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https://repositorio.ufrn.br/handle/123456789/19459| Title: | Caracterização petrográfica e litogeoquímica de granitoides ediacaranos no extremo NE da Província da Borborema (NE do Brasil) com ênfase nos plútons Gameleira, Pitombeira e Taipu |
| Authors: | Oliveira, Maria Tatiany Duarte de |
| Advisor: | Nascimento, Marcos Antonio Leite do |
| Keywords: | Província Borborema;Domínio São José de Campestre;Plúton Pitombeira;Plúton Taipu;Plúton Gameleira;Petrografia;Litogeoquímica |
| Issue Date: | 26-Feb-2014 |
| Publisher: | Universidade Federal do Rio Grande do Norte |
| Citation: | OLIVEIRA, Maria Tatiany Duarte de. Caracterização petrográfica e litogeoquímica de granitoides ediacaranos no extremo NE da Província da Borborema (NE do Brasil) com ênfase nos plútons Gameleira, Pitombeira e Taipu. 2014. 89f. Dissertação (Mestrado em Geodinâmica e Geofísica) - Centro de Ciências Exatas e da Terra, Universidade Federal do Rio Grande do Norte, Natal, 2014. |
| Portuguese Abstract: | A área estudada situa-se, geograficamente, no extremo NE do Estado do Rio Grande do Norte situados nos municípios de Taipu e Poço Branco e geologicamente inseridos no Terreno Cristalino São José do Campestre pertencente à Província Borborema, onde observando relações de campo, dados petrográficos e geoquímicos, permitiram individualizar três plútons denominados: Gameleira, Taipu e Pitombeira. O Plúton Gameleira é composto por rochas granodioríticas caracterizadas por fenocristais zonados de plagioclásios e tendo anfibólio e biotita como máficos principais. Quimicamente, são rochas metaluminosas, de natureza cálcio-alcalina e apresentam caráter magnesiana. O Plúton Pitombeira é composto por duas fácies: (a) uma monzogranítico à sienogranítica de textura grossa a porfirítica caracterizada por fenocristais de K-feldspato e (b) uma de composição quartzo diorítica a tonalítica distinta por suas ripas de plagioclásio parcialmente zonadas e com borda de resfriamento. Quimicamente são rochas transicionais entre metaluminosas a peraluminosas, de natureza subalcalina (cálcio-alcalina de alto K) e caráter ferroso. Por fim, o Plúton Taipu é formado por rochas monzograníticas a sienograníticas, contendo biotita como máfico principal. São rochas peraluminosas, de natureza subalcalinas (cálcio-alcalina de alto K) e caráter ferroso. No que se refere às análises de elementos terras raras (ETR), pode-se inferir que os três plútons estudados apresentam anomalias negativas de Eu e enriquecimento em ETR leves, com razões de LaN/YbN entre 9,38 a 16,20 ppm (Plúton Gameleira), 17,99 a 31,39 ppm (fácies granítica do Plúton Pitombeira), 14,15 a 21,81 ppm (fácies diorítica do Plúton Pitombeira) e 15,17 a 175,41 ppm (Plúton Taipu). Analisando os dados químicos e os diagramas em conjunto é possível sugerir que os plútons estudados pertencem a um ambiente tectônico tardi a pós-colisional. Abstract The studied area is geographically situated in the extreme northeastern of Rio Grande do Norte State located in the municipalities of Taipu and Poço Branco and geologically entered in the Crystalline Land São José do Campestre which belongs to Borborema Province, where by observing the field relations, petrographic and geochemical datas, has allowed to individualize three plutons named: Gameleira, Taipu and Pitombeira. The Gameleira Pluton consists in granodioritic rocks characterized by phenocrysts zoned plagioclase having amphibole and biotite as the main mafic. Which are Chemically, metaluminous rocks, naturally from calc-alkaline and present magnesian character. The Pitombeira Pluton consists in two facies: (a) one monzogranite-syenogranite to coarse texture and to the porphyritic characterized by K-feldspar phenocrysts and (b) quartz dioric-tonalitic composition to a distinct for its laths of plagioclase partially zoned and also with cooling edges. Chemically are transitional rocks between metaluminous to peraluminous, naturally from subalkaline (high-K calc-alkaline) and ferrous character. Thus, the Taipu pluton is formed by monzagranitic-sienogranitic rocks, containing biotite as its main mafic. They are peraluminous rocks, naturally subalkaline (high-K calc-alkaline) and ferrous character. As regards to the rare earth elements analysis (REE), which can be inferred that the three studied plutons exhibit negative anomalies of Eu and REE slight enrichment, with ratios of LaN / YbN between 9.38 to 16.20 ppm (Gameleira Pluton) 17.99 to 31.39 ppm (Pluton Pitombeira granitic facies), from 14.15 to 21.81 ppm (Pluton Pitombeira dioritic facies) and from 15.17 to 175.41 ppm (Pluton Taipu). Analyzing the chemical and diagrams datas to one another, it’s allowed to suggest that the studied plutons belong to a late tectonic environment to a post-collisional. |
| Abstract: | The studied area is situated in the northeastern extremity of the Rio Grande do Norte State, between the municipalities of Taipu and Poço Branco, and is geologically inserted into the São José do Campestre Crystalline Terrain within the Borborema Province, where the analysis of field relationships, petrographic and geochemical data allowed the distinction of three plutons named: Gameleira, Taipu and Pitombeira. The Gamaleira Pluton is composed of granodioritic rocks characterized by zoned plagioclase phenocrysts, with amphibole and biotite as the main mafic phases. Geochemically, these are metaluminous rocks of calc-alkaline nature and magnesian character. The Pitombeira Pluton encompasses two facies: (a) a coarse-grained to porphyritic monzo- to syenogranitic facies marked by K-feldspar phenocrysts; and (b) a quartz dioritic to tonalitic facies with partially zoned plagioclase laths showing chilled rims. Geochemically, rocks of the monzo- to syenogranitic facies are transitional between metaluminous and peraluminous, display a subalkaline nature (high K calc-alkaline) and a ferroan character, whereas rocks of the quartz dioritic to tonalitic facies are metaluminous, with shoshonitic affinity and ferroan character. Lastly, the Taipu Pluton is made of monzoto syenogranitic rocks with biotite as the chief mafic mineral. They are peraluminous rocks of subalkaline nature (high-K calc-alkaline) and ferroan character. Regarding the rare-earth elements (REE), it is possible to conclude that the three studied plutons display negative Eu anomalies and a relative enrichment of LREE over HREE, with LaN/YbN ratios between 9.39 to 16.20 (Gameleira Pluton), 17.99 to 31.39 (granitic facies of the Pitombeira Pluton), 14.15 to 21.81 (dioritic facies of the Pitombeira Pluton) and 15.17 to 175.41 (Taipu Pluton). Based on the combined investigation of geochemical data and discrimination tectonic diagrams, a late- to post-collisional tectonic environment is suggested for the plutons here studied |
| URI: | https://repositorio.ufrn.br/jspui/handle/123456789/19459 |
| Appears in Collections: | PPGG - Mestrado em Geodinâmica e Geofísica |
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|---|---|---|---|---|
| MariaTatianyDuarteDeOliveira_DISSERT.pdf | 9,62 MB | Adobe PDF |  View/Open |
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