Pub Date : 2018-12-22DOI: 10.21715/GB2358-2812.2018322115
David B. Smith, A. Demetriades, P. Caritat, Xueqiu Wang
Global-scale, or continental-scale, geochemical surveys cover millions of square kilometers of the Earth’s surface generally at a very low sample density (1 site per 1,000 to 10,000 km 2 ). Geochemical patterns produced from these low-density surveys reflect processes that act at the broad scale of sampling. These processes are related to many factors including tectonics, climate, weathering, geochemical and mineralogical composition of the original soil parent material, continental-scale glaciation, topography, regional-scale alteration and mineralization, and in some cases, human activity. A multi-element geochemical atlas of the Earth’s land surface based on this type of survey has been a topic of discussion among applied geochemists since the 1980s. Over the past 15 years, several global-scale geochemical surveys have been conducted (Australia, China, Europe, India, Mexico, United States of America) and the data and maps are being used as a tool to aid in environmental and resource management. In 2016, the establishment of both the International Union of Geological Sciences (IUGS) Commission on Global Geochemical Baselines and the United Nations Educational, Scientific and Cultural Organization (UNESCO) International Centre for Global-Scale Geochemistry has provided a hopeful future for continuing global-scale geochemical mapping in other parts of the world, with the ultimate product being a global geochemical database and atlas derived from this data set.
{"title":"The history, progress, and future of global-scale geochemical mapping","authors":"David B. Smith, A. Demetriades, P. Caritat, Xueqiu Wang","doi":"10.21715/GB2358-2812.2018322115","DOIUrl":"https://doi.org/10.21715/GB2358-2812.2018322115","url":null,"abstract":"Global-scale, or continental-scale, geochemical surveys cover millions of square kilometers of the Earth’s surface generally at a very low sample density (1 site per 1,000 to 10,000 km 2 ). Geochemical patterns produced from these low-density surveys reflect processes that act at the broad scale of sampling. These processes are related to many factors including tectonics, climate, weathering, geochemical and mineralogical composition of the original soil parent material, continental-scale glaciation, topography, regional-scale alteration and mineralization, and in some cases, human activity. A multi-element geochemical atlas of the Earth’s land surface based on this type of survey has been a topic of discussion among applied geochemists since the 1980s. Over the past 15 years, several global-scale geochemical surveys have been conducted (Australia, China, Europe, India, Mexico, United States of America) and the data and maps are being used as a tool to aid in environmental and resource management. In 2016, the establishment of both the International Union of Geological Sciences (IUGS) Commission on Global Geochemical Baselines and the United Nations Educational, Scientific and Cultural Organization (UNESCO) International Centre for Global-Scale Geochemistry has provided a hopeful future for continuing global-scale geochemical mapping in other parts of the world, with the ultimate product being a global geochemical database and atlas derived from this data set.","PeriodicalId":34597,"journal":{"name":"Geochimica Brasiliensis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45722777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-22DOI: 10.21715/GB2358-2812.2018322136
A. Demetriades, David B. Smith, Xueqiu Wang
Planning an effective geochemical sampling campaign to meet survey objectives should be based on a phased or stepwise use of applied geochemical methods, starting from a desktop study that collects and evaluates all available data and information. This is followed by a field investigation, which should begin with an orientation survey, where a variety of sampling media, sample preparation methods, and analytical protocols are tested with the objective of finding the most cost-effective methodology to be applied in the succeeding steps of the follow-up and detailed investigations. Sampling is the most important part in any geochemical survey for mineral exploration or environmental purposes. Apart from sampling, another significant part of a survey is sample preparation. Mistakes in sampling and sample preparation are difficult to trace and affect the final results and success of a survey. Hence, these are the two parts of a geochemical survey that should be performed with the utmost care. Sampling procedures for stream sediment, overbank or floodplain sediment, stream water, ground water, rock, and residual soil are described, as well as sampling in the laboratory. The importance of randomisation of samples and implementation of strict quality control procedures are also discussed. Finally, it is emphasised that the success of any geochemical survey, including global geochemical baseline mapping, depends on the training of the applied geochemist.
