Luís Vítor Duarte

University of Coimbra | UC · Department of Earth Sciences

Radioisotopes' concentrations and the mineralogical variability highlight important challenges in the context of the Lusitanian Basin (LB) infilling. Field gamma-ray spectrometry have shown a significant dispersion in radioisotope concentrations related to vertical and lateral variations of lithology. In this work, principal component analysis and...

Subsurface stratigraphic data on the Lusitanian Basin need to be better interpreted, and the conceptualization of its evolution is mostly constrained to outcrop studies. Gamma-ray spectrometry has shown promise in the subsurface of organic marly successions by correlating geological units, identifying marly and organic-rich intervals, and providing...

Supported by the analysis of 19 onshore and offshore wells in the western Lusitanian Basin (Portugal), a characterization of the petroleum potential of the Coimbra Formation (Fm), a carbonate unit of Sinemurian age (Lower Jurassic), is presented. The good stratigraphic, sedimentologic and geochemical knowledge in outcrop, gamma-ray log analysis all...

The Lower Jurassic sedimentary successions of the Lusitanian Basin includes several organicrich intervals and levels. From the systematic analysis carried out in outcrop studies, gamma-ray spectrometry has shown a significant dispersion of radioisotope concentrations in organic-rich facies. In this study, the principal component analysis and hierar...

Choanoflagellates are microeukaryotes that inhabit freshwater and marine environments and have long been regarded as the closest living relatives of Metazoa. Knowledge on the evolution of choanoflagellates is key for the understanding of the ancestry of animals, and although molecular clock evidence suggests the appearance of choanoflagellates by l...

This research is focused on the ammonoids of Oxynotum Zone and Raricostatum Zone (Densinodulum Subzone) from Asturian (Spain) and Lusitanian (Portugal) basins. They come from expanded sections from where 216 specimens have been collected. These have been classified in eight genera and 15 species that belong to families Echioceratidae, Oxynoticerati...

The Lusitanian Basin is located in central western Portugal and is mainly composed of Jurassic sediments. The macro and microfossil biostratigraphy of this depocentre is well studied, but palynological works are scarce. We address this with a high-resolution palynostratigraphic study of a Lower and Middle Jurassic succession of the Lusitanian Basin...

Large-scale release of isotopically light carbon is responsible for the carbon isotope excursion (CIE) of the Toarcian Oceanic Anoxic Event during the Lower Jurassic. Proposed sources include methane hydrate dissociation, volcanogenic outgassing of carbon dioxide and/or thermogenic methane release from the Karoo-Ferrar magmatic province (southern A...

Outcrop observations offer valuable insights into depositional architecture as a primary control on facies and reservoir properties variability, in contrast to subsurface cases, where observation points are limited to well locations. Two dominantly high-energy shallow-water carbonate case studies were analysed, including outcrops of a Bathonian-Cal...

The second-order Pliensbachian–Toarcian crisis affected major groups of marine organisms. While its impact has been intensively studied for ammonites, the response of belemnites is only currently emerging through quantitative studies. Novel overall and regional diversity analyses suggest that belemnite richness in the NW-Tethys drops at the Pliensb...

De entre as sucessões sedimentares do Meso-Cenozoico português, as séries carbonatadas de origem marinha do Jurássico Inferior da Bacia Lusitânica são das que registam maior conteúdo em matéria orgânica, reconhecendo-se o seu potencial petrolífero. Como tal, são as que mostram particular interesse no potencial de geração de hidrocarbonetos, evidênc...

The study across the Pliensbachian–Toarcian boundary sedimentary record in the Bizanet section of the Pyrenean Basin (southern France) revealed the presence of solid bitumen. This secondary organic matter was characterized using petrographic (transmitted and reflected white lights, incident blue light, and scanning electron microscopy) and geochemi...

The Toarcian Oceanic Anoxic Event, also known as the Jenkyns Event, was a hyperthermal episode which occurred during the early Toarcian (c. 183 Ma; Early Jurassic) and resulted in numerous collateral effects including global warming, enhanced weathering, sea-level change, carbonate crisis, marine anoxia–dysoxia, and a second-order mass extinction....

Lower Jurassic sedimentary successions in the Atlantic margin basins include several organic-rich intervals, some with source rock potential; time-equivalent units are also identified in on- and offshore areas worldwide. Despite decades of research, it is still unclear which mechanisms lead to the deposition of organic-rich sediments during the Ear...

