Extension and early orogenic inversion along the basal detachment of a hyper-extended rifted margin: an example from the Central Pyrenees (France)

2021 ◽  
pp. jgs2020-003
Author(s):  
Paul Angrand ◽  
Mary Ford ◽  
Maxime Ducoux ◽  
Michel De Saint Blanquat
Keyword(s):  
Cross Sections ◽  
Sedimentary Cover ◽  
Low Grade ◽  
Content Type ◽  
The North ◽  
Metamorphic Zone ◽  
Supplementary Material ◽  
Tectonic Loading ◽  
Rifted Margin

The North Pyrenean Zone (NPZ) inverts remnants of an Aptian-Cenomanian rifting during which subcontinental mantle was exhumed. These remnants contain a syn-rift HT-LP metamorphic domain, the Internal Metamorphic Zone (IMZ). New field and RSCM data and structural cross-sections constrain the structural and metamorphic relationships between the IMZ and the underlying low-grade NPZ. The IMZ is a tectonic nappe that overthrusts the European margin along the 3M Fault. Along this contact, the Tuc de Haurades peridotite is surrounded by tectonic breccia composed of ductilely deformed carbonate and sparse lherzolite clasts that passes upward into foliated marbles. Marbles contain top-to-south ductile shear, recording ongoing extensional deformation that marks the onset of HT metamorphism. During Early Cretaceous rifting, European Mesozoic sedimentary cover metamorphosed and its base brecciated as it slid basinward on Triassic salt onto exhumed mantle. As the exhumed mantle domain closed during early convergence, the detached metamorphosed cover was transported northward and thrust into the distal European margin, sampling lherzolite tectonic lenses. This triggered the first tectonic loading on the European plate. This study highlights the role of the IMZ in the early Pyrenean orogenic phase and gives new insights on the E-W diversity of structural setting of the NPZ peridotites.Table with RSCM temperatures and original and high quality photographs of the samples are available on the GSL Figshare portal https://doi.org/10.6084/m9.figshare.c.5539260.

scholarly journals Evolution of a salt-rich transtensional rifted margin, eastern North Pyrenees, France

2020 ◽  
Vol 178 (1) ◽  
pp. jgs2019-157 ◽  
Author(s):  
M. Ford ◽  
J. Vergés
Keyword(s):  
Sedimentary Cover ◽  
Google Earth ◽  
Rift System ◽  
Content Type ◽  
The North ◽  
Deep Faults ◽  
Supplementary Material ◽  
Uplift And Erosion ◽  
Rifted Margin ◽  
Early Late

In this field study we reinterpret the narrow eastern North Pyrenean Zone, France, as an inverted salt-rich transtensional rift system based on identification of halokinetic depositional sequences across rift platform to distal rift margin domains with a cumulative throw of >2.8 km on steep Cretaceous faults. The rift platform records extension on detached rotational faults above Triassic evaporites from Jurassic to Aptian with uplift and erosion during the Albian. Transtensional Aptian–Albian minibasins align along the salt-rich rift margin fault zone. In the Aptian–Albian main rift large en echelon synclinal minibasins developed between salt walls, although Jurassic diapiric evolution is likely. Upper Cretaceous units locally record continuing diapirism. The Boucheville and Bas Agly depocentres, altered by synrift HT metamorphism, form the distal rift domain terminating south against the North Pyrenean Fault. The narrowness of the Pyrenean rift, shape of minibasins, en echelon oblique synclinal depocentres and folds coupled with a discontinuous distribution and intensity of HT metamorphism support a transtensional regime along the Iberia–Europe plate margin during late Early and early Late Cretaceous. In this model, the distal European margin comprises deep faults limiting laterally discontinuous crustal domains and ‘hot’ pull-apart basins with mantle rocks directly beneath sedimentary cover.Supplementary material: A table summarizing the stratigraphy of the NE Pyrenees and an interpreted Google Earth view of the Quillan syncline and minibasin are available at https://doi.org/10.6084/m9.figshare.c.5100036

Contractional salt tectonics and role of pre-existing diapiric structures in the Southern Pyrenean foreland fold–thrust belt (Montsec and Serres Marginals)

