Brazilian Journal of Geology最新文献_第8页

Open-system magmatic evolution and crystallization conditions of the Ediacaran shoshonitic rocks from the São João do Sabugi Pluton, Borborema Province, NE Brazil 巴西东北部borborrema省<s:1> o jo<e:1> o do Sabugi岩体埃迪卡拉纪浅玄岩的开放体系岩浆演化与结晶条件

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-05-14 DOI: 10.1590/2317-4889202120200040

Dayvison Bruno Cordeiro de Paiva, F. C. Vilalva, Z. Souza, M. Nascimento

{"title":"Open-system magmatic evolution and crystallization conditions of the Ediacaran shoshonitic rocks from the São João do Sabugi Pluton, Borborema Province, NE Brazil","authors":"Dayvison Bruno Cordeiro de Paiva, F. C. Vilalva, Z. Souza, M. Nascimento","doi":"10.1590/2317-4889202120200040","DOIUrl":"https://doi.org/10.1590/2317-4889202120200040","url":null,"abstract":"Abstract The Sao Joao do Sabugi Pluton (SJSP) (∼579 Ma) is one of the most expressive occurrences of Ediacaran, syn- to post-collisional shoshonitic rocks in the Rio Piranhas-Serido Domain, Borborema Province, NE Brazil. The petrography, whole rock and mineral composition of this pluton were investigated to characterize its open-system magmatic differentiation processes. The pluton is composed of three rock groups: gabbro-diorite, with clinopyroxene ± orthopyroxene ± amphibole ± biotite; monzodiorite, with amphibole and biotite (± pyroxenes); and granodiorite, with biotite as the main mafic mineral. Evidences of open-system processes, including partially resorbed metasediment xenoliths, are widespread. These rocks are metaluminous, alkali-calcic and magnesian, and have shoshonitic affinity. They show relative LILE and LREE enrichment and pronounced negative Nb-Ta anomalies. Major and trace element geochemical modeling favors magma differentiation by fractional crystallization (56–62%) after crustal assimilation of ∼30% of local paragneisses and schists from the Serido Group in a relatively stationary magma chamber at crustal depth, under pressures of 5–6 kbar, temperatures of ∼800–1,000°C and relatively oxidizing conditions. The less evolved gabbro-diorite was generated by ∼18% modal dynamic partial melting of a metasomatized mantle source.","PeriodicalId":9221,"journal":{"name":"Brazilian Journal of Geology","volume":"1 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83049130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Landslide recognition using SVM, Random Forest, and Maximum Likelihood classifiers on high-resolution satellite images: A case study of Itaóca, southeastern Brazil 在高分辨率卫星图像上使用支持向量机、随机森林和最大似然分类器进行滑坡识别:以巴西东南部Itaóca为例

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202120200105

H. C. Dias, L. Sandre, Diego Alejandro Satizábal Alarcón, C. Grohmann, J. A. Quintanilha

{"title":"Landslide recognition using SVM, Random Forest, and Maximum Likelihood classifiers on high-resolution satellite images: A case study of Itaóca, southeastern Brazil","authors":"H. C. Dias, L. Sandre, Diego Alejandro Satizábal Alarcón, C. Grohmann, J. A. Quintanilha","doi":"10.1590/2317-4889202120200105","DOIUrl":"https://doi.org/10.1590/2317-4889202120200105","url":null,"abstract":"Landslide identification is important for understanding their conditioning factors, and for constructing susceptibility, risk, and vulnerability maps. In remote sensing this can be accomplished manually or through classifiers. This study compares three image classifiers (Maximum Likelihood, Random Forest, and Support Vector Machines (SVM)) used in identifying landslides in Itaóca (São Paulo, Brazil). Two datasets were used: a RapidEye-5 (5 m) image and a Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) (12.5 m). Seven pixel-based classifications were produced, two for each classifier and a binary class that identified only landslides and non-landslides. One classification contained five spectral bands (5B), while the other contained six bands (6B) and included the slope derived from the DEM. The results were validated using Kappa index and F1 score. The SVM 6B classification achieved the best results among the validation indices used herein. It identified a landslide area of 399,325 m². The results contribute to landslide mapping in tropical environments using pixel-based classifiers. However, although the SVM classification was successful, only landslides with larger areas were captured by the algorithms, con-firming the importance of conducting further analyses using images with finer spatial resolution.","PeriodicalId":9221,"journal":{"name":"Brazilian Journal of Geology","volume":"176 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76945875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 7

Isotopic study of the Pb-Zn (Cu-Ag) Santa Maria Deposit, Caçapava do Sul Region, Rio Grande do Sul, Brazil 巴西南里奥格兰德州南卡帕拉帕瓦地区圣玛利亚铅锌(铜银)矿床同位素研究

