Weathering of metapelites from the Quadrilátero Ferrífero mineral province, southeastern Brazil

Leão, Marcio Fernandes; Barroso, Emílio Velloso; Polivanov, Helena; Marques, Eduardo Antônio Gomes; Vargas, Eurípedes do Amaral

doi:10.1007/s10064-017-1036-1

Cited by 10 publications

(5 citation statements)

References 32 publications

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“…As physical weathering is processed, creating preferential spaces for water to enter the rock, opaque minerals are dissolved and iron oxides are precipitated. These results are in agreement with studies carried out in phyllites under tropical (Leão et al, 2017) and subtropical (Marques et al, 2017;Marques et al, 2020;Robert & Hack, 2020) climates. Figures 4, 5, and 6 show the main implications of weathering on the matrix of this rock.…”

Section: Main Characteristics Of the Studied Phyllitessupporting

confidence: 92%

“…The lowest obtained durability index corresponds to phyllite W3 from profile Phy01 (Table 3). It can be explained by the reduced internal cohesion of its matrix, which was also pointed out by Leão et al (2017) in altered sericite phyllites from the same site. These phyllites are characterized by levels of mafic and siliceous minerals that fill foliation (Fig.…”

Section: Durabilitymentioning

confidence: 59%

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Influence of Weathering and Correlations Between Wave Propagation Velocity and Durability with Physical and Mechanical Parameters in Phyllites

Carvalho¹,

Leão²,

Marques³

2020

S&R

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Ultrasonic longitudinal wave velocity (Vp) and durability are characteristics largely determined in geotechnical evaluations. These properties are useful in the analysis of weathered rocks because they usually have good relationships with physical and mechanical properties of rocks. Additionally, the tests to obtain these parameters are easy to perform. However, few studies have been performed specifically on low degree metamorphic rocks. The purpose of this study is to evaluate the influence of weathering on these parameters, as to propose correlations between Vp and some mechanical and physical parameters. This study was carried out using phyllites from three weathering profiles located along the highway BR-356, Minas Gerais, Brazil. The results reveal a clear influence of weathering on Vp and durability mainly due to increased porosity. However, as the variation of this parameter is heterogeneous, the relationship between Vp, durability, and weathering is not uniform, although they present general trends. The behavior shown by porosity reflects the complex role of chemical weathering on fractures. The non-uniform pattern of Vp and durability throughout the weathering classes is also a consequence of the heterogeneity and anisotropy intrinsic to these phyllites. The empirical relationships established exhibit good correlation coefficients.

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Section: Main Characteristics Of the Studied Phyllitessupporting

confidence: 92%

Section: Durabilitymentioning

confidence: 59%

Influence of Weathering and Correlations Between Wave Propagation Velocity and Durability with Physical and Mechanical Parameters in Phyllites

Carvalho¹,

Leão²,

Marques³

2020

S&R

Self Cite

View full text Add to dashboard Cite

show abstract

“…The difficulty in obtaining information increases when rocks and soils are in subsurface layers, requiring new techniques for efficient access. This difficulty is even high for weathered materials in terms of sample representativeness and geotechnical properties (Leão et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Application of direct and indirect methods for predicting geotechnical dam foundation issues on weathered metamorphic rocks under tropical conditions

Leão¹

2020

Acta Geodynamica Et Geomaterialia

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Weathering profiles in tropical regions usually present great heterogeneity and anisotropy of geological materials. High structural complexity and great bedrock irregularity are added when these profiles are composed of metamorphic rocks. Therefore, geological-geotechnical research initiatives in these regions imply indirect methods associated with direct methods. In this context, we studied the San Juan dam foundation in the Dominican Republic, geologically composed of young residual schist soil cover (up to 20 m), in which occurs schist layers of low resistance to SPT (2 SPT blows/30 cm) consistent with a massive and stratified marble rock, which tends to concentrate karst cavities. This geological condition, associated with the vast extent of the dam influence area, motivated the adoption of an indirect method by electrical resistivity intending to identify sites with the possibility of occurrence of cavities filled or not under the reservoir foundation and in the dam axis itself. Subsequently, a more rational initiative of mixed drillings was carried out in sites with such possibility, resulting in discarding these hypotheses and demonstrating that these cavities correspond to graphite schists and non-karst marbles, competent materials as dam foundation.

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“…Researches about geological-geotechnical behavior of weathered profiles of low metamorphic grade rocks are few, even though there are many efforts. In addition, the great number of propositions and terminologies makes it hard to understand and apply some terms, mainly because classifications depend on the weathering active process and not just on the rock initial features and its geological and structural context [1,3].…”

Section: Introductionmentioning

confidence: 99%

Characterization of Weathered Soft Rock Mass by Index Tests

M¹

2018

IJPBP

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The understanding of geotechnical and geomechanical rock mass behavior is challenging, mainly regarding weathered parts, since they may trigger stability issues. Soft Rocks, as phyllite, are known to enhance these problems. In this case, a road cut on a highway between the cities of Ouro Preto and Mariana (MG – Brazil) was studied, showing a particular weathering zone with changing conditions. After morphological description and geological fragmentation (using geological hammer, the Schmidt hammer and a switchblade) of the weathering zone, tests were done on rock matrix and rock mass in order to identify the discontinuity features. Physical properties were determined by physical index, using the point load test and slake durability test. The results permit to define the weathering zone, showing some huge anisotropy and heterogeneity in the rock properties.

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Weathering of metapelites from the Quadrilátero Ferrífero mineral province, southeastern Brazil

Cited by 10 publications

References 32 publications

Influence of Weathering and Correlations Between Wave Propagation Velocity and Durability with Physical and Mechanical Parameters in Phyllites

Influence of Weathering and Correlations Between Wave Propagation Velocity and Durability with Physical and Mechanical Parameters in Phyllites

Application of direct and indirect methods for predicting geotechnical dam foundation issues on weathered metamorphic rocks under tropical conditions

Characterization of Weathered Soft Rock Mass by Index Tests

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