scholarly journals MAPEAMENTO GEOLÓGICO DA REGIÃO DE GOUVEIA / MG COM AUXÍLIO DE MÉTODOS GEOFÍSICOS

2013 ◽  
Author(s):  
Paulo Roberto Antunes Aranha ◽  
Rodrigo Macedo Pena ◽  
Luiz Guilherme Knauer
Keyword(s):  
Ground Penetrating Radar ◽  
Minas Gerais ◽  
Geophysical Data ◽  
Igneous Rocks ◽  
A Value ◽  
Minas Gerais State ◽  
Geologic Map ◽  
Ground Penetrating

Na região da cidade de Gouveia, Serra do Espinhaço, Minas Gerais, devido a escassez de afloramentos, foramutilizados métodos geofísicos de cintilometria e Georadar buscando-se desenvolver um critério geofísicona individualização das litologias não-aflorantes presentes na área, mesmo com a presença de milonitos eforte intemperismo. Os dados geofísicos foram analisados separadamente para cada perfil obtido, e um valorem torno de 185 CPS (cintilações por segundo) para rochas do Complexo de Gouveia indeformado e 80CPS para rochas da Formação Barão de Guaicuí pôde ser considerado como guia prospectivo. Ademais, asimagens da subsuperfície puderam mostrar estruturas: falhas, fraturas, presença de colúvios, etc. Nesta áreaforam identificadas quatro unidades lito-estratigráficas principais: (a) Complexo de Gouveia, representadopor granitos s.l; (b) Formação Barão do Guaicuí, representado por quartzo-sericita-xisto típico; (c) FormaçãoGalho do Miguel, representado por espessos pacotes homogêneos de quartzito esbranquiçado puro e fino,e (d) rocha metabásica representada por rochas máficas e maciças de coloração levemente esverdeadas.Destaca-se uma foliação milonítica principal, S1, de atitude dominante 095-085/40 e falhamentos regionaisde orientação geral NW/SE. Nos xistos e granitos esta foliação rotaciona e deforma grãos, podendo aparecertodos os termos miloníticos.ABSTRACT: The Gouveia region, Espinhaço Ridge, Minas Gerais State, is marked by the lack of outcrops, geophysicscintilometry and Ground Penetrating Radar methods were used in order to attach a litostratigraphicindividualization criteria, even with strong milonitization and laterization. These geophysical data wasindividually analyzed and a value of 185 CPS for indeformed Gouveia Complex and 80 CPS for Barão doGuaiuí Formation could be taken as prospect guidance. The radargrams were useful to realize the subsurfacestructure, faults, fractures, and coluvium. In this area four main litostratigraphic units was identified: (a)Gouveia Complex, represented by s.l granites (b) Barão do Guaicuí Formation, formed by typical quartzsericite-schist (c) Galho do Miguel Formation, represented by a thick, white and homogenous layer of quartziteand (d) Basic Igneous rocks, composed by mafic and massive, lightly greenly. A main milonitic foliationoccurs, S1, dipping 095-085/40 as well as regional NW / SE fractures. In the schist and granite, that foliationcauses rotation and deformation of some minerals. Milonitic rocks can also be found.Keywords: georadar, gamma survey, geologic map

scholarly journals GEOPHYSICAL METHODS FOR BR TAILINGS DAM RESEARCH AND MONITORING IN THE MINERAL COMPLEX OF TAPIRA - MINAS GERAIS, BRAZIL

2019 ◽  
Vol 37 (3) ◽  
pp. 275
Author(s):  
Demetrius Cunha Gonçalves da Rocha ◽  
Marco Antonio da Silva Braga ◽  
Camilla Tavares Rodrigues
Keyword(s):  
Electrical Resistivity ◽  
Water Table ◽  
Ground Penetrating Radar ◽  
Geophysical Methods ◽  
Minas Gerais ◽  
Minas Gerais State ◽  
Indirect Indicator ◽  
Mining Complex ◽  
Ground Penetrating ◽  
2D And 3D