{"title":"General concepts of geochemical mapping at global, regional, and local scales for mineral exploration and environmental purposes","authors":"A. Demetriades, David B. Smith, Xueqiu Wang","doi":"10.21715/GB2358-2812.2018322136","DOIUrl":"https://doi.org/10.21715/GB2358-2812.2018322136","url":null,"abstract":"Planning an effective geochemical sampling campaign to meet survey objectives should be based on a phased or stepwise use of applied geochemical methods, starting from a desktop study that collects and evaluates all available data and information. This is followed by a field investigation, which should begin with an orientation survey, where a variety of sampling media, sample preparation methods, and analytical protocols are tested with the objective of finding the most cost-effective methodology to be applied in the succeeding steps of the follow-up and detailed investigations. Sampling is the most important part in any geochemical survey for mineral exploration or environmental purposes. Apart from sampling, another significant part of a survey is sample preparation. Mistakes in sampling and sample preparation are difficult to trace and affect the final results and success of a survey. Hence, these are the two parts of a geochemical survey that should be performed with the utmost care. Sampling procedures for stream sediment, overbank or floodplain sediment, stream water, ground water, rock, and residual soil are described, as well as sampling in the laboratory. The importance of randomisation of samples and implementation of strict quality control procedures are also discussed. Finally, it is emphasised that the success of any geochemical survey, including global geochemical baseline mapping, depends on the training of the applied geochemist.","PeriodicalId":34597,"journal":{"name":"Geochimica Brasiliensis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49280584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-22DOI: 10.21715/GB2358-2812.2018322180
G. Salomão, R. Dall’Agnol, P. Sahoo, Jair da Silva Ferreira Junior, M. Silva, P. W. S. Filho, J. Berrêdo, W. N. Júnior, M. Costa
Geochemical survey in the Vermelho (VSB) and Sororo (SSB) sub-basins of the Itacaiunas basin in southeastern Amazonian region has shown that the physical-chemical parameters of stream water do not display accentuated variations between the rainy and dry seasons. Except for Fe and Mn, in general most metals show low contents in water and evidences of significant contamination were not observed. Higher contents were mostly registered during the rainy season. Fe is regularly distributed in water in the studied area and the increase of its concentration was favored by deforestation. Mn contents increase during the dry season possibly due to biogeochemical processes. High Fe and Mn contents in water are inherent to the specific local conditions prevalent in the Amazonian region. Geogenic influence in metal distribution in water is significant for Co, Cr, Cu, Ni, Pb, Sn, V, and Zn. Anthropic effects are subordinate except for Fe and Mn or in local areas. The definition of threshold values for As, Co, Cr, and Pb, was limited, however, threshold values for Cu, Ni, Sn, V, and Zn were estimated for at least one season in each sub-basin. Threshold values of total iron were obtained (5 to 6 mg/L and 2 to 3 mg/L in the rainy and dry seasons, respectively). Estimated Mn threshold values are 0.30 to 0.45 mg/L in the rainy season and in the dry season they decrease to 0.20 to 0.30 mg/L in VSB and increase to 1.3 to 1.4 mg/L in SSB.
