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Gagg, Gilberto, and Sérgio Florêncio de Souza. "Geração de mapas de anomalia Bouguer a partir de dados gravimétricos terrestres e do EGM2008." Revista Brasileira de Geomática 5, no. 2 (May 16, 2017): 186. http://dx.doi.org/10.3895/rbgeo.v5n2.5510.
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Um dos propósitos da determinação da gravidade é a obtenção das anomalias da gravidade. O campo de gravidade é um campo potencial e sofre influência da constituição geológica, pois a densidade das rochas gera pequenas variações nos valores de gravidade. As reduções matemáticas buscam eliminar a influência de fatores que interferem no campo de gravidade. A anomalia Bouguer remove o efeito gravitacional das rochas existentes entre o ponto de observação e o nível de referência. Dados da missão gravimétrica GRACE (Gravity Recovery and Climate Experiment) tem auxiliado na densificação das informações, pois muitos modelos geopotenciais são deficientes devido a irregular distribuição dos dados gravimétricos. Assim, efetuou-se um estudo para o estado do Rio Grande do Sul-RS, visando gerar mapas de anomalia Bouguer através de uma análise gravimétrica sob dois aspectos: uso exclusivo de dados do modelo EGM2008 (envolve uso de dados GRACE), e uso combinado de dados EGM2008 (porção oceânica e porção continental externa ao RS) com dados terrestres de campo para o Rio Grande do Sul. Concluiu-se que o emprego de dados de missão satelitais facilmente acessíveis, permitiu gerar mapas de anomalias Bouguer que atendem objetivos de cunho geral e até regional, com a vantagem de serem atuais e uniformemente espaçados.
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Motoki, Akihisa, Luiz Carlos Chaves Novais, Kenji Freire Motoki, Leonardo Costa de Oliveira, Ricardo De Souza Fasolo, and Adrienne Brito Lima. "SATELLITE-DERIVED GRAVIMETRY FOR ABROLHOS CONTINENTAL SHELF, STATES OF ESPÍRITO SANTO AND BAHIA, BRAZIL, AND ITS RELATION TO TECTONIC GENESIS OF SEDIMENTARY BASINS." Revista Brasileira de Geofísica 32, no. 4 (December 1, 2014): 735. http://dx.doi.org/10.22564/rbgf.v32i4.554.
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ABSTRACT. This paper presents the results of satellite-derived gravimetry for Abrolhos Continental Shelf and the adjacent areas, States of Esp´ırito Santo and Bahia,Brazil, and discusses tectonic genesis of the sedimentary basins. The free-air and Bouguer anomalies on the continental shelf show a gradual increase from coast tocontinental shelf break. The total difference of 135 mGal indicates crust thinning of 4.5 km. The Bouguer anomaly increases beyond the shelf break and continues upto the abyssal plane. The total difference of 260 mGal suggests crustal thinning of 9.0 km. The studied area has two types of passive continental margin: 1) ES-typewith high continental slope, low and narrow continental rise, and high free-air and Bouguer anomalies; 2) SP-type with low continental slope, high and wide continentalrise, and low gravity anomalies. There are three types of sedimentary basins with different geologic structure and tectonic genesis: 1) Basins on the continental shelf,CSH-type; 2) Basin on the continental rise, CRS-type; 3) Continental rift basin, CRF-type. The CSH-type, as Esp´ırito Santo basin, has coherent free-air and Bougueranomalies 40 to 50 mGal lower than the adjacent areas. The sedimentary deposits are 2.0 to 2.5 km thick. The basement depression is sustained by mechanical strengthwithout isostatic compensation. The normal faults of basin border are limited within upper crust. The CRS-type, as Pedro Can´ario basin, has low local residual Bougueranomaly with difference of 40 mGal. The sedimentary deposits are more than 2.7 km thick. The continental side basin border is under isostatic compensation due todeep normal fault between continental slope and continental rise. The oceanic side border is sustained by mechanical strength of the basement. The CRF-type, BesnardPassage, is a continental rift basin originated from mantle pull-apart tectonism. The rift bottom is under complete isostatic compensation. The normal faults of the grabenborder continue to the mantle. The Moho depth along the rift is at least 6.5 km shallower than the adjacent areas.Keywords: satellite-derived gravimetry, Abrolhos Continental Shelf, sedimentary basin, crustal thinning, isostatic compensation. RESUMO. Este artigo apresenta os resultados da gravimetria por satélite para a Plataforma Continental de Abrolhos e as áreas adjacentes, ES-BA, e discute as gêneses tectônicas das bacias sedimentares. As anomalias ar-livre e Bouguer na plataforma continental mostram um aumento gradativo a partir da costa até a quebra da plataforma continental. A diferença total de 135mGal indica afinamento da crosta continental de 4,5 km. A anomalia Bouguer se apresenta além da quebra da plataformae continua até o assoalho abissal. A diferença total de 260 mGal sugere afinamento crustal de 9,0 km. Na área estudada, observam-se dois tipos de margem continental passiva: 1) Tipo ES com talude continental alto, elevação continental baixa e curta e anomalias ar-livre e Bouguer altos; 2) Tipo SP com talude continental baixo, elevação continental alta e extensa e anomalias gravimétricas baixas. Existem três tipos de bacias sedimentares com estrutura geológica e gênesis tectônicas diferentes: 1) Bacias na plataforma continental, Tipo CSH; 2) Bacias na elevação continental, Tipo CRS; 3) Bacia de rifte continental, Tipo CRF. O Tipo CSH, como a bacia do Espírito Santo, possui anomalias ar-livre e Bouguer coerentes 40 a 50 mGal mais baixas do que as áreas adjacentes. Os depósitos sedimentares são de 2,0 a 2,5 km de espessura. A depressão do embasamento é sustentada pela rigidez mecânica sem compensação isostática. As falhas normais das bordas de bacias são limitadas dentro da crosta superior. O Tipo CRS, como a bacia Pedro Canário, tem baixa anomalia Bouguer local com diferença de 40 mGal. Os depósitos sedimentares têm mais de 2,7 km de espessura. A borda da bacia do lado continental está sob compensação isostática devido à falha normal profunda entre talude continental e elevação continental. Aborda do lado oceânico é sustentada pela rigidez mecânica do embasamento. O Tipo CRF, Passagem Besnard, é uma bacia do rifte continental originada do tectonis mode distensão do manto. O fundo da bacia está sob compensação isostática completa. As falhas normais da borda do graben continuam até o manto. A profundidade da Moho ao longo do rifte é pelo menos 6,5 km mais rasa do que as áreas adjacentes.Palavras-chave: gravimetria por satélite, Plataforma Continental de Abrolhos, bacia sedimentar, afinamento crustal, compensação isostática.
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Gagg, Gilberto, and Sérgio Florêncio de Souza. "Análise morfoestrutural na região da bacia de Pelotas a partir do emprego de mapas de anomalia Bouguer e perfis gravimétricos." Revista Brasileira de Geomática 7, no. 1 (April 1, 2019): 003. http://dx.doi.org/10.3895/rbgeo.v7n1.8799.
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Dados gravimétricos, inclusive aqueles advindos de missões satelitais, são uma grande ferramenta nos estudos regionais para áreas que envolvam aplicações geológicas e mesmo oceanográficas, pois auxiliam em estudos sobre a caracterização, evolução e o comportamento da crosta terrestre, tanto para áreas continentais como oceânicas. Dados de gravimetria foram usados como subsídio à análise morfoestrutural na região da Bacia de Pelotas-RS. Foi adotado o modelo geopotencial EGM2008 através das anomalias Bouguer, que possibilitou a elaboração de mapas e perfis gravimétricos. Através da análise dos mapas de anomalias Bouguer e perfis gravimétricos gerados, verificou-se que as anomalias Bouguer aumentam positivamente da costa em direção às maiores profundidades oceânicas, o que caracteriza um progressivo afinamento crustal associado à deriva continental. O comportamento das anomalias Bouguer evidenciou a presença de uma ruptura conhecida como Charneira Albo-aptiana ou Falha de Rio Grande na plataforma continental. A incidência de valores de anomalias significativamente positivas na região do Baixo de Mostardas sugere a presença de uma massa de maior densidade nesta região. A resolução dos dados gravimétricos utilizados neste estudo não permitiu evidenciar a presença de paleocanais na região, sendo necessária uma maior resolução espacial, associada a outros métodos de investigação.
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LIMA, Fabio Ullmann Furtado de, and Leila Maria Véspoli de CARVALHO. "INVERSÃO GRAVIMÉTRICA 3D DE CORPOS SALINOS NA BACIA DE CAMPOS UTILIZANDO DADOS DE SENSORIAMENTO REMOTO." Geosciences = Geociências 38, no. 2 (August 20, 2019): 451–66. http://dx.doi.org/10.5016/geociencias.v38i2.12527.