ABSTRACT. The use of geophysical methods in the BR dam at Tapira mining complex in Minas Gerais state, Brazil, had as main objective to develop a research geophysical methodology complementary to the existing conventional monitoring system. Electrical resistivity and GPR (ground penetrating radar) methods were used. Ten geophysical sections were acquired parallel to the main axis of the BR dam. The water table level delineated by geophysics was later compared to five type-sections data, which comprised the readings of 9 water level indicators (INA’s). The electrical resistivity results delineated the level of the water table and showed the moisture areas in the BR dam. Low resistivity zones (LRZ) were correlated with regions saturated or with a high moisture content with resistivity responses below 250 ohm-m. The GPR responses, saturated zones presented strong attenuation in the reflectors, being this effect smaller with the decrease in the water content. In some sections it was possible to correlate, patterns of reflectors to different resistive zones. Geophysics results showed great efficiency in the BR dam investigation and monitoring, through the generation of continuous indirect indicator data. Which after processing resulted in a complete 2D and 3D view of the interior of the studied dam.Keywords: electrical resistivity, geotechnics, applied geophysics.RESUMO. A utilização de métodos geofísicos na barragem BR do complexo de mineração de Tapira no estado de Minas Gerais, Brasil, teve como principal objetivo desenvolver uma metodologia geofísica investigativa complementar ao monitoramento hoje existente. Foram utilizados os métodos geofísicos de eletrorresistividade e GPR (ground penetrating radar). Durante a aquisição de dados foram levantadas 10 linhas paralelas ao eixo principal do barramento. O nível freático delineado pela geofísica foi posteriormente comparado com o nível freático de 5 seções-tipo mapeado pelas leituras de 9 indicadores de nível d’água (INA’s). Os resultados da eletrorresistividade delinearam de forma precisa o nível freático, diferenciando áreas secas das úmidas ao longo do barramento. Zonas de baixa resistividade (ZBR), foram correlacionadas com regiões do maciço possivelmente saturadas ou com alto teor de umidade (< 250 ohm-m). Em resposta ao GPR, zonas saturadas apresentaram forte atenuação nos refletores, sendo esta atenuação menor com a diminuição no teor de água. Em algumas seções, foram correlacionados padrões dos refletores a diferentes zonas resistivas. A geofísica mostrou ter uma grande eficácia na investigação e monitoramento dessas estruturas, através da geração de indicadores indiretos contínuos, que após processamento resultaram em um imageamento completo em 2D e 3D do interior da barragem estudada.Palavras-chave: resistividade elétrica, geotecnia, geofísica aplicada.

scholarly journals Caracterização em multiescala de carbonatos neoproterozóicos da Pedreira GMD, Formação Lagoa do Jacaré, Grupo Bambuí, Paraopeba-MG

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Alex Rodrigues de Freitas ◽  
Alexandre Uhlein ◽  
Márcio Vinícius Santana Dantas ◽  
Thaís Keuffer Mendonça
Keyword(s):  
Ground Penetrating Radar ◽  
Minas Gerais ◽  
Ground Penetrating

O método Caracterização Multiescalar de Reservatórios (Camures) vem se consolidando como uma importante ferramenta e que tem auxiliado na caracterização dos mais diferentes tipos de afloramentos e seções de rochas sedimentares. O objetivo deste trabalho compreende a aplicação desse método em um afloramento da Formação Lagoa do Jacaré, Grupo Bambuí, representado por uma pedreira desativada na região de Paraopeba, centro-norte de Minas Gerais. Para tanto, utilizaram-se diferentes ferramentas investigativas em macro, meso e microescalas de análise para caracterização dessa unidade nesse afloramento. A caracterização litofaciológica de detalhe na pedreira revelou cinco litofácies carbonáticas principais. Dados geofísicos de Ground Penetrating Radar (GPR) e raios gama foram levantados para auxiliar no reconhecimento das principais geometrias e litologias presentes na área, bem como na correlação lateral dos perfis levantados na pedreira. A análise petrográfica microscópica mostra a ocorrência de seis fácies. A análise das litofácies e estruturas sedimentares presentes apontam para deposição sob influência de ondas de tempestade em diversos ciclos tempestíticos em plataforma carbonática rasa. Essa sequência é definida na base por brechas intraclásticas, representando momentos de alta energia, passando a momentos de menor energia que favorecem a deposição carbonática fina com estratificações hummocky e plano-paralelas, marcas onduladas associadas, até raros momentos de calmaria com deposição de sedimentos carbonáticos finos na transição antepraia-plataforma (shoreface-offshore).

Integrated interpretation of 2D ground-penetrating radar, P-, and S-wave velocity models in terms of petrophysical properties: Assessing uncertainties related to data inversion and petrophysical relations

2017 ◽  
Vol 5 (1) ◽  
pp. T121-T130 ◽  
Author(s):  
Jens Tronicke ◽  
Hendrik Paasche
Keyword(s):  
Monte Carlo ◽  
Ground Penetrating Radar ◽  
Geophysical Data ◽  
Engineering Practice ◽  
Quantitative Interpretation ◽  
Petrophysical Properties ◽  
S Wave ◽  
Velocity Models ◽  
Data Inversion ◽  
Ground Penetrating

Near-surface geophysical techniques are extensively used in a variety of engineering, environmental, geologic, and hydrologic applications. While many of these applications ask for detailed, quantitative models of selected material properties, geophysical data are increasingly used to estimate such target properties. Typically, this estimation procedure relies on a two-step workflow including (1) the inversion of geophysical data and (2) the petrophysical translation of the inverted parameter models into the target properties. Standard deterministic implementations of such a quantitative interpretation result in a single best-estimate model, often without considering and propagating the uncertainties related to the two steps. We address this problem by using a rather novel, particle-swarm-based global joint strategy for data inversion and by implementing Monte Carlo procedures for petrophysical property estimation. We apply our proposed workflow to crosshole ground-penetrating radar, P-, and S-wave data sets collected at a well-constrained test site for a detailed geotechnical characterization of unconsolidated sands. For joint traveltime inversion, the chosen global approach results in ensembles of acceptable velocity models, which are analyzed to appraise inversion-related uncertainties. Subsequently, the entire ensembles of inverted velocity models are considered to estimate selected petrophysical properties including porosity, bulk density, and elastic moduli via well-established petrophysical relations implemented in a Monte Carlo framework. Our results illustrate the potential benefit of such an advanced interpretation strategy; i.e., the proposed workflow allows to study how uncertainties propagate into the finally estimated property models, while concurrently we are able to study the impact of uncertainties in the used petrophysical relations (e.g., the influence of uncertain, user-specified parameters). We conclude that such statistical approaches for the quantitative interpretation of geophysical data can be easily extended and adapted to other applications and geophysical methods and might be an important step toward increasing the popularity and acceptance of geophysical tools in engineering practice.

