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Geoconservation Research 2021, Volume 4 / Issue 1 / pages(93-103) European UNESCO Geoparks: Original Article Paleobiodiversity in the Darriwilian (Middle Ordovician) of the Naturtejo UNESCO Global Geopark (Portugal) Sofia Pereira1,*, Jorge Colmenar1, Cristiana de Jesus Paulo Esteves2, Ícaro Dias da Silva3, Miguel Pires1, Carlos Neto de Carvalho3,4 1 Centro de Geociências, Universidade de Coimbra, Rua Sílvio Lima, 3030-790 Coimbra, Portugal 2 Department of Geology, Ghent University. Krijgslaan 281, S8. 9000 Ghent, Belgium 3 Instituto Dom Luiz, Departamento de Geologia, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal 4 Geopark Naturtejo Meseta Meridional. Centro Cultural Raiano. Avenida Joaquim Morão, 6060-101, Idanha- a-Nova, Portugal Abstract Middle Ordovician successions occur at Naturtejo UNESCO Global Geopark in five Variscan-folded, kilometer- to tens of kilometer-long structures. Four of them revealed to be fossiliferous in the different recognized lithostratigraphic units, middle- Corresponding Author: to-uppermost Darriwilian in age, with particular emphasis for Brejo Fundeiro Sofia Pereira Centro de Geociências, (Oretanian regional chronostratigraphic stage) and Fonte da Horta (Dobrotivian Universidade de Coimbra, regional stage) formations. Recent paleontological and biostratigraphic works Rua Sílvio Lima, 3030-790 have detected most of the previously recorded and new fossil sites, improving the Coimbra, Portugal. Middle Ordovician biostratigraphy of this region and updating the knowledge of its Email: [email protected] fossil assemblages, which are fairly more diverse than previously considered. The good preservation of the fossils and their relevance to understanding the climax of the Global Ordovician Diversification Event at high paleolatitude shallow marine environments, as well as the protection or identification of some of the fossil sites as UNESCO Geopark’ geosites, make certain their interpretation and use in already existing geotrails and new interpretation centers and school programs. Keywords: Naturtejo Geopark, Brejo Fundeiro Formation, Fonte da Horta Formation, Oretanian, Dobrotivian, Central Portugal Article information Received: 2020-10-26 Accepted: 2020-12-22 DOI: 10.30486/gcr.2020.1913411.1054 How to cite: Pereira S, Colmenar J, Esteves CJP, Dias da Silva I, Pires M & Neto de Carvalho C (2021). Paleobiodi- versity in the Darriwilian (Middle Ordovician) of the Naturtejo UNESCO Global Geopark (Portugal). Geoconservation Research.4(1):93-103. doi: 10.30486/gcr.2020.1913411.1054 Geoconservation Research e-ISSN: 2588-7343 p-ISSN: 2645-4661 © Author(s) 2020, this article is published with open access at http://gcr.khuisf.ac.ir This work is licensed under a Creative Commons Attribution 2.0 Generic License. 93 Geoconservation Research Volume 4 / Issue 1 2021 / pages(93-103) Introduction also reported from the Brejo Fundeiro and the Ca- Naturtejo UNESCO Global Geopark joined the bril formations (e.g., Delgado 1908; Young 1985). European and Global Geoparks networks under Finally, the paleontological record of the Monte da the auspices of UNESCO, in 2006. It was includ- Sombadeira Formation is sparse, but documented ed in the International Geosciences and Geoparks (e.g., Delgado 1908; Cooper 1980; Romão 2006). Programme of UNESCO in 2015 as a territory of 5067 km2, covering the municipalities of Castelo Within the Naturtejo Geopark area, fossiliferous Branco, Idanha-a-Nova, Nisa, Oleiros, Penama- Oretanian and/or Dobrotivian units are represent- cor, Proença-a-Nova, and Vila Velha de Ródão, ed in four of its five structural Variscan-folded located in Central Portugal. Represented by de- structures: the