Browsing by Author "Ferreira, Ezequiel"
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- Cartografía Geológica del Plan Nacional de Geología de Angola (PLANAGEO)Publication . Merino-Martínez, E.; Rodrigues, José Feliciano; Martín-Banda, Raquel; Francés, Alain Pascal; Feria, María Carmen; López-Bahut, T.; Ferreira, Ezequiel; García-Lobón, J. L.; Gumiel, J. C.; Cuervo, I.; Victorino, Américo da Mata; Manuel, JoséRESUMEN: La cartografía geológica fue la actividad central en la que se basó el Plan Nacional de Geología de Angola (PLANAGEO). Los trabajos de cartografía geológica realizados por el consorcio UTE PLANAGEO (IGME/LNEG/IIA) en el sur de Angola (476.512 km2), desarrollados entre 2016 y 2020, comprendieron 44 cartas a escala 1:250.000, 15 cartas a escala 100.000, 8 mapas de síntesis a escala 1:500.000 y 4 mapas geotemáticos a escala 1:1.000.000. A partir de estos trabajos, fueron distinguidos diversos dominios geológicos en el sur del Escudo de Angola, delimitados por macroestructuras bien definidas en los modelos geofísicos. Los mapas y sus memorias asociadas reúnen todo el conocimiento generado durante PLANAGEO, siendo un manual de referencia geológica y un modelo para futuros estudios geológico-mineros. Los mapas geológicos realizados constituyen la base de una infraestructura regional de conocimiento geológico de la región sur de Angola, y proporcionan información básica para el aprovechamiento óptimo del territorio y desarrollar el potencial de los recursos naturales del país.
- Zircon U-Pb and Lu-Hf isotopes reveal the crustal evolution of the SW Angolan Shield (Congo Craton)Publication . Ferreira, Ezequiel; Lehmann, Jeremie; Rodrigues, José Feliciano; Hayes, Ben; Merino-Martinez, Enrique; Milani, Lorenzo; Bybee, Grant M.; Smith, Trishya M. Owen; García-Lobón, J. L.; Tassinari, Colombo C. G.; Ueckermann, Henriette; Sato, Kei; Silva, Paulo Bravo; Correia, João; Labaredas, José; Duarte, Laurent; Molekwa, Mmasetena Anna; Manuel, José; Victorino, Américo da MataABSTRACT: The crustal evolution of the Angolan Shield (AS) remains poorly constrained. To address this, we analysed U-Pb and Lu-Hf isotopes in detrital and igneous zircons to investigate the age and provenance of extensive sedimentary strata in southwestern Angola and use it as a proxy to gain insight into the Archean to Mesoproterozoic evolution of the region. Mesoproterozoic maximum depositional ages for the Iona (<1323 +/- 13 Ma), Ompupa (<1215 +/- 13 Ma), and Cahama (<1184 +/- 23 Ma) siliciclastics challenge previous correlations with the Paleoproterozoic Chela Group. Provenance analysis reveals that the Mesoproterozoic strata were derived internally from the AS. Our combined dataset indicates that the widespread Eburnean magmatism (-2.05-1.93 Ga) resulted from reworking of Archean crust, possibly in collision orogens. A major increase in the eHf(i) and eNd(i) values at - 1.87-1.73 Ga indicates a change in geodynamics, with magmatism of the Epupa-Namibe Metamorphic Complex (ENMC) generated in an extensional accretionary orogen at the southern margin of the Eburnean-Archean crustal block. Magmatism resumed in the Mesoproterozoic (-1.56-1.50 Ga), with suprachondritic eHf(i) values indicating significant juvenile addition. The Kunene Complex (KC: -1.50-1.36 Ga) anorthosite-mangerite-charnockite-granite magmatism displays variable eHf(i) and eNd(i) values, consistent with mixing between reworked ENMC-crust and juvenile melts in a long-lived accretionary orogen back-arc region. Post-KC (-1.36-1.30 Ga) magmatism shows an increased juvenile contribution, potentially linked to partial melting of ENMC and - 1.56-1.50 Ga juvenile crust during an orogenic event, or alternatively, related to renewed slab retreat and back-arc extension. The Hf isotopic compositions of - 1.29-1.18 Ga zircons are compatible with a renewed input from the depleted mantle and/or reworking of the earlier - 1.56-1.50 Ga juvenile crust. Emplacement of - 1.13-1.10 Ga mafic dikes/sills marks the end of Mesoproterozoic magmatism in the AS. Our new data enhance our understanding of the Archean to Mesoproterozoic crustal evolution of the AS.