Journal of the Geological Survey of Brazil <p><strong>SCOPE AND MISSION</strong></p> <p><strong>Journal of the Geological Survey of Brazil (JGSB)</strong> is a peer-reviewed, open-access periodical, published three times a year (April, August, and December) by the Geological Survey of Brazil, which is attached to the Ministry of Mines and Energy of Brazil.</p> <p>Our Mission is the dissemination of original, high-quality scientific research, and in-depth reviews of relevant subjects that cover all disciplines of the Earth Sciences in Brazil, and elsewhere, intending to be of interest to a broad audience of geological scientists.</p> en-US <p>The papers are published in the open access format, being freely available to any user, under a <a title="CC-BY Creative Commons license" href="" target="_blank" rel="noopener">CC-BY Creative Commons license</a>.&nbsp;</p> <p>By submitting this manuscript for evaluation, the authors are aware of&nbsp;the&nbsp;<a title="CC-BY Creative Commons license" href="" target="_blank" rel="noopener">CC-BY Creative Commons license</a>. In the case of manuscript approval, the author responsible for the manuscript (corresponding author), hereinafter referred to as CEDENTE (ASSIGNOR), hereby assigns and transfers to <u>CPRM-Serviço Geológico do Brasil</u>, holder of the JGSB, free of charge, on his behalf and on behalf from all co-authors, <u>the right of the first publication.</u> This includes the rights of editing, publication, translation into another language and reproduction by any process, worldwide, today and in the future.&nbsp;</p> <p>After the first publication by the JGSB, <u>authors hold the copyright without restrictions</u> and are allowed to&nbsp;disclose and distribute their work through personal website pages and institutional repositories.</p> <p>At the same time, the ASSIGNOR declares that the content of the manuscript is of sole responsibility of the authors and that this content does not infringe the copyrights and/or other property rights of third parties, that is, that any contents of the manuscript and its attachments, if taken from other publications, are duly referenced and, when necessary, the permissions for publications of such contents were requested by the authors from the copyright holders; that the disclosure of images (if any) has been authorized and that it assumes full moral and/or patrimonial responsibility, due to its content, before third parties.</p> (Evandro Klein) (Support) Thu, 13 Oct 2022 15:51:56 +0000 OJS 60 Deep crustal structure of the Sergipano Belt, NE-Brazil, revealed by integrated modeling of gravity, magnetic, and geological data <p>The Sergipano Belt is located in the Southern Subprovince of Borborema Province in the Northeast of Brazil. Its tectonic framework was consolidated in the Pan-African-Brasiliano Orogeny at the end of the Neoproterozoic. The most recent geological models indicate that its evolution occurred over a complete Wilson Cycle. Gravity and magnetic data profiles that crossed the Sergipano Belt from south to north were modeled jointly by the forward method to provide a 2D view of the deep crustal structure. The modeling process was linked and supported by the use of geological data and models. The result revealed the deep structure of the crust and identified the geometry of the main geological domains to the depth of Moho discontinuity. The folds and thrusts toward the São Francisco Craton are a persistent and deep feature in the Southern crust of the Sergipano Belt. The general tectonic context of the models is compatible with the subduction and collision of the São Francisco Paleoplate under the Pernambuco-Alagoas Superterrane, sutured in the São Miguel do Aleixo Shear Zone. The presence of dense blocks at the base of the crust was interpreted as layers of ophiolites placed by obduction. The metasediments of the Vaza Barris and Macururé domains are tabular bodies with thicknesses lower than 5 km, which dip horizontally or at a low angle on the flanks of the shear zones. Small vertical bodies of lower density within the Macururé Domain have a correlation with granitic intrusions. In the Canindé Domain there is a dense layer in the lower crust that was interpreted as the relicts of the oceanic crust that based a back-arc basin. The granitic bodies modeled north of the Canindé Domain and correlated with the Serra do Catu batholith in Pernambuco-Alagoas Superterrane, may be the record of subduction of this crust to the north. The data and models revealed geophysical differences between the Jirau do Ponciano and Rio Coruripe domains, and the crust north of the Palmeira dos Índios Shear Zone. These terranes are separated by shear zones with evident expression in gravity and magnetic data. However, the existence of Neoproterozoic metasedimentary supracrustal rocks partially covering both the domains and zones and the boundary shear indicates that the junction among these blocks occurred before the deposition of Neoproterozoic sediments.