Fajão-Muradal, the Vila Velha de posits from the Neoproterozoic to the Quaternary, Ródão, and the Penha Garcia synclines plus the the Ordovician successions are among the main Monforte da Beira folded structure. During the features of the Naturtejo geological heritage, ex- first decades of geological studies in Portugal, the posed in large, kilometers to tens of kilometers Middle Ordovician of these sectors was consid- long, Variscan-folded structures, forming Appa- ered poorly fossiliferous, bearing solely rare and lachian-type landforms and representing some of badly preserved remains, what was interpreted its most famous geosites (e.g., the Penha Garcia as being related to deeper environments (Delga- Ichnological Park and the Portas de Ródão Natural do 1908). During the second half of the twenti- Monument). eth century, the discovery of Middle Ordovician fossiliferous levels in Fajão-Muradal, Vila Velha The Middle Ordovician is the most fossiliferous de Ródão and Penha Garcia synclines changed Ordovician series across the Central Iberian Zone. somewhat this interpretation (e.g., Thadeu 1951; The so-called “tristani beds” (Born 1916), due to Ribeiro et al. 1965, 1967; Perdigão 1971; Young the abundance of the trilobite Neseuretus tristani 1988), but their paleontological record was rarely in these shallow marine deposits, represents the figured (e.g., Neto de Carvalho et al. 2014), and Oretanian-Dobrotivian interval (correlated with the idea of a low potential for this paleontological most of the global Darriwilian Stage), which hosts heritage remains. the most classical Portuguese Ordovician fos- sil sites (e.g. Valongo, Arouca and Buçaco; e.g., In this work, we show this potential through a se- Romano 1982; Couto et al. 1997; Guy & Lebrun lection of specimens from old and new fossil sites, 2010). While in Northern Portugal these stages improving the Middle Ordovician biostratigraphy are represented by a homogeneous succession of this region and updating the knowledge of its of shales and siltstones (Valongo and Moncorvo fossil assemblages, which are fairly more diverse formations) overlying the ‘Armorican Quartzite’ than previously considered. (Santa Justa and Marão formations, Romano & Diggens 1974; Sá et al. 2005), in central Portu- Stratigraphic Settings of Naturtejo Oretanian/ gal this interval is represented by intercalation of Dobrotivian (Darriwilian) Sequences mudstones and sandstones units: Brejo Fundeiro, The studied area belongs to the Central Iberian Monte da Sombadeira, Fonte da Horta, and Cabril Zone (CIZ) of the Iberian Massif, corresponding formations (Cooper 1980; Young 1988). Among to post-Cambrian metasedimentary sequences that these, the lower Dobrotivian Fonte da Horta For- lie in angular unconformity on the Beiras Group mation is the most fossiliferous unit, providing (upper Ediacaran -?lower Cambrian). Five NNW- highly diverse assemblages (mainly brachiopods, SSE to WNW-ESE major Variscan-folded struc- trilobites, ostracods, molluscs, hyolithids, bryozo- tures, preserving lower Paleozoic successions ans, and crinoids), with fewer but frequent fossils ranging in age from Lower Ordovician (Tremado- 94 Pereira: Middle Ordovician of the Naturtejo UNESCO Global Geopark cian) up to, at most, lower Silurian (Llandovery), The Oretanian/Dobrotivian (middle to upper occur within the Geopark: Fajão-Muradal, Vila Darriwilian) succession among the Naturtejo Velha de Ródão, Penha Garcia, Castelo Branco area starts with the Brejo Fundeiro Formation – Unhais-o-Velho and Monforte da Beira sectors (20-120 m), conformably overlying the Serra do (Fig. 1). Only the southern half of the 32 km-long Brejo and Penha Garcia formations (‘Armorican Fajão-Muradal Syncline lies within Naturtejo