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Foi realizada a inversão tridimensional de dados gravimétricos oriundo de sensoriamento remoto com o objetivo de estimar as geometrias em sub-superfície de dois corpos salinos inseridos na Bacia de Campos. As modelagens dos corpos são baseadas em informações a priori tais como: contrastes de densidade entre corpos e o meio, números de prismas e números de vértices de cada prisma que, superpostos, modelarão a forma dos corpos salinos, profundidades e distâncias radiais mínimas e máximas dos corpos, coordenadas de origem dos prismas (a partir das quais o modelo começará a construir os corpos salinos), entre outros. Todas estas informações a priori provêm de um ensaio sísmico de reflexão realizados na região de estudo. Foram modelados paredões de sal considerando dois casos distintos: uma anomalia residual Bouguer aberta (caso 1) e outra fechada (caso 2). As geometrias dos paredões de sal foram modeladas satisfatoriamente em ambos os casos. Entretanto, o tamanho do paredão no caso 1 teve que ser subestimado para se obter um melhor ajuste entre as isogais observadas e preditas. Conclui-se que o modelo parece mais eficiente em modelar anomalias Bouguer fechadas do que abertas.
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Marangoni, Yára Regina, Denise Silva de Moura, and Herbert Ferreira. "Mapas de anomalias gravimétricas da Cidade Universitária Armando Salles de Oliveira – USP/SP." Geologia USP. Série Científica 17, no. 2 (August 1, 2017): 257. http://dx.doi.org/10.11606/issn.2316-9095.v17-120698.
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A Cidade Universitária Armando de Salles Oliveira, da Universidade de São Paulo (CUASO –USP/SP), é considerada um laboratório natural de pesquisas em Ciências da Terra. Ao longo de mais de duas décadas, dados gravimétricos foram obtidos como forma de treinamento de alunos e técnicos, formando um conjunto de 787 pontos distribuídos em 8 km2. O mapa de anomalia ar-livre apresenta forte correlação com a topografia, enquanto o mapa de anomalia Bouguer não apresenta correlação com a topografia e a geologia. Este mapa permitiu identificar um gradiente EW centrado na área, revelando uma estrutura de subsuperfície, modelada, neste mesmo estudo, como uma falha praticamente vertical, com atitude 090/80 N e cerca de 50 m de deslocamento vertical.
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Subagio, Subagio, and Tatang Patmawidjaya. "POLA ANOMALI BOUGUER DAN ANOMALI MAGNET DAN KAITANNYA DENGAN PROSPEK SUMBER DAYA MINERAL DAN ENERGI DI PULAU LAUT, PULAU SEBUKU DAN SELAT SEBUKU, KALIMANTAN SELATAN." JURNAL GEOLOGI KELAUTAN 11, no. 3 (February 16, 2016): 115. http://dx.doi.org/10.32693/jgk.11.3.2013.236.
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Anomali Bouguer Pulau Laut, Pulau Sebuku, dan Selat Sebuku dapat dikelompokkan menjadi dua wilayah anomali meliputi anomali berpola melingkar dengan kisaran nilai dari 40 hingga 64 mGal, dan anomali berpola lurus dengan kisaran nilai 40 hingga 50 mGal. Anomali magnet di daerah ini bervariasi dari -700 hingga 1600 nT, membentuk pola tinggian dan rendahan. Anomali Bouguer berpola melingkar dengan kisaran nilai 45-64 mGal mencerminkan batuan ultrabasa yang relatif mendekati permukaan. Batuan ultrabasa yang tersingkap di permukaan dicirikan oleh anomali magnet tinggi. Anomali Bouguer berpola kontur lurus sejajar menunjukkan sesar naik maupun sesar turun yang terdapat di daerah tersebut. Sesar naik yang berkembang di daerah penelitian umumnya terdapat di Pegunungan Meratus yang mempunyai mendala geologi sama. Anomali Bouguer dan anomali magnet rendah mencerminkan cekungan sedimen. yang diakibatkan oleh adanya gaya tarikan yang pernah ada. Batuan terobosan yang dijumpai, diduga terbentuk bersamaan dengan periode gaya tarikan ini. Serangkaian proses tektonik yang hasilnya terekam pada anomali Bouguer, anomali magnet, dan singkapan batuan memberi implikasi kemungkinan terdapatnya sumber daya energi dan mineral di daerah penelitian. Mineralisasi logam diperkirakan dapat dijumpai di sekitar daerah terobosan. Bijih besi, nikel, dan kromit kemungkinan terdapat di daerah ultra-mafik, sedangkan batubara di daerah cekungan sedimen.
Kata kunci : Anomali Bouguer, anomali magnet, sumber daya energi dan mineral, sesar naik dan sesar turun.
Bouguer anomaly of the Laut Island, Sebuku Island, and The Sebuku Strait can be grouped into two anomaly groups covering the circular pattern anomaly with range from 40 to 64 mGals, and the straight pattern with range of values from 40 to 50 mGals. The range of magnetic anomalies in the study area area from -700 to 1600 nT, forming high and low anomay patterns. The circular pattern of the Bouguer anomalies with range from 45 to 64 mGals reflects that the ultramafic rocks relatively close to the surface, while exposed ultrabasic rocks are indicated by high magnetic anomalies. Paralled pattern contour of Bouguer anomaly show a thrust faults and normal faults in this area. Thrust faults of commonly develop in Meratus Mountaint that has the same geological setting. The low Bouguer and magnetic anomalies reflect a sedimentary basin caused by previous tensional force. The intrusion rocks found in the study area suggest to be formed together with this tensional force period. A series of tectonic events recorded in Bougue anomaly, magnetic anomaly, and out crops gave the implication the possibility the present of energy and mineral resources in the study area. Metal mineralization suggests to be found in the intrusion area. Irons, nickels and chromites supposed can be found in the ulta-mafic area, while coal can be found in the sedimentary basin.
Keywords : Bouguer anomalies, magnetic anomalies, energy and mineral resources, thrust and normal faults.
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Liana, Yeni Rima, Tri Maria Magdalena Wea, Wihdatus Syarifah, Supriyadi Supriyadi, and Khumaedi Khumaedi. "Analisis Anomali Bouguer Data Gaya Berat Studi Kasus di Kota Lama Semarang." JRST (Jurnal Riset Sains dan Teknologi) 4, no. 2 (September 30, 2020): 63. http://dx.doi.org/10.30595/jrst.v4i2.6301.
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Kota Lama Semarang merupakan salah satu obyek wisata sejarah yang berada di kota Semarang dan pada tahun 2016 masuk sebagai salah satu nominasi World Heritage Site. Penelitian ini bertujuan untuk melakukan analisis anomali Bouguer data gaya berat studi kasus di Kawasan Kota Lama Semarang untuk membantu mengidentifikasi struktur bawah permukaan tanah di Kawasan tersebut yang setiap tahunnya selalu terjadi banjir rob, genangan air dan penurunan permukaan tanah. Pengolahan data anomali Bouger menggunakan software Oasis Montaj 6.4.2. Tahap awal dilakukan koreksi pasang surut (TC) dan koreksi apungan (DC). Tahap berikutnya dilakukan koreksi lanjut yang terdiri dari koreksi udara bebas (FAC) dan koreksi Bouguer (BC) hingga didapat kontur anomali udara bebas (FAA) dan kontur anomali Bouguer (BA). Nilai BA di Kawasan Kota Lama Semarang dengan interval 10,58 mGal s.d 11,65 mGal dengan koreksi FAC mempunyai rentang 1,48 mGal s.d 3,09 mGal, anomali FAA mempunyai rentang 11,1 mGal s.d 12,7 mGal serta koreksi gobs mempunyai rentang 978118,88 mGal s.d 978118,50 mGal. Kawasan dengan anomali Bouguer tinggi memiliki struktur batuan dengan densitas yang tinggi dibandingkan dengan Kawasan lainnya. Nilai anomali Bouguer semakin ke utara semakin rendah, dan semakin ke selatan semakin tinggi.
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Pebrian, Mutiara Qalbi, Marwan Marwan, and Nazli Ismail. "Interpretasi Data Anomali Gravitasi untuk Identifikasi Endapan Aluvium di Kuala Gigieng, Aceh Besar." Risalah Fisika 3, no. 1 (April 29, 2019): 15–19. http://dx.doi.org/10.35895/rf.v3i1.119.
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Abstrak – Aceh Besar dan Kota Banda Aceh merupakan kawasan pesisir yang dipengaruhi oleh proses sedimentasi. Kawasan ini didominasi oleh daratan berupa delta akibat aktivitas Sungai Krueng Aceh. Proses sedimentasi dapat dikaji menggunakan metode gravitasi berdasarkan distribusi percepatan gravitasi bawah permukaan. Pengukuran data gravitasi menggunakan alat Gravitimeter Scintrex CG-5. Jumlah titik pengukuran adalah 120 dan luas area pengukuran adalah 1858 × 725 m2.. Terdapat beberapa koreksi dalam pengolahan data gravitasi, seperti koreksi drift, pasang surut, lintang, koreksi udara bebas, koreksi bouguer dan koreksi medan. Koreksi-koreksi ini dilakukan untuk mendapatkan Anomali Bouguer Lengkap. Data anomali Bouger lengkap tersebut dipisahkan antara efek lokal dan regional. Profil nilai Anomali residual digunakan untuk pemodelan ke depan menggunakan Software Grav2Dc. Model 2D menunjukkan struktur bawah permukaan daerah penelitian terdiri dari 3 lapisan. Lapisan pertama diinterpretasikan sebagai lapisan aluvium 2 jenis pengendapan yaitu batuan aluvium pasiran (ρ = 1,66 gr/cm3) dan batu lempung (ρ = 2,07 gr/cm3) yang berada pada kedalaman 0-350 meter. Lapisan kedua diinterpretasikan sebagai batupasir (ρ = 2,11 gr/cm3). Lapisan ketiga diinterpretasikan sebagai batupasir tufaan (ρ = 2.18 gr/cm3) sebagai lapisan paling tua pada kedalaman 375 meter. Urutan pengendapan dimulai dari batupasir, batu lempung dan aluvium pasiran, kemudian terjadi pengulangan pengendapan antara aluvium pasiran dan batu lempung disebabkan oleh erosi pantai di atas permukaan.Kata kunci: metode gayaberat, anomali Bouger lengkap, Grav2Dc, endapan aluvium, Kuala Gigieng
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Tematur, Godensius, Jehunias L. Tanesib, and Redi K. Pingak. "INTERPRETASI BAWAH PERMUKAAN GUNUNG ANAK RANAKAH DENGAN PEMODELAN DUA DIMENSI (2D) BERDASARKAN DATA ANOMALI GRAVITASI LOKAL." Jurnal Fisika : Fisika Sains dan Aplikasinya 3, no. 1 (December 16, 2018): 54–58. http://dx.doi.org/10.35508/fisa.v3i1.595.