{"title":"Geochemical distribution and threshold values determination of heavy metals in stream water in the sub-basins of Vermelho and Sororó rivers, Itacaiúnas River watershed, Eastern Amazon, Brazil","authors":"G. Salomão, R. Dall’Agnol, P. Sahoo, Jair da Silva Ferreira Junior, M. Silva, P. W. S. Filho, J. Berrêdo, W. N. Júnior, M. Costa","doi":"10.21715/GB2358-2812.2018322180","DOIUrl":"https://doi.org/10.21715/GB2358-2812.2018322180","url":null,"abstract":"Geochemical survey in the Vermelho (VSB) and Sororo (SSB) sub-basins of the Itacaiunas basin in southeastern Amazonian region has shown that the physical-chemical parameters of stream water do not display accentuated variations between the rainy and dry seasons. Except for Fe and Mn, in general most metals show low contents in water and evidences of significant contamination were not observed. Higher contents were mostly registered during the rainy season. Fe is regularly distributed in water in the studied area and the increase of its concentration was favored by deforestation. Mn contents increase during the dry season possibly due to biogeochemical processes. High Fe and Mn contents in water are inherent to the specific local conditions prevalent in the Amazonian region. Geogenic influence in metal distribution in water is significant for Co, Cr, Cu, Ni, Pb, Sn, V, and Zn. Anthropic effects are subordinate except for Fe and Mn or in local areas. The definition of threshold values for As, Co, Cr, and Pb, was limited, however, threshold values for Cu, Ni, Sn, V, and Zn were estimated for at least one season in each sub-basin. Threshold values of total iron were obtained (5 to 6 mg/L and 2 to 3 mg/L in the rainy and dry seasons, respectively). Estimated Mn threshold values are 0.30 to 0.45 mg/L in the rainy season and in the dry season they decrease to 0.20 to 0.30 mg/L in VSB and increase to 1.3 to 1.4 mg/L in SSB.","PeriodicalId":34597,"journal":{"name":"Geochimica Brasiliensis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46527288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-22DOI: 10.21715/GB2358-2812.2018322199
N. Mirlean, M. Gripp
We have carried out a geochemical mapping of soil cover of industrial and residential sectors of the city of Rio Grande (RS). Various anomalous zones of mercury, copper, zinc, lead, nickel, chromium and iron have been identified, which corresponded to the historic-spatial allocation of different industries in the city. The mapping of the city's territory using the complex eco-geochemical index Zc demonstrated that most of the urban area is contaminated with metals up to the level requiring mandatory mitigation measures. The application of the method of sequential subtraction from the complex index of elements by the degree of their participation in the contamination of the territory made it possible to establish a paragenetic association of metals Cu, Pb, Zn, which forms the centers of metal contamination in the city. Based on the data received, an assessment of the pollution of the urban area was carried out in accordance with Brazilian legislation . This evaluation testified that studied soil belongs to Class 4 according to legislative norms, which means that the city needs immediate environmental management in terms of eliminating risks to human health and the environmental planning of future land use.
{"title":"Geochemical mapping and environmental indexing of an urban area (Rio Grande, RS)","authors":"N. Mirlean, M. Gripp","doi":"10.21715/GB2358-2812.2018322199","DOIUrl":"https://doi.org/10.21715/GB2358-2812.2018322199","url":null,"abstract":"We have carried out a geochemical mapping of soil cover of industrial and residential sectors of the city of Rio Grande (RS). Various anomalous zones of mercury, copper, zinc, lead, nickel, chromium and iron have been identified, which corresponded to the historic-spatial allocation of different industries in the city. The mapping of the city's territory using the complex eco-geochemical index Zc demonstrated that most of the urban area is contaminated with metals up to the level requiring mandatory mitigation measures. The application of the method of sequential subtraction from the complex index of elements by the degree of their participation in the contamination of the territory made it possible to establish a paragenetic association of metals Cu, Pb, Zn, which forms the centers of metal contamination in the city. Based on the data received, an assessment of the pollution of the urban area was carried out in accordance with Brazilian legislation . This evaluation testified that studied soil belongs to Class 4 according to legislative norms, which means that the city needs immediate environmental management in terms of eliminating risks to human health and the environmental planning of future land use.","PeriodicalId":34597,"journal":{"name":"Geochimica Brasiliensis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46961299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-04DOI: 10.21715/GB2358-2812.2018321079
A. Horn, W. Trindade, P. Aranha, A. P. Magalhães, I. Torres
The industrial, farming and housing occupation of the upper to middle San Francisco basin is getting stronger, resulting in an increase of the environmental impact. Marginal lagoons, which are important support for wildlife and water supply are invaded during the flooding of the river and filled with material. The aim of this study was to characterize the particle size distribution, chemical and mineral development shown in the profiles of these marginal lagoons and correlate with the environmental evolution and impacts. Granulometric and geophysical studies were carried out using combined sieves, GPR (Ground Penetrating Radar), total chemical analysis by X-Ray Fluorescence and sequential leaching analyses by Inductively Coupled Plasma-Optical Emission Spectroscopy. The granulometric and mineralogical results showed a predominance of silt, alternating with sandy layers, indicating the annual and seasonal energy evolution and depositional source. Investigations with GPR show horizontal sets formed by the change of energy deposition. Selected elements (Ni, Zn, Co, As, Pb, Cu) showed a continue enrichment with higher concentration on the surface. All elements concentrations are related to the clay/silt fraction, thus allowing the use of this fraction for the investigation of the impact assessment. Chromium is related to sandy layers indicating its correlation with the mineral content. The positive correlation between Ni, Zn and Pb indicate industrial influence (refinement of Zn, heavy industry) the correlation Cu, Ni, Co and As may derive from the use of agro products. The elements Pb, Zn and Cu presented at the top of the profiles concentrations above legislation limits.
