scholarly journals Integrating geological mapping and geophysical analyses in Southern Espinhaço Range, eastern edge of the São Francisco Craton, Brazil

2021 ◽  
Vol 39 (1) ◽  
Author(s):  
William Medina Leite Féres ◽  
Pedro Ângelo Almeida Abreu ◽  
Wilbor Poletti
Keyword(s):  
Gamma Ray ◽  
Gravity Data ◽  
Geological Mapping ◽  
Gamma Ray Spectrometry ◽  
Narrow Strip ◽  
Espinhaço Range ◽  
Structural Framework ◽  
Regional Tectonic ◽  
History Of ◽  
General Geometry

ABSTRACT. The São Francisco Craton is one of the fundamental pieces on the evolutionary history of the Gondwana supercontinent. At its southeast edge, the Southern Espinhaço Range (SER) is built mainly by Paleo- and Mesoproterozoic units of the Espinhaço Supergroup. At its western domain, one of its major components, the Conselheiro Mata Group, occurs as a relatively narrow strip, being composed by a succession of formations related to coastal and shallow marine environments. Aiming to present and discuss an integrated research, detailed fieldwork was carried out, gamma-ray spectrometry data were reprocessed, and ground gravity data were acquired. This integration allows clarifying the regional crustal structure and the general geometry of the Espinhaço basin. The defined gamma-ray spectrometry domains fit well to the lithological types and structural framework of the stratigraphic units. Bouguer residual anomaly highlights an amplitude of 27 mGal, ranging from -12 to 15 mGal, outlining a gravity compartmentation defined by a central negative anomaly (CNA) surrounded by positive anomalies, which is approximately in conformity with the regional tectonic segments. The CNA conforms to the main axis of SER, indicating the residual metasedimentary coverage of the Espinhaço basin. Its center, positioned above the Lamarão anticline, houses the nucleus of the precursor basin of Conselheiro Mata Group.Keywords: gravimetry; Espinhaço Supergroup; Conselheiro Mata Group.Integrando mapeamento geológico e análises geofísicas na Serra do Espinhaço Meridional, borda leste do Cráton São Francisco, BrasilRESUMO. O Cráton São Francisco é uma das peças fundamentais da história evolutiva do Supercontinente Gondwana. Em sua borda sudeste, a Serra do Espinhaço Meridional é formada, principalmente, por unidades Paleo- a Mesoproterozoicas do Supergrupo Espinhaço. Um de seus principais componentes, o Grupo Conselheiro Mata, ocorre como uma faixa relativamente estreita no domínio ocidental da serra, sendo composto por uma sucessão de formações relacionadas a ambientes marinhos rasos e costeiros. Com o objetivo de apresentar e discutir uma pesquisa integrada, foram realizados trabalho de campo detalhado, processamento de dados gamaespectrométricos e aquisição de dados gravimétricos terrestres. Tal integração permite esclarecer a estrutura crustal regional e a geometria geral da bacia Espinhaço. Os domínios gamaespectrométricos definidos ajustam-se bem às litologias e ao arcabouço estrutural das unidades estratigráficas. Anomalias Bouguer residuais demonstram uma amplitude de 27 mGal, variando entre -12 a 15 mGal, concordando aproximadamente com os segmentos tectônicos regionais e esboçando uma compartimentação gravimétrica definida por uma anomalia negativa central (CNA), cercada por anomalias positivas. A CNA concorda com o eixo principal da Serra do Espinhaço Meridional, definindo a cobertura metassedimentar residual da bacia Espinhaço. Seu centro, posicionado sobre o anticlinal do Lamarão, abriga o núcleo da bacia precursora do Grupo Conselheiro Mata.Palavras-chave: gravimetria; Supergrupo Espinhaço; Grupo Conselheiro Mata.

scholarly journals ANÁLISE GEOFÍSICA DA REGIÃO DO RIO CONCEIÇÃO, QUADRILÁTERO FERRÍFERO, ASSOCIADOS A DADOS DE CAMPO, PETROGRÁFICOS E DE IMAGENS AÉREAS

2020 ◽  
Vol 39 (1) ◽  
pp. 47-63
Author(s):  
Jorge RONCATO ◽  
Ana Luiza de CARVALHO ALMEIDA ◽  
Bárbara MACEDO ◽  
Matheus OLIVEIRA
Keyword(s):  
Gamma Ray ◽  
Aerial Images ◽  
Gamma Ray Spectrometry ◽  
Local Structures ◽  
Structural Framework ◽  
Quadrilátero Ferrífero ◽  
Airborne Geophysics ◽  
Mapping Process ◽  
Geological Map ◽  
Airborne Geophysical Data

