Surveying the Alentejo continental shelf for minerals and Quaternary environmental changes: preliminary results of the MINEPLAT project survey

The tectonic uplift of South Portugal in the last 5 Million years (My) was firstly identified on the basis of morphologic criteria by Mariano Feio (1952, “The evolution of the relief of Baixo Alentejo and Algarve”, transl.). However, the assessment of continental vertical movements off Portugal and its relation with tectonics was only initiated in the 1990-ies. This work was carried out in the framework of FP6 and FP7 in the domains of Natural Hazards funded by the European Community. The swath bathymetry cartography of the southwest part of the Iberian Peninsula resulted from the effort of European and national projects, of 19 oceanographic surveys, a total of 200 ship time days executed from 2000 to 2006, involving 14 research institutions from 7 European countries. As a result of this effort together with acquisition and interpretation of thousands of km of seismic reflection profiles, the Pliocene-Quaternary uplift of the Alentejo continental margin (SW Portugal) is now widely accepted by the scientific community. This uplift has not been yet quantified but it is possible that can have contributed to erosion and deposition of metallic ores as placers in the continental shelf. This argues in favor of the potential existence of placers in the continental shelf and the need for the detailed investigation that will allow determination of ideal location for placers deposition in the past Pliocene-Quaternary (5 My). The source for metals can arguably be associated to the Iberian Pyrite Belt ores hosted in the Alentejo Paleozoic formations and to the hyper-alkaline intrusions of Sines and Monchique of Late Cretaceous age. Artificial renourishment of beaches with offshore sand has not been assessed for the Alentejo littoral, despite that the coast located to the south of the Sines segment shows high susceptibility to erosion. This has been observed on a regular basis as the beaches are frequently devoid of sand, thus jeopardizing their touristic potential. The detailed assessment of good quality sand deposits between approximately 30m and 50m below sea level aims at minimizing this problem that affects the economy of littoral of Alentejo. The MINEPLAT project (Assessment of the mineral resources potential in the continental shelf of Alentejo and of the environmental conditions caused by the tectonic uplift in the Pliocene-Quaternary) aims at assessing the existence of mineral deposits off the Alentejo. The MINEPLAT-1 geophysical survey acquired very high resolution multi-channel reflection seismics, swath bathymetry, backscatter and magnetic data in a test area. The preliminary results show: previously unknown NNW-SSE aligned magnetic anomalies, possibly corresponding to buried Late Cretaceous alkaline rocks; faults affecting recent sediments; well defined patches of sediments associated to morphologic traps. Future work will involve ground-truthing to characterize the shallow deposits.Alentejo 2020 contract ALT20-03-0145-FEDER-00001

Cataloguing Quaternary paleo-coastlines in West and Southwest Portugal. Economic, societal and geologic implications

A catalogue of paleo-coast lines in Southwest and South Portugal is presented based on direct field observation and on recent multibeam and backscatter bathymetric surveys. Above sea level, coastline classification was based on field observation of i) wave cut platforms directly associated with ii) notches and/or marine sand deposits with shell clasts, iii) speleothems interbedded with sand deposits and iv) beach rock slabs. Below sea level morphologic and archeologic criteria were used such as, i) buried cliffs under ii) prograding submarine prodeltas or littoral prisms, iii) hard rock surfaces interbedded with mobile sand deposits (possibly beach rock slabs), iv) lagoon depressions associated to coastal barriers sometimes buried by submerged river deltas and v) long wrinkled escarpments. Coastline erosive surfaces ranging from ∼30 m above present-day sea level to ∼120 m below present-day sea level were cataloged. The highest notches with beach sand and bioclasts appear to be well above Quaternary sea level high-stands within the realm of an area that is associated with Pliocene thrusting and uplift. This together with a series of close located well-preserved wave cut platforms and notches from ∼30m above sea level to ∼70 m below sea level require dating. Establishing an absolute chronology for these paleo-coastlines will contribute for understanding the different contributions from eustatic variations, littoral environments (sedimentation contributions) or vertical tectonic movements. The highly curvilinear pattern of the recently discovered paleo-coastlines in SW Portugal, between 30m to 80m below present day sea level, which mimics the present day coastline pattern, is associated with the inherited Paleozoic tectonic fabrics. These escarpments and embayments act as sand traps off the Iberian Pyrite Belt, worldwide famous for its base metals sulphide deposits. Ground truthing for characterizing these mobile deposits is in course looking for possible mineral placers. Thorough mapping of rocky outcrops is also important for habitat mapping, fisheries and diving activities in a region that is under tectonic uplift and needing artificial sand nourishment for keeping beaches attractive. This work was supported by the following projects: MINEPLAT- Assessment of the mineral resources potential in the continental shelf of Alentejo and of the environmental conditions caused by the tectonic uplift in the Pliocene-Quaternary (ALT20-03-0145-FEDER-000013), EMODnet Geology (European Marine Observation Data network, EASME/EMFF/2016/006

