Structure of the Sardinia Channel: crustal thinning and tardi-orogenic extension in the Apenninic-Maghrebian orogen; results of the Cyana submersible survey (SARCYA and SARTUCYA) in the western Mediterranean

2004 ◽  
Vol 175 (6) ◽  
pp. 607-627 ◽  
Author(s):  
Georges H. Mascle ◽  
Pierre Tricart ◽  
Luigi Torelli ◽  
Jean-Pierre Bouillin ◽  
Roberto Compagnoni ◽  
...  
Keyword(s):  
Sedimentary Cover ◽  
Western Mediterranean ◽  
Crustal Thickening ◽  
Granitic Rocks ◽  
Kinematic Evolution ◽  
Crustal Thinning ◽  
Central Ridge ◽  
Back Arc ◽  
Tyrrhenian Basin

Abstract The Sardinia Channel is located in a 400 km-long submerged section of the Apennine-Maghrebian branch of the Alpine chain. The Sardinia Channel connects the Algerian-Ligurian-Provençal to the Tyrrhenian oceanic basins. The structure of this region results from the superposition of two tectonic regimes: an earlier crustal thickening and a later crustal thinning. The crustal thickening is the consequence of the shortening which occurred in the late Oligocene–early Miocene during the build up of the Apennine-Maghrebian Orogen. This thickening is coeval with the rotation of the Corsican-Sardinian block and the opening of the Provençal-Algerian back-arc basin. All of these structures, as well as the magmatic arcs in Sardinia and Tunisia, i.e. the Galite Archipelago, are connected to the subduction of the Tethyan Ocean. The crustal thinning is associated with the rifting of the Tyrrhenian Basin, which occurred just before the Messinian salinity crisis and was accompanied by significant erosion throughout the region. This erosion was followed by a period of thermal subsidence linked to the opening of the Tyrrhenian oceanic basin in the Plio-Quaternary, interspersed with minor episodes of compression. On the Sardinian margin, the dives led to the discovery of a submarine volcano, dated at 12.6 Ma, and composed of shoshonitic andesites with lamprophyre inclusions, and to the characterization of the nature and structure of the underlying basement, consisting of tilted blocks of Hercynian metamorphic and granitic rocks and their sedimentary cover. The sea floor morphology reflects this structure. The other areas of the Sardinia Channel explored, i.e. its southern margin and central ridge, belong to the Calabrian-Peloritanian-Kabylian group (CPK). They are composed of a metamorphic and granitic Hercynian basement deformed during the Alpine orogeny, which is stratigraphically overlain by an Oligo-Miocene detrital cover of Peloritanian or Kabylian type, and tectonically overlain by the so-called “flysch nappe”. Throughout the CPK domain these formations were subjected during the Oligo-Miocene, at ca. 23 Ma ago, to a first denudation event, and during the Tortonian, ca. 10-8 Ma ago, to a second denudation, which has been connected to the opening of the Tyrrhenian basin. Structures, microstructures and thermochronological data indicate relatively low P-T conditions for the extensional deformations: this suggests that these units remained at shallow depths in the Apennine-Maghrebian Orogen, and were relatively preserved from the Messinian erosion. The age (12.5 Ma) and nature of the volcanic sequence in the Sorelles is closely comparable with the calc-alkaline suite of the Galite Archipelago, Tunisia. Thus, the data gathered during the dives in the Sardinia Channel give new constraints to the reconstruction of the kinematic evolution not only of the region, but also to the entire western Mediterranean.

scholarly journals The Geon 14 arc-related mafic rocks from the central Grenville Province

2018 ◽  
Vol 55 (6) ◽  
pp. 545-570 ◽  
Author(s):  
Barun Maity ◽  
Aphrodite Indares
Keyword(s):  
Granulite Facies ◽  
Crustal Thickening ◽  
Grenville Province ◽  
Long Duration ◽  
Crustal Thinning ◽  
Isotopic Analyses ◽  
Southeastern Margin ◽  
Intermediate Unit ◽  
Arc Setting ◽  
Back Arc