2021 ◽  
pp. jgs2020-085 ◽  
Author(s):  
Laura Burrel ◽  
Antonio Teixell
Keyword(s):  
Cross Sections ◽  
Foreland Basin ◽  
Salt Tectonics ◽  
Structural Development ◽  
Field Observations ◽  
Content Type ◽  
Growth Strata ◽  
Structural Style ◽  
Supplementary Material

Triassic Keuper evaporites have long been recognized as the main detachment level for thrusting in the Pyrenean fold–thrust belts. The deformed Late Cretaceous–Eocene foreland basin of the Southern Pyrenees has structures and stratal geometries that can be interpreted as related to salt tectonics (e.g. unconformities, rapid thickness variations, long-lived growth fans and overturned flaps), although they have been overprinted by shortening and thrusting. Based on field observations and published maps, we build new structural cross-sections reinterpreting two classic transects of the Southern Pyrenees (Noguera Ribagorçana and Noguera Pallaresa river transects). The sequential restoration of the sections explores the variations in structural style, addressing the role of halokinesis in the tectonic and sedimentary development. In the Serres Marginals area, we propose that salt pillows and diapirs started developing locally during the Mesozoic pre-orogenic episode, evolving into a system of salt ridges and intervening synclines filled with early synorogenic sediments. Rapid amplification of folds recorded by widespread latest Cretaceous–Paleocene growth strata is taken as marking the onset of contractional folding in the area. During Pyrenean compression, folding mechanisms transitioned from dominantly halokinetic to a combination of buckling and differential sedimentary loading. Squeezing of salt diapirs and thrust welding occurred as salt ridges were unroofed. We provide new field observations that lead to a reinterpretation of the regional structural development and contribute to the debate about the role of salt tectonics in the Pyrenees.Supplementary material: Table S1, giving the thickness of the main stratigraphic units, is available at https://doi.org/10.6084/m9.figshare.c.5287737

Changes in gamma-aminobutyric acid and somatostatin in epileptic cortex associated with low-grade gliomas

1992 ◽  
Vol 77 (2) ◽  
pp. 209-216 ◽  
Author(s):  
Michael M. Haglund ◽  
Mitchel S. Berger ◽  
Dennis D. Kunkel ◽  
JoAnn E. Franck ◽  
Saadi Ghatan ◽  
...  
Keyword(s):  
Epileptiform Activity ◽  
Aminobutyric Acid ◽  
Low Grade ◽  
Tumor Infiltration ◽  
Gamma Aminobutyric Acid ◽  
Content Type ◽  
Low Grade Gliomas ◽  
Neuronal Populations ◽  
Significant Difference

✓ The role of specific neuronal populations in epileptic foci was studied by comparing epileptic and nonepileptic cortex removed from patients with low-grade gliomas. Epileptic and nearby (within 1 to 2 cm) nonepileptic temporal lobe neocortex was identified using electrocorticography. Cortical specimens taken from four patients identified as epileptic and nonepileptic were all void of tumor infiltration. Somatostatin- and γ-aminobutyric acid (GABAergic)-immunoreactive neurons were identified and counted. Although there was no significant difference in the overall cell count, the authors found a significant decrease in both somatostatin- and GABAergic-immunoreactive neurons (74% and 51 %, respectively) in the epileptic cortex compared to that in nonepileptic cortex from the same patient. It is suggested that these findings demonstrate changes in neuronal subpopulations that may account for the onset and propagation of epileptiform activity in patients with low-grade gliomas.

The onset of the early Toarcian flooding of the Pliensbachian carbonate platform of Central Tunisia (North-South Axis) as inferred from trace fossils and geochemistry

2021 ◽  
pp. SP514-2021-10
Author(s):  
Matías Reolid ◽  
Mohamed Soussi ◽  
Jesús Reolid ◽  
Wolfgang Ruebsam ◽  
Ilef Belhaj Taher ◽  
...  
Keyword(s):  
Carbonate Platform ◽  
High Energy ◽  
Trace Fossils ◽  
Energy Conditions ◽  
Local Conditions ◽  
Content Type ◽  
The North ◽  
Sea Bottom ◽  
Supplementary Material ◽  
South Axis

