European Multidisciplinary Sea floor and Water Column Observatory - Portugal

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Multiproxy characterization of high energy layers in the nner continental shelf of Quarteira (Southern Portugal) - Preliminary results

Publication . Santos, Jacqueline; Drago, Teresa; Moura, Delminda; Magalhães, Vitor; Roque, Cristina; Silva, Pedro F.; Rodrigues, Ana Isabel; Terrinha, Pedro; Anxo, Mena; Francés, Guillermo; Lopes, Ana; Alberto, Ana; Baptista, Maria Ana

The occurrence of sedimentary layers indicating high energy events is common in the continental shelves sedimentary record. Their presence has been usually related either to tsunami waves or storm waves. In both cases, the identification of the transport mechanism requires a variety of proxies. This work presents the preliminary results of the analysis of a gravity core (MW-107) collected at ca. 57 m water depth in the inner continental shelf of Quarteira (Algarve) and aims to identify potential high energy events.

2022-07Conference object

Open access

Understanding the Atlantic influence on climate and vegetation dynamics in western Iberia over the last 2000 years

Publication . Santos, Ricardo N.; Rodrigues, Teresa; Naughton, Filipa; Schefuß, Enno; Oliveira, Dulce; Moreno, João; Raposeiro, Pedro M.; Gil-Romera, Graciela; Morgan, Alistair; Leira, Manel; Gomes, Sandra D.; Ladd, S. Nemiah; Trigo, Ricardo M.; Ramos, Alexandre M.; Hernández, Armand

Predicting the environmental impact of climate change in extremely sensitive areas, like western Iberia, requires an understanding of the long-term interactions between climate and vegetation. Here we present a novel hightemporal resolution multiproxy analysis, including plant-wax n-alkane isotope data, pollen analysis, macrocharcoal identification, chironomid and diatom records of sediments from a mountain lake in central Portugal. We examined the evolution of the Atlantic and Mediterranean climate influences over the last two millennia, exploring their connection with major atmospheric patterns and impacts on the climatic signal and vegetation dynamics in this understudied region. During the Roman Period (RP; ca. -200 – 500 AD), the study area was characterized by grass dominance, with high temperatures indicated by chironomid composition and microcharcoal content. The increase in plant-wax δ2 H values during this period suggests a shift from wet to dry conditions. The Early Middle Ages (EMA; ca. 500–900 AD) were characterized by colder and a transition to wetter conditions, as indicated by the vegetation and plant-wax n-alkane isotope data. The Medieval Climate Anomaly (MCA; ca. 900–1300 AD) was generally warm, with a short initial lake level drop. This period exhibits the maximum expansion of the Mediterranean forest over the last 2 ka and possibly proximal moisture sources. During the Little Ice Age (LIA; 1300–1850 AD), a reduction of the Mediterranean forest and a strong depletion of plant-wax δ2 H values suggest cold and wet conditions with strong influence of remote Atlantic moisture, with the coldest and wettest phase of the last 2 ka detected between 1550 and 1900 AD. The post-LIA period, from 1900 AD onwards, shows a change to the present warmer and drier conditions, in a highly anthropized landscape. We also demonstrate that major changes in climate have influenced vegetation patterns, with these changes mainly controlled by large-scale atmospheric dynamics. This underscores the sensitivity of western Iberian ecosystems to climate shifts, enriches the current regional understanding of climate-vegetation interplay, and offers valuable insights for future climate change projections.

2024-08Journal article

Open access

Sedimentological characterization of a sedimentary record from the Portimão Bank (SW Iberia): Late Quaternary-Holocene paleoenvironmental implications

Publication . Martins, Mélinda; Veiga-Pires, Cristina; Ercilla, Gemma; Drago, Teresa

Over the centuries, Earth's oceans have served as repositories of invaluable historical data within their sedimentary layers. Deep-sea sedimentary archives collected through sedimentary cores constitute essential reservoirs of complete information for the reconstruction of paleoenvironments. The present study focuses on the re-examination of a sedimentary core, piston core named PC06, extracted at the base of the Portimão bank, located southwest of the Iberian margin. This core spans the last 49,000 years of Earth's history and was collected at a depth of 3 520 meters of water as part of the Spanish MONTERA project, entitled “Seamounts of the Southern Iberian Peninsula: tectonics and sedimentation” (CTM 2009-14157-C02 CSIC). The main objective of this work was to identify and characterize the paleoenvironmental conditions prevailing during this period, through a multidisciplinary study, including sedimentological, mineralogical, and geochemical analyses. Our analysis reveals environmental changes close to Portimão Bank during the Late Pleistocene and Holocene. Four lithofacies define distinct sedimentary units, reflecting conditions dating from 49,000 years BP to the present. Notable periods, including the Last Glacial Maximum and the Holocene, highlight the impact of climate, sea level changes, and ocean circulation and productivity on sediment characteristics. The study emphasizes the role of bottom currents and their potential link to deep water flow in the North Atlantic, and the presence of pyrite throughout the sedimentary record indicates the impact of anoxic conditions, influencing the transition from an anoxic environment to a well-oxygenated environment. Furthermore, the study highlights the complexity of deep-water transport, highlighting the influence of the Portimão Bank on sedimentation patterns. Overall, the analysis provides a nuanced understanding of the environmental evolution of the Portimão Bank over the past 49,000 years. These findings have broader implications for our understanding of past climatic and oceanographic conditions and their impact on sedimentation processes in this region.

2024-02-04Master thesis

Open access

Millennial‐Scale Climate Variability Potentially Shaped the Early Interglacial Optimum in Southern Europe

Publication . Desprat, Stéphanie; Guillem, Gauthier; Sánchez Goñi, Maria Fernanda; Rodrigues, Teresa; Yin, Qiuzhen; Grimalt, Joan O.

The seasonal and latitudinal distribution of insolation is considered the main factor controlling the magnitude and timing of interglacial periods. However, despite small differences in insolation forcing, vegetation and hydrology in southern Europe during past interglacials are variable and the gradual change in insolation cannot explain the observed short‐lived forest optimum. Here we focus on vegetation and hydroclimatic changes at orbital‐ and suborbital‐scales in southwestern Europe during two past warm interglacial periods with reduced ice‐sheets, namely Marine Isotope Stages (MIS) 9e and 5e. We provide new pollen and sea surface temperatures records for MIS 9e from IODP Site U1385. This pollen record shows a forest expansion in southern Iberia over a 14 ky interval, bracketed by the millennial‐scale cooling events of Termination IV and MIS 9d. Between 334.5 and 332.5 ka, forest expansion reached a maximum, suggesting increased winter moisture during early MIS 9e. Model‐data comparison for MIS 9e and 5e shows that insolation is the main driver of the orbital‐scale vegetation and precipitation changes in Iberia, atmospheric CO2 forcing playing a secondary role. The high‐frequency component of the MIS 9e and 5e forest timeseries highlights the early interglacial forest and precipitation maxima as prominent suborbital events lasting ∼2 ky. We propose that the primarily insolation‐driven forest and precipitation optima were fostered by the non‐equilibrium conditions generated by the millennial‐scale deglacial variability during the early interglacials. Additionally, the early end of these optima may have been favored by a cooling and drying event that is part of the persistent intra‐interglacial variability.

2024-10Journal article

Open access