The Quaternary sediments structure in the upper Dnieper river valley based on combined geophysical survey

2020 ◽  
pp. 104-115
Author(s):  
S. S. Bricheva ◽  
I. N. Modin ◽  
A. V. Panin ◽  
K. D. Efremov ◽  
V. M. Matasov
Keyword(s):  
Electrical Resistivity ◽  
Ground Penetrating Radar ◽  
Electrical Resistivity Tomography ◽  
Geological Mapping ◽  
Geophysical Data ◽  
Quaternary Sediments ◽  
Resistivity Tomography ◽  
Geophysical Techniques ◽  
Geological Section ◽  
Ground Penetrating

Geophysical techniques Ground Penetrating Radar (GPR) and Electrical Resistivity Tomography (ERT) are used for the geological mapping and description of inner structure of sediments of the Upper Dnieper zone. Geophysical data assisted locating the boreholes and correlation the horizons between them. The information obtained by geophysics provided a basis to identify the rerouting of the upper Dnieper valley due to the Valdaian glaciation. GPR data on frequencies 50–250 MHz allowed to describe the upper part of geological section, ERT provided data up to 80–100 m depth. We performed the modified focusing inversion, based on major boundaries obtained with GPR, to correct ERT inversion model.

REFLECTION COEFFICIENT OF AN ELECTROMAGNETIC WAVE IN CONDUCTIVE MEDIA

2018 ◽  
pp. 100-106
Author(s):  
M. S. Sudakova ◽  
M. L. Vladov ◽  
M. R. Sadurtdinov
Keyword(s):  
Reflection Coefficient ◽  
Ground Penetrating Radar ◽  
Electromagnetic Waves ◽  
Water Contamination ◽  
Survey Design ◽  
Direct And Inverse Problems ◽  
The Difference ◽  
Ground Penetrating ◽  
Ideal Dielectric

Within the ground penetrating radar bandwidth the medium is considered to be an ideal dielectric, which is not always true. Electromagnetic waves reflection coefficient conductivity dependence showed a significant role of the difference in conductivity in reflection strength. It was confirmed by physical modeling. Conductivity of geological media should be taken into account when solving direct and inverse problems, survey design planning, etc. Ground penetrating radar can be used to solve the problem of mapping of halocline or determine water contamination.

Deteksi Bentuk Objek Bawah Tanah Menggunakan Pengolahan Citra B-Scan pada Ground Penetrating Radar (GPR)

2017 ◽  
Vol 3 (1) ◽  
pp. 73-83
Author(s):  
Rahmayati Alindra ◽  
Heroe Wijanto ◽  
Koredianto Usman
Keyword(s):  
Signal Processing ◽  
Ground Penetrating Radar ◽  
Post Processing ◽  
Data Survey ◽  
Ground Penetrating

Ground Penetrating Radar (GPR) adalah salah satu jenis radar yang digunakan untuk menyelidiki kondisi di bawah permukaan tanah tanpa harus menggali dan merusak tanah. Sistem GPR terdiri atas pengirim (transmitter), yaitu antena yang terhubung ke generator sinyal dan bagian penerima (receiver), yaitu antena yang terhubung ke LNA dan ADC yang kemudian terhubung ke unit pengolahan data hasil survey serta display sebagai tampilan output-nya dan post  processing untuk alat bantu mendapatkan informasi mengenai suatu objek. GPR bekerja dengan cara memancarkan gelombang elektromagnetik ke dalam tanah dan menerima sinyal yang dipantulkan oleh objek-objek di bawah permukaan tanah. Sinyal yang diterima kemudian diolah pada bagian signal processing dengan tujuan untuk menghasilkan gambaran kondisi di bawah permukaan tanah yang dapat dengan mudah dibaca dan diinterpretasikan oleh user. Signal processing sendiri terdiri dari beberapa tahap yaitu A-Scan yang meliputi perbaikan sinyal dan pendektesian objek satu dimensi, B-Scan untuk pemrosesan data dua dimensi  dan C-Scan untuk pemrosesan data tiga dimensi. Metode yang digunakan pada pemrosesan B-Scan salah satunya adalah dengan  teknik pemrosesan citra. Dengan pemrosesan citra, data survey B-scan diolah untuk didapatkan informasi mengenai objek. Pada penelitian ini, diterapkan teori gradien garis pada pemrosesan citra B-scan untuk menentukan bentuk dua dimensi dari objek bawah tanah yaitu persegi, segitiga atau lingkaran. 

Sign in / Sign up

Export Citation Format

Share Document