11 documents found, page 1 of 2
Petrografia e litoquímica das formações ferríferas bandadas da região de Quixer...
Veríssimo, César Ulisses Vieira; Magini, Christiano; Parente, Clóvis Vaz; Nogueira Neto, José de Araújo; Almeida, Afonso Rodrigues deTwo new occurrences of banded iron formations (BIF’s) had been identified in the regions of Quixeramobim and Boa Viagem, Ceará State. The occurrences are associated to the Neoarchean to Paleoproterozoic rocks of the Cruzeta Complex, whose Sm/Nd - TDM model ages vary between 2,3 and 3,2 Ga. The chemical analyses of major elements in six samples show a relatively simple chemical composition, with SiO 2 and Fe2O3 ...
Age of magmatic events in the Eopaleozoic Jaibaras Basin, NE Brazil: Constraint...
Garcia, Maria da Gloria Motta; Parente, Clóvis Vaz; Silva Filho, Wellington Ferreira da; Almeida, Afonso Rodrigues deThe Late Neoproterozoic to Early Paleozoic Jaibaras Basin is located between the southeastern margin of the Medio Coreaú Domain (MCD) and northwestern edge of the Cear a Central Domain (CCD) of the Borborema Province, Northeastern Brazil, which is also the location of the main axis of the Transbrasiliano Lineament. The lower volcano-sedimentary rocks in the Jaibaras Basin are composed of two lower Vendian-Cambr...
Geology, petrography and mineral chemistry of iron oxide-apatite occurrences (I...
Parente, Clóvis Vaz; Veríssimo, César Ulisses Vieira; Botelho, Nilson Francisquini; Xavier, Roberto Perez; Menez, Jacqueline; Lino, Ramon de OliveiraIron oxide-apatite (IOA) occurrences have recently been identified in the western sector of the Neoproterozoic Santa Quitéria magmatic arc (Ceará state, northeast Brazil), close to the boundary with the Paleozoic Parnaíba Basin. The IOA mineralization is hosted by albitized metadiorites and metavolcano-sedimentary rocks, which are crosscut by a late- to post-Brasiliano/Pan-African biotite granite intrusion with...
Vestiges of a continental margin ophiolite type in the Novo Oriente region, Bor...
Pitombeira, João Paulo Araújo; Amaral, Wagner da Silva; Uchôa Filho, Evilarde Carvalho; Fuck, Reinhardt Adolfo; Dantas, Elton Luiz; Parente, Clóvis VazThe Novo Oriente Group is a restricted well-preserved metasedimentary sequence, composed of two tectonic-stratigraphic sequences in the southwestern portion of the Cear a Central Domain, NE Brazil. The Bonsucesso Formation comprises mainly quartzite and metamafic rocks and the Caraúbas Formation is dominantly metapelitic, with chemical sedimentary contribution, metamafic and metaultramafic rocks. New integrated...
The Itataia phosphate-uranium deposit (Ceará, Brazil) new petrographic, geochem...
Veríssimo, César Ulisses Vieira; Santos, Roberto Ventura; Parente, Clóvis Vaz; Oliveira, Claudinei Gouveia de; Cavalcanti, José Adilson DiasThe Itataia phosphate-uranium deposit is located in Santa Quiteria, in central Cear a State, northeastern Brazil. Mineralization has occurred in different stages and involves quartz leaching (episyenitization), brecciation and microcrystalline phase formation of concretionary apatite. The last constitutes the main mineral of Itatiaia uranium ore, namely collophane. Collophanite ore occurs in massive bodies, len...
Depósitos de escarnitos mineralizados em ferro e cobre do arco magmático de San...
Parente, Clóvis Vaz; Veríssimo, Cesar Ulisses Vieira; Botelho, Nilson Francisquini; Santos, Ticiano José Saraiva dos; Oliveira, Claudinei Gouveia deW-Mo skarns deposits in the Borborema Province have been known since the 40’s, however, until this study there were no records of Fe-Cu skarns. In Ceará State, Brazil, the first occurrences of Fe-Cu skarns were identified recently in the Magmatic Arc of Santa Quiteria, product of superposition of several magmatic arcs, ranging from juvenile arc (870 – 800 Ma), up to continental collision (625 – 600 Ma). The ska...
Carbon isotope fluctuations in Precambrian carbonate sequences of several local...
Sial, Alcides N.; Ferreira, Valderez P.; Almeida, Afonso R. de; Romano, Antonio W.; Parente, Clóvis Vaz; Costa, Marcondes L. da; Santos, Victor H.Carbon isotope fluctuations in Precambrian sedimentary carbonates between 2.8 Ga and 0.60 Ga in Brazil are examined in this study. The carbonate facies of the BIF of the 2.8 Ga-old Carajás Formation, state of Pará in northern Brazil, has rather homogeneous delta13C (-5 o/ooPDB), compatible with carbonatization of a silicate protolith by a CO2-rich fluid from mantle degassing. The Paleoproterozoic Gandarela Form...
Geology and geochemistry of paleoproterozoic magnesite deposits (-1.8Ga), State...
Parente, Clóvis Vaz; Ronchi, Luis Henrique; Sial, Alcides Nóbrega; Guillou, Jean Jacques; Arthaud, Michel Henri; Fuzikawa, KazuoFive important magnesite mines and small occurrences in the state of Ceara form a sequence of lenses that extend, discontinuously, for over 140km. The magnesite rocks are hosted by metadolomites with lutecite, sulphate nodules pseudomorphosed by fiber-radiated quartz, scapolite and dissolution breccias. This metacarbonate sequence is more voluminous and more calcic in the southwestern extremity ofthe belt, but ...
A hydrothermal karst-hosted U-P deposit related to Pangea break-up: Itataia dep...
Cavalcanti, José Adilson D.; Bessa, Maria Dulcinea M. R.; Santos, Roberto Ventura; Veríssimo, Cesar U. V.; Parente, Clóvis VazThe Itataia U-P deposit holds the second largest uranium reserve in Brazil. All of the uranium is contained within the microcrystalline structure of fluorapatite, which is the ore mineral of the collophanite bodies. The main lithology that hosts the mineralization is marble, and the collophanite occurs as massive bodies, stockwork vein, breccia, filling vugs in episyenites, and disseminated in host rocks. This ...
Modelagem multidados dos corpos metamáficos-ultramáficos do greenstone belt Ser...
Sousa, Herdivânia Pires de; Parente, Clóvis Vaz; Magini, Christiano; Ximenes, Dillano Rodrigues BastosThe Serra das Pipocas Greenstone Belt, with rhyacian age (2.1 - 2.2Ga), is part of the Archean/Paleoproterozoic core of the Ceará Central Domain, and is located at the northern portion of Borborema Province, near the municipality of Independência and neighboring areas. Lithostructural mapping techniques associated with the analysis of airborne geophysical (Magnetometry and Gamma spectrometry), spectral (Landsat...