</p> Roberto Gusmão de Oliveira, Nitzschia Domingos, Walter Medeiros Copyright (c) 2022 Journal (JGSB) and the authors Thu, 13 Oct 2022 00:00:00 +0000 The Zona Transversal Domain of the Borborema Province, northeastern Brazil: Synthesis of the Archean to Cambrian evolution, and new tectono-stratigraphic interpretation <p>The Transversal Zone Domain (TZD) is the central segment of the Borborema Province, with its limits given by the Patos and Pernambuco shear zones, to the north and south respectively. This part of the province presents Archean nuclei surrounded by Paleoproterozoic units that together correspond to the basement of belts of Neoproterozoic metasupracrustal rocks. All this set was intruded by syn to post-tectonic granitoids related to the Brasiliano Orogeny (c. 640 – 500 Ma). The TZD records important shear zones of regional scale, dextral (Patos and Pernambuco), and sinistral (Serra do Caboclo, Afogados da Ingazeira and Congo), being the dextral used to delimit the TZD of adjacent domains and the sinistral ones for internal compartmentalization in four subdomains: Piancó-Alto Brígida, Alto Pajeú, Alto Moxotó and Rio Capibaribe. The lithostratigraphic units of this domain were described and organized in a way that would be regionally presentable. An unprecedented dating is presented for a metagranitoid of the Serra de Jabitaca Complex, with maximum crystallization age at 1790 ± 40 Ma and metamorphism at 615 ± 3 Ma. The tectonic evolution of the domain begins with an orogenic event and development of magmatic arches at the beginning of the Paleoproterozoic (involving Archean portions), in addition to an extensional event at the end of this period, already in the transition with the Mesoproterozoic. The Neoproterozoic begins with two extensional events (Cariris Velhos and pre-Brasiliano) until the formation of the magmatic arches related to Brasiliano Orogeny.</p> Frank Gurgel Santos, Camila Basto, Felipe Lima, Roberta Brasilino, Vladimir Medeiros, Débora Morais, Tercyo Pinéo, Jocilene Santana Copyright (c) 2023 Journal (JGSB) and the authors Fri, 06 Jan 2023 00:00:00 +0000 New zircon U-Pb dating and review of geological and geochronological data with implications for lithostratigraphy and crustal evolution of North Borborema Province, northeastern Brazil <p>The northern portion of the Borborema Province, located north of the Patos Shear Zone (northeast of Brazil) is formed by litho-stratigraphic units dating from the Archean to the Neoproterozoic, with complex evolution resulting from several orogenic and extensional events occurring in this interval. In this work, the litho-stratigraphic units of the Northern Borborema Province were reviewed and ordered here, regarding the rock associations and their chronological positioning. Zircon U-Pb dating of three samples of migmatitic orthogneisses from the Rio Piranhas-Seridó Domain, defined crystallization ages of 561 ± 2 Ma, 574 ± 6 Ma and 547 ± 5 Ma for their protoliths. Thus, the origin of the orthogneisses is related to the syn- to late-tectonic magmatism in relation to the Brasiliano Orogeny. From the Jaguaretama Complex, U-Pb dating of detrital zircons of a migmatitic schist indicates Paleoproterozoic sources, with a maximum deposition age of 2144 Ma. The protolith of a migmatitic orthogneiss has crystallization age of 2186 ± 10 Ma, therefore, contemporary compared to other litho-stratigraphic units of the Borborema Province, which are interpreted as having been developed in the Rhyacian Orogeny.</p> Tercyo Rinaldo Gonçalves Pinéo, Felipe Grandjean da Costa, Camila Franco Basto, Joseneusa Brilhante Rodrigues, Vladimir Cruz de Medeiros, Edney Smith de Moraes Palheta, Bruno de Oliveira Calado, Rogério Cavalcante, Raissa Beloti de Mesquita, Frank Gurgel Santos, Débora Melo Ferrer de Morais, Jocilene dos Santos Santana Copyright (c) 2022 Journal (JGSB) and the authors Thu, 08 Dec 2022 00:00:00 +0000 Review of the lithostratigraphy of the Mesozoic basins of the Borborema Province, Northeastern Brazil <p>Diversas bacias sedimentares fanerozoicas se desenvolveram sobre as rochas da Província Borborema. A formação e abertura do Oceano Atlântico influenciou eventos tectônicos que reativaram grandes lineamentos internos da província (Transbrasiliano, Senador Pompeu, Patos e Pernambuco) culminando com diversas estruturas dentre elas os meios grabens onde se depositaram os sedimentos das bacias intracontinentais. Esta deformação teve papel fundamental no desenvolvimento