The late Paleoproterozoic to Mesoproterozoic (ca. 1.7–1.2 Ga) evolution of the active southeastern margin of Laurentia terminated with the Grenvillian continental collision and the development of a large, hot, long-duration orogen at ca. 1.09–0.98 Ga. As a result, much of the hinterland of the Grenville Province consists of Paleoproterozoic and Mesoproterozoic rocks, mostly preserved as an imbricate stack of high-grade gneisses, that represent a potential repository of active-margin processes. This study presents geochronologic, geochemical, and isotopic analyses of two granulite-facies suites of ca. 1.45–1.40 Ga mafic tholeiites from the Canyon domain (Manicouagan area, central Grenville Province). One suite consists of 1439 +76/–68 Ma high-FeTi mafic sills with εNd values of –0.4 (TDM 2.57–2.72 Ga), indicate derivation from variably depleted to enriched MORB-type mantle sources, probably in an extensional back-arc setting, before intrusion in a ca. 1.5 Ga supracrustal metasedimentary sequence. The other, previously dated, 1410 ± 16 Ma Mafic to intermediate unit exhibits εNd values of 0.0 to +0.9 (TDM 2.02–2.25 Ga), and variably enriched MORB to arc geochemical signatures, for which formation in a transitional back-arc to arc setting is suggested. Integrated with published information, the new data support a model of a long-lived continental-margin arc and intermittent back-arc development on southeast Laurentia during the mid-Mesoproterozoic (ca. 1.5–1.4 Ga), in which repeated short periods of extension and crustal thinning in the back-arc or intra-arc regions were followed by compression and crustal thickening.

Back-arc extension dated from natural time markers across the Western Tyrrhenian Basin

2020 ◽  
Author(s):  
Virginie Gaullier ◽  
Gaël Lymer ◽  
Frank Chanier ◽  
Agnès Maillard ◽  
Isabelle Thinon ◽  
...  
Keyword(s):  
Sedimentary Basins ◽  
Western Mediterranean ◽  
Distal Margin ◽  
Proximal Margin ◽  
Western Mediterranean Sea ◽  
Natural Time ◽  
Back Arc ◽  
Short Time ◽  
Subduction System ◽  
Tyrrhenian Basin

<p>The rifting of the Eastern Sardinian margin is considered to have occurred during the Neogene, by back-arc extension related to the eastward migration of the Apennine subduction system, leading to the development of the Tyrrhenian Basin, Western Mediterranean Sea. The locus of the extension during the rifting is interpreted to have occurred first in the East-Sardinia Basin (proximal margin), and then in the Cornaglia Terrace (distal margin). However, the dynamics of the Western Tyrrhenian Basin during the rifting is still largely undated, and the kinematics of the development of the different domains of the Eastern Sardinian margin remains poorly understood. This is due to the sparsity of dated rock samples within the basin, mainly recovered locally during ODP Leg 103, and because the timing of activity of the structures of the basin has been addressed so far using regional data, whose resolution is insufficient to observe the timing of the extension at the scale of a fault plane.</p><p>In this study, we use a 2400 km-long high-resolution seismic-reflection dataset acquired along the Eastern Sardinian margin during the “METYSS” research cruises in 2009 and 2011, and specifically designed to observe the block-bounding faults and the syn-rift and post-rift units. We interpret the syn-tectonic markers of the crustal deformation across the Eastern Sardinian margin, and we use the seismic markers of the Messinian Salinity Crisis (MSC) that provide exceptional and accurate natural time markers, to estimate the age of faults development and understand their evolution within the Western Tyrrhenian Basin.</p><p>Our observations demonstrate that the rifting was polyphased across the Western Tyrrhenian Basin, and that syn-rift extension was active on the proximal margin long before the MSC, whereas the distal Cornaglia Terrace developed only a short time before the MSC. Surprisingly, our interpretations also evidence significant post-rift reactivation of some structures of the Eastern Sardinian margin. These reactivations, formerly considered to be very minor or absent in the Western Tyrrhenian Basin, started in the Pliocene and occurred up to very-recent times along local fault-planes, as shown by the deformation of the shallowest Pleistocene layers and the seafloor.</p><p>Our results permit to precise the timing of the syn-rift and post-rift evolution of the Eastern Sardinian margin. Given the rarity of natural time makers in offshore sedimentary basins to address the dynamics of basins development, we expect our results to provide useful comparisons to study the kinematics of extension at other back-arc basins worldwide.</p>

scholarly journals Morphometric and Nutritional Characterization of the Main Spanish Lentil Cultivars

Agriculture ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 741
Author(s):  
Javier Plaza ◽  
M. Remedios Morales-Corts ◽  
Rodrigo Pérez-Sánchez ◽  
Isabel Revilla ◽  
Ana M. Vivar-Quintana
Keyword(s):  
Scientific Evidence ◽  
Nutrient Content ◽  
Mediterranean Area ◽  
Western Mediterranean ◽  
Protein Food ◽  
Content Assessment ◽  
Protein Levels ◽  
Nutritional Characteristics ◽  
Clear Differentiation

Nowadays, there is a growing demand for high-quality vegetal protein food products, such as pulses and lentils in particular. However, there is no scientific evidence on the nutritional and morphometric characterization of the main lentil cultivars in the Western Mediterranean area. For this reason, the aim of this work is to carry out a morphometric and nutritional characterization of the main Spanish lentil cultivