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Quadros, Telmo Fernando Perez de; Koppe, Jair Carlos; Strieder, Adelir José; Costa, João Felipe Coimbra Leite

doi:10.1023/a:1022608505873

Cited by 33 publications

(13 citation statements)

References 12 publications

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“…Regarding the usage of airborne gamma-ray applied to gold prospecting, the contrasting behavior or antagonism between the K and Th radioelements defined by Ostrovskiy (1975) has been represented as a chief parameter. In fact, since its conception, this relationship became one of, if not the main, pathfinders in gold prospective studies involving this methodology, and the K/eTh (or eTh/K) map has been exhaustively used (e.g., Shives et al 2000, Quadros et al 2003, Almasi et al 2015, Ohioma et al 2017. The key feature recognized are, in general, zones of hydrothermal alteration evidenced by an increase of K even in high-potassium host rocks (Hoover & Pearce 1990).…”

Section: Discussionmentioning

confidence: 99%

The role of airborne geophysics in the investigation of gold occurrences in the Itapetim Region, Borborema Province, Northeast Brazil

2019

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We present a combined analysis of airborne geophysical data (magnetics and gamma-ray spectrometry) and field aspects of Itapetim lode gold district region, aiming to identify structurally deformed and hydrothermally altered zones, which are suggestive of gold mineralized sectors. The main geophysical lineaments are oriented in the NE-SW and E-W directions and display a clear correlation with the major gold-bearing structures in the region. In the magnetic maps, the key pathfinder for gold occurrences is their association with strongly magnetized areas positioned along the Itapetim Shear Zone and outer contour of Teixeira Batholith. In the field, such structures are materialized in protomylonitic and mylonitic rocks that present evidence of ductile and brittle deformation, whereas kinematic criteria are suggestive of a transpressional tectonic regime. In addition, the main radiometric pattern is characterized by K enrichment, which is correlated with a hydrothermal mineral assemblage dominated by quartz, potassium feldspar, and tourmaline. Based on the obtained data integration, we produced an integrative map and located ten new target areas of possible gold mineralization, which is correlative to other well-known lode deposits in Northeast Brazil and Africa.

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Section: Discussionmentioning

confidence: 99%

The role of airborne geophysics in the investigation of gold occurrences in the Itapetim Region, Borborema Province, Northeast Brazil

2019

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“…The radiometric response of weathered materials can contribute significantly to the comprehension of the weathering and geomorphological history of the region. This method has been extensively used to improve geological mapping, especially in areas where few outcrops were accessible [e.g., Graham and Bonham-Carter, 1993;Cook et al, 1996;Wilford et al, 1997] and to map hydrothermal alteration zones associated with certain types of mineral deposits, such as lode Au, porphyry Cu-Au and volcanic hosted massive suphides (Cu-Pb-Zn) [e.g., Shives et al, 2000;Airo, 2002;Quadros et al, 2003].…”

Section: Introductionmentioning

confidence: 99%

Contributions of gamma‐ray spectrometry to terrestrial impact crater studies: The example of Serra da Cangalha, northeastern Brazil

Vasconcelos

Leite

Crósta

2012

Geophysical Research Letters

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Several geophysical methods have been used for decades for the identification and exploration of impact craters. Most of them are based on seismic, potential fields and electrical data, focusing on exploration of anomalies caused by changes in physical properties or by structures associated with the formation of the crater. Gamma‐ray spectrometry is usually not mentioned among the geophysical methods employed in crater studies, although it is known that impact cratering processes cause a number of physical/chemical changes in the country rocks. These changes include the remobilization of hydrothermal fluids which directly modify the composition of target rocks and, subsidiarily, of soils related to these rocks. Therefore, the distribution of radioactive elementsK, Th and Uhas the potential to map such modifications. We present the analysis of gamma‐ray signatures at the Serra da Cangalha impact structure, located in northeastern Brazil, using methods for enhancingKanomalies and also the overall gamma‐ray signatures. These results provide valuable information on the distinct zones within the crater and might contribute to the understanding of hydrothermal enrichment processes produced as a result of the impact event.

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“…Many hydrothermal alteration minerals contain 40 K, which is associated with K during the hydrothermal processes. 40 K is responsible for most gamma radiation emitted by primary radioactive isotope of the Earth's crust [11], [20]. Therefore, hydrothermal alteration minerals (sericite, biotite, K-feldspars and many K-bearing clay minerals) can be mapped using radiometric data [11].…”

Section: Resultsmentioning

confidence: 99%

“…The survey was conducted at 200 m flight spacing and constant altitude over an average topographic elevation of 60 m for the spectrometer, 45 m for the magnetometer and 30 m for the electromagnetic coils. Data were processed by various filtering and enhancement techniques for noise removal and data correction [20]. The total magnetic intensity map was prepared using reduced-to-pole (RTP) method.…”

Section: Specifications Of Airborne Geophysical Datasetmentioning

confidence: 99%

Application of Airborne Geophysical and ASTER Data for Hydrothermal Alteration Mapping in the Sar-Kuh Porphyry Copper Area, Kerman Province, Iran

Honarmand¹

2016

OJG

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Known deposits are appropriate sites for investigating significant exploratory keys that could be helpful in mineral exploration in corresponding regions or similar areas. This study was performed to delineate hydrothermal alteration model and some geophysical characteristics of the SarKuh porphyry copper deposit located within the southern part of the central Iranian Cenozoic magmatic belt (CICMB). Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images have been used to produce hydrothermal alteration map using a fractal-aided spectral angle mapper (SAM) method. Airborne data were used to study magnetic-radiometric properties of the deposit. Image processing of ASTER images and laboratory studies proved the presence of two types of phyllic ale ration called intense and weak phyllic based on abundance of sericite mineral. It realized that radiometric anomalies of 40 K, eTh and eU are limited to boundary of phyllic zone. Radiometric ratios e.g. eTh/ 40 K were good enough to enhance phyllic zone.

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Cited by 33 publications

References 12 publications

The role of airborne geophysics in the investigation of gold occurrences in the Itapetim Region, Borborema Province, Northeast Brazil

The role of airborne geophysics in the investigation of gold occurrences in the Itapetim Region, Borborema Province, Northeast Brazil

Contributions of gamma‐ray spectrometry to terrestrial impact crater studies: The example of Serra da Cangalha, northeastern Brazil

Application of Airborne Geophysical and ASTER Data for Hydrothermal Alteration Mapping in the Sar-Kuh Porphyry Copper Area, Kerman Province, Iran

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