Browsing by Author "Pires, Cristina Veiga"
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- Benchmarks and sediment source(s) of the 1755 Lisbon tsunami deposit at Boca do Rio EstuaryPublication . Font, Eric; Pires, Cristina Veiga; Pozo, Manuel; Nave, Silvia; Costas, Susana; Ruiz Muñoz, Francisco; Abad, Manuel; Simões, Nuno; Duarte, Sílvia; Rodríguez-Vidal, JoaquínStandardizing the signature of tsunami deposits has been identified as a major limitation for the identification of paleo-tsunami deposits. This limitation mostly arises from the strongly source-dependent nature of these deposits, which in turn determines their composition and depositional architecture, and from the effect of the local morphology of the corresponding depositional environment. Here, we provide new high-resolution mineralogical, geochemical and micro/macrofauna data of the 1755 tsunami layer of Boca do Rio estuary (Algarve, Portugal) with the aim of unraveling the signatures of estuarine tsunami deposits and linking them to possible sediment sources. We also apply for the first time diffuse reflectance spectrophotometry (DRS) analysis. Our results show that the 1755 tsunami deposit of the Boca do Rio estuary is featured by an enhancement in Sr and Ca, which are linked to the input of biogenic and detrital carbonates (shell fragments and limestone clasts) from the beach foreshore and a strong depletion in most terrestrial- and marine-sensitive indicators. The latter is interpreted as resulting from the reworking of the estuarine clays and subsequent dilution within a huge volume of sand eroded from the coastal barrier. It confirms that in the case of the Boca do Rio estuary, the sediment source is essentially proximal and coastal. Textural and mineralogical features between the base and the top of the tsunami layer suggest the imprint of run-up and backwash currents derived from a unique wave. Micro and macrofauna analysis and DRS data of the siliciclastic fraction show slight but significant environmental changes occurring just after the tsunami, which could be provoked by an eventual closure of the estuary mouth.
- Benchmarks, sediment source and hydrodynamics of the 1755 Lisbon tsunami deposit at Boca do Rio EstuaryPublication . Font, Eric; Pires, Cristina Veiga; Pozo, Manuel; Nave, Silvia; Costas, Susana; Ruiz Muñoz, Francisco; Abad, Manuel; Simões, Nuno; Duarte, Sílvia
- Detrital zircon geochronology of the Carboniferous Baixo Alentejo Flysch Group (South Portugal); constraints on the provenance and geodynamic evolution of the South Portuguese ZonePublication . Rodrigues, B.; Chew, David; Jorge, Raul CG Santos; Fernandes, Paulo; Pires, Cristina Veiga; Oliveira, José TomásU–Pb detrital zircon data from the Baixo Alentejo Flysch Group in the South Portuguese Zone show significant age differences between formations. The Visean Mértola Formation and Serpukhovian to early Bashkirian Mira Formation are dominated by zircons in the 316–388?Ma age range, whereas the late Bashkirian to late Moscovian Brejeira Formation is dominated by zircons with an age range of 498–687?Ma. Detrital zircons spanning an age range of 0.9–1.1?Ga are present in the Brejeira Formation but are absent in the Mértola and Mira formations. Detrital zircon ages of the Mértola and Mira formations indicate provenance from an extra-basinal source (Ossa–Morena Zone) with a minor intra-basinal contribution (South Portuguese Zone). The abundant presence of detrital zircon with age ranges of 500–750 and 0.9–1.1?Ga in the Brejeira Formation suggests a sediment source from the Avalon–Meguma terranes with limited recycling from the SW Portugal Domain. The different inferred source areas for the Baixo Alentejo Flysch Group formations are attributed to the presence of a forebulge that was formed in Mid-Visean times during the foreland phase of the South Portuguese Zone. The forebulge acted as a physical barrier separating sub-basins that accumulated the Mértola–Mira and Brejeira sediments respectively.
- Identification of tsunami deposits and their impact on coastal zones : a study case of the Boca do Rio estuary (Algarve, Portugal)Publication . Font, Eric; Pires, Cristina Veiga; Pozo, Manuel; Nave, Silvia; Costas, Susana; Ruiz Muñoz, Francisco; Abad, Manuel; Simões, Nuno; Duarte, Sílvia
- Testing rock magnetic and AMS method in tsunami and storm-induced depositsPublication . Font, Eric; Pires, Cristina Veiga; Ruiz Muñoz, Francisco; Pozo, Manuel; Abad, Manuel; Duarte, Sílvia; Simões, Nuno; Nave, Silvia; Costas, Susana; Rebêlo, Luís Pina