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ABSTRAK
Penelitian geofisika dengan menggunakan metode gravitasi telah dilakukan di Gunung Anak Ranakah dan sekitarnya di kabupaten Manggarai Nusa Tenggara Timur pada bulan Juni sampai dengan bulan Juli 2016. Penelitian ini bertujuan untuk mengetahui kondisi geologi bawah permukaan daerah penelitian dengan menggunakan data anomali udara bebas dari Sandwell dan Smith 2016. Data tersebut direduksi dengan koreksi atmosfer, koreksi Bouguer Sederhana, dan koreksi kurvatur hingga memperoleh anomali Bouguer Lengkap. Data anomali Bouguer dibawa ke bawah bidang topografi dengan metode kontinuasi ke bawah sedalam 300 m menggunakan program Magpic. Selanjutnya dilakukan pemodelan 2 dimensi menggunakan program Grav2DC. Hasil yang diperoleh menunjukkan bahwa kondisi geologi bawah permukaan gunung Anak Ranakah dan Sekitarnya didominasi oleh batuan basalt (densitas 2,70 -3.30 ), andesit (densitas 2.4 -2.8 ), dan soil (densitas 1.2 -2.40 ).
Kata kunci: Anomali Gravitasi, Pemodelan 2D, Gunung Anak Ranakah
ABSTRACT
Geophysical research by using the gravity method has been carried out on the Ranakah child mountain and surrounding areas in Manggarai Regency of East Nusa Tenggara in June until July 2016. This research aims to know the condition of the subsurface geology of the area of research using the free air anomaly data from Sandwell and Smith 2016. The data are reduced by atmospheric correction, Simple Bouguer correction, and the correction of curvature to obtain complete Bouguer anomalies. Bouguer anomaly data brought down the field topography with continuation method down as deep as 300 m using the Magpic. Then, 2 dimensional modeling is done using the Grav2DC. The results obtained show that the geological conditions under the surface of the Ranakah Child mountaoin and its surrounding area was dominated by basalt rocks (density of ), andesite (density of ), and soil rocks (density of ).
Keywords: Gravity Anomaly, 2D Modelling, Ranakah child Mountain.
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Supriyadi, Supriyadi, Khumaedi Khumaedi, Sugiyanto Sugiyanto, and F. Setiaswan. "Pemisahan Anomali Regional dan Residual Data Gayaberat Studi Kasus di Kota Lama Semarang." Physics Education Research Journal 1, no. 1 (August 31, 2019): 29. http://dx.doi.org/10.21580/perj.2019.1.1.3927.
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Telah dilakukan penelitian dengan menggunakan metode gayaberat untuk mengidentifikasi struktur bawah permukaan di Kawasan Kota Lama Semarang sebagai survei awal untuk keperluan mitigasi bencana. Pengolahan data gayaberat untuk mengidentifikasi struktur bawah permukaan dilakukan melalui beberapa tahapan. Tahap awal dilakukan dengan koreksi awal berupa koreksi pasang surut dan koreksi apungan, kemudian dilakukan koreksi lanjut hingga didapat kontur anomali Bouguer lengkap. Melalui anomali Bouguer lengkap dapat dipisahkan anomali gaya berat regional dan residual. Pemisahan anomali regional dari anomali Bouguer dalam penelitian ini menggunakan metode <em>moving average </em>(perata-rataan bergerak) sedangkan anomali residual didapatkan dengan cara mengurangkan anomali Bouguer dengan anomali regional. Pemisahan anomali regional dan residual penting untuk dilakukan pada penelitian identifikasi struktur bawah permukaan untuk menginterpretasikan struktur geologi dan mendapatkan target yang dicari. Nilai anomali regional di Kawasan Kota Lama Semarang antara 28.0 mGal – 28.4 mGal sedangkan untuk anomali residual memiliki antara 31.6 mGal – 32.8 mGal.
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Apeh, O. I., E. C. Moka, and V. N. Uzodinma. "Evaluation of Gravity Data Derived from Global Gravity Field Models Using Terrestrial Gravity Data in Enugu State, Nigeria." Journal of Geodetic Science 8, no. 1 (December 1, 2018): 145–53. http://dx.doi.org/10.1515/jogs-2018-0015.
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Abstract Spherical harmonic expansion is a commonly applied mathematical representation of the earth’s gravity field. This representation is implied by the potential coeffcients determined by using elements/parameters of the field observed on the surface of the earth and/or in space outside the earth in the spherical harmonic expansion of the field. International Centre for Gravity Earth Models (ICGEM) publishes, from time to time, Global Gravity Field Models (GGMs) that have been developed. These GGMs need evaluation with terrestrial data of different locations to ascertain their accuracy for application in those locations. In this study, Bouguer gravity anomalies derived from a total of eleven (11) recent GGMs, using sixty sample points, were evaluated by means of Root-Mean-Square difference and correlation coeficient. The Root-Mean-Square differences of the computed Bouguer anomalies from ICGEMwebsite compared to their positionally corresponding terrestrial Bouguer anomalies range from 9.530mgal to 37.113mgal. Additionally, the correlation coe_cients of the structure of the signal of the terrestrial and GGM-derived Bouguer anomalies range from 0.480 to 0.879. It was observed that GECO derived Bouguer gravity anomalies have the best signal structure relationship with the terrestrial data than the other ten GGMs. We also discovered that EIGEN-6C4 and GECO derived Bouguer anomalies have enormous potential to be used as supplements to the terrestrial Bouguer anomalies for Enugu State, Nigeria.
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Constantino, Renata, and Eder Cassola Molina. "BASEMENT STRUCTURES IN SANTOS BASIN (BRAZIL) FROM SATELLITE ALTIMETRY AND MARINE GEOPHYSICS." Revista Brasileira de Geofísica 33, no. 1 (November 19, 2015): 29. http://dx.doi.org/10.22564/rbgf.v33i1.599.
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ABSTRACT. This paper estimated the basement depth of the Santos Basin region, S˜ao Paulo State, Brazil, combining gravity data obtained from satellite altimetry and marine gravimetry, bathymetric data and sediment thickness from international data banks, and crustal thickness data available in the region. The first step consisted of calculating the gravity effect of sediments in Santos Basin, and the Crustal Mantle Interface (CMI) was modeled from constrained gravity inversion. Subsequently, the reliability of the models obtained was tested by flexural analysis with satisfactory results, as the flexural and gravimetric CMIs showed good agreement. The gravity effect of flexural CMI and the gravity effect of sediments were then calculated and subtracted from the original Bouguer anomaly. The residual field thus obtained, which is assumed to represent the topographical features of the basement, was inverted in the last step of the work, providing information that shows a basement with features of up to 700 m that appear to be in agreement with tectonic features previous discussed, such as the Avedis volcanic chain. The basement depth estimated during this study showed depths ranging from 1,500 to 10,500 m, and the deepest region is consistent with the Cabo Frio Fault. The methodology used in the study showed that from a combined data analysis, it is possible to obtain a three-dimensional model of the basement in ocean areas. This non-seismic approach can be advantageous in terms of efficiency and cost. The knowledge of the basement can offer important insights for the development of genetic and tectonic models of exploratory interest in the region.Keywords: basement, Santos Basin, gravity. RESUMO. Este trabalho visa estimar a profundidade do embasamento na região da Bacia de Santos por meio de uma análise combinada de dados gravimétricos obtidos a partir de altimetria por satélite e gravimetria marinha, com dados batimétricos e modelos de espessura sedimentar provenientes de bancos de dados internacionais e dados de espessura crustal disponíveis na região. Na primeira etapa do trabalho foi calculado o efeito do pacote sedimentar no sinal gravimétrico na Bacia de Santos, como também foi modelada a profundidade da Interface Crosta Manto (ICM) a partir de inversão gravimétrica com vínculos. Na etapa seguinte, a confiabilidade dos modelos obtidos foi testada através de an´álise flexural e o resultado foi satisfatório, mostrando que a ICM flexural e a ICM gravimétrica estão em concordância. Prosseguindo para etapa seguinte, o efeito gravimétrico da ICM encontrada por análise flexural e o efeito gravimétrico dos sedimentos foram então calculados e subtraídos da anomalia Bouguer original. O campo residual assim obtido, que se admite representar as feições topográficas do embasamento, foi invertido na última etapa do trabalho, fornecendo informações que mostram um embasamento com feições topográficas de até 700 m, que parecem estar em concordância com feições tectônicas discutidas em trabalhos pretéritos, como por exemplo a cadeia vulcânica Avedis. A profundidade do embasamento estimada durante este trabalho mostrou profundidades que vão desde 1.500 a 10.500 m, sendo que a região mais profunda corresponde à falha de Cabo Frio. Este trabalho demonstrou que, a partir de uma análise combinada de dados, é possível obter um modelo tridimensional do embasamento. O método, por ser não sísmico, pode ser vantajoso em questões de eficiência. O conhecimento deste embasamento é crucial na identificação de feições tectônicas, enquanto as informações sobre sua profundidade e topografia podem oferecer importantes subsídios para a elaboração de modelos genéticos e tectônicos de interesse exploratório na região.Palavras-chave: embasamento, Bacia de Santos, gravimetria.