There is no consensus about the geological nature of the westernmost portion of the Iberian Massif. In the present research, the detrital zircon U–Pb signatures of Jurassic strata of the Lusitanian Basin, known to be west-sourced, are combined with published U–Pb data for the Precambrian-Palaeozoic basement and other Lusitanian Basin units to bette...

There is no consensus about the geological nature of the westernmost portion of the Iberian Massif. In the present research, the detrital zircon U–Pb signatures of Jurassic strata of the Lusitanian Basin, known to be west-sourced, are combined with published U–Pb data for the Precambrian-Palaeozoic basement and other Lusitanian Basin units to bette...

The study of past climate changes is pivotal for understanding the complex biogeochemical interactions through time between the geosphere, atmosphere, hydrosphere and biosphere, which are critical for predicting future global changes. The Toarcian Oceanic Anoxic Event, also known as the Jenkyns Event, was a hyperthermal episode which occurred durin...

High-resolution analysis of the late Pliensbachian-early Toarcian belemnite assemblages from the Peniche section (Lusitanian Basin) has enabled, for the first time, recognition of eight taxa of the suborder Belemnitina, previously reported from contemporaneous northwest Tethyan and Arctic sections. The presence of Bairstowius amaliae sp. nov. in th...

Book of abstracts: https://iasprague2021.com/_files/200000408-0be8b0be8e/ias-prague-2021-book-of-abstracts.pdf

Book of abstracts: https://iasprague2021.com/_files/200000408-0be8b0be8e/ias-prague-2021-book-of-abstracts.pdf

In this paper, we present a detailed review of upper Pliensbachian-lower Toarcian kerogen assemblages from the southern areas of the West Tethys shelf (between Morocco and northern Spain) and demonstrate the use of the Phytoclast Group as a tracer of palaeoenvironmental changes in the early Toarcian. The kerogen assemblages in the studied sections...

Uncertainties related to in situ gamma-ray spectrometry measurements have been widely acknowledged. Despite being commonly used in exploration, the evaluation of the uncertainty range of K, U and Th gamma spectrometry field measurements is generally limited due to the lack of corresponding laboratory measurements. Estimating uncertainty, however, i...

New evidence is presented on the Triassic–Jurassic boundary in the northern Lusitanian Basin, Portugal, based on miospore assemblages from a composite Upper Triassic to Lower Jurassic succession of the Silves Group. The latter comprises, from base to top, the Conraria, Penela, Castelo Viegas and the Pereiros formations. Three informal palynological...

This contribution is an overview of the Early Jurassic dinoflagellate cysts of the Lusitanian Basin in Portugal, with particular emphasis on the effects of the Jenkyns Event (Toarcian Oceanic Anoxic Event – T-OAE) on the evolution of this planktonic group. We review and discuss data from 214 samples from six Lower Jurassic successions (upper Sinemu...

The Toarcian Oceanic Anoxic Event (T-OAE) is marked by major paleoenvironmental and paleoceanographical changes at a global scale, associated to a severe disturbance of the global carbon cycle, and organic-rich facies deposition. Here, a multi-proxy approach (petrographic and geochemical techniques) was applied to the study of the organic content o...

The Toarcian–Aalenian(?) Cabo Carvoeiro Formation in the Lusitanian Basin (LB), Portugal, is characterized by a succession of mixed carbonate–siliciclastic sediments deposited under the influence of an active horst-graben system caused by the progressive tectonic uplift of the Berlengas basement block. Towards the top of the succession, this format...

A Miocene succession exposed at the Cabo Ledo and Miradouro da Lua sections in the Onshore Kwanza Basin, Angola, was examined for palynology. Palynomorphs of preliminary late Miocene age identified are presented herein. The upper part of the Quifangondo Formation is dated as middle Tortonian in age based on the co-occurrence of the pollen grain Fen...

The Santos Basin in offshore Brazil belongs to the major carbonate reservoir province known informally as the Pre-Salt. A detailed analysis of cores, plugs, sidewall samples and thin-sections from two wells in a sector of this basin was undertaken, on an interval corresponding to the upper part of the Lower Cretaceous Barra Velha Formation. Several...

RESUMO O Jurássico Inferior da Bacia Lusitânica contém três intervalos ricos em matéria orgânica, considerados como tendo potencial para a geração de hidrocarbonetos: a Unidade F da Formação de Coimbra, o Membro de Polvoeira da Formação Água de Madeiros e o Membro Margo-calcários com níveis betuminosos da Formação de Vale das Fontes. Estes interval...

The correlation between radon exposure and the increased probability of lung cancer is widely recognized. In Portugal, several efforts have been made to estimate the radon potential in granitic rocks, however, existing knowledge on sedimentary rocks is limited. For this reason, extensive representative sampling was conducted in the well-known Lower...