{"title":"Evironmental evaluation of the middle São Francisco River basin between Três Marias and Pirapora, using chemical and geophysical investigation in sediment profiles from selected marginal lagoons","authors":"A. Horn, W. Trindade, P. Aranha, A. P. Magalhães, I. Torres","doi":"10.21715/GB2358-2812.2018321079","DOIUrl":"https://doi.org/10.21715/GB2358-2812.2018321079","url":null,"abstract":"The industrial, farming and housing occupation of the upper to middle San Francisco basin is getting stronger, resulting in an increase of the environmental impact. Marginal lagoons, which are important support for wildlife and water supply are invaded during the flooding of the river and filled with material. The aim of this study was to characterize the particle size distribution, chemical and mineral development shown in the profiles of these marginal lagoons and correlate with the environmental evolution and impacts. Granulometric and geophysical studies were carried out using combined sieves, GPR (Ground Penetrating Radar), total chemical analysis by X-Ray Fluorescence and sequential leaching analyses by Inductively Coupled Plasma-Optical Emission Spectroscopy. The granulometric and mineralogical results showed a predominance of silt, alternating with sandy layers, indicating the annual and seasonal energy evolution and depositional source. Investigations with GPR show horizontal sets formed by the change of energy deposition. Selected elements (Ni, Zn, Co, As, Pb, Cu) showed a continue enrichment with higher concentration on the surface. All elements concentrations are related to the clay/silt fraction, thus allowing the use of this fraction for the investigation of the impact assessment. Chromium is related to sandy layers indicating its correlation with the mineral content. The positive correlation between Ni, Zn and Pb indicate industrial influence (refinement of Zn, heavy industry) the correlation Cu, Ni, Co and As may derive from the use of agro products. The elements Pb, Zn and Cu presented at the top of the profiles concentrations above legislation limits.","PeriodicalId":34597,"journal":{"name":"Geochimica Brasiliensis","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42209805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-04DOI: 10.21715/GB2358-2812.2018321020
Renan Siqueira, A. N. Sial, V. P. Ferreira
Granitos Ediacaranos calci-alcalinos, calci-alcalinos de alto potassio, shoshoniticos, peralcalinos e trondhjemiticos intrudiram o Terreno Cachoeirinha-Salgueiro (CST) no Dominio da Zona Transversal, Nordeste do Brasil. Os plutons Tamboril e Olho d’Agua tem assembleias mineralogicas semelhantes, mas texturas distintas. O pluton Olho d’Agua e composto de clinopiroxenio-biotita tonalito de granulacao media, equigranular, com anfibolio e epidoto magmatico, enquanto que o pluton Tamboril consiste de biotita granodiorito medio a grosso, porfiritico, com clinopiroxenio e megacristais de plagioclasio. Nos plutons Tamboril e Olho d’Agua, clinopiroxenio e substancialmente menos abundante quando ha a presenca de epidoto, ou seja, o aumento de clinopiroxenio modal e diretamente proporcional a diminuicao do epidoto modal, assim como ocorre no pluton Pedra Branca. Os xenolitos ricos em anfibolios sao considerados fragmentos que se destacaram de uma fonte profunda e podem representar restitos da fusao parcial de uma fonte anfibolitica. Elementos maiores apontam estes plutons como calcio-alcalinos de alto-K, metaluminosos, com caracteristicas de granitos magnesianos do tipo Cordilheirano. A norma CIPW aponta uma composicao de monzogranito para o pluton Tamboril e granodiorito para o pluton Olho d’Agua. Estes plutons tem valores de susceptibilidade magnetica baixos (≈0,3×10 -3 SI), que sao tipicos de granitos do tipo-S. Entretanto, granitos tipo-I com epidoto magmatico no Terreno Cachoeirinha−Salgueiro tambem tem baixos valores de susceptibilidade magnetica (<0,5×10 -3 SI) porque o Fe +3 esta ligado a estrutura do epidoto. A mineralogia metaluminosa mostra que e improvavel que os magmas de Tamboril e Olho d’Agua sofreram assimilacao crustal. Zonacoes oscilatorias em fina escala e inclusoes de biotita e epidoto comuns em megacristais de plagioclasios e feldspatos potassicos sugerem conveccao na câmara magmatica ou variacao de condicoes fisico-quimica durante a cristalizacao. Parece haver duas geracoes de clinopiroxenios: idiomorfico, sem inclusoes e hipidiomorficos, com inclusoes de diversos minerais. Estes ultimos, cheios de inclusoes, podem ser considerados residuos da fonte original do magma.