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Morais de Araújo Júnior, João Carlos, Willian Alexandre De Lima Moura, Isis Mayara Gomes da Silva, Osvaldo José Correia Filho, and João Adauto De Souza Neto. "Caracterização Estrutural da Região Central do Graben do Cupe, Bacia Sedimentar de Pernambuco: Implicações para o Padrão Atual da Rede de Drenagem." Revista Brasileira de Geografia Física 13, no. 5 (October 22, 2020): 2355. http://dx.doi.org/10.26848/rbgf.v13.5.p2355-2370.
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A área de estudo está inserida no contexto geológico do Graben do Cupe, região de borda da Bacia Sedimentar de Pernambuco (BPE) com o embasamento cristalino adjacente. O Graben do Cupe é considerado um importante depocentro da região onshore dessa bacia e sua origem está ligada à abertura do Oceano Atlântico Sul. A partir da integração de dados gravimétricos, dados altimétricos obtidos por LIDAR e dados de campo, foi possível realizar uma caracterização estrutural dos principais lineamentos gravimétricos e topográficos que cortam a região central do Graben do Cupe. O mapa de anomalia bouguer residual revelou que o arcabouço estrutural mais profundo da BPE é representado por falhas normais de direção NE-SW, bem como falhas transcorrentes sinistrais, de direção NW-SE e dextrais ENE-WSW. A mesma orientação de lineamentos topográficos foi obtida através da interpretação dos dados altimétricos. Os rios inseridos na área de estudo seguem a mesma orientação dos lineamentos topográficos e gravimétricos, NW-SE e NE-SW. O mapeamento estrutural revelou que os lineamentos gravimétricos e topográficos estão associados à direção da foliação NE-SW, presente no embasamento adjacente a bacia, e às falhas originadas durante a fase rifte da BPE; A) NE-SW e NNE-SSW caracterizadas como falhas normais e B) NW-SE que corresponde a falhas oblíquas. As estruturas mais profundas tanto do embasamento, quanto as estruturas rifte que compartimentam o Graben do Cupe foram responsáveis por controlar a evolução quaternária da paisagem, o que provocou a captura da drenagem de alguns cursos fluviais, e o significante condicionamento tectônico dos vales fluviais. Structural Characterization of the Central Region of the Graben Cupe, Pernambuco Sedimentary Basin: Implications for the Current Pattern of the Drainage Network A B S T R A C TThe study area is inserted in the geological settings of the Cupe Graben, which is located in the border region of the Pernambuco Basin with the adjacent crystalline basement. The Cupe Graben is considered an important depocenter in the onshore region of this basin and its origin is linked to the opening of the South Atlantic Ocean. From the integration of gravimetric data, altimetric data obtained by LIDAR and field data, it was possible to carry out a structural characterization of the main gravimetric and topographic lineaments that cut the central region of Cupe Graben. The residual bouguer anomaly map revealed that the deep structural framework of the BPE is represented by normal faults NE-SW and NNE-SSW and sinistral strike slip faults NW-SE. The same orientation of topographic lineaments was obtained through the interpretation of the topographic lineaments. The rivers inserted in the study area have the same orientation as the topographic and gravimetric lineaments, NW-SE and NE-SW. The structural mapping revealed that the gravimetric and topographic lineaments are related to foliation in the adjacent basement NE-SW, and the faults originated during the BPE rift phase; A) NE-SW and NNE-SSW characterized as normal faults and B) NW-SE which corresponds to oblique faults. The deeper structures of both the basement and the rift structures that constraint the Cupe Graben were responsible for controlling the quaternary evolution of the landscape, which caused the capture of the drainage of some rivers, and the strong conditioning of the drainage network.Keywords: Cupe Graben, Pernambuco Basin, structural geology, river capture.
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Muhajirin, Muhajirin, Nazli Ismail, and Bukhari Bukhari. "The Computation of Residual and Regional Anomaly of Gravity Method Data By Polynomial Filter Using Microsoft Excel." Journal of Aceh Physics Society 9, no. 2 (May 1, 2020): 37–41. http://dx.doi.org/10.24815/jacps.v9i2.15745.
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Eksplorasi metode gravitasi umumnya dilakukan untuk mencari objek di bawah permukaan yang dangkal sehingga perlu dilakukan pemisahan anomali residual dan regional dari anomali Bouguer lengkap. Perhitungan anomali residual biasanya menggunakan software khusus untuk pengolahan data geofisika yang berlisensi atau algoritma dengan bahasa pemrograman, sedangkan program Microsoft Excel pada PC dan notebook biasa digunakan untuk perhitungan polinomial pada pengolahan data statistik. Penelitian ini memperkenalkan cara menghitung anomali residual menggunakan Microsoft Excel dengan filter polinomial. Hasil validasi yang menggunakan model sintetik menunjukkan bahwa perhitungan tersebut dapat diaplikasikan pada data metode gravitasi. Apalikasi pada data lapangan diperoleh bahwa anomali residual berfrekuensi tinggi, sedangkan anomali regional berfrekuensi rendah. Nilai anomali residual dipengaruhi oleh trendline anomali Bouguer lengkap dalam domain jarak. Hasil ini relatif sama dengan hasil perhitungan software lainnya. Gravity method exploration was generally conducted to seek the object in shallow underground so that required residual and regional anomaly separation of complete Bouguer anomaly. The residual anomaly separation was usually used by the special softwares for geophysics that require licency or algorithm by programming language, however the program of Microsoft Excel in the PC or notebook was usually applied to compute the polynomial filter for statistic data analysis. This research introduces how to compute residual anomaly using Microsoft Excel through polynomial filter. The validation result of sintetic model shows that the computation using Microsoft Excel can be applied to gravity method data. The application of field data was obtained that residual anomaly has high frecuency, whereas residual anomaly has low frecuency. The value of residual anomaly was influenced by trendline of complete Bouguer anomaly in distance domain. This result relatively equal to the result of other softwares. Keywords: gravity method, residual anomaly, regional anomaly, polynomial filter, Microsoft Excel
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Šliaupa, Saulius, Žydrūnas Dėnas, and Larisa Korabliova. "BOUGUER ANOMALIJŲ ŽEMĖLAPIO PATIKSLINIMAS GIS PRIEMONĖMIS." Geodesy and cartography 31, no. 2 (August 3, 2012): 41–46. http://dx.doi.org/10.3846/13921541.2005.9636663.
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Gravitacinio lauko variacijas geriausiai atspindi Bouguer anomalijų žemėlapis, kuri sudarant, be kitų parametrų, labai svarbu žinoti tarpinio sluoksnio, t. y. sluoksnio, esančio tarp Žemes paviršiaus ir jūros lygio, tankį. Pagal priimtą metodiką Lietuvos Bouguer anomalijų žemėlapis sudarytas įvedus pastovų 2,30 g/cm3 tankį. Tačiau geologiniai tyrimai rodo, kad viršutiniams sluoksniams būdingas labai ryškus uolienų sudėties ir atitinkamai tankio kitimas, todėl dabar naudojamas gravitacinio lauko žemėlapis nėra visai tikslus. Anomalijų laisvajame ore ir aukščiu koreliacija rodo, kad vidutinis tarpinio sluoksnio tankis yra gerokai mažesnis (mažesnis nei 2,24 g/cm3). Straipsnyje pateikiama nauja tarpinio sluoksnio tankiu įvertinimo, taikant GIS technologijas, metodika. Pagal iš 13 222 gręžinių gautą informaciją s udarytas detalus tankių žemėlapis. Šie duomenys automatiškai pervesti į gravitacinius stebėjimo taškus, atitinkamai perskaičiuotas Bouguer anomalijų žemėlapis. Masių deficitas, palyginti su ankstesniu tarpinio sluoksnio modeliu, kinta nuo +10 000 kg/m2 Šiaures Lietuvos centrinėje dalyje iki –30 000 kg/m2 — –50 000 kg/m2 didžiojoje Lietuvos dalyje. Atitinkamai gerokai pakoreguotos ir Bouguer anomalijų reikšmes. Skirtumas siekia net 2–3 mGal Baltijos aukštumose, 0,5–1 mGal Žemaitijos aukštumose ir –0,5 mGal Šiaures Lietuvos centrinėje dalyje. Siūloma metodika galima plačiai taikyti ir kituose regionuose tikslinant gravitacinio lauko žemėlapius. Be to, tai leidžia koreguoti ir kitus gravitacinio lauko žemėlapius (pvz., nustatant geoidą).
