Brazilian Journal of Geology最新文献_第8页

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

Marine or freshwater? Accessing the paleoenvironmental parameters of the Caldas Bed, a key marker bed in the Crato Formation (Araripe Basin, NE Brazil) 海洋的还是淡水的?巴西东北部Araripe盆地克拉托组关键标志层Caldas层古环境参数获取

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202120200009

F. G. Varejão, V. D. Silva, M. L. Assine, L. Warren, S. Matos, M. G. Rodrigues, F. Fürsich, M. Simões

{"title":"Marine or freshwater? Accessing the paleoenvironmental parameters of the Caldas Bed, a key marker bed in the Crato Formation (Araripe Basin, NE Brazil)","authors":"F. G. Varejão, V. D. Silva, M. L. Assine, L. Warren, S. Matos, M. G. Rodrigues, F. Fürsich, M. Simões","doi":"10.1590/2317-4889202120200009","DOIUrl":"https://doi.org/10.1590/2317-4889202120200009","url":null,"abstract":"The Aptian Crato Formation is world renowned for its well-preserved fossils in microbially-induced laminated limestones, which are regarded as one of the main Cretaceous Konservat-Lagerstätte of the geological record. Detailed stratigraphic investigation and mapping of the up to 90-m-thick Crato Formation at the eastern border of the Araripe Plateau allowed recognition of a regionally persistent fossil-bearing muddy interval, herein defined as the Caldas Bed. At its type locality, it is defined as an up to 2-m-thick coarsening-upward succession of grey/green mudstone and interbedded sandy siltstone and claystone. The 0.85- to 2-m-thick interval was recognized in several localities along the outcrop belt, and it is bounded by sharp, lower ( Konservat-Lagerstätte limestone) and upper (sandstone and heterolithic facies) contacts. Despite previous literature data suggesting the presence of marine mollusks, the bed contains freshwater bivalves, small gastropods, spinicaudatans, plant remains, trace fossils, and rare ostracods. The Caldas Bed records benthic paleocommunities representing a short-term isochronous regional freshening event, marked by abrupt changes in sedimentation pattern, bathymetry, salinity, oxygenation and water","PeriodicalId":9221,"journal":{"name":"Brazilian Journal of Geology","volume":"15 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83693992","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: 17

Provenance study of Phanerozoic rocks from the Cordillera Real of Bolivia 玻利维亚科迪勒拉雷亚尔显生宙岩石物源研究

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202120210036

A. R. Iriarte, U. Cordani, M. Basei

引用次数: 1

Climatically induced changes in late Quaternary bathyal ostracod assemblages of the Camamu Basin, Brazil 巴西Camamu盆地晚第四纪深海介形类组合的气候变化

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202120210039

C. T. Bergue, M. Ritter, J. Coimbra, K. B. Costa

引用次数: 3