http://repositorio.ufc.br/handle/riufc/315 2026-04-14T10:01:28Z 2026-04-14T10:01:28Z Martins, Jackson Alves Castro, Neivaldo Araújo de Castelo Branco, Raimundo Mariano Gomes http://repositorio.ufc.br/handle/riufc/65398 2023-10-10T17:24:05Z 2016-01-01T00:00:00Z

Título: A morfologia superficial da estrutura circular de São Miguel do Tapuio (Piauí-BR) e casos similares no território brasileiro Autor(es): Martins, Jackson Alves; Castro, Neivaldo Araújo de; Castelo Branco, Raimundo Mariano Gomes Abstract: The circular structure of São Miguel do Tapuio (ECSMT) is a striking geomorphological feature noted in the Mesopaleozoic sandstones of Parnaiba basin (Piaui-BR). In this work the morphological characterization of ECSMT surface was mainly provided using SRTM topographic data. Such characterization allowed us to outline a 20 Km diameter and define the following: the circular structural pattern distinguished in its relief, the high symmetrical degree, the presence of borders and core topographically uplifted, as well as the correlation of relief features with deformed and thermal transformed compartments described according to field surveys and petrographic studies. The features of the main circular and semi-circular structures of endogenous source (ECSCOEN) and exogenous source (ECSCOEX) found in the Brazilian territory allow us to establish that the ECSCOEN with diameters from 8 to 38 Km barely have perfect circular morphology, they are associated directly or indirectly to Mesozoic igneous complex; the ECSCOEX presents perfect circular morphology with diameters from 4.5 to 40 Km and they are highly coplex impact structures. The morphological characteristics of ECSMT surface are compatible with the ones shown by the ECSCOEX. Despite the structural and textural features found in the ECSMT may be only suggestive to classify them as an ECSCOEX type, in the other hand, the lack of identification of the outcropping and/or subsurface igneous rock does not allow us to classify it as an ECSCOEN type. Tipo: Artigo de Periódico

2016-01-01T00:00:00Z Lima, Jefferson Valdemiro de Guimarães, Ignez de Pinho Santos, Lucilene Farias, Douglas José Antunes, José Victor http://repositorio.ufc.br/handle/riufc/65311 2023-10-10T17:33:53Z 2017-01-01T00:00:00Z

Título: Química mineral e condições de cristalização de granitos intrudidos ao longo da Zona de Cisalhamento Remígio - Pocinhos, NE do Brasil: Plúton Pilõezinhos Autor(es): Lima, Jefferson Valdemiro de; Guimarães, Ignez de Pinho; Santos, Lucilene; Farias, Douglas José; Antunes, José Victor Abstract: The Pilõezinhos Pluton (PP). comprises a ~100 km2-elongated intrusion in the NE part of the Transversal Domain of the Borborema Province. It is composed of monzogranites and syenogranites, subdivided into two distinct petrographic facies. The PP intrudes the boundary between the dextral Remigio - Pocinhos and sinistral Matinhas shear zones. The main objective of this work is to characterize the conditions of crystallization from the PP granites. The main mineralogy was characterized by petrography and Electron Microprobe mineral chemistry analysis. It consists of quartz; alkali feldspars (microcline and pertite); plagioclase, ranging from oligoclase to andesine; siderophillite-rich biotite; and amphibole, with composition ranging from hastingsite to Fe-tschermakite. The accessory mineralogy comprises titanite, zircon, apatite, oxides, dominantly ilmenite, and allanite grains holding large amount of REE. The mineral chemistry defined that the magma crystallization occurred at temperature ranging from 745 to 1003 °C, defined from the amphibole – plagioclase geothermometer and Zr geothermometer, and pressure from 4.28-5.98 kbar (geobarometer of AlT in hornblendas).Iron-rich mafic mineralogy and the presence of primary ilmenite suggest crystallization under low fO2conditions, below the FMQ buffer. Rebalancing in subsolidus conditions occurs due to the action of late fluids, with temperatures ranging from 505 to 566 ° C, is suggested by the presence of sericite, chlorite and myrmekite. The mineralogical, chemical and structural features suggest that the PP granites represent A2-type magmatism, which evolved by fractional crystallization. Tipo: Artigo de Periódico

2017-01-01T00:00:00Z Pedrosa, Adriana Albuquerque Claudino-Sales, Vanda Cavalcante, Itabaraci Nazareno Carvalho, Alexandre Medeiros http://repositorio.ufc.br/handle/riufc/65310 2023-10-10T17:33:42Z 2019-01-01T00:00:00Z

Título: Recent dune migration along the coastal plain of Canoa Quebrada, Ceará state, Northeast Brazil Autor(es): Pedrosa, Adriana Albuquerque; Claudino-Sales, Vanda; Cavalcante, Itabaraci Nazareno; Carvalho, Alexandre Medeiros Abstract: In the coastal area of Ceará State, northeast Brazil, there are large mobile dunefields, including barchans, barchanoid dunes and sandsheets. The migration rate of these dunes, as measured by several studies, varies between 32 m/y and 9 m/y. This paper analyzes the migration of the dunes in Canoa Quebrada Beach, located in the eastern coast of Ceará State, using remote sensing of aerial photos and satellite imagery from 1988 to 2013 (25 years). The resulting data indicate an average migration rate varying from 1.8 m/y to 9.3 m/y. This is the lowest rate of migration measured for large and undeveloped mobile dunes in Ceará State. The analysis indicates that the element responsible for this low rate is the low wind speed. However, the installation of wind power turbines in the area – which demanded the fixation of part of the dunes to prevent the equipment from being buried and from aeolian erosion – might be another reason for the decreasing dune migration. The dune migration decrease may increase the sedimentary deficit in the coastline downdrift of Canoa Quebrada Beach. Tipo: Artigo de Periódico

2019-01-01T00:00:00Z Mattos, Irani Clezar Artur, Antonio Carlos Nogueira Neto, José de Araújo http://repositorio.ufc.br/handle/riufc/65297 2023-10-10T17:27:04Z 2013-01-01T00:00:00Z

Título: Caracterização petrográfica e tecnológica de granitosornamentais do stock granítico Serra do Barriga, Sobral/CE Autor(es): Mattos, Irani Clezar; Artur, Antonio Carlos; Nogueira Neto, José de Araújo Abstract: Petrographic analysis and technological behaviour of four varieties of granitic dimension stones from Serra da Barriga stock, in NNW Ceará State, Brazil, are presented in this work. The investigated rock types are commercially known as Rosa Iracema, Rosa Olinda, Branco Savana and Branco Cristal Quartzo and are classified as isotropic, inequigranular syenogranites and monzogranites, medium to coarse grained, with colours ranging between pink and white. The technological tests results, of physical and mechanical parameters were very similar between the four rock samples and put the analysed granites as having good technological properties, suitable for coatings for both indoors and outdoors environments. The correlations between rock physical and mechanical characteristics results, show the importance of mineralogical, textural and structural aspects of some dimension stone granites technological properties. Among the verified most influence petrographic parameters, stand out the rocks coarse grains, quartz content, microcracking level, mineral weathering, which control, higher or lower level, apparent porosity, water absorption, mechanical resistance (uniaxial and flexural strength), impact, Amsler abrasion, thermal expansion and ultrasonic waves propagation, of that granites. Tipo: Artigo de Periódico

2013-01-01T00:00:00Z