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Karunianto, Adhika Junara, Dwi Haryanto, Fajar Hikmatullah, and Agus Laesanpura. "Penentuan Anomali Gayaberat Regional dan Residual Menggunakan Filter Gaussian Daerah Mamuju Sulawesi Barat." EKSPLORIUM 38, no. 2 (November 30, 2017): 89. http://dx.doi.org/10.17146/eksplorium.2017.38.2.3921.
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AbstrakMetode gayaberat merupakan metode geofisika yang sudah sering digunakan dalam prospeksi sumberdaya mineral. Parameter objek pencarian berdasarkan variasi pengukuran percepatan gayaberat di permukaan yang diakibatkan oleh variasi perubahan geologi bawah permukaan. Lokasi penelitian di daerah Mamuju Provinsi Sulawesi Barat yang secara tektonik merupakan wilayah geologi kompleks berada pada pertemuan tiga lempeng besar yaitu Pasifik, Indo-Australia, dan Eurasia serta Lempeng Filipina yang berukuran lebih kecil. Selain itu Mamuju merupakan wilayah dengan laju dosis radioaktivitas tinggi sehingga berpotensi memiliki sumberdaya mineral radioaktif. Tujuan dari penelitian adalah mendapatkan anomali gayaberat dengan cara melakukan pemisahan dan interpretasi secara kualitatif anomali gayaberat regional dan residual. Nilai Anomali Bouguer Lengkap (ABL) daerah penelitian yang didapat dari hasil pengukuran adalah 46,0 – 115,7 mgal. Berdasarkan peta ABL tersebut proses pemisahan anomali gayaberat regional dan residual dilakukan dengan menggunakan teknik Gaussian Filtering. Teknik filtering ini bekerja berdasarkan analisis spektrum perubahan amplitudo gayaberat secara spasial yang hasilnya berupa bilangan gelombang dengan cutoff sebesar 1,1736 x 10-3/ m dan panjang gelombang sebesar 5373,45 m. Anomali gayaberat regional dan residual berturut-turut memiliki rentang nilai 51,8 sampai 102 mGal dan -10,4 sampai 14,8 mGal. Kedalaman wilayah spektrum masing-masing anomali tersebut dapat dihitung berdasarkan panjang gelombangnya yaitu anomali regional sebesar 970,97 m dan anomali residual sebesar 100,21 m. Terdapat lima zona berdasarkan peta anomali residualnya yaitu zona A, B, C, D, dan E. Anomali gayaberat positif paling besar terdapat pada zona A dan B yang diperkirakan dipengaruhi oleh keberadaan lava Adang dengan arah penyebaran relatif utara – selatan. AbstractGravity method is a geophysical method that has been frequently used in prospecting mineral resources. The parameter of searched object is based on variations of gravity acceleration measurements on the surface due to variations in sub-surface geological changes. Research area is located in Mamuju Area of West Sulawesi Province where tectonically a complex geological region, which is at a meeting of three large plates, the Pacific plate, the Indo-Australian plate and the Eurasian plate and the smaller Philippine plate. In addition, Mamuju is an area with a high radioactivity dose rate that has potency to radioactive minerals resources. The purpose of the research is to obtain gravity anomalies by using qualitative separation and interpretation of regional and residual gravity anomalies. Complete Bouguer Anomaly (CBA) value of the research area obtained from the measurements was 46.0 – 115.7 mGal. Based on the CBA map, the separation process of regional gravity anomalies and residual using Gaussian filtering technique conducted. This filtering technique works based on spectral analysis of gravity amplitude changes in spatial where the result is a cutoff wave number of 1.1736 x 10-3/meter and a wavelength of 5373.45 m. The regional and residual gravity anomalies range from 51.8 to 102 mGal and -10.4 to 14.8 mGal respectively. The depth of influence of each anomaly is calculated based on their spectral wavelengths, resulting 970.97 m and 100.21 m for regional and residual anomalies respectively. There are five zones based on the residual anomaly map, which are zones A, B, C, D and E. The heaviest positive gravity anomaly is found in zone A and B, which is predicted to be influenced by Adang lava with relative north – south distribution.
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Popadyev, V. V., and D. A. Kuliev. "Application of global geopotential models to high-precesion levelling processing." Geodesy and Cartography 926, no. 8 (September 20, 2017): 2–9. http://dx.doi.org/10.22389/0016-7126-2017-926-8-2-9.
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The article studies the properties of the high-degree gravity field model EGM-2008 in the calculation of integral characteristics at large distances several times greater than the spatial resolution of the model. As an example of an indirect evaluation of a high-degree model, a gravimetric correction was computed into the sum of the measured elevations along the line of the high-precision I class leveling of the Krasnovodsk – Chardzhou line located in Turkmenistan. Using the calculator ICGEM, the Bouguer anomalies were calculated at each point of the line, then the attraction of the Bouguer layer (used heights are from catalog) excluded for the transition to free-air anomalies. In parallel, for a direct evaluation of the model, a regular grid of Bouguer anomalies with a step of 2 angular minutes within line area was also obtained, which were then compared with the anomalies from the gravity map J-40 of scale 1
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Kuhn, M., W. E. Featherstone, and J. F. Kirby. "Complete spherical Bouguer gravity anomalies over Australia." Australian Journal of Earth Sciences 56, no. 2 (March 2009): 213–23. http://dx.doi.org/10.1080/08120090802547041.
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Bernabini, M., P. Favaro, and L. Orlando. "Density in Bouguer anomalies and its consequences." Journal of Applied Geophysics 32, no. 2-3 (August 1994): 187–97. http://dx.doi.org/10.1016/0926-9851(94)90020-5.
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Zaenudin, Ahmad, Ilham Dani, and Niar Amalia. "DELINEASI SUB-CEKUNGAN SORONG BERDASARKAN ANOMALI GAYA BERAT." JURNAL GEOCELEBES 4, no. 1 (February 6, 2020): 14. http://dx.doi.org/10.20956/geocelebes.v4i1.7976.
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Delineasi Sub-Cekungan Sorong ini diinterpretasi melalui pola anomali gayaberat, pola patahan, bukaan (rifting), tinggian dari anomali residual, dengan analisis Second Vertical Derivative (SVD), pemodelan 2D dan structural noses. Metode pengolahan data yang dilakukan dalam penelitian ini ialah melakukan koreksi gaya berat hingga didapatkan Anomali Bouguer Lengkap, melakukan analisis spektrum untuk mendapatkan estimasi kedalaman regional dan residual serta lebar jendela penapisan, melakukan pemisahan anomali regional dan residual dengan metode moving average, melakukan analisis SVD, melakukan interpretasi kualitatif dan kuantitatif. Hasil pengolahan menunjukkan bahwa pola Anomali Bouguer Lengkap daerah penelitian pada bagian Selatan didominasi oleh anomali rendah dengan nilai 58 hingga 76 mGal. Sedangkan anomali tinggi mendominasi bagian Utara dengan nilai 88 hingga 106 mGal. Kedalaman residual sekitar 2,7 km di bawah permukaan sedangkan kedalaman regional sekitar 10 km di bawah permukaan. Anomali residual daerah penelitian memiliki nilai anomali -9 hingga 10 mGal. Anomali regional daerah penelitian memiliki nilai anomali 60 hingga 100 mGal. Berdasarkan interpretasi kualitatif dan kuantitatif menunjukkan bahwa terdapat satu sub-cekungan pada daerah penelitian yang terletak pada Arar nose. Arah migrasi hidrokarbon berasal dari arah Barat ke Timur mengikuti struktur patahan. Berdasarkan penelitian ini, diasumsikan bahwa sesar utama Sorong tidak hanya berupa jenis sesar geser namun juga merupakan jenis sesar normal.
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Varga, M., and J. Stipčević. "Gravity anomaly models with geophysical interpretation of the Republic of Croatia, including Adriatic and Dinarides regions." Geophysical Journal International 226, no. 3 (May 10, 2021): 2189–99. http://dx.doi.org/10.1093/gji/ggab180.
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SUMMARY Models of gravity corrections and anomalies are created and distributed over the territory of the Republic of Croatia, including the Adriatic and Dinarides regions. Published models cover the study area between 42.0°N < φ < 46.6°N and 13.0°E < λ < 19.5°E with a 1′ × 1′ resolution. Distributed models include gravity corrections and anomalies of normal gravity, atmosphere, free air, Bouguer, terrain, complete Bouguer and topographic–isostatic according to the Airy–Heiskanen model. A high-resolution digital elevation/bathymetry model was prepared from SRTMv3.0 and GEBCO2019 models. It was then used for the computation of topographic and topographic–isostatic gravity effects using rectangular prisms with constant crustal density. Gridding of the scattered gravity data was performed with the Kriging interpolation method using complete Bouguer anomalies by implementing the remove–grid–restore methodology. Developed models were interpreted providing insights into the topography-reduced (anomalous) Earth’s gravity field reflecting the variations in mass/density distribution within the crust and upper mantle over the study area.
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Martinez, Patricia, Mario Gimenez, Andres Folguera, and Federico Lince Klinger. "Integrated seismic and gravimetric model of Jocolí Basin, Argentina." Interpretation 2, no. 2 (May 1, 2014): T57—T68. http://dx.doi.org/10.1190/int-2012-0022.1.