Quartzite’, Cooper 1980; Bayet-Goll & Neto de area, roughly south of the Zêzere River (Fig. 1). Carvalho 2020). This metapelitic unit is recog- For this reason, herein we will focus only on the nized throughout all Naturtejo sectors, thickening Muradal sector when referring to Fajão-Muradal southwards, from solely 20 m in southern half Syncline. of the Fajão-Muradal Syncline to 120 m in Vila Figure 1. Simplified geological map of the Naturtejo UNESCO Global Geopark (adapted from the 1:500000 map published by Serviços Geológicos de Portugal, Oliveira et al. 1992) with the location of the four sectors indicated in the text: 1 – Fajão-Muradal Syncline; 2 – Vila Velha de Ródão Syncline; 3 – Penha Garcia Syncline; 4 – Monforte da Beira folded structure. Velha de Ródão, and eastwards, to about 80 m. regressive storm-generated sandstones sequence The Brejo Fundeiro Formation is assigned to the of lower Dobrotivian age (ca. uppermost Darriwil- regional Oretanian stage (middle to upper Darri- ian). Its thickening and coarsening tendency south wilian). In Castelo Branco – Unhais-o-Velho and and eastwards in Portuguese Central Iberian Zone Monforte da Beira exposures, the lower Paleozo- (Young 1985), is also verified in the studied area, ic succession is preserved only up to part of the being only 5 m thick in Fajão-Muradal, 20 m in Brejo Fundeiro Formation, being impossible to Vila Velha de Ródão and 50 m in the Penha Garcia estimate its original thickness. A sudden change Syncline. Conformably overlying these micace- in lithology marks the base of the following unit, ous sandstones is the Fonte da Horta Formation the Monte da Sombadeira Formation (5-50 m), a (20-65 m), consisting of mudstones with rare 95 Geoconservation Research Volume 4 / Issue 1 2021 / pages(93-103) sandstone beds, also of lower Dobrotivian age. Paleontology and Biostratigraphy It was recognized throughout the synclines of 1. Fajão-Muradal Syncline (southern sector) Fajão-Muradal, Vila Velha de Ródão and Penha The first Middle Ordovician fossils from the Fa- Garcia. The Fonte da Horta Formation rapidly jão-Muradal
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  • Ordovician Stratigraphy and Benthic Community Replacements in the Eastern Anti-Atlas, Morocco J

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    Ordovician stratigraphy and benthic community replacements in the eastern Anti-Atlas, Morocco J. Javier Alvaro, Mohammed Benharref, Jacques Destombes, Juan Carlos Gutiérrez-Marco, Aaron Hunter, Bertrand Lefebvre, Peter van Roy, Samuel Zamora To cite this version: J. Javier Alvaro, Mohammed Benharref, Jacques Destombes, Juan Carlos Gutiérrez-Marco, Aaron Hunter, et al.. Ordovician stratigraphy and benthic community replacements in the eastern Anti- Atlas, Morocco. The Great Ordovician Biodiversification Event: Insights from the Tafilalt Biota, Morocco, 485, The Geological Society of London, pp.SP485.20, In press, Geological Society, London, Special Publication, 10.1144/SP485.20. hal-02405970 HAL Id: hal-02405970 https://hal.archives-ouvertes.fr/hal-02405970 Submitted on 13 Nov 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. The Geological Society Special Publications Ordovician stratigraphy and benthic community replacements in the eastern Anti-Atlas, Morocco --Manuscript Draft-- Manuscript Number: GSLSpecPub2019-17R1 Article Type: Research article Full Title: Ordovician stratigraphy and benthic community replacements in the eastern Anti-Atlas, Morocco Short Title: Ordovician stratigraphy of the Anti-Atlas Corresponding Author: Javier Alvaro Instituto de Geociencias SPAIN Corresponding Author E-Mail: [email protected] Other Authors: MOHAMMED BENHARREF JACQUES DESTOMBES JUAN CARLOS GUTIÉRREZ-MARCO AARON W.