AbstractThe flooding of the Lower Jurassic shelf in the North Gondwana Palaeomargin during the early Toarcian occurred on a fragmented and irregular topography affected by differential subsidence—due to the activity of listric faults along the North-South Axis of Tunisia—that favoured lateral changes in facies and thickness at a kilometric scale. The onset of Toarcian sedimentation (Polymorphum ammonite Zone, NJT5c nannofossil Subzone) in two adjacent sections was characterised by the deposition of limestones under high-energy conditions. The Châabet El Attaris section was located in a depressed sub-basin, and recorded restricted environmental conditions owing to water stagnation and an oxygen-depleted sea-bottom. Therefore, dark mudstones developed, with increased TOC contents and enhanced accumulation of redox-sensitive elements. The sedimentation of limestones bearing gutter cast structures is related to gravity flows probably linked to storm activities. These processes favoured the remobilization of sediments at the sea floor, as well as oxygen input to bottom waters, as shown by the record of trace fossils including Zoophycos, Ophiomorpha, and secondarily, Chondrites and Diplocraterion. The thinly interbedded dark mudstones are locally rich in thin-shelled bivalves that re-colonised the sea bottom after the sedimentation of these high-energy deposits, and subsequently underwent mass mortality related to the return of oxygen-depleted conditions. The Kef El Hassine section is located in the upper part of a tilted, less subsident block, as indicated by its reduced thickness compared with the Châabet El Attaris section; the absence of dark mudstones implies oxic conditions. The Polymorphum Zone consists of limestones showing evidence of sedimentation under high-energy conditions, along with hardgrounds. The occurrence of Zoophycos (deep-tiers) in the upper part of some limestone beds of the Polymorphum Zone is linked to minor erosive processes. The top of the high-energy sequence—below the deposits of a marly interval corresponding to the Levisoni Zone—is interpreted as a hardground given the high content of belemnites and Arenicolites, some of them boring on the eroded Zoophycos and Thalassinoides. This study shows that the sedimentary expression of the Jenkyns Event is not uniform across Tunisia, supporting the importance of local conditions in determining the development of anoxic conditions.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5510162

A levee breach induced by internal erosion in Western Australia.

2021 ◽  
pp. qjegh2021-037
Author(s):  
Scott Davidson ◽  
Paul Baker
Keyword(s):  
Western Australia ◽  
Internal Erosion ◽  
North Coast ◽  
Sandy Gravel ◽  
Content Type ◽  
The North ◽  
Levee Breach ◽  
Piping Erosion ◽  
A Site

This case study presents a levee breach induced by piping erosion under cyclonic conditions in 2019. The levee is a 2.5 m high, 500 m long, mass earth fill embankment; with no cut-off trench, core, or ancillary structures. Located near Port Hedland on the north coast of Western Australia; its purpose is diversionary, to redirect cyclonic surface water away from the nearby Great Northern Highway. The levee was founded directly on Alluvium in 1987; and formed of locally sourced clayey sandy gravel. In 2003, the levee was partially excavated to enable the placement of a buried pipeline through the levee.Following a cyclonic event in 2019, a 27 m length of the levee breached, resulting in significant scour of the foundation and downstream soil. A site visit and investigation were conducted shortly thereafter, where in situ testing and laboratory soil tests on the levee and foundation materials were conducted.Analysis of the site observations and laboratory testing data led to the probable failure mechanism being theorised as having been initiated within the foundation by piping erosion within sand-rich beds of Alluvium. The large quantity of water ponding upstream of the levee then caused a progressive washout and breach of the levee.Thematic collection: This article is part of the Role of water in destabilizing slopes collection available at: https://www.lyellcollection.org/cc/Role-of-water-in-destabilizing-slopes

Carboniferous records of the Zoophycos group of trace fossils from England, Wales, the Isle of Man and the North Sea

2020 ◽  
Vol 63 (2) ◽  
pp. 135-145
Author(s):  
Duncan McLean ◽  
Matthew Booth ◽  
David J. Bodman ◽  
Finlay D. McLean
Keyword(s):  
North Sea ◽  
Trace Fossils ◽  
Depositional Environments ◽  
Common Component ◽  
Content Type ◽  
Clastic Rocks ◽  
Isle Of Man ◽  
The North ◽  
The North Sea ◽  
Supplementary Material