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Gravity measurements and reinterpretations of previously released seismic lines were made, focusing on the provincial border between neighboring provinces San Juan and Mendoza. A Bouguer anomaly map was obtained after the processing of gravimetric data, which were previously filtered, to obtain the Bouguer residual anomalies used for studying the geologic structures located on the upper crust. The analysis of these Bouguer residual anomalies allowed identification of the Jocolí Basin in a foreland position within a triangle zone at the boundary of the Precordillera fold-and-thrust belt with the Sierras Pampeanas thick-skinned foreland province. The seismic images allowed interpretation of three horizons: Paleozoic, Triassic, and Tertiary-Quaternary ages. The authors have reinterpreted the seismic and well data and reconstructed gravity models for the area under study aiming at unraveling the deep structure of the region and identifying features with potential for oil and gas exploration.
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Oktavia, Dwi Intan, Azrul Azwar, and Zulfian Zulfian. "Anomali Gravitasi Daerah Manifestasi Panas Bumi Bitung Berdasarkan Data Satelit GeoSat dan ERS-1." PRISMA FISIKA 7, no. 2 (July 10, 2019): 51. http://dx.doi.org/10.26418/pf.v7i2.33431.
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Daerah manifestasi panas bumi di kawasan Bitung telah diidentifikasi berdasarkan data anomali medan gravitasi terkoreksi hingga koreksi udara bebas yang diperoleh dari Geodetic Satellite (Geosat) dan European Remote Sensing-1 (ERS-1). Dari data ini kemudian dilakukan koreksi Bouger dan koreksi medan. Nilai anomali medan gravitasi yang dijadikan sebagai data identifikasi adalah nilai anomali gravitasi lokal yang telah dipisahkan menggunakan filter Second Vertical Derrivative (SVD). Manifestasi ditunjukkan oleh anomali tinggi dan rendah dengan nilai 6.5 mGal dan -7.5 mGal. Daerah dengan anomali tinggi dan rendah diduga sebagai daerah panas bumi di kawasan Bitung. Kata Kunci : anomali gravitasi, panas bumi, data satelit, Bitung, koreksi Bouger.
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Zahorec, Pavol, Juraj Papčo, Peter Vajda, and Stanislav Szabó. "High-precision local gravity survey along planned motorway tunnel in the Slovak Karst." Contributions to Geophysics and Geodesy 49, no. 2 (June 1, 2019): 207–27. http://dx.doi.org/10.2478/congeo-2019-0011.
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Abstract Results from a detailed gravity survey realized along the planned highway tunnel in the karstic area of Slovak Karst in the eastern Slovakia are presented. Detailed gravity profiles crossed an area of rugged topography, therefore the terrain corrections played a crucial role in the gravity data processing. The airborne laser scanning technique (LiDAR) was used in order to compile a high-resolution digital terrain model (DTM) of the surrounding area and to calculate terrain corrections properly. The difference between the Bouguer anomalies calculated with an available nationwide DTM and those with new LiDAR-based model can be significant in some places as it is presented in the paper. A new method for Bouguer correction density analysis based on surface data is presented. Special underground gravity measurements in the existing nearby railway tunnel were also conducted in order to determine the mean density of the topographic rocks. The Bouguer anomalies were used to interpret lithological contacts and tectonic/karstic discontinuities.
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Triều, Cao Đình, Lê Văn Dũng, Phạm Nam Hưng, Mai Xuân Bách, Nguyễn Hữu Tuyên, Thái Anh Tuấn, and Bùi Anh Nam. "Một số kết quả bước đầu nghiên cứu cấu trúc móng trước Kainozoi khu vực Tp Hồ Chí Minh và kế cận trên cơ sở tài liệu trọng lực." VIETNAM JOURNAL OF EARTH SCIENCES 30, no. 4 (May 13, 2008): 335–45. http://dx.doi.org/10.15625/0866-7187/31/4/11775.
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Mickus, K. L., C. L. V. Aiken, and W. D. Kennedy. "Regional‐residual gravity anomaly separation using the minimum‐curvature technique." GEOPHYSICS 56, no. 2 (February 1991): 279–83. http://dx.doi.org/10.1190/1.1443041.
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One of the most difficult problems in gravity interpretation is the separation of regional and residual gravity anomalies from the Bouguer gravity anomaly. This study discusses the application of the minimum‐curvature method to determine the regional and residual gravity anomalies.
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Murata, Yasuaki, Kazunari Nawa, Masao Komazawa, Rie Morijiri, Toshio Hiroshima, Masahiko Makino, Toshitsugu Yamazaki, Kiyokazu Nishimura, Shigeo Okuma, and Shichi Ryuichi. "Bouguer Gravity Anomalies in Kagoshima District, Kyushu, Japan." BULLETIN OF THE GEOLOGICAL SURVEY OF JAPAN 58, no. 11-12 (2007): 351–70. http://dx.doi.org/10.9795/bullgsj.58.351.
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HIROSHIMA, Toshia, Rie MORIJIRI, Masao KOMAZAWA, Masahiko MAKINO, Yasuaki MURATA, and Kazunari NAWA. "Bouguer Gravity Anomalies in Oita district, Kyushu, Japan." BULLETIN OF THE GEOLOGICAL SURVEY OF JAPAN 53, no. 1 (2002): 11–36. http://dx.doi.org/10.9795/bullgsj.53.11.
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Nawa, Kazunari, Yasuaki Murata, Masao Komazawa, Rie Morijiri, Toshio Hiroshima, Masahiko Makino, Fumitoshi Murakami, Kiyoyuki Kisimoto, Shigeo Okuma, and Ryuichi Shichi. "Bouguer Gravity Anomalies in Miyazaki District, Kyushu, Japan." BULLETIN OF THE GEOLOGICAL SURVEY OF JAPAN 56, no. 5-6 (2005): 183–208. http://dx.doi.org/10.9795/bullgsj.56.183.
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Subba Rao, D. V. "Resolving Bouguer anomalies in continents-A new approach." Geophysical Research Letters 23, no. 24 (December 1, 1996): 3543–46. http://dx.doi.org/10.1029/96gl03471.
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Riad, Samir, and Hassan A. El Etr. "Bouguer anomalies and lithosphere-crustal thickness in Uganda." Journal of Geodynamics 3, no. 1-2 (July 1985): 169–86. http://dx.doi.org/10.1016/0264-3707(85)90027-4.
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LaFehr, T. R. "Standardization in gravity reduction." GEOPHYSICS 56, no. 8 (August 1991): 1170–78. http://dx.doi.org/10.1190/1.1443137.
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Gravity reduction standards are needed to improve anomaly quality for interpretation and to facilitate the joining together of different data sets. To the extent possible, data reduction should be quantitative, objective, and comprehensive, leaving ambiguity only to the interpretation process that involves qualitative, subjective, and geological decisions. The term (Bouguer anomaly) describes a field intended to be free of all nongeologic effects—not modified by a partial geologic interpretation. Measured vertical gradients of gravity demonstrate considerable variation but do not suggest, as often reported, that the normal free‐air gradient is in error or needs to be locally adjusted. Such gradients are strongly influenced by terrain and, to a lesser extent, by the same geologic sources which produce Bouguer anomalies. A substantial body of existing literature facilitates the comprehensive treatment of terrain effects, which may be rigorously implemented with current computer technology. Although variations in topographic rock density are a major source of Bouguer anomalies, a constant density appropriate to the area under investigation is normally adopted as a data reduction standard, leaving a treatment of the density variations to the interpretation. A field example from British Columbia illustrates both the variations in vertical gravity gradients which can be encountered and the conclusion that the classical approach to data reduction is practically always suitable to account for the observed effects. Standard data reduction procedures do not (and should not) include reduction‐to‐datum. The interpreter must be aware, however, that otherwise “smooth” regional Bouguer anomalies caused by regional sources do contain high‐frequency components in areas of rugged topography.
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Chakravarthi, V. "Automatic gravity optimization of 2.5D strike listric fault sources with analytically defined fault planes and depth-dependent density." GEOPHYSICS 76, no. 2 (March 2011): I21—I31. http://dx.doi.org/10.1190/1.3541957.
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An automatic gravity inversion technique in the space domain simultaneously estimates the parameters of strike-limited listric fault sources and regional gravity background from a set of observed Bouguer gravity anomalies. The fault profile and regional effect are described by unknown polynomial functions of arbitrary but prescribed degree. Furthermore, the density contrast within the fault structure is presumed to be known, according to a prescribed parameterized nonlinear function of depth, in geologic settings where the detached downthrown block consists of a series of sedimentary beds whose density increases with depth. The inversion is automatic in that it initializes and determines polynomial coefficients for the fault boundary and regional gravity background from a set of observed Bouguer gravity anomalies and improves them iteratively until the modeled gravity anomalies mimic the observed anomalies. An analysis of a set of gravity anomalies attributable to a synthetic model of a listric fault structure in the presence of pseudorandom noise with and without regional background has disclosed that the algorithm yields reliable interpretations with modest error in model geometry, even in the presence of pseudorandom noise. In the presence of regional gravity background and pseudorandom noise, the estimated parameters of the structure deviate marginally from the true ones. The derived density-depth model of the Jharia coal basin in India, a pull-apart basin, has been used to analyze the observed Bouguer gravity anomalies of a boundary fault. The interpretation has yielded information consistent with drilling results and geologic setting of the basin.