The Quadrilátero Ferrífero region, located in the southeast portion of the São Francisco Craton, is one of the main metallogenic provinces in Brazil. Fieldwork, petrography, high-resolution airborne geophysics (magnetic and gamma-ray spectrometry data), and aerial images allowed us to produce a new map at the 1:25,000 scale, with important contributions in the lithotypes detailing, understanding of the geological structures and relationship between the different stratigraphic units. Interpretation of airborne geophysical data integrated with field structural and lithological observations were successfully employed in the creation of the litho-structural framework in a poorly exposed Proterozoic and Archean terrain. Airborne gamma-ray spectrometry data aided in the mapping process in areas with regolith cover including erosional ridges. The magnetic total derivative image revealed regional and local structures. In addition, our work details the units of occurrence of Rio das Velhas and Minas Supergroup. The aerial coverage of the Mindá and Santa Quitéria formations strongly increased, as well as the area of the Cauê Formation was better defined. The new geological map provides many improvements over the pre-existing maps. New lithological facies and structures were identified and others become more visible and lithologicalboundaries are refined or confirmed.

scholarly journals PROSPECTING PHOSPHORITES USING AIRBORNE GEOPHYSICS IN NORTHEASTERN GOIÁS STATE – BRAZIL

2012 ◽  
Vol 30 (4) ◽  
pp. 459 ◽  
Author(s):  
Chris Busnello Fianco ◽  
Roberta Mary Vidotti ◽  
Augusto César Bittencourt Pires ◽  
Adriana Chatack Carmelo
Keyword(s):  
Information Integration ◽  
Gamma Ray ◽  
Wave Length ◽  
Field Work ◽  
Short Wave ◽  
Statistical Correlation ◽  
Geological Mapping ◽  
Geochemical Data ◽  
Gamma Ray Spectrometry ◽  
Airborne Geophysics

A área do projeto está localizada na parte central do Brasil, na região nordeste do Estado de Goiás. As rochas fosfáticas ocorrem no Grupo Bambuí, na parte leste da Faixa de Dobramentos Brasília (FDB), na borda oeste do Cráton do São Francisco. As rochas mineralizadas na área de estudo estão associadas a calcários com apatita. Buscando maior eficiência e rapidez na descoberta de novos alvos prospectivos de rochas sedimentares fosfáticas, foi realizado o processamento dos dados aerogeofísicos juntamente com a correlação estatística dos dados geoquímicos. A integração destes dados proporcionou alvos potenciais que serão investigados com mapeamento geológico e geofísica terrestre (gamaespectrometria) para produzir parâmetros de calibração e comparação com as informações de geofísica aérea. A integração de informações geológicas e mapas de estimativa de eU e P mostraram que rochas ígneas e crostas lateríticas apresentam os teores mais altos de eU e eTh, conforme esperado. Entretando foram identificadas anomalias com pequeno comprimento de onda nos sedimentos das formações Serra de Santa Helena e Sete Lagoasdo Grupo Bambuí, onde são conhecidas ocorrências de corpos fosfáticos na área. O próximo passo deste trabalho será a investigação em campo destas anomalias encontradas, por meio de perfis geológicos e gamaespectrometria terrestre. ABSTRACT. The project area is located in the central part of Brazil, on the northeast region of Goiás State. The phosphatic rocks occur in the Bambuí Group, on the eastern portion of the Faixa de Dobramentos Brasília – Brasília Fold Strip (FDB), on the western border of the São Francisco Craton. In the area under investigation, themineralized rocks are associated with limestone and apatite. In order to discover new prospective targets of phosphatic sedimentary bodies, a faster and more objective airborne geophysics data processing method was carried out together with statistical correlation of geochemical data. The integration of these data identified potential mineralized targets to be checked with geologic mapping and ground geophysics (gamma-ray spectrometry) to produce a parameter of calibration and comparison with the airborne geophysical information. Integration of geologic information and estimate maps of eU and P shows that igneous rocks and lateritic crusts present the high estgrades of uranium and thorium elements, as expected. However, short wave length anomalies were identified in sediments of the Serra de Santa Helena and Sete Lagoas formations (Bambuí Group), where known phosphatic bodies occur in the studied area. The next step of this work will be field work to check these anomalies, with geological mapping and ground gamma-ray profiles.Keywords: applied geophysics, multiple regressions, phosphorites, uranium, Bambuí Group.

Utilization of airborne gamma ray spectrometric data for geological mapping and radioactive mineral exploration of Gabel Umm Tineidba area, south eastern desert, Egypt

2015 ◽  
Vol 12 (2) ◽  
pp. 149-160 ◽  
Author(s):  
Tharwat H. Abdel Hafeez ◽  
Mohamed A. S. Youssef ◽  
Waheed H. Mohamed
Keyword(s):  
Gamma Ray ◽  
Mineral Exploration ◽  
Eastern Desert ◽  
Geological Mapping ◽  
Gamma Ray Spectrometry ◽  
Spectrometric Data ◽  
South Eastern ◽  
Uranium Exploration ◽  
Geological Information ◽  
Surface Geology