{"title":"Granitos com epidoto magmático e clinopiroxênio: plútons Tamboril e Olho d’Água, Terreno Cachoeirinha−Salgueiro, Nordeste do Brasil","authors":"Renan Siqueira, A. N. Sial, V. P. Ferreira","doi":"10.21715/GB2358-2812.2018321020","DOIUrl":"https://doi.org/10.21715/GB2358-2812.2018321020","url":null,"abstract":"Granitos Ediacaranos calci-alcalinos, calci-alcalinos de alto potassio, shoshoniticos, peralcalinos e trondhjemiticos intrudiram o Terreno Cachoeirinha-Salgueiro (CST) no Dominio da Zona Transversal, Nordeste do Brasil. Os plutons Tamboril e Olho d’Agua tem assembleias mineralogicas semelhantes, mas texturas distintas. O pluton Olho d’Agua e composto de clinopiroxenio-biotita tonalito de granulacao media, equigranular, com anfibolio e epidoto magmatico, enquanto que o pluton Tamboril consiste de biotita granodiorito medio a grosso, porfiritico, com clinopiroxenio e megacristais de plagioclasio. Nos plutons Tamboril e Olho d’Agua, clinopiroxenio e substancialmente menos abundante quando ha a presenca de epidoto, ou seja, o aumento de clinopiroxenio modal e diretamente proporcional a diminuicao do epidoto modal, assim como ocorre no pluton Pedra Branca. Os xenolitos ricos em anfibolios sao considerados fragmentos que se destacaram de uma fonte profunda e podem representar restitos da fusao parcial de uma fonte anfibolitica. Elementos maiores apontam estes plutons como calcio-alcalinos de alto-K, metaluminosos, com caracteristicas de granitos magnesianos do tipo Cordilheirano. A norma CIPW aponta uma composicao de monzogranito para o pluton Tamboril e granodiorito para o pluton Olho d’Agua. Estes plutons tem valores de susceptibilidade magnetica baixos (≈0,3×10 -3 SI), que sao tipicos de granitos do tipo-S. Entretanto, granitos tipo-I com epidoto magmatico no Terreno Cachoeirinha−Salgueiro tambem tem baixos valores de susceptibilidade magnetica (<0,5×10 -3 SI) porque o Fe +3 esta ligado a estrutura do epidoto. A mineralogia metaluminosa mostra que e improvavel que os magmas de Tamboril e Olho d’Agua sofreram assimilacao crustal. Zonacoes oscilatorias em fina escala e inclusoes de biotita e epidoto comuns em megacristais de plagioclasios e feldspatos potassicos sugerem conveccao na câmara magmatica ou variacao de condicoes fisico-quimica durante a cristalizacao. Parece haver duas geracoes de clinopiroxenios: idiomorfico, sem inclusoes e hipidiomorficos, com inclusoes de diversos minerais. Estes ultimos, cheios de inclusoes, podem ser considerados residuos da fonte original do magma.","PeriodicalId":34597,"journal":{"name":"Geochimica Brasiliensis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43113318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-04DOI: 10.21715/GB2358-2812.2018321001
Luisa Costa Martins Vieira, T. M. Dussin, Leila Nunes Menegasse Velásquez
Elementos maiores e tracos das rochas carbonaticas neoproterozoicas da Formacao Sete Lagoas aflorantes na regiao englobando a Area de Protecao ambiental do Carste Lagoa Santa, a norte de Belo Horizonte, foram analisados para obter informacoes sobre as condicoes paleoambientais de deposicao. A base Formacao Sete Lagoas e representada pelo Membro Pedro Leopoldo de composicao pelito-carbonatica, caracterizado por teores variados de Ca (14,6-39,4%) e Si (0,23-20,12%) e baixo conteudo de Mg (0,05-1,98%) e Al (0,08-3,9%). Os teores de Th, U e Zr sao elevados e os padroes de ETR+Y sao caracterizados por leve enriquecimento de ETR pesados, anomalias positivas de La e negativas de Ce. O Membro Pedro Leopoldo e sobreposto pelas rochas carbonaticas mais puras e escuras do Lagoa Santa. Estes marmores mostram altas concentracoes de Ca (38,6 a 40,5%) e mais baixos teores de Si (0,02-1%), de Mg (0,08-0,23%) e de Al (0,01-0,27%). Sao caracterizados por concentracoes mais baixas de Th, U e Zr relativamente a sequencia inferior, anomalias negativas de La e positivas de Ce e Y, e por ampla variacao do fracionamento de ETR leves e pesados. As caracteristicas petrograficas e geoquimicas sugerem que a sedimentacao comecou em ambiente marinho, sob aguas profundas, anoxicas e com marcada contribuicao terrigena. As caracteristicas quimicas do Membro Lagoa Santa indicam que neste periodo o ambiente de deposicao mudou, evoluindo para mais proximal e oxico.