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Pellokila, Aryanti Irnawati, Jehunias L. Tanesib, and Bernandus Bernandus. "IDENTIFIKASI KEBERADAAN BASEMENT DI BAWAH CEKUNGAN TIMOR BERDASARKAN DATA ANOMALI GRAVITASI DENGAN PEMODELAN TIGA DIMENSI." Jurnal Fisika : Fisika Sains dan Aplikasinya 3, no. 1 (December 16, 2018): 1–11. http://dx.doi.org/10.35508/fisa.v3i1.588.
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ABSTRAK
Metode Gravitasi adalah metode yang digunakan untuk mencari perbedaan nilai gravitasi dari satu titik ke titik yang lain di suatu tempat yang disebabkan oleh distribusi massa yang terdapat di bawah permukaan daerah penelitian. Telah dilakukan identifikasi keberadaan basement terhadap data anomali Bouguer lengkap di Cekungan Timor dengan posisi geografis 9.40 LS – 10.40 LS dan 123.50 BT – 125.40 BT. Identifikasi keberadaan basement di bawah Cekungan Timor dilakukan berdasarkan data anomali medan gravitasi. Data anomali medan gravitasi yang digunakan dalam penelitian adalah hasil pengukuran Geodetic Satellite dan European Remote Sensing Satellite yang telah terkoreksi hingga koreksi udara bebas. Berdasarkan hasil inversi 3D, densitas rata-rata secara keselurahan dari lapisan pertama hingga lapisan kesepuluh adalah 2.662 . Cekungan Timor yang merupakan sebuah tempat terakumulasinya sedimen dan memiliki basement yang merupakan jenis batuan metamorf dari kedalam 3.86 km hingga 20 km yang kuat dan bersifat tidak meloloskan air maka cekungan ini diduga memiliki potensi adanya jebakan sumber energi alam berupa minyak dan gas.
Kata kunci: Gravitasi, batuan dasar, Cekungan, anomali Bouguer lengkap, densitas, pemodelan.
ABSTRACT
Gravity method is a method used to find the difference of gravity value from one point to another in a place caused by mass distribution which is below the surface of research area. Basement identification of complete Bouguer anomaly data has been done in the Timor Basin with geographical position 9.40 LS – 10.40 LS dan 123.50 BT – 125.40 BT. The identification of the basement under the Timor Basin is based on gravity field anomaly data. The gravity field anomaly data used in the research is the result of measurement of Geodetic Satellite and European Remote Sensing Satellite which has been corrected to free air correction. Based on the inversion, the overall average density from the first layer to the tenth layer 2.662 . Timor Basin which is a place of accumulation of sediment and has a basement which is a type of metamorphic rocks from within 3.86 km to 20 km strong and is not pass the water hence this basin has the potential of a trap of natural energy sources in the form of oil and gas.
Keywords: Gravity, Basement, Basin, complete Bouguer anomaly, density, modeling.
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Bakkali, Saad. "THE USE OF THE LOGARITHMIC IMAGE PROCESSING APPLIED TO ANALYSING BOUGUER GRAVITY ANOMALY MAP (TANGIER-TETUAN’S AREA -MOROCCO)." Nexo Revista Científica 28, no. 2 (March 21, 2017): 97–107. http://dx.doi.org/10.5377/nexo.v28i2.3479.
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Image processing is a powerful tool for the enhancement of edges in images used in the interpretation of geophysical potential field data. Arial and terrestrial gravimetric surveys were carried out in the region of Tangier-Tetuan. From the observed and measured data of gravity Bouguer gravity anomalies map was prepared. This paper reports the results and interpretations of the transformed maps of Bouguer gravity anomaly of the Tangier-Tetuan area using the logarithmic image processing. Filtering analysis based on classical image process was applied. Operator image process like the logarithmic operator and the associated gamma correction tool are used. This paper also present the results obtained from this image processing analysis of the enhancement edges of the Bouguer gravity anomaly map of the Tangier-Tetuan zone.
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Damayanti, Ledia, Syamsurijal Rasimeng, and Ilham Dani. "Pemisahan anomali regional-residual data gayaberat daerah Karangsambung Jawa Tengah menggunakan metode trend surface analysis." Jurnal Teras Fisika 3, no. 2 (September 8, 2020): 156. http://dx.doi.org/10.20884/1.jtf.2020.3.2.2765.
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Pemisahan anomali regional-residual pada metode gravitasi di daerah Karang Sambung Jawa Tengah menggunakan metode tren surface analysis. Pemisahan daerah ini dibuat dengan menggunakan bahasa program Matlab dan kemudian dibuat penampangnya dalam software Surfer. Interpretasi kualitatif dilakukan dengan mengamati data gayaberat berupa anomali Bouguer. Sedangkan Interpretasi kuantitatif dilakukan untuk memahami lebih dalam hasil interpretasi kualitatif dengan membuat penampang gayaberat pada peta kontur anomali. Berdasarkan hasil analisis spektrum hasil penapisan dengan lebar jendela 23x23 km didapatkan peta anomali regional. Nilai anomali residual yang didapat berkisar antara -45 sampai 30 mGal yang menunjukkan pola anomali negatif hingga positif. Anomali negatif berkisar antara -45 sampai -10 mGal, sedangkan anomali positif berkisar antara 0 sampai 30 mGal.
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Saibi, Hakim, Diab Bakri Hag, Mohammed Saeed Mohammed Alamri, and Hamdan Abdo Ali. "Subsurface structure investigation of the United Arab Emirates using gravity data." Open Geosciences 13, no. 1 (January 1, 2021): 262–71. http://dx.doi.org/10.1515/geo-2020-0233.
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Abstract The crustal structure beneath the United Arab Emirates (UAE) is still relatively unknown. Here, we use regional gravity data to constrain the subsurface density distribution and structure of the crust of the UAE by applying diverse gravity derivatives methods such as horizontal derivative (HDR), analytic signal (AS), and tilt angle (TA) to analyze the subsurface structure and perform three-dimensional (3D) gravity inversion for imaging crustal structure from the surface down to 35 km depth. The results are compared with known geological regional structures and the location of the petroleum fields. The Bouguer anomalies range from −100.8 to 113.5 mGal. The 3D gravity inversion results and the maximum Bouguer values coincide with the ophiolitic Hajar mountains in the east and the successive anticlines (uplifted basement rocks) and synclines in different parts of UAE, which could be promising sites for future mining and petroleum exploration. Also, the 3D density model results and the minimum Bouguer anomalies are located over the Aruma Basin, eastern UAE Platform, and Low Central UAE Platform, which can be the places for deep groundwater aquifers. These new results from HDR, AS, and TA successfully identify known geological structures, especially in the eastern part of UAE.
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Greenhouse, John P., and Mark Monier-Williams. "A gravity survey of the Dundas buried valley west of Copetown, Ontario." Canadian Journal of Earth Sciences 23, no. 1 (January 1, 1986): 110–14. http://dx.doi.org/10.1139/e86-012.
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A total of 243 Bouguer gravity readings have been completed over a 9 km2 area covering the terminus of the Dundas buried valley, a prominent reentrant in the Niagara Escarpment. A 1.5 mGal (15 μm s−2) Bouguer anomaly clearly defines an abrupt closure of the bedrock topography west of Copetown, confirming and extending the results of earlier seismic reflection and refraction surveys. An apparent tributary in the contoured gravity, entering the terminus from the south, is unfortunately poorly resolved. It underlies property to which access was denied. The Bouguer gravity data are transformed to a model of the bedrock depth via a three-dimensional model. The mean error between data and model gravity, after correcting the former for a regional gradient, is less than 0.1 mGal (1 μm s−2). The estimated error in the observations themselves is ± 0.11 mGal (1.1 μm s−2). The observed Bouguer gravity is compared with that which would be produced by the present Niagara Gorge were it to underlie the survey area. The magnitude and dimensions of the computed anomalies are remarkably similar.
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Morijiri, Rie, Toshio Hiroshima, Masao Komazawa, Masahiko Makino, Yasuaki Murata, Kazunari Nawa, Jun Nishijima, and Toru Mogi. "Bouguer Gravity Anomalies in the Fukuoka area, Kyushu,Japan." BULLETIN OF THE GEOLOGICAL SURVEY OF JAPAN 53, no. 7-8 (2002): 573–94. http://dx.doi.org/10.9795/bullgsj.53.573.
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Tracey, Ray, and Aki Nakamura. "Complete Bouguer Anomalies for the Australian National Gravity Database." ASEG Extended Abstracts 2010, no. 1 (December 2010): 1–3. http://dx.doi.org/10.1081/22020586.2010.12041840.
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Fan, Pow-Foong. "Geology and Bouguer anomalies of Hainan Island and vicinity." Energy 10, no. 3-4 (March 1985): 331–40. http://dx.doi.org/10.1016/0360-5442(85)90050-7.
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Auzan, Rifatul, and Yudha Arman. "Delineasi Subcekungan Daerah Menggala dan Sekitarnya, Provinsi Lampung Berdasarkan Anomali Magnetik dan Gaya Berat." POSITRON 10, no. 2 (December 29, 2020): 61. http://dx.doi.org/10.26418/positron.v10i2.42800.