The present work utilizes airborne gamma ray spectrometric data in a trial to refine surface geology of igneous, metamorphic and sedimentary rocks, detect any radioactive mineralization at Gabel Umm Tineidba area South Eastern Desert, Egypt. The study area is covered by rock exposures ranging in age from the Precambrian to Quaternary. Airborne gamma ray spectrometry can be very helpful in mapping surface geology. This provides estimates of the apparent surface concentrations of the most common naturally occurring radioactive elements, such as potassium (K), equivalent uranium (eU) and equivalent thorium (eTh). This is based on the assumption that, the absolute and relative concentrations of these radioelements vary measurably and significantly with lithology. The composite image technique is used to display simultaneously three parameters of the three radioelement concentrations and their three binary ratios on one image. The technique offers much in terms of lithological discrimination, based on color differences and showed efficiency in defining areas, where different lithofacies occur within areas mapped as one continuous lithology. The integration between surface geological information and geophysical data led to detailing the surface geology and the contacts between different rock units. Significant locations or favourable areas for uranium exploration are defined, where the measurements exceed (X+2S), taking X as the arithmetic mean of eU, eU/eTh and eU/K measurements and S as the standard deviation corresponding to each variables. The study area shows the presence of fifteen relatively high uraniferous zone. In addition, the trend analysis based on the total count map and the published geological map shows that, most of the well-developed structural lineaments have NS, ENE, NNE and NNW trends.

scholarly journals AIRBORNE GEOPHYSICAL DATA ANALYSIS APPLIED TO GEOLOGICAL INTERPRETATION IN THE ALTA FLORESTA GOLD PROVINCE, MT

2013 ◽  
Vol 31 (1) ◽  
pp. 169 ◽  
Author(s):  
Danilo Barbuena ◽  
Carlos Roberto de Souza Filho ◽  
Emilson Pereira Leite ◽  
Emílio Miguel Junior ◽  
Rafael Rodrigues de Assis ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Phase 1 ◽  
Structural Complexity ◽  
Real Data ◽  
Theoretical Models ◽  
Gold Deposits ◽  
Hydrothermal Systems ◽  
Geological Mapping ◽  
Gamma Ray Spectrometry ◽  
High Potassium

The Alta Floresta Gold Province (AFGP) is located in the central-southern portion of the Amazon Craton. In its eastern segment there are more than one hundred gold deposits hosted in volcanic and plutonic rocks of medium to high content of potassium. In many of these deposits the gold ore is correlated spatially and genetically hydrothermal systems and mainly hosted into the silicification potassic and sericitic. In this context, this work focuses on understanding the geological context of the region and the possibility of expanding new exploratory frontiers through techniques further traditional geological mapping. The processing and interpretation of airborne magnetic and gamma-ray spectrometry data of the Juruena-Teles Pires Project (Phase 1) allowed the production of a new regional geological map of the eastern portion of the AFGP. Additionally, theoretical models showed that despite the limitations of the reduction to the pole at low latitudes, the magnetic enhancements proposed can be applied to real data through the use of directional filtering to eliminate the features generated in the magnetic declination direction. The Total Horizontal Derivative of the Tilt Derivative (THDR-TDR) method proved the best enhancement for the interpretation of the structures, showing a structural complexity similar to that proposed for the evolution of the province. The interpretation of the products based on the gamma-ray spectrometry channels allowed the reinterpretation of different geological units, including the individualization of a new high-potassium intrusive unit, which in the context of AFGP may have metallogenetic potential. RESUMO: A Província Aurífera de Alta Floresta (PAAF) situa-se na porção centro-sul do cráton Amazônico. Em seu segmento leste, ocorrem mais de uma centena de depósitos auríferos hospedados em rochas plutônicas e vulcânicas de médio a alto potássio. Além disso, em muitos desses depósitos o minério aurífero apresenta relação espacial e genética com alterações hidrotermais, preferencialmente alterações do tipo potássica e sericítica. Nesse contexto, o trabalho enfoca o entendimento do contexto geológico dessa região e a possibilidade de expansão de novas fronteiras exploratórias por meio de técnicas que vão além do mapeamento geológico tradicional. Assim, através do processamento e interpretação de dados aeromagnetométricos e aerogamaespectrométricos do projeto Juruena-Teles Pires (Fase 1) gerou-se um novo mapa geológico regional da porção leste da PAAF. Adicionalmente, por meio de modelos teóricos observou-se que apesar das limitações da redução ao polo em baixas latitudes, os realces magnéticos propostos podem ser aplicados aos dados reais mediante o uso de filtros direcionais que eliminem os artefatos gerados na direção da declinação magnética. O método Inclinação do Sinal Analítico do Gradiente Horizontal Total (ISA-GHT) mostrou-se como o realce mais adequado para a interpretação de lineamentos, revelando uma complexidade estrutural similar àquela proposta para a evolução da província. A interpretação dos produtos gerados com base nos canais gamaespectrométricos permitiu a reinterpretação de diversas unidades geológicas, inclusive a individualização de uma nova unidade intrusiva de alto potássio, que nocontexto da PAAF pode possuir potencial metalogenético.Palavras-chave: Província Aurífera de Alta Floresta; dados aerogeofísicos; interpretação geológica

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