The stratigraphical occurrence of ostracod assemblages of the uppermost Pliensbachian (emaciatum Biozone) and Lower–Middle Toarcian (polymorphum, levisoni and bifrons biozones) at Peniche, western Portugal, is reported, an interval that encompasses the Toarcian Global Boundary Stratotype Section and Point (GSSP) and the Toarcian Oceanic Anoxic Even...

The loss of carbonate production during the Toarcian Oceanic Anoxic Event (T-OAE, ca. 183 Ma) is hypothesized to have been at least partly triggered by ocean acidification linked to magmatism from the Karoo-Ferrar large igneous province (southern Africa and Antarctica). However, the dynamics of acidification have never been directly quantified acro...

The Toarcian Oceanic Anoxic Event (TOAE) is characterised by a perturbation of the global carbon cycle and the widespread deposition of organic matter (OM)-rich strata/sediments in the northern areas of the West Tethys Shelf, in several northern European epicontinental basins. Contrariwise, in the southern areas of the West Tethys Shelf such as wes...

The Cenomanian—Turonian boundary is marked by worldwide paleoenvironmental and paleoceanographical changes that are associated with a perturbation of the global carbon cycle and black shale deposition, called the Oceanic Anoxic Event 2 (OAE2). The objective of this study is to precisely characterize the nature of the organic matter, its variability...

The objective of this study is to investigate the relationship between early Toarcian climatic events and the composition of kerogen assemblages in the Lusitanian Basin (Portugal). In particular, we aim to understand how the Pliensbachian–Toarcian Event (Pl–Toa Event) and Toarcian Oceanic Anoxic Event (TOAE) affected the continental areas of the we...

Many aspects of the supposed hyperthermal Toarcian Oceanic Anoxic Event (T-OAE, Early Jurassic, c. 182 Ma) are well understood but a lack of robust palaeotemperature data severely limits reconstruction of the processes that drove the t-oAe and associated environmental and biotic changes. new oxygen isotope data from calcite shells of the benthic fa...

Callapez, P.M. & Duarte, L. V. (2004). Seilium Saxum Sculptus Ab Prima Origo Mundi ou simples meditação de filosofia natural praticada sob a forma de uma saída de campo aos testemunhos das profundezas telúricas do globo terrestre, destinada a reverendíssimos professores já colocados ou com esperança futura de tal e consignada à mui formosa e fronde...

The Lower Jurassic Água de Madeiros (AM Fm) and Vale das Fontes (VF Fm) Formations, and the Upper Jurassic Cabaços Formation (Cab Fm) are considered the most important units with petroleum source-rock potential in the Lusitanian Basin, and the likely sources for its widespread hydrocarbon occurrences. Nonetheless, the bottom-water redox conditions...

The Cenomanian-Turonian boundary is marked by global sea-level highstands and one of the warmest periods of the Mesozoic, with high pCO2 levels linked to a massive magmatic episode. This is associated with the establishment of a worldwide marine anoxia, the deposition of organic-rich facies and disturbances of the global carbon cycle, the so-called...

Body-size reduction is considered an important response to current climate warming and has been observed during past biotic crises, including the Pliensbachian-Toarcian crisis, a second-order mass extinction. However, in fossil cephalopod studies, the mechanisms and their potential link with climate are rarely investigated and palaeobiological scal...

Geochemical and palynofacies analysis of 38 samples from the Middle Atlas Basin (Aït Moussa and Issouka sections, Morocco) allowed to investigate sea-level changes, climate, and tectonics and impact on depositional environments in the westernmost Tethyan Gondwana-margin during the Late Pliensbachian–Early Toarcian and the Pliensbachian–Toarcian Eve...

Body size changes have been investigated through episodes of environmental crisis among several groups of organisms but the relative contribution of within-lineage size changes, selective extinction and origination of taxa on these patterns is still being debated. Rapid warming, anoxia, and perturbations of the carbon cycle linked with volcanic act...

Body size changes have been investigated through episodes of environmental crisis among several groups of organisms but the relative contribution of within-lineage size changes, selective extinction and origination of taxa on these patterns is still being debated. Rapid warming, anoxia, and perturbations of the carbon cycle linked with volcanic act...

Resumo: As sucessões do Jurássico Inferior e Médio da Bacia Lusitânica compreendem várias unidades sedimentares com grande diversidade litológica e que varia desde sedimentos siliciclásticos de origem continental distal a carbonatos de origem marinha. O objetivo do presente estudo centra-se na identificação dos fatores determinantes para estimar a...