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202120200091

David Ramos Pereira, M. Macambira, Karen Pires, Samuel Bouças do Lago

{"title":"Isotopic study of the Pb-Zn (Cu-Ag) Santa Maria Deposit, Caçapava do Sul Region, Rio Grande do Sul, Brazil","authors":"David Ramos Pereira, M. Macambira, Karen Pires, Samuel Bouças do Lago","doi":"10.1590/2317-4889202120200091","DOIUrl":"https://doi.org/10.1590/2317-4889202120200091","url":null,"abstract":"The Camaquã Mines, in the central-southern region of Rio Grande do Sul State, Brazil, contain the largest deposits of base metals (Camaquã, Cu; Santa Maria, Pb-Zn) in the Camaquã Basin. The host rocks are consisted of sandstones and conglomerates of the Santa Bárbara Group and interbedded volcanic rocks of undefined stratigraphic position. Peperitic features were identified in a mineralized trachytic sill. An age of 565 ± 5 Ma (U-Pb LA-MC-ICP-MS) was obtained for another trachytic rock, which allowed for the identification, for the first time, of the Acampamento Velho Formation in the Camaquã Mines region. Stratigraphic relations demonstrate that both rocks represent this magmatism. Data from Pb isotopes and spatial relationship observed in the field indicate a possible genetic link between Acampamento Velho Formation and Camaquã mineralization. Pb isotopic data also suggest a predominantly older crustal source (1.07 Ga model age) for Pb and possibly for the other metals, with intermediate or mixed origin, suggesting that magmatic-hydrothermal fluids leached the metals from the percolated rocks of the basement.","PeriodicalId":9221,"journal":{"name":"Brazilian Journal of Geology","volume":"50 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74135522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Evidence of Paleoproterozoic phosphogenesis in the Salvador-Curaçá Orogen (Tanque Novo-Ipirá Complex), northeastern São Francisco Craton, Brazil 巴西<s:1>弗朗西斯科克拉通东北部萨尔瓦多-库拉<s:1>造山带(Tanque novo - ipir<e:1>杂岩)古元古代磷化作用的证据

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202120190137

Tatiana Silva Ribeiro, A. Misi, Luís Rodrigues Oliveira, J. H. S. Sá, D. Debruyne, Ib Silva Câmara

引用次数: 1

Origin and metamorphism of graphite from Formiga, Minas Gerais (Brazil) 巴西米纳斯吉拉斯州Formiga地区石墨的成因及变质作用

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202120200083

Luiza Carneiro de Rezende, A. O. Chaves, S. L. Ramos

{"title":"Origin and metamorphism of graphite from Formiga, Minas Gerais (Brazil)","authors":"Luiza Carneiro de Rezende, A. O. Chaves, S. L. Ramos","doi":"10.1590/2317-4889202120200083","DOIUrl":"https://doi.org/10.1590/2317-4889202120200083","url":null,"abstract":"During the Paleoproterozoic Era, the Brazilian cratons experienced orogenic events that modified the archean basement and sedimentary successions. In the southern São Francisco Craton, it can be recognized evidence of an orogenic event that happened between Rhyacian and Orosirian periods. It is related to the closure of an oceanic basin at this time, which led to the collision between the Archean Divinópolis and Campo Belo metamorphic complexes. Graphite schist occurs close to the cities of Formiga and Itapecerica (Minas Gerais), located between these complexes. To contribute to the understanding of the origin and metamorphism of the graphite from Formiga, petrographic studies, X-ray diffraction (XRD) and Raman spectroscopy analyses have been done. XRD and Raman methods revealed that the temperatures record-ed by graphite are around 460°C. However, Raman data showed that the crystallite sizes correspond to higher metamorphic grade conditions (amphibolite to granulite facies). Temperatures of 460°C are probably associated with hydrothermal processes along faults in post-collisional stage. The presence of todorokite, a mineral typical of deep-sea Mn nodules formed by microorganisms, in association with graphite from Formiga, suggests a biogenic origin for the graphite occurrence.","PeriodicalId":9221,"journal":{"name":"Brazilian Journal of Geology","volume":"51 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72946153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Sequence stratigraphy of clastic and carbonate successions: applications for exploration and production of natural resources 碎屑和碳酸盐岩层序地层学:在自然资源勘探和生产中的应用

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202120210014

A. Magalhães, D. G. C. Fragoso, G. Gabaglia, G. J. S. Terra, A. H. Melo, P. R. O. Andrade, F. Guadagnin, F. P. Lima-Filho

引用次数: 3

Accretionary models for the Neoproterozoic evolution of the Borborema Province: advances and open questions borborrema省新元古代演化的增生模式:进展与悬而未决的问题

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202120200104

Lauro Santos, F. Caxito

引用次数: 13

Deformation mechanisms, mineral chemistry and zircon U-Pb geochronological constraints in the south Patos shear zone: implications for the crustal evolution of the Borborema Province, NE Brazil 南Patos剪切带的变形机制、矿物化学和锆石U-Pb年代学约束:对巴西东北部borborrema省地壳演化的启示