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Delineasi subcekungan daerah Menggala dan sekitarnya dilakukan berdasarkan anomali magnetik dan gravitasi. Data anomali magnetik dan anomali Bouguer yang digunakan sudah melewati proses koreksi. Subcekungan daerah Menggala diasosiasikan dengan nilai anomali magnetik dan gravitasi yang rendah. Berdasarkan hasil yang diperoleh, sebanyak 9 (sembilan) subcekungan dengan isian sedimen berupa tuff, lempung, endapan rawa dan mineral diamagnetik teridentifikasi. Setiap subcekungan dibatasi oleh batuan beku dengan kedalaman berkisar 1 km dari permukaan. Subcekungan yang diidentifikasi memiliki arah timurlaut, baratlaut dan barat-baratlaut ke timurtenggara. Batuan basement (dasar) daerah Menggala diduga berupa batuan granit yang memiliki nilai densitas dan suseptibilitas masing-masing 2,643 g/cm3 dan 0,033767 SI.
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Luo, Fan, Xin Tao, Guangming Fu, Chong Zhang, Kun Zhang, and Jiayong Yan. "Usporedba različitih pristupa Bouguer-ove redukcije na temelju satelitskih gravimetrijskih podataka." Geofizika 37, no. 2 (December 23, 2020): 237–61. http://dx.doi.org/10.15233/gfz.2020.37.7.
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Satellite gravity data are widely used in the field of geophysics to study deep structures at the regional and global scales. These data comprise free-air gravity anomaly data, which usually need to be corrected to a Bouguer gravity anomaly for practical application. Bouguer reduction approaches can be divided into two methods based on the coordinate system: the spherical coordinates method (SBG) and the Cartesian coordinates method; the latter is further divided into the CEBG and CBG methods, which do and do not include the Earth’s curvature correction. In this paper, free-air gravity anomaly data from the eastern Tibetan Plateau and its adjacent areas were used as the basic data to compare the CBG, CEBG, and SBG Bouguer gravity correction methods. The comparison of these three Bouguer gravity correction methods shows that the effect of the Earth’s curvature on the gravitational effect increases with increasing elevation in the study area. We want to understand the inversion accuracy for the data obtained by different Bouguer gravity reduction approaches. The depth distributions of the Moho were obtained by the interface inversion of the Bouguer gravity anomalies obtained by the CBG, CEBG, and SBG, and active seismic profiles were used as references for comparison and evaluation. The results show that the depths of the Moho obtained by the SBG inversion are more consistent with the measured seismic profile depths. Therefore, the SBG method is recommended as the most realistic approach in the process of global or regional research employing gravity data.
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Rocha, Paula Lúcia Ferrucio da, and Luiz Fernando Santana Braga. "Análise e interpretação de dados gravimétricos nas porções terrestre e marítima do Brasil Meridional." Anuário do Instituto de Geociências 20 (January 1, 1997): 201–14. http://dx.doi.org/10.11137/1997_0_201-214.
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We have interpreted the Bouguer anomaly map from South Brazil and its adjoining oceanic areas, using the land data from the SAGP Project (1990), and the marine data derived from GEOSAT. With the aid of the vertical derivatives and the maximum horizontal gradientes of the Bouguer anomalies we have mapped the boundaries between the major lithospheric compartments, here characterized by their gravity signatures. Two dimensional gravity modelling with available geological constraints have also been performed aiming to estimate the crustal thicknesses within each individual compartment. We show that the gravity responses of the continental, transitional and oceanic lithospheres are well distinguished.
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Hipkin, R. G. "Bouguer anomalies and the geoid: a reassessment of Stokes' method." Geophysical Journal International 92, no. 1 (January 1, 1988): 53–66. http://dx.doi.org/10.1111/j.1365-246x.1988.tb01120.x.
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Urrutia-Fucugauchi, Jaime, and Jesus Hernan Flores-Ruiz. "Bouguer Gravity Anomalies and Regional Crustal Structure in Central Mexico." International Geology Review 38, no. 2 (February 1996): 176–94. http://dx.doi.org/10.1080/00206819709465330.
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Fraga, H., and A. Introcaso. "Un modelo gravimétrico litosférico para la Subcuenca Lomas de Olmedo (Cuenca del Norte y Noroeste) en la provincia de Salta - Argentina." Geofísica Internacional 29, no. 2 (April 1, 1990): 89–99. http://dx.doi.org/10.22201/igeof.00167169p.1990.29.2.790.
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Se calcularon los efectos gravimétricos originados por: a) el relleno sedimentario y b) la "raíz" andina, en una sección que atraviesa la Subcuenca Lomas de Olmedo. La anomalía de Bouguer observada fue corregida por ambos efectos, obteniéndose una respuesta gravimétrica residual positiva. Proponemos aquí un modelo gravimétrico litosférico, con una corteza atenuada, coherente con el origen tectónico y estilo extensional de la subcuenca. En él la anomalía residual fue justificada mediante materiales astenosféricos ascendidos a través de la litosfera, hasta alcanzar niveles corticales y además mediante la incorporación de rocas básicas en los términos inferiores de la subcuenca.
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Sanchez-Rojas, Javier. "New Bouguer Gravity Maps of Venezuela: Representation and Analysis of Free-Air and Bouguer Anomalies with Emphasis on Spectral Analyses and Elastic Thickness." International Journal of Geophysics 2012 (2012): 1–15. http://dx.doi.org/10.1155/2012/731545.
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A new gravity data compilation for Venezuela was processed and homogenized. Gravity was measured in reference to the International Gravity Standardization Net 1971, and the complete Bouguer anomaly was calculated by using the Geodetic Reference System 1980 and 2.67 Mg/m3. A regional gravity map was computed by removing wavelengths higher than 200 km from the Bouguer anomaly. After the anomaly separation, regional and residual Bouguer gravity fields were then critically discussed in term of the regional tectonic features. Results were compared with the previous geological and tectonic information obtained from former studies. Gravity and topography data in the spectral domain were used to examine the elastic thickness and depths of the structures of the causative measured anomaly. According to the power spectrum analysis results of the gravity data, the averaged Moho depths for the massif, plains, and mountainous areas in Venezuela are 42, 35, and 40 km, respectively. The averaged admittance function computed from the topography and Free-Air anomaly profiles across Mérida Andes showed a good fit for a regional compensation model with an effective elastic thickness of 15 km.
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Vasanthi, A., and K. Mallick. "Bouguer gravity anomalies and occurrence patterns of kimberlite pipes in Narayanpet-Maddur Regions, Andhra Pradesh, India." GEOPHYSICS 70, no. 1 (January 2005): J13—J24. http://dx.doi.org/10.1190/1.1852778.
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The Narayanpet Kimberlite field, that lies southwest of Hyderabad, the capital city of Andhra Pradesh, India, hosts a number of kimberlite pipes. These pipes appear to be randomly positioned. However, based on regional geologic structures revealed by Bouguer gravity anomalies, especially in a regional gravity map, their locations form a definite pattern. In the Narayanpet-Maddur region, regional Bouguer gravity contours exhibit some features of geologic interest: (1) the eastward convex regional contours show an increase in convexity from the Maddur and Kotakonda area on the east to Narayanpet on the west, (2) convexity is maximum in the vicinity of Narayanpet, where a large number of Kimberlite pipes occur nearly parallel to the regional contour, and (3) between Narayanpet and the Maddur-Kotakonda region, kimberlite pipes occur at intersections of three eastward, convex concentric zones with four lineaments, one trending northeast-southwest and the other three nearly east-west. These linear trends are believed to be radial, extensional, deep-fracture zones, through which kimberlite magma erupted about 1100 Ma. Modeling the residual gravity anomaly over one of the four profiles shows fairly good agreement between observed and computed fields. Based on analysis of Bouguer gravity anomalies and modeling of the residual gravity field, likely locations for kimberlite pipes are the contact zones between granite plutons and the country rocks that coincide with the northeast-southwest–trending radial faults that pass through Narayanpet and Kotakonda to the south and through Kazipur to the north.
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Hidayat, Wahyu, and Wrego Seno Giamboro. "Analisis Continuous Wavelet Transform (CWT) Anomali Residual Medan Gravitasi Di Situs Geologi Karangsambung Kebumen Jawa Tengah." Jurnal Mineral, Energi dan Lingkungan 2, no. 2 (February 11, 2019): 61. http://dx.doi.org/10.31315/jmel.v2i2.2368.
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Gravity method is a passive geophysical method that provides information on the distribution of rock density below the surface. The gravity method has a weakness at the level of ambiguity in determining the depth of the anomaly. This study aims to determine the depth of the anomaly using Continuous Wavelet Transform (CWT) analysis to overcome the value of ambiguity, so that the results obtained have a high degree of accuracy. The research method is data survey / acquisition and data analysis. This research was conducted in Karangsambung Kebumen, Central Java with the acquisition of gravitational data as many as 56 measurement points. The results of data acquisition then analyzed included reading to mGal, tool height correction, drift, tides, latitude, free air correction, Bouguer correction, and field correction. The results of this correction obtained Complete Bouguer Anomalies (ABL) values which were then reduced to flat fields and regional-residual anomaly filters. The next step is CWT analysis by making incisions on residual anomaly maps. The results showed that the source of the anomaly was between ± 39.2 - 122.9 meters.