Nature and origin of gas trapped in sediments in the Tagus River ebb-delta, off Lisbon, Portugal, the TAGUSGAS project

The Tagus River ebb-delta is located near an important city center off Lisbon, Portugal. The Tagus delta hosts various kilometer scale landslides, the most important of which has been mapped and described with a presumable age of ~11 ky and 10 km in length, 4 km wide and 20 m of maximum thickness. An equivalent area of gas trapped in the sediments has also been reported (Terrinha et al., 2019). The TAGUSGAS project aims at characterizing the nature and source of the gas. A multibeam and backscatter survey was carried out recently covering an area of 44 km2. Several morphologic artifacts were found. The magnetic survey carried out simultaneously allows at discriminating the anthropogenic origin of some of these artifacts. It also allows at distinguishing gas and igneous rock sources of acoustic blanking in the seismic reflection record. The multibeam and backscatter basemap also serves as a tool to decide targets for seafloor sites for sample collection. The authors would like to acknowledge the FCT financial support through project UIDB/50019/2020 – IDL and TAGUSGAS project (PTDC/CTA-GEO/31885/2017)

The continent-to-ocean transition in the Iberia Abyssal Plain

Conceptual models of magma-poor rifting are strongly based on studies of the nature of the basement in the continent-to-ocean transition of the Iberia Abyssal Plain, and suggest that exhumed mantle abuts extended continental crust. Yet, basement has only been sampled at a few sites, and its regional nature and the transition to seafloor spreading inferred from relatively low-resolution geophysical data are inadequately constrained. This uncertainty has led to a debate about the subcontinental or seafloor-spreading origin of exhumed mantle and the rift-related or oceanic nature of magmatic crust causing the magnetic J anomaly. Different interpretations change the locus of break-up by >100 km and lead to debate of the causative processes. We present the tomographic velocity structure along a 360-km-long seismic profile centered at the J anomaly in the Iberia Abyssal Plain. Rather than delineating an excessive outpouring of magma, the J anomaly occurs over subdued basement. Furthermore, its thin crust shows the characteristic layering of oceanic crust and is juxtaposed to exhumed mantle, marking the onset of magma-starved seafloor spreading, which yields the westward limit of an ~160-km-wide continent–ocean transition zone where continental mantle has been unroofed. This zone is profoundly asymmetric with respect to its conjugate margin, suggesting that the majority of mantle exhumation occurs off Iberia. Because the J anomaly is related to the final break-up and emplacement of oceanic crust, it neither represents synrift magmatism nor defines an isochron, and hence it poorly constrains plate tectonic reconstructions

Non-halide sediments from the Loule diapir salt mine: characterization and environmental significance

