The Metamorphic and Plutonic Rocks of the Almansor River: Geological Heritage to Preserve

Authors

Manuel Francisco Perira
Department of Geosciences at the School of Science and Technology (ECT) University of Évora
http://orcid.org/0000-0001-9032-2318
Keywords: Migmatites; Gneisses; Granitic rocks; Orogeny; Pangea Supercontinent; Carboniferous; Geological site; Natural Heritage

Synopsis

In the Almansor River, surrounding Montemor-o-Novo city, are found outcrops of metamorphic rocks formed around 340 million years ago, at least 11 km depth and under high temperatures (migmatites and gneisses) in association with magmatic rocks (granitic rocks). The geodiversity observed here has an extraordinary scientific and educational interest that should be preserved and studied for the benefit of present and future generations. This work intends, by summarizing the geological information that is available in the scientific literature on these geological sites, to warn of the importance of implementing actions for the valorization, conservation, and dissemination of the Natural Heritage in the Alentejo region.

Author Biography

Manuel Francisco Perira, Department of Geosciences at the School of Science and Technology (ECT) University of Évora

Manuel Francisco Pereira is a lecturer at the Department of Geosciences of the School of Sciences and Technology (ECT) and a researcher at the Institute of Earth Sciences of the University of Évora (UÉ). He graduated in Geology in 1991 at the Faculty of Sciences of the University of Lisbon (FCUL) and joined UÉ as a trainee researcher in 1992. In 1995, he obtained a master's degree in Internal Dynamics Geology at FCUL, and in 1996 he started his university teaching career at UÉ. He obtained a Ph.D. in 2000, and the title of Aggregate in 2009 in Geology at UÉ. He is currently responsible for curricular units of the 1st cycle of Biology and Geology (Stratigraphy; Geodynamics and Tectonics) and of the 2nd cycle of Geology (Tectonics and Sedimentary Processes) and of Paleontology (Geochronology applied to Paleontology). In 2022, according to the SCOPUS database, he has 89 references of articles published in scientific journals, 2412 citations in 905 documents, and h-index = 30.

References

Dias da Silva, Í.; Pereira, M.F.; Silva, J.B.; Gama, C., (2018). Time-space distribution of silicic plutonism in a gneiss dome of the Iberian Variscan Belt: The Évora Massif (Ossa-Morena Zone, Portugal): Tectonophysics, 747–748, 298–317, https://doi.org/10.1016/j.tecto.2018.10.015.

Moita, P.; Santos, J.F.; Pereira, M.F., (2009). Layered granitoids: Interaction between continental crust recycling processes and mantle-derived magmatism: Examples from the Évora Massif (Ossa-Morena Zone, southwest Iberia, Portugal): Lithos, 111, 3, 125–141, https://doi.org/10.1016/j.lithos.2009.02.009.

Pereira, M.F.; Silva, J.B.; Chichorro, M.; Moita, P.; Santos, J.F.; Apraiz, A.; Ribeiro, C., (2007). Crustal growth and deformational processes in the northern Gondwana margin: Constraints from the Évora Massif (Ossa-Morena zone, southwest Iberia, Portugal), In: Linnemann, U., Nance, R.D., Kraft, P., Zulauf, G., (Eds.), The Evolution of the Rheic Ocean: From Avalonian-Cadomian Active Margin to Alleghenian-Variscan Collision, Geological Society of America Special Paper 423, 333–358, https://doi.org/10.1130/2007.2423(16).

Pereira, M.F.; Chichorro, M.; Williams, I.S.; Silva, J.B., (2008). Zircon U-Pb geochronology of paragneisses and biotite granites from the SW Iberian Massif (Portugal): Evidence for a palaeogeographical link between the Ossa-Morena Ediacaran basins and the West African craton, In: Ennih, N., Liégeois, J.-P., (Eds.), The Boundaries of the West African Craton, The Geological Society of London Special Publication 297, 385–408, https://doi.org/10.1144/SP297.18.

Pereira, M.F.; Chichorro, M.; Williams, I.S.; Silva, J.B.; Fernández, C.; Díaz-Azpíroz, M.; Apraiz, A.; Castro, A., (2009). Variscan intra-orogenic extensional tectonics in the Ossa-Morena Zone (Évora-Aracena-Lora del Río metamorphic belt, SW Iberian Massif): SHRIMP zircon U-Th-Pb geochronology, In: Murphy, J.B., Keppie, J.D., Hynes, A.J., (Eds.), Ancient Orogens and Modern Analogues, The Geological Society of London Special Publication 327, 215–237, https://doi.org/10.1144/SP327.11.

Pereira, M.F.; Chichorro, M.; Silva, J.B.; Ordóñez-Casado, B.; Lee, J.K.W.; Williams, I.S., (2012), Early Carboniferous wrenching, exhumation of high-grade metamorphic rocks and basin instability in SW Iberia: Constraints derived from structural geology and U–Pb and 40Ar–39Ar geochronology: Tectonophysics, 558–559, 28–44, https://doi.org/10.1016/j.tecto.2012.06.020.

Pereira, M.F.; Chichorro, M.; Fernández, C.; Silva, J.B.; Matias, F.V., (2013). The role of strain localization in magma injection into a transtensional shear zone (Variscan belt, SW Iberia). Journal of the Geological Society, London, 170, 93-105, https://doi.org/10.1144/jgs2012-008.

Pereira, M.F.; Chichorro, M.; Moita, P.; Santos, J.F.; Solá, A.M.R.; Williams, I.S.; Silva, J.B.; Armstrong, R.A., (2015). The multistage crystallization of zircon in calc-alkaline granitoids: U-Pb age constraints on the timing of Variscan tectonic activity in SW Iberia, International Journal of Earth Sciences, 104, 1167–1183, https://doi.org/10.1007/s00531-015-1149-3.

Pereira, M.F.; Gama, C.; Dias da Silva, Í.; Silva, J.B.; Hofmann, M.; Linnemann, U.; Gärtner, A., (2020). Chronostratigraphic framework and provenance of the Ossa-Morena Zone Carboniferous basins (southwest Iberia), Solid Earth, 11, 4, 1291–1312, https://doi.org/10.5194/se-11-1291-2020.

Pereira, M.F.; Fuenlabrada, J.M.; Rodríguez, C.; Castro, A., (2022), Changing Carboniferous Arc Magmatism in the Ossa-Morena Zone (Southwest Iberia): Implications for the Variscan Belt. Minerals, 12, 597. https://doi.org/10.3390/min12050597

Rodríguez, C.; Pereira, M.F.; Castro, A.; Gutiérrez-Alonso, G.; Fernández, C., (2021), Variscan intracrustal recycling by melting of Carboniferous arc-like igneous protoliths (Évora Massif, Iberian Variscan belt): Geological Society of America Bulletin, 134, 5-6, 1549-1570. https://doi.org/10.1130/B36111.1

As Rochas Metamórficas e Plutónicas do Rio Almansor
Published
December 12, 2022

Details about this monograph

ISBN-13 (15)
978-972-778-293-2