{"title":"Geoquímica e condições paleoambientais de deposição das rochas carbonáticas da Formação Sete Lagoas na região da Área de Proteção Ambiental Carste de Lagoa Santa, MG","authors":"Luisa Costa Martins Vieira, T. M. Dussin, Leila Nunes Menegasse Velásquez","doi":"10.21715/GB2358-2812.2018321001","DOIUrl":"https://doi.org/10.21715/GB2358-2812.2018321001","url":null,"abstract":"Elementos maiores e tracos das rochas carbonaticas neoproterozoicas da Formacao Sete Lagoas aflorantes na regiao englobando a Area de Protecao ambiental do Carste Lagoa Santa, a norte de Belo Horizonte, foram analisados para obter informacoes sobre as condicoes paleoambientais de deposicao. A base Formacao Sete Lagoas e representada pelo Membro Pedro Leopoldo de composicao pelito-carbonatica, caracterizado por teores variados de Ca (14,6-39,4%) e Si (0,23-20,12%) e baixo conteudo de Mg (0,05-1,98%) e Al (0,08-3,9%). Os teores de Th, U e Zr sao elevados e os padroes de ETR+Y sao caracterizados por leve enriquecimento de ETR pesados, anomalias positivas de La e negativas de Ce. O Membro Pedro Leopoldo e sobreposto pelas rochas carbonaticas mais puras e escuras do Lagoa Santa. Estes marmores mostram altas concentracoes de Ca (38,6 a 40,5%) e mais baixos teores de Si (0,02-1%), de Mg (0,08-0,23%) e de Al (0,01-0,27%). Sao caracterizados por concentracoes mais baixas de Th, U e Zr relativamente a sequencia inferior, anomalias negativas de La e positivas de Ce e Y, e por ampla variacao do fracionamento de ETR leves e pesados. As caracteristicas petrograficas e geoquimicas sugerem que a sedimentacao comecou em ambiente marinho, sob aguas profundas, anoxicas e com marcada contribuicao terrigena. As caracteristicas quimicas do Membro Lagoa Santa indicam que neste periodo o ambiente de deposicao mudou, evoluindo para mais proximal e oxico.","PeriodicalId":34597,"journal":{"name":"Geochimica Brasiliensis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45037486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-04DOI: 10.21715/gb2358-2812.2018321095
P. Phani
Trends in concentration of selected trace elements in residual soils on four known diamondiferous kimberlite pipes (3, 4, 8 and 9) occurring at Lattavaram within the Wajrakarur Kimberlite Field (WKF) is attempted for the first time. The pipes 3 and 4 are exposed whereas the 8 and 9 are concealed under calcrete and colluvium. For this purpose, elements like Nb, Cr, Ni, Co, Zr, Mg, Sr and La are used to understand their concentrations in the kimberlitic soils in comparison with background granitic soils. It is observed that the soils on kimberlite pipes show conspicuous enrichment of elements such as Cr, Co, Nb, Ni, Mg and Sr when compared to soils in the country rock granitoid. However, no much variation in the elements La and Zr patterns between the kimberlitic and background soils is noticed. The high pulse in trace elements in kimberlitic soils is attributed to the presence of primary kimberlitic minerals and their weathered products in the soil. This particular aspect of pedogeochemistry is envisaged to be useful as an exploration tool in search of kimberlites in cratonic parts of southern India. An enrichment of Nb content upto 45 ppm in residual soils may be considered as anamolous in the craonic parts of Indian subcontinent, which needs to be confirmed and taken forward in conjunction with high resolution geological mapping, geophysics followed up by drilling for confirmation of kimberlite/lamproite occurrence.
