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Previous issue date: 2016-02-26 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A qu?mica mineral de granitos, juntamente com revis?o de dados qu?micos de rocha total e petrografia foram utilizados para determinar as condi??es de cristaliza??o e as implica??es na g?nese de granitos C?lcio-alcalinos de alto K Porfir?ticos. Seis corpos gran?ticos foram analisados: Monte das Gameleiras, Barcelona, Acari, Cara?bas, Tour?o e Catol? do Rocha, localizados nos dom?nios Rio Piranhas-Serid? e S?o Jos? de Campestre, NE do Brasil. Os pl?tons s?o representados por monzogranitos, texturalmente possuem f?cies porfir?tica compreendendo fenocristais de K-feldspato com tamanhos entre 5 a 15 cm. K-feldspato, plagiocl?sio e quartzo constituem a parag?nese f?lsica e dominante; enquanto biotita e anfib?lio representam os minerais m?ficos principais; titanita, minerais opacos, allanita, ep?doto, apatita e zirc?o s?o os principais acess?rios. Em rela??o ao ?ndice de Shand o granito Monte das Gameleiras mostra-se mais metaluminoso, enquanto os outros seguem a transi??o metaluminoso a peraluminoso. Em diagramas discriminantes qu?micos estes se apresentam com car?ter transicional (subalcalino). As an?lises de petrografia e qu?mica n?o exp?e as diferen?as dos granitos, por?m os resultados de qu?mica mineral revelam as diferen?as dos mesmos e podem ser divididos em dois grupos: a leste (Monte das Gameleiras, Barcelona e Acari) e a oeste (Cara?bas, Tour?o e Catol? do Rocha). As raz?es Fe/(Fe+Mg) da biotita mostra um aumentam do grupo leste para oeste com valores de 0,48 a 0,64 e 0,66 a 0,92 respectivamente. As raz?es Mg/(Mg+Fe2) do anfib?lio diminui nesse sentido com valores de 0,40 a 0,57 e 0,06 a 0,31. As condi??es de cristaliza??es para os granitos a leste (Monte das Gameleiras, Barcelona e Acari) mostram press?o entre 4.2 kbar a 5.8 kbar, com profundidades que variam de 15,9 km a 20,5 km a uma temperatura entre 710 ?C a 734?C e a oeste (Cara?bas, Tour?o e Catol? do Rocha) com press?es de 5,4 kbar a 7,1 kbar e profundidades que variam de 20 km a 23 km a uma temperatura entre 729 ?C - 753 ?C. Ambas as ?reas, tanto leste como oeste foram gerados a partir de magmas oxidados. As profundidades das intrus?es gran?ticas podem estar relacionadas aos deslocamentos de falhas e ao alto conte?do de ?gua e vol?teis que permitem que o magma de alguns plutons atinja n?veis mais rasos em rela??o aos outros. Os resultados mostram um aumento sistem?tico de temperatura e press?o de cristaliza??o dos pl?tons de leste para oeste sugerindo um espessamento crustal nessa dire??o nos dois dom?nios geol?gicos pesquisados. / The mineral chemistry from granites, chemical of whole rock and review of petrography
were used to determine the crystallization conditions and the implications in the genesis of
high-K calc-akaline granites that are porphyritics, localizated in the Rio Piranhas-Serid?
(RPSD) and S?o Jos? de Campestre Domains (SJCD). Six granitic bodies were analyzed
and that for the intrusive granites within the SJCD were named East granites: Monte das
Gameleiras, Barcelona. The Acari granite intrudes the area RPSD, however, was called as
granite east due to the characteristics of mineral chemistry is similar to east granites.
Granites Cara?bas, Tour?o and Catol? do Rocha are intrusive in the RPSD and called west
granites. The six bodies are located in the northeast of the Borborema Province, NE Brazil.
The plutons are represented by monzogranites wich have porphyritic facies with
phenocrysts of K-feldspar with sizes between 5 and 15 cm. The K-feldspar, plagioclase
and quartz are the dominant paragenesis; while the biotite and amphibole are the main
mafic minerals; and titanite, opaque minerals, allanite, epidote, apatite and zircon are the
accessories minerals. The Monte das Gameleiras granite shows metaluminous aluminium
saturation index, whereas the others plutons metaluminous to peraluminous. In
geochemical diagrams, the granites present with transitional character (subalcalino). The
petrographic and geochemical analysis didn't show the differences between the plutons, but
according to the mineral chemistry they can be divided into two groups: Monte das
Gameleiras, Barcelona and Acari (east) and Cara?bas, Tour?o e Catol? do Rocha (west).
The Fe/(Fe + Mg) ratio of biotite shows an increase from east to west group with values
from 0.45 to 0.64 and 0.66 to 0.92 respectively, and the Mg / (Mg + Fe2) of amphibole
decreases with values from 0.40 to 0.57 and from 0.07 to 0.31. The crystallization
parameters of east granites, The crystallization conditions for granites east (Monte das
Gameleiras, Barcelona and Acari) show pressure between 3.8 kbar to 5.5 kbar, with depths
ranging from 14 km to 21 km at a temperature between 701 ? C to 742?C and west
(Cara?bas, Tour?o and Catol? Rock) with pressures to 4.8 kbar to 6.2 kbar and depths
ranging from 18 km to 23 km at a temperature between 723 ? C - 776 ? C. Both areas, east
and west were generated from magmas oxidized with ?FQM values (-1 a +2.0). The
depths of granite intrusion failures may be related to offsets and high water content and
volatile that allow the magma some plutons reaches shallower levels in relation to the
other. The results show a systematic increase in temperature and crystallization pressure
east of plutons west suggesting crustal thickening in that direction. The results show a systematic increase in temperature and crystallization pressure east to west plutons, suggesting crustal thickening in that direction in the two domains studied.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/21307 |
| Date | 26 February 2016 |
| Creators | Campos, Benedita Cleide de Souza |
| Contributors | 90459261487, http://lattes.cnpq.br/5356037408083015, Mariano, Gorki, 07019785387, http://lattes.cnpq.br/9480872229631779, Medeiros, Vladimir Cruz de, 28943180497, http://lattes.cnpq.br/9369889068441214, Vilalva, Frederico Castro Jobim, Nascimento, Marcos Antonio Leite do |
| Publisher | Universidade Federal do Rio Grande do Norte, PROGRAMA DE P?S-GRADUA??O EM GEODIN?MICA E GEOF?SICA, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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