The Zoophycos group of trace fossils is common in Carboniferous to recent marine strata and sediments, and is a common component of ichnofaunas in the Visean and Namurian stages of England and Wales. A review of new and published records indicates that it is often present in limestones and sandstones of Chadian to Arnsbergian age. Thereafter it is less common, and restricted to clastic rocks. There are no known records within Carboniferous strata above the lowest Westphalian. The form is most common and often abundant in limestones of the Yoredale facies in the upper Visean and lower Namurian stages of northern England, particularly so in northern Northumberland. Where detailed sedimentological data exist, they indicate that the organisms responsible for the Zoophycos group burrowed into unconsolidated carbonate substrate that was deposited under low accumulation rates, often affected by storm wave action and where seawater flow provided a nutrient supply. However, in mixed carbonate–clastic settings, the deep-tier nature of Zoophycos may indicate that the organism lived in overlying shallow-marine, clastic-dominated depositional environments and burrowed down into the carbonate substrate. The same may be true of siliciclastic depositional settings where the presence of Zoophycos in some sandstones may reflect the palaeoenvironment of the overlying, finer-grained transgressive marine (prodelta and distal mouth bar) deposits.Supplementary material: A spreadsheet with details of Carboniferous records of Zoophycos group fossils from England, Wales, the Isle of Man and the North Sea is available at https://doi.org/10.6084/m9.figshare.c.4994636

Post-orogenic exhumation in the western Pyrenees: evidence for extension driven by pre-orogenic inheritance

2020 ◽  
pp. jgs2020-079
Author(s):  
Charlotte Fillon ◽  
Frédéric Mouthereau ◽  
Sylvain Calassou ◽  
Raphaël Pik ◽  
Nicolas Bellahsen ◽  
...  
Keyword(s):  
Thermal Evolution ◽  
Foreland Basin ◽  
Normal Faulting ◽  
Axial Zone ◽  
Content Type ◽  
The North ◽  
Supplementary Material ◽  
Thermal Histories ◽  
Relationship Of ◽  
Western Pyrenees

We discuss the drivers of the Pyrenean post-orogenic exhumation, including drainage migration, flexural rebound and tectonic reactivation.We provide new low-temperature thermochronological data and inverse thermal modeling from both the hinterland and foreland of the western Pyrenees. Our new thermochronological ages range from 6.6 to 61.4 Ma and reveal a Late Miocene exhumation phase in several massifs. The contrasting thermal histories define a domain of focused exhumation in the western Pyrenees that coincides with the present-day extensional tectonics in a region to the north of the Axial Zone. Based on the inferred cooling rates and paleogradient estimates, we highlight an exhumation phase of c. 1 mm yr–1 between 11 and 9 Ma in the Axial Zone, well above rates expected for a post-orogenic evolution. The thermal evolution inferred from three boreholes of the Aquitaine foreland basin reveals that sediments eroded from the hinterland did not accumulate in the Piedmont region but were transported offshore in the Bay of Biscay. We infer that the significant c. 10 Ma post-orogenic exhumation event must be related to the modern normal faulting regime of the western Pyrenees, associated with contrasting crustal thickness and densities, inherited from the Mesozoic rift evolution of the northern Pyrenees.Supplementary material: Laboratory analytical procedures, radial plot visualization of AFT detrital data and Age/eU relationship of AHe and ZHe samples are available at https://doi.org/10.6084/m9.figshare.c.5212581

scholarly journals Use of a Human-Like Low-Grade Bacteremia Model of Experimental Endocarditis To Study the Role of Staphylococcus aureus Adhesins and Platelet Aggregation in Early Endocarditis

2012 ◽  
Vol 81 (3) ◽  
pp. 697-703 ◽  
Author(s):  
Tiago Rafael Veloso ◽  
Aziz Chaouch ◽  
Thierry Roger ◽  
Marlyse Giddey ◽  
Jacques Vouillamoz ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Platelet Aggregation ◽  
Surface Protein ◽  
Infection Process ◽  
Low Grade ◽  
Content Type ◽  
Fibrinogen Binding ◽  
Aggregation Property ◽  
Surface Adhesins

