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GeoBioSciences, GeoTechnologies and GeoEngineering
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Factors driving sediment compositional change in the distal area of the Ria de Vigo (NW Spain): oceanographic processes vs. paleopollution
Publication . Virginia Alves Martins, Maria; Cazelli, Lucas; Yhasnara, Missilene; da CristineSilva, Layla; Barros Saibro, Murilo; Bobco, Fabia Emanuela Rafaloski; Rubio, Belen; Ferreira, Bruna; Castelo, Wellen Fernanda Louzada; Santos, José Francisco; Ribeiro, Sara; Frontalini, Fabrizio; Martínez-Colón, Michael; Pereira, Egberto; Antonioli, Luzia; Geraldes, Mauro; Rocha, Fernando; Sousa, Silvia Helena Mello e; Dias, Joao
We analyze potential Late Holocene metal contamination along a sediment core collected in the distal zone of Ria de Vigo (North Spain). Statistical treatment of the dataset based on a multiproxy approach enabled us to identify and disentangle factors influencing the depositional processes and the preservation of the records of this activity in the area over the last approximate to 3000 years BP. Some layers of the analyzed core have significant enrichment in Cu and a moderate enrichment in Ag, Mo, As, Sb, S, Zn, Ni, Sn, Cd, Cr, Co, Pb, and Li. The enrichment of these elements in some layers of this core may be related to mining activities that have taken place since classical times in the region. Successive phases of pollution were identified along the core KSGX24 related to the Late Bronze Age (approximate to 3000-2450 years BP), Iron Age (approximate to 2450-1850 years BP), Roman times (approximate to 1850-1550 years BP), Middle Ages (approximate to 1250-500 years BP), and industrial and modern (approximate to 250-0 years BP) anthropic activities. The protection of the Cies Islands, the erosive and transport capacity of the rivers in the region, oscillations of the oceanographic and climatic regime, atmospheric contamination, and diagenetic sedimentary processes might have contributed to the accumulation and preservation of this record in the distal region of the Ria de Vigo. The studied core shows that the industrial and preindustrial anthropic impacts caused an environmental liability and contributed to the presence of moderate to heavy pollution of various metals in surface and subsurface sediment layers in the distal sector of the Ria de Vigo, which could be a hazard to biota.
Palaeoenvironments, stratigraphy and taphonomy of an Upper Triassic vertebrate-bearing unit, Silves Group, central Algarve, southern Portugal
Publication . Ruciński, Maciej; Ezquerro Ruiz, Lope; Campos, Hugo; Mateus, Octávio; Fernandes, Paulo; Vilas-Boas, Margarida; Atfy, Haytham El; Werneburg, Ingmar
Triassic to Lower Jurassic deposits known as the Silves Group in the Algarve, southernPortugal, have been studied for over 150 years. However, many of this unit’s sedimento-logical, stratigraphical, and palaeontological aspects remain poorly documented. Here, we present novel observations on sedimentology, stratigraphy, taphonomy, and fauna atthe Rocha da Pena site, located in the central part of the Algarve Basin. The investigatedsequence is established to correspond to the upper part of the Silves Group. The mud-stone, calcrete, and palustrine carbonate facies comprise most of the sequence thicknessand are interpreted as having been deposited within coastal alluvial mudflats to palus-trine settings under semi-arid and seasonal climates. The overlying siltstone and sand-stone facies indicate an environmental shift towards tidally influenced environments,subsequently covered by the latest Triassic to earliest Jurassic volcaniclastics and basalticlava flows. Furthermore, novel faunal elements, including actinopterygian and union-oid bivalves, are described from mudstone layers. New fossiliferous beds are identifiedwithin palustrine facies that yield numerous but poorly preserved materials assigned tocyamodontoid placodonts, hybodont sharks, and actinopterygians. The poor preserva-tion of the remains is attributed to the pedogenetic processes prevalent in the palustrinedepositional setting. A distinct faunal composition between the mudstone and palustrinefacies is observed. It is preliminarily hypothesized to be likely linked with salinity fluctu-ations, but sampling bias cannot currently be excluded. The recovered vertebrate faunaaligns most closely with the Carnian and, to a lesser extent, the Norian fossil record.Nonetheless, the precise age of the fossil-bearing levels remains uncertain and can cur-rently be reliably constrained to the upper Carnian–Rhaetian interval. Consequently,this work provides new insights into the palaeoenvironmental evolution of the westernTethys margin during the Late Triassic and highlights the relevance of the Silves Groupin reconstructing coastal-continental ecosystem dynamics in southwestern Iberia.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
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6817 - DCRRNI ID
Número da atribuição
UID/GEO/04035/2019