The sedimentary record of the Mesozoic Algarve Basin (south Portugal) spans from the Triassic to the Lower Cretaceous. Following the initial phase of Pangaea breakup and the related continental sedimentation during the Triassic, the sedimentation evolved through transitional (Triassic-Jurassic transition) to marine (Jurassic) environments. During the Hettangian a thick sequence of evaporites deposited in the basin. Most of the occurrences of these deposits have undetermined volumes, due to the post depositional diapiric movements. At the central Algarve, under the town of Loulé, a salt wall of up to > 1 km across, > 3 km in length and > 2 km in height has been exploited for the chemical industry (Loulé Diapir - LD). Most of the sediments that constitute LD are halides (> 99% halite), the exception being a package of non-halide sediments, constituted by carbonates (dolomite and magnesite) and sulphates (anhydrite) in various proportions with a maximum thickness of 3 meters. This package has a distinctive mesoscopic aspect of three layers of approximately the same thickness, different colours and primary sedimentary structures: black-brow-grey, from bottom to top. The sediments of this package were studied with a multidisciplinary approach aiming their mineralogical and chemical characterization, the determination of the organic matter content and origin, as well as the characterization and understanding of the chemical processes that occurred during the emplacement and compression of the LD: (i) X-ray diffraction for the determination of the mineral phases present and semi-quantification using the RIR-Reference Intensity Ratio method; (ii) micro analysis of the mineralogical samples by Scanning Electron Microscopy coupled to Energy Dispersive Spectroscopy; (iii) REE content determination by ICP-MS; (iv) determination of the carbon content by CHN Elemental analysis; (v) determination of the organic matter content by elemental analysis and their composition by pyrolysis-GC-MS; (vi) determination of the carbon and nitrogen stable isotopic ratios of the organic matter; (vii) anisotropy of the magnetic susceptibility to study it emplacement mode. The LD is deformed by a set of shear-zones and thrusts formed during the Cenozoic Alpine compression that are underlined by the presence of a fine grained, non-halide material, whose nature and characterization was also done, using the same analytical methods. The preliminary mineralogical and geochemical results show a clear pattern in the evolution of the environmental conditions of the sedimentation with influence on the availability of the dissolved cations. The three of the sediment package showed distinct organic carbon content reaching 4.42% in the black horizon, five times the values found in the adjacent layers. By using the rare earth elements as geochemical tracers of sediment provenance, shale normalised profiles suggest that sediment particles from the three layers have the same origin. However, the non-halide sediments retained in the shear zones showed a different profile with an increase of MREE and a positive Eu anomaly. This work was done in the scope of the MEDSALT - Uncovering the Mediterranean salt giant, COST action CA15103

Integrated thematic geological mapping of the Atlantic Margin of Iberia.

This paper synthesizes the geology of the Atlantic Margin off the coast of Iberia and surrounding Abyssal Plains using published thematic mapping freely downloadable from EMODNET-Geology portal at different scales. Selected information was chosen in order to highlight mineral occurrences and natural hazards overlaid on geological and morphological maps. Altogether, this information is published and interpreted here for the first time; nevertheless this exercise can be carried out by anyone interested and allows different visualizations of geological objects. Cross-correlations of geological objects and processes can easily arise. Because all of the information (each piece of data and metadata) in the EMODNET-Geology portal has bibliographic references associated, readers are able to find the original source of information. It is shown that clicking in and out of layers of information (that cannot be found all together in a single scientific paper) allows quick cross-correlation using the EMODNET Geology thematic portal. This allows a free, versatile and quick way of cross-correlating geological objects and processes in vast marine areas and their comparison with onshore geolog

Multi-scale and multi-disciplinary investigation of the southwest Portuguese Continental shelf, the MINEPLAT project