{"title":"Role of trace element Pedogeochemistry in Diamond Exploration- A first Report from Lattavaram Kimberlite Cluster, Wajrakarur Field, Eastern Dharwar Craton, southern India","authors":"P. Phani","doi":"10.21715/gb2358-2812.2018321095","DOIUrl":"https://doi.org/10.21715/gb2358-2812.2018321095","url":null,"abstract":"Trends in concentration of selected trace elements in residual soils on four known diamondiferous kimberlite pipes (3, 4, 8 and 9) occurring at Lattavaram within the Wajrakarur Kimberlite Field (WKF) is attempted for the first time. The pipes 3 and 4 are exposed whereas the 8 and 9 are concealed under calcrete and colluvium. For this purpose, elements like Nb, Cr, Ni, Co, Zr, Mg, Sr and La are used to understand their concentrations in the kimberlitic soils in comparison with background granitic soils. It is observed that the soils on kimberlite pipes show conspicuous enrichment of elements such as Cr, Co, Nb, Ni, Mg and Sr when compared to soils in the country rock granitoid. However, no much variation in the elements La and Zr patterns between the kimberlitic and background soils is noticed. The high pulse in trace elements in kimberlitic soils is attributed to the presence of primary kimberlitic minerals and their weathered products in the soil. This particular aspect of pedogeochemistry is envisaged to be useful as an exploration tool in search of kimberlites in cratonic parts of southern India. An enrichment of Nb content upto 45 ppm in residual soils may be considered as anamolous in the craonic parts of Indian subcontinent, which needs to be confirmed and taken forward in conjunction with high resolution geological mapping, geophysics followed up by drilling for confirmation of kimberlite/lamproite occurrence.","PeriodicalId":34597,"journal":{"name":"Geochimica Brasiliensis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47443131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-04DOI: 10.21715/GB2358-2812.2018321062
Said Abdallah
Atraves do estudo de litogeoquimica dos granitos localizados no norte do Mato Grosso (Brasil) permitiu identificar caracteristicas geoquimicas, em relacao aos elementos menores e maiores, de series magmaticas calcio-alcalina alto K, semelhantes aos granitos tipo A2, possivelmente com origem mantelica contaminado por elementos crustais. A assinatura geoquimica assemelha-se aos granitos de sistemas Pos-colisionais a Pos-orogenicos, alguns tendendo para caracteristicas geoquimicas de ambiente de sistemas Intraplaca a Anorogenicos. As idades geocronologicas U-Pb situam-se entre o Orosiriano (Paleoproterozoico) ate o Calimiano (Mesoproterozoico) e em funcao da distribuicao multielementar e o padrao de elementos terras raras, aplicando-se varios modelos discriminantes, estes apresentam uma mesma origem ou fonte primordial para estas granitogeneses.