ABSTRACTAnimal models of infective endocarditis (IE) induced by high-grade bacteremia revealed the pathogenic roles ofStaphylococcus aureussurface adhesins and platelet aggregation in the infection process. In humans, however,S. aureusIE possibly occurs through repeated bouts of low-grade bacteremia from a colonized site or intravenous device. Here we used a rat model of IE induced by continuous low-grade bacteremia to explore further the contributions ofS. aureusvirulence factors to the initiation of IE. Rats with aortic vegetations were inoculated by continuous intravenous infusion (0.0017 ml/min over 10 h) with 106CFU ofLactococcus lactispIL253 or a recombinantL. lactisstrain expressing an individualS. aureussurface protein (ClfA, FnbpA, BCD, or SdrE) conferring a particular adhesive or platelet aggregation property. Vegetation infection was assessed 24 h later. Plasma was collected at 0, 2, and 6 h postinoculation to quantify the expression of tumor necrosis factor (TNF), interleukin 1α (IL-1α), IL-1β, IL-6, and IL-10. The percentage of vegetation infection relative to that with strain pIL253 (11%) increased when binding to fibrinogen was conferred onL. lactis(ClfA strain) (52%;P= 0.007) and increased further with adhesion to fibronectin (FnbpA strain) (75%;P< 0.001). Expression of fibronectin binding alone was not sufficient to induce IE (BCD strain) (10% of infection). Platelet aggregation increased the risk of vegetation infection (SdrE strain) (30%). Conferring adhesion to fibrinogen and fibronectin favored IL-1β and IL-6 production. Our results, with a model of IE induced by low-grade bacteremia, resembling human disease, extend the essential role of fibrinogen binding in the initiation ofS. aureusIE. Triggering of platelet aggregation or an inflammatory response may contribute to or promote the development of IE.

Portuguese research shows value of entrepreneurial training in developing necessary skills

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Keyword(s):  
Entrepreneurship Education ◽  
Education And Training ◽  
Content Type ◽  
The North ◽  
Entrepreneurial Skills ◽  
The Creation ◽  
Entrepreneurial Training ◽  
Training Programmes ◽  
And Training

Purpose The goal was to study how entrepreneurship education and training programmes (EETPs) influence the development of entrepreneurial competencies and creation of business venture Design/methodology/approach The authors tested a series of hypotheses on the EETPs designed for the Sabor Entrepreneurship Programme (SEP), in northern Portugal. They used a detailed questionnaire. At the time of the research (2018), the SEP had had five editions across Sabor’s five municipalities. The main aim of the EETPs was to train participants to run their own companies. Findings The study showed that the entrepreneurship education and training programmes (EETP) developed in the Sabor Region in the north helped participants to develop entrepreneurial skills. Despite these positive results, the researchers were unable to prove statistically that the programme had a definite influence on the creation of companies. Too many other factors, such as financing, bureaucracy and access to information proved critical in the formation of new businesses. Originality/value The researchers were motivated to carry out their research because EETPs have been rapidly expanding throughout the world, but there is no consensus about their effectiveness, or about the best elements to include. To bridge the gaps, the authors examined the role of EETPs in the development of entrepreneurial skills and the creation of businesses.

Palaeomycology: A modern mycological view of fungal palynomorphs

2021 ◽  
pp. SP511-2020-47
Author(s):  
Noelia B. Nuñez Otaño ◽  
M. Virginia Bianchinotti ◽  
Mario C. N. Saparrat
Keyword(s):  
Fungal Spores ◽  
Diagnostic Tools ◽  
Fungal Ecology ◽  
Transport Mechanisms ◽  
Spore Dispersal ◽  
Content Type ◽  
Fungal Biology ◽  
Supplementary Material ◽  
Fungal Assemblages

AbstractFungal spores are increasingly used as reliable proxies in paleoenvironmental reconstructions; however, little attention is paid to the ecological tolerances of the fungi themselves and the signal the fungi provide. This chapter provides a much-needed background in fungal biology and ecology of monophyletic Dikarya (Ascomycota and Basidiomycota), as well as taphonomic considerations which could be included in any use as palaeoecological indicators. It is intended to help those who are interested in using fungal spores as palaeoecological indicators to make more informed interpretations. A recapitulation of spore dispersal strategies and distances is presented for a better understanding of the transport mechanisms of fungal spores. Likewise, pigmentation is discussed, as it results in significant taphonomic bias in fossil fungal assemblages and, as some dark-colored pigmentation is authigenic while some develops during taphonomy. A key element of this chapter is discussion of the environmental role of fungi, including modern versus palaeo-approaches to fungal ecology, fungal assemblages, and diversity patterns as diagnostic tools to infer paleoenvironments.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5342039

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