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202120210048

Carolina Peixoto de Souza, Luís Gustavo Ferreira Viegas, Lauro Santos

引用次数: 4

Mineral chemistry and genetic implications of garnet from the São João del Rei Pegmatitic Province, Minas Gerais, Brazil 巴西米纳斯吉拉斯州<s:1> o jo<e:1> o del Rei伟晶岩省石榴石矿物化学及成因意义

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202120190136

Sarah Siqueira da Cruz Guimarães Sousa, C. Ávila, R. Neumann, F. Faulstich, F. Alves, Taís Proença Cidade, V. Silva

{"title":"Mineral chemistry and genetic implications of garnet from the São João del Rei Pegmatitic Province, Minas Gerais, Brazil","authors":"Sarah Siqueira da Cruz Guimarães Sousa, C. Ávila, R. Neumann, F. Faulstich, F. Alves, Taís Proença Cidade, V. Silva","doi":"10.1590/2317-4889202120190136","DOIUrl":"https://doi.org/10.1590/2317-4889202120190136","url":null,"abstract":"The pegmatites of the São João del Rei Pegmatitic Province are related to the Siderian protoliths of the Cassiterita and Resende Costa orthogneisses and to the Ritápolis metagranitoid of Ryacian age. Chemical analysis of garnet from twelve pegmatites reveal two different types of grains, which were found in the same pegmatitic body in six of these samples. One garnet type has almandine-spessartine composition (Sps 11.7-58.8 Alm 36.8-86.5 Prp 0.1-4.1 Grs 0.0-1.4 Adr 0.0-2.6 ), grains with orange and pink tones, and scarce mineral inclusions. These garnet grains may have been formed at the magmatic stage of pegmatite crystallization. The composition of these grains plot exclusively on the Alm-Sps axis at the Prp+Grs+Adr+Uvr × Alm × Sps diagram, as expected from garnet crystallized in pegmatites, and an expansion of the field associated to pegmatites is proposed. The second type has a distinct chemical composition (Sps 26.9-84.8 Alm 3.6-40.0 Prp 0.0-10.4 Grs 9.3-45.6 Adr 0.1-3.4 ), displaying enrichment in Ca. This Ca-enriched garnet has irregular shaped colourless grains and abundant mineral inclusions. These grains may have been formed by Ca-metasomatism during the late-stage crystallization of the pegmatites.","PeriodicalId":9221,"journal":{"name":"Brazilian Journal of Geology","volume":"14 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81969998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Field availability and mobility of metals in Ferralsols developed on ultramafic rock of Niquelândia, Brazil 在巴西niquel<s:1>印度超基性岩石上开发的Ferralsols金属的现场可用性和流动性

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202120200092

J. Garnier, C. Quantin, S. Raous, E. Guimarães, T. Becquer

{"title":"Field availability and mobility of metals in Ferralsols developed on ultramafic rock of Niquelândia, Brazil","authors":"J. Garnier, C. Quantin, S. Raous, E. Guimarães, T. Becquer","doi":"10.1590/2317-4889202120200092","DOIUrl":"https://doi.org/10.1590/2317-4889202120200092","url":null,"abstract":"Ultramafic (UM) rocks are defined as igneous rocks that contain more than 90% of mafic minerals. Soils derived from ultramafic rock are generally nutrient-deficient and have concomitant high concentrations of potentially phytotoxic trace elements (Ni, Cr, Co, Mn). Consequently, to assess the dynamics of nutrients and metals in the ultramafic complex of Niquelândia (Brazil), soil solutions have been sampled in soils characterized by high Cr(VI) availability. The metal contents in surficial water have also been analyzed to investigate the metals’ leaching and mobility. Soil solutions featured low nutrient contents, a large Ca:Mg imbalance, and high Ni and Cr concentrations. Chromium was present in its toxic dissolved form (Cr(VI)) in the soil and surficial solutions. Metals concentrations were often above the toxic limit for biota and were therefore able to affect soil functioning. Ni behavior in the topsoil appeared to be primarily controlled by organic matter, while Cr was more likely to be released from Fe-oxides by anionic exchange. This result agreed with the Cr(VI) lability assessed using isotopic exchange kinetics in a companion study. In these serpentinic tropical soils, the highly leached Fe-oxide horizons appear to play a large role in the sequestration and diffuse leaching of labile Cr(VI) and Ni, respectively, in the deeper part of soil profiles and the topsoil. At the catchment scale, surficial solutions results suggest that metals may be exported to surrounding ecosystems that are not adapted to these metals.","PeriodicalId":9221,"journal":{"name":"Brazilian Journal of Geology","volume":"95 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76957065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2