{"title":"Estudo litogeoquímico dos granitóides do norte do Mato Grosso (Brasil), litogênese do sistema plutônico granítico pós-colisional a intraplaca na porção sul do cráton amazônico","authors":"Said Abdallah","doi":"10.21715/GB2358-2812.2018321062","DOIUrl":"https://doi.org/10.21715/GB2358-2812.2018321062","url":null,"abstract":"Atraves do estudo de litogeoquimica dos granitos localizados no norte do Mato Grosso (Brasil) permitiu identificar caracteristicas geoquimicas, em relacao aos elementos menores e maiores, de series magmaticas calcio-alcalina alto K, semelhantes aos granitos tipo A2, possivelmente com origem mantelica contaminado por elementos crustais. A assinatura geoquimica assemelha-se aos granitos de sistemas Pos-colisionais a Pos-orogenicos, alguns tendendo para caracteristicas geoquimicas de ambiente de sistemas Intraplaca a Anorogenicos. As idades geocronologicas U-Pb situam-se entre o Orosiriano (Paleoproterozoico) ate o Calimiano (Mesoproterozoico) e em funcao da distribuicao multielementar e o padrao de elementos terras raras, aplicando-se varios modelos discriminantes, estes apresentam uma mesma origem ou fonte primordial para estas granitogeneses.","PeriodicalId":34597,"journal":{"name":"Geochimica Brasiliensis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44005026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-04DOI: 10.21715/GB2358-2812.2018321048
Ana Carina Matos Silva, Sanye Soroldoni Guimarães, Olívia-Maria Cordeiro de-Oliveira, Í. T. A. Moreira, J. Triguis, Manoel Jerônimo Moeira-Cruz
In an oil spill in mangrove areas, there is a great possibility of oil aggregation with suspended particulate matter, which may determine the bottom sediment as the final destination of OSA (Oil-Suspended Particulate Matter Aggregates), posing a great risk to Benthic organisms. Ecotoxicity tests with these organisms have been widely used as one of the most accurate forms of biological monitoring of the anthropogenic impacts on this ecosystem. The present work evaluates the ecotoxicity of the exposure to OSA in mangrove sediments, collected along the Pardo river estuary, Canavieiras, Bahia, through pilot scale (microscale) trials. The procedure was performed using acute exposure toxicological tests to determine LC50 (lethal concentration 50%) using the benthic copepod Nitokra sp. For the purpose of comparison, two scenarios were performed, the first considers the aqueous phase of the OSA simulation protocol in microscale, and the second, the elutriate from sediment and oil homogenized in different fractions. It was verified that the formation of the OSA has a much less toxic potential (LC50 70.71) in relation to elutriate formed from the percentages of homogenized sediment with crude oil (LC50 5.59) confirming its potential as an effective form of cleaning for oil treatment in water.
{"title":"Sensibilidade do copépode Nitokra sp. à exposição ao agregado óleo-material particulado em suspensão (OSA)","authors":"Ana Carina Matos Silva, Sanye Soroldoni Guimarães, Olívia-Maria Cordeiro de-Oliveira, Í. T. A. Moreira, J. Triguis, Manoel Jerônimo Moeira-Cruz","doi":"10.21715/GB2358-2812.2018321048","DOIUrl":"https://doi.org/10.21715/GB2358-2812.2018321048","url":null,"abstract":"In an oil spill in mangrove areas, there is a great possibility of oil aggregation with suspended particulate matter, which may determine the bottom sediment as the final destination of OSA (Oil-Suspended Particulate Matter Aggregates), posing a great risk to Benthic organisms. Ecotoxicity tests with these organisms have been widely used as one of the most accurate forms of biological monitoring of the anthropogenic impacts on this ecosystem. The present work evaluates the ecotoxicity of the exposure to OSA in mangrove sediments, collected along the Pardo river estuary, Canavieiras, Bahia, through pilot scale (microscale) trials. The procedure was performed using acute exposure toxicological tests to determine LC50 (lethal concentration 50%) using the benthic copepod Nitokra sp. For the purpose of comparison, two scenarios were performed, the first considers the aqueous phase of the OSA simulation protocol in microscale, and the second, the elutriate from sediment and oil homogenized in different fractions. It was verified that the formation of the OSA has a much less toxic potential (LC50 70.71) in relation to elutriate formed from the percentages of homogenized sediment with crude oil (LC50 5.59) confirming its potential as an effective form of cleaning for oil treatment in water.","PeriodicalId":34597,"journal":{"name":"Geochimica Brasiliensis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43288952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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