The Early Toarcian is characterized by major worldwide environmental changes recorded in an organic-rich black shale sedimentation and carbon cycle disturbances, the so-called Toarcian Oceanic Anoxic Event (T-OAE) (e.g. Jenkyns, 2010). This organic-rich sedimentation is particularly recorded in shallow marine epicontinental basins that developed as...

The Mesozoic is marked by periods of profound climatic and paleoceanographic changes of the planet, representing major environmental perturbations and global carbon cycle disturbances, the so-called oceanic anoxic events (OAEs). These events are usually characterized by the deposition of sediments rich in organic matter (OM) which further validates...

Resumo: O Jurássico Inferior em S. Pedro de Moel (Bacia Lusitânica; BL) revela unidades estratigráficas com potencial de geração de hidrocarbonetos: i) Unidade F da Formação (Fm) de Coimbra; ii) Membro (Mb) de Polvoeira da Fm Água de Madeiros; e iii) Mb Margo-calcários com níveis betuminosos da Fm Vale das Fontes. Apesar de décadas de pesquisa, est...

The early Toarcian Oceanic Anoxic Event (T-OAE) is associated with an "excess" of C 12 in the atmospheric and ocean carbon reservoirs and widespread occurrence of organic-rich facies around the globe (e.g. Hesselbo et al., 2007; Jenkyns, 2010). The T-OAE is recorded as a pronounced negative carbon isotopic excursion (CIE) in carbonates, fossil wood...

Dinoflagellates, together with diatoms and coccolithophores, form a major element of the marine eukaryotic phytoplankton, and are significant primary producers. Based on the fossil record, dinoflagellates appeared in Middle Triassic and during the Early Jurassic (late Pliensbachian) and underwent an important evolutionary radiation episode, with th...

Dinoflagellates, together with diatoms and coccolithophores, form a major element of the marine eukaryotic phytoplankton, and are significant primary producers. Based on the fossil record, dinoflagellates appeared in Middle Triassic and during the Early Jurassic (late Pliensbachian) and underwent an important evolutionary radiation episode, with th...

The early Toarcian Oceanic Anoxic Event (T-OAE) is associated with an “excess” of C ¹² in the atmospheric and ocean carbon reservoirs and widespread occurrence of organic-rich facies around the globe. The T-OAE is recorded as a pronounced negative carbon isotopic excursion (CIE) in carbonates, fossil wood, and kerogens at the base of the Serpentinu...

The early Toarcian Oceanic Anoxic Event (T-OAE) is associated with an “excess” of C ¹² in the atmospheric and ocean carbon reservoirs and widespread occurrence of organic-rich facies around the globe. The T-OAE is recorded as a pronounced negative carbon isotopic excursion (CIE) in carbonates, fossil wood, and kerogens at the base of the Serpentinu...

The Toarcian Oceanic Anoxic Event (T-OAE, ~ 183 Ma) was an episode of extreme warmth, environmental changes and carbon cycle perturbation. We present a high-resolution study of the Peniche section (Lusitanian Basin, Portugal), recently defined as the Toarcian Global Stratotype Section and Point, to provide a review of the Pliensbachian–Toarcian (Pl...

The Early Toarcian Oceanic Anoxic Event (T-OAE) is characterised by major palaeoenvironmental and palaeoceanographical changes (ocean anoxia, global warming, ocean acidification, among other), and a severe perturbation of the global carbon cycle. Although widespread oceanic anoxia was a significant control on the occurrence of organic-rich facies d...

Abstract. At Peniche, Portugal, the GSSP for the base of the Toarcian and in a Submediterranean province, a value of 0.707 073 ± 0.000 002 (2s. e., n = 13) is determined for 87Sr/86Sr at the base of the Toarcian. In Yorkshire, UK, a Subboreal province, the base of the Toarcian has an 87Sr/86Sr value of0.707 072 ± 0.000 002 (2s. e., n = 23). The sim...

A global view of the Mesozoic-Cenozoic geodynamic evolution of the Iberian microplate is necessary to determine the role of inherited Variscan structures in the configuration of the Alpine Cycle. Furthermore, it is important to reconstruct the extensional Mesozoic geometries of the Iberian margins, presently inverted during the Cenozoic compression...

During the Late Triassic-Middle Jurassic interval Iberia acted as a passive margin, where extensional or transtensional faulting, linked to the propagation of the Central Atlantic and the opening of the Ligurian Tethys, generated a NW and NE trending fault system that conditioned facies and thickness distribution. These faults also favored the impl...