Brazilian Journal of Geology最新文献_第9页

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

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

Age and petrogenesis of the beryl-bearing granitic magmatism of the Velasco Pegmatite District, Pampeana Province, NW Argentina 阿根廷西北部潘皮亚纳省Velasco伟晶岩区含绿柱石花岗质岩浆活动的年龄和岩石成因

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202120210030

F. Sardi, Silvana Marangone, J. M. Fuenlabrada

引用次数: 0

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

High-precision laser ablation inductively coupled plasma mass spectrometry determination of trace elements in geological glasses by internal standardization 高精度激光烧蚀电感耦合等离子体质谱法测定地质玻璃中的微量元素

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202120210018

A. Wegner, F. Leitzke, C. Porcher, R. Conceição, M.E.B. Gomes, D. G. Cedeño, M. R. O. Souza

引用次数: 0

Practical mineralogical quantification of bentonites supported for a PXRD calibrated hkl model PXRD校准hkl模型支持膨润土的实际矿物学定量

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202120200088

David Enrique Vega Porras, R. Angélica, S. Paz

{"title":"Practical mineralogical quantification of bentonites supported for a PXRD calibrated hkl model","authors":"David Enrique Vega Porras, R. Angélica, S. Paz","doi":"10.1590/2317-4889202120200088","DOIUrl":"https://doi.org/10.1590/2317-4889202120200088","url":null,"abstract":"In the bentonite industry — exploration and beneficiation — ore quality control has been traditionally carried out using the swelling parameter, denominating those that swell as naturally sodium bentonites and those that do not as naturally non-sodium bentonites. However, the properties of the bentonites can vary due to the quantity and cationic type of montmorillonite. The variation in those properties cannot always be predicted, because there is still no consolidated and convenient method for clays mineralogical quantification. A quantification via PXRD using the Rietveld method is only reliable when all the crystalline structures of the mineral phases are known. This is not the case for bentonites, since the montmorillonite shows turbostratic disorder that leads to extremely wide and asymmetric non-basal reflections that are not considered in the available structural models. Thus, in this work, is generate a calibrated hkl model for a Brazilian montmorillonite applying the combined Rietveld-Le Bail-Internal Standard method developed by Paz et al . (2018). The study concluded that the combined method is a good choice for the mineralogical quantification of the bentonites, handling turbostratic disorder of montmorillonite, since the develop hkl phase model showed good results in mixtures with >50% montmorillonite content (greater precision and reproducibility).","PeriodicalId":9221,"journal":{"name":"Brazilian Journal of Geology","volume":"19 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72872816","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: 3

Influence of preexisting structures on the variation of neotectonic paleostress orientation in an area of the Southeastern Brazilian Margin 巴西东南边缘地区先存构造对新构造古应力方向变化的影响

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202120190132

T. C. Brêda, C. L. Mello, A. Moraes

{"title":"Influence of preexisting structures on the variation of neotectonic paleostress orientation in an area of the Southeastern Brazilian Margin","authors":"T. C. Brêda, C. L. Mello, A. Moraes","doi":"10.1590/2317-4889202120190132","DOIUrl":"https://doi.org/10.1590/2317-4889202120190132","url":null,"abstract":"The Southeastern Brazilian Margin presents a NE-SW-striking structural framework, which is characteristic of the Neoproterozoic Ribeira Belt. Other important structural trends along the area are associated with E-W and NW-SE-striking structures, being most related to the Mesozoic-Cenozoic tectonic evolution. A succession of Cenozoic tectonic events has been described by many authors in the Southeastern Brazilian. Among those Cenozoic tectonic events, a Neogene to Quaternary E-W dextral strike-slip regime (EW-DT) shows a wide distribution, presenting some variations in the stress field orientation. This research investigates the influence of the preexisting structural framework on the variation of the paleostress field orientation associated with the EW-DT tectonic event in a selected area in the onshore continental margin of the Southeastern Brazil. The study was carried out in three main stages: lineament analysis, paleostress field analysis, and numerical mechanical modeling. The paleostress field related to the EW-DT tectonic event in the studied area presents: NNW-SSE-striking maximum horizontal stress, and counterclockwise rotation influenced by the structural framework. Regarding this, the regional variation of the paleostress field is influenced by a preferential reactivation of NE-SW-striking structures while sets of approximately E-W-striking structures are the main local control of counterclockwise rotation of the stress field.","PeriodicalId":9221,"journal":{"name":"Brazilian Journal of Geology","volume":"9 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73091852","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

Mineralogy, geochemistry and parent rock of Décio bauxite-bearing lateritic profile (Rondon do Pará, Eastern Amazon) 东亚马逊Rondon do par<e:1>含铝土矿红土剖面的矿物学、地球化学和母岩特征

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202120210037

Pabllo Henrique Costa dos Santos, M. Costa

引用次数: 3

Continental freshwater carbonate coated grains: oncoids in Quaternary deposits of the Serra da Bodoquena region, Central-West Brazil 大陆淡水碳酸盐包覆颗粒:巴西中西部Serra da Bodoquena地区第四纪沉积物中的蛇尾类

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202220210042

Adelita Carolina Rodrigues, Larissa da Rocha Santos, L. Cury, A. B. Rumbelsperger

引用次数: 0

Support method for interpretation of regional groundwater monitoring in urban areas 城市区域地下水监测解译的支持方法

IF 1.4 4区地球科学

Brazilian Journal of Geology Pub Date : 2021-01-01 DOI: 10.1590/2317-4889202120200053

Fabio Pileggi, R. Hirata, Nataly Aranda, Bruno Conicelli

引用次数: 2