanpura ◽

D Sukmayadi

Keyword(s):

Data Acquisition ◽

Gravity Data ◽

Geophysical Methods ◽

Geological Mapping ◽

Data Compilation ◽

Gravity Observation ◽

Variation Range ◽

Using Data ◽

Topographic Variation ◽

Relative Gravimeter

Abstract The study of field camp geophysics in Karangsambung has been done since 1996 until 2019 by geophysical engineering ITB. During the field activities, students was assigned with several data acquisition using various geophysical methods. One of the most common method to conducted alongside with surface geological mapping is gravity. Compilation of gravity data during the activities will be presented in this work. There are two categories of data compilation during 24 years: data compilation 1996-2004, and 2005-2019. The observation conducted using relative gravimeter with data distribution already cover geological surface map in the study area (Luk-Ulo Melange Complex, Karangsambung Formation, Totogan Formation, and Diabas Intrusion). The pattern of gravity observation shows correlated with topographic variation. Range gravity observation from this study is about 62 mGal.

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Studi Identifikasi Struktur Geologi Bawah Permukaan Untuk Mengetahui Sistem Sesar Berdasarkan Analisis First Horizontal Derivative (FHD), Second Vertical Derivative (SVD), Dan 2,5D Forward Modeling Di Daerah Manokwari Papua Barat

Jurnal Geofisika Eksplorasi ◽

10.23960/jge.v4i2.15 ◽

2020 ◽

Vol 4 (2) ◽

pp. 62-76

Author(s):

Shiska Yulistina

Keyword(s):

Cross Section ◽

Gravity Data ◽

Bouguer Anomaly ◽

Forward Modeling ◽

Research Area ◽

Geological Structure ◽

North West ◽

Vertical Derivative ◽

Horizontal Derivative ◽

Papua Barat

In general, Manokwari has a geological structure that is in the form of a folding area found in the highlands of the mountains. Among the creases, there is a fault up and the fault down. In coastal or marine areas found many reefs and corals. The study of gravity was conducted in the Manokwari area of West Papua with the aim to know the subsurface geological structures based on FHD (First Horizontal Derivative), SVD (Second Vertical Derivative) and 2.5D Forward Modeling on the residual anomaly maps of the study area. The results showed that the research area has Bouguer Anomaly value ranged from 4 mGal to 96 mGal with the low anomaly at the left side of the research area lengthwise relatively in north-west to south-east direction, the middle-value anomaly spreads in the west-east area of research area, high anomaly scattered in the northern part of the research area. The results of the 2.5D subsurface modeling and the SVD and FHD analysis indicated the presence of a Thrust Fault on the C-C’ cross-section, on the B-B’ cross-section there is a Diorite Lembai intrusion with the density value is 2.75 gr/cc, whereas the A-A' cross-section which intersects with Sorong fault were not found any fault or rock intrusion based on observed gravity data of the research area.

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Reservoir Identification Based on Gravity Method at “AUN” Geothermal Field

E3S Web of Conferences ◽

10.1051/e3sconf/201912514008 ◽

2019 ◽

Vol 125 ◽

pp. 14008

Author(s):

Annisa Dwi Hafidah ◽

Yunus Daud ◽

Alfian Usman

Keyword(s):

Gravity Data ◽

Geothermal Field ◽

Gravity Inversion ◽

Eurasian Plate ◽

Gravity Method ◽

Vertical Derivative ◽

Horizontal Derivative ◽

Sumatra Island ◽

Result Show ◽

Subsurface Layers

Sumatra Island has the largest geothermal potential in Indonesia spread along the subduction zone between the Indian-Australian plate and the Eurasian plate. “AUN” geothermal field located in Sumatra Island and considered to be one of the largest potential geothermal prospects in Indonesia. This study is focused on identifying the prospect of “AUN” geothermal field using gravity method. First Horizontal Derivative (FHD) and Second Vertical Derivative (SVD) analysis were applied in order to determine a more accurate boundary of the fault. 3D inversions of gravity data were used to reconstruct subsurface model. The result show that analysis of First Horizontal Derivative (FHD) and Second Vertical Derivative (SVD) can confirm southwest-northeast fault and caldera structure as a boundary of geothermal reservoir and 3D gravity inversion can show subsurface layers with density 2.5 gr/cc to 2.8 gr/cc inside the boundary which is determined as a heat source in “AUN” geothermal field.

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