Please use this identifier to cite or link to this item: http://repositorio.ufc.br/handle/riufc/64732
Type: Artigo de Periódico
Title: History of volcanism and sedimentation synchronous with plutonism during Rhyacian in Serra das Pipocas Greenstone Belt, Borborema Province, NE Brazil
Authors: Sousa, Herdivânia Pires de
Parente, Clóvis Vaz
Magini, Christiano
Ximenes, Dillano Rodrigues Bastos
Dantas, Elton Luiz
Caby, Renaud
Rosa Júnior, Cecílio Aguiar
Keywords: Paleoproterozoic;Ceará Central Domain;Magnesian schists;Metabasalt;Geochemistry;Geochronology
Issue Date: 2019
Publisher: Journal of South American Earth Sciences
Citation: SOUSA, Herdivânia Pires de et al. History of volcanism and sedimentation synchronous with plutonism during Rhyacian in Serra das Pipocas Greenstone Belt, Borborema Province, NE Brazil. Journal of South American Earth Sciences, [s. l.], v. 95, n. 102220, p. 1-20, 2019.
Abstract: The Serra das Pipocas Greenstone Belt is one of the rare Paleoproterozoic greenstone belts within the Borborema Province. It is on the west border of the Archean/Paleoproterozoic Nucleus (Cruzeta and Mombaça Complex) of the Ceará Central Domain, northern portion of the Borborema Province. The Serra das Pipocas Greenstone Belt has an elongated sigmoidal shape encompassing about 1000 km2 of the Ceará Central Domain. It consists of a metavolcanosedimentary sequence formed by metasedimentary psammitic-pelitic-marly rocks and interleaved metaultramafic and metamafic rocks, represented by chlorite-anthophyllite-actinolite/tremolite schists and amphibolites. Layers of metatuffs, metabasic, meta-acid sills (metadacites), metacherts, gondites and banded iron formations occur within the metamafic rocks. Actinolite, metagabbro, metadiorite bodies, metabasic dike, Neoproterozoic metagranodiorites and leucogranites crosscut the metavolcanosedimentary sequence. Close to the borders of metagranodioritic bodies (zircon U–Pb 2181 ± 4.4 Ma), the metavolcanosedimentary sequence is hydrothermally altered. The metaultramafic rock (chlorite-anthophyllite-actinolite/tremolite schist) contains high MgO (> 18 wt%), low alkali (≤1 wt%) and TiO2 (< 0.8 wt%) and Al2O3/TiO2 ratios between 9.94 and 27.26, with a mean value of 17.13. Values of (Gd/Yb)N vary between 1.00 and 1.88, which attest affiliation with komatiite protoliths, between the Munro and Barberton types. The amphibolites are usually fine-grained and depleted in ΣREE (33.14–45.02 ppm), with low (La/Yb)CH values (0.74–3.82). This reflects weak LREE enrichment in relation to HREE, and no Ce and Eu anomalies [(Eu/Eu*)n between 0.98 and 1.04]. Such patterns are similar to TMORB (1.7–4.3). Additionally, some mafic-ultramafic metaplutonic rocks present chemical composition similar to their volcanic counterparts, and this may indicate cumulates or sills contemporary to this sequence. Zircon U–Pb dating using LA-ICP-MS of three distinct metadacite occurrences (western border: 2234 ± 13 Ma, eastern border: 2212 ± 13 Ma, and central portion: 2156 ± 45 Ma) and metagranodiorites (2181 ± 4.4 Ma) indicates that the sequence was formed during the Rhyacian/Orosirian and later affected by late Neoproterozoic.
URI: http://www.repositorio.ufc.br/handle/riufc/64732
ISSN: 0895-9811
Access Rights: Acesso Aberto
Appears in Collections:DGL - Artigos publicados em revista científica

Files in This Item:
File Description SizeFormat 
2019_art_epsousa.pdf22,53 MBAdobe PDFView/Open


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.