The MINEPLAT project (Assessment of the mineral resources potential in the continental shelf of Alentejo and of the environmental conditions caused by the tectonic uplift in the PlioceneQuaternary) allowed acquisition of 1700 km of ultra- high resolution seismic profiles, and full coverage of multibeam bathymetry and acoustic backscatter of 1450 km2 and 1940km of magnetic data of the Alentejo continental shelf, SW Portugal. 270 sediment samples were collected (Smyth-Macyntire dredges and multicores) and processed for sediment, geochemical and mineralogical analyses (granulometry, Xray diffractometry, major and trace metals analysis). The wealth of data is meeting its full processing phase. Preliminary interpretation of the large dataset has already allowed to understand various novel contributions: i) identification of various sea level stand stills in Pliocene-Quaternary times; ii) drainage network during low stand sea levels; iii) grainsize dependency on submarine relief and inherited morphology from low stand periods; iv) eustatic, oceanographic, fluvial and depth dependency of the post-alpine orogeny deposits of Pliocene-Quaternary age; v) location of deposits with high-quality sand for beach nourishment; and vi) identification of submarine harbor waste disposal sites and their environmental impact and dispersal; vii) high resolution mapping of magnetic anomalies related with magmatic events that can be source of heavy minerals. The authors would like to acknowledge the FCT financial support through project UIDB/50019/2020 – IDL and MINEPLAT project ALT20-03-0145-FEDER-00001

VEGF Promotes Malaria-Associated Acute Lung Injury in Mice

The spectrum of the clinical presentation and severity of malaria infections is broad, ranging from uncomplicated febrile illness to severe forms of disease such as cerebral malaria (CM), acute lung injury (ALI), acute respiratory distress syndrome (ARDS), pregnancy-associated malaria (PAM) or severe anemia (SA). Rodent models that mimic human CM, PAM and SA syndromes have been established. Here, we show that DBA/2 mice infected with P. berghei ANKA constitute a new model for malaria-associated ALI. Up to 60% of the mice showed dyspnea, airway obstruction and hypoxemia and died between days 7 and 12 post-infection. The most common pathological findings were pleural effusion, pulmonary hemorrhage and edema, consistent with increased lung vessel permeability, while the blood-brain barrier was intact. Malaria-associated ALI correlated with high levels of circulating VEGF, produced de novo in the spleen, and its blockage led to protection of mice from this syndrome. In addition, either splenectomization or administration of the anti-inflammatory molecule carbon monoxide led to a significant reduction in the levels of sera VEGF and to protection from ALI. The similarities between the physiopathological lesions described here and the ones occurring in humans, as well as the demonstration that VEGF is a critical host factor in the onset of malaria-associated ALI in mice, not only offers important mechanistic insights into the processes underlying the pathology related with malaria but may also pave the way for interventional studies

Neuroproteção na ressecção cirúrgica de gliomas cerebrais: revisão da evidência atual

Os gliomas cerebrais são tumores primários do sistema nervoso central que se desenvolvem a partir de células gliais e têm alta morbimortalidade. Seu tratamento padrão envolve a ressecção cirúrgica, radioterapia e quimioterapia, os quais possivelmente podem levar os pacientes a um prognóstico desfavorável. Nesse contexto, a neuroproteção entra como uma aliada para minimizar os efeitos colaterais da ressecção cirúrgica e melhorar a sobrevida e a qualidade de vida dos pacientes. Nesse sentido, o presente estudo tem como objetivo discutir sobre a evidência atual da neuroproteção na ressecção cirúrgica de gliomas cerebrais. Para isso, foram selecionados quatro artigos que que abordavam sobre a evidência atual da neuroproteção na ressecção cirúrgica de gliomas cerebrais, por meio de uma estratégia de busca com recorte temporal entre 2014 e 2023, nas bases de dados PubMed (Medline), Embase e Cochrane Library. Os resultados indicam que o grupo de pacientes que recebeu dexmedetomidina apresentou melhora significativa na cognição e redução da inflamação cerebral em comparação com o grupo-controle pós-ressecção dos gliomas cerebrais, além de menor incidência de efeitos colaterais anestésicos, como náusea e vômitos (p < 0,05). Ademais, foi observado que a modulação da via metabólica do glutamato/glutamina pode inibir o crescimento de gliomas e proteger o parênquima cerebral. Nesse sentido, as evidências atuais indicam que proteger as células nervosas é uma estratégia importante para minimizar os efeitos colaterais da ressecção cirúrgica de gliomas cerebrais, e a dexmedetomidina e a co-cultura de células de glioma e astrócitos que aumenta a concentração extracelular de glutamato e glutamina parecem ser importantes aliadas nessa profilaxia