das bacias da margem continental que formam os segmentos WNW-ESE e N-S do nordeste brasileiro. Este trabalho aborda a porção terrestre das bacias mesozoicas inseridas no contexto da Província Borborema e objetiva disponibilizar uma revisão litoestratigráfica acrescida de alguns dados inéditos das bacias interiores e da Bacia Jatobá. As descrições das bacias marginais foram subdivididas pelos seguintes domínios estruturais: equatorial dextral, ortogonal e a ramificação sul sinistral. As bacias do Ceará e Potiguar fazem parte da margem equatorial. O domínio ortogonal engloba as bacias Pernambuco e Paraíba e é composto pelo bloco crustal equivalente a Zona Transversal da Província Borborema, limitado pelos lineamentos Pernambuco e Patos. As bacias de Sergipe-Alagoas estão situadas na ramificação sinistral. As bacias intracontinentais equivalem aos <em>failed rift arms</em> que são compostos por riftes abortados e os semi-grabens das bacias interiores do nordeste do Brasil. O sistema de rifte Reconcavo-Tucano-Jatobá que foi abortado ainda no Cretáceo Inferior é representado na área da Província Borborema pelas bacias do Tucano Norte e Jatobá. As bacias interiores se concentram na região da Zona Transversal, entretanto, a norte do Lineamento Patos ocorrem importantes bacias como a de Iguatu e Rio do Peixe. As bacias do domínio ortogonal correspondem ao trecho final de rifteamento, sendo uma ruptura tardia no Aptiano devido à rigidez do embasamento. Em função do potencial de exploração petrolífera, as bacias marginais são as que mais apresentam dados disponíveis na literatura. Tanto as bacias marginais de menor potencial petrolífero (como as bacias Pernambuco e Paraíba), quanto às bacias interiores do nordeste, abrangendo a jatobá, precisam de atualização litoestratigráfica mais consistente para consolidar e validar novas unidades propostas.</p> Débora Melo Ferrer de Morais, Cleide Regina Moura da Silva, Frank Gurgel Santos, Tercyo Pinéo, Jocilene dos Santos Santana Copyright (c) 2022 Journal (JGSB) and the authors Fri, 18 Nov 2022 00:00:00 +0000 The arsenic contamination event of Santana, Amapá State, Brazil, and the high values of arsenic in the brownish Amazon waters <p>The contamination with arsenic in Santana led to the perception that the brownish waters of the Amazon River carry arsenic, at a rate higher than 235,000 tonnes per year, and it seems important that this arsenic should be studied in detail. The anomaly was caused by the discharge of tailings of a pellet plant in an excavated sump. These tailings were composed of iron- and arsenic-rich minerals, crystallized at above 900°C in the metallurgical process, which become unstable when submersed in fresh water at pH 5.0-6.0. In the sump, iron, arsenic, manganese, and other metals were slowly solubilized from the minerals, entering the groundwater. When iron got in contact with the water organic compounds, it formed a gel, absorbing As, Mn, and other metals, as it normally happens during weathering in the Amazon. The sump has been built in practically impermeable clayey soil, which made the gel move slowly, giving time to form hard concretions of limonite, characteristic of the Amazonian soil. Iron, manganese, arsenic and other metals were retained in the concretions, and the arsenic-bearing iron gels went for a maximum of some hundreds of meters away from the sump. Soon after the identification of the contamination, the water of the sump was, under close control, discharged into the Amazon River, and the tailings were removed to high ground. In sequence, as it was impossible to properly isolate the tailings, they were sold and shipped away. In the meantime, there were complaints that persons have been affected by arsenic-contaminated water that flowed from a broken dam (that never existed) into a small creek that crossed a community, and that people that consumed the water had cancer. A large medical team was called by the local government, thousands of persons were examined, diseases were found, and none related to arsenic. Analysis of blood and hair presented arsenic in limits worldwide accepted as normal. As samples of the Amazon showed a conspicuous presence of arsenic, they led to the study of the river waters for arsenic. Information is presented to correct misunderstandings present in the literature. Two important points are commented on to understand the event. One is the geological affinity of arsenic with iron. The other is that the toxicity of a solid is determined by how much of the toxic element is liberated for contamination; the standards used for the proper definition of toxicity of a solid are presented.</p> Wilson Scarpelli Copyright (c) 2023 Journal (JGSB) and the authors Mon, 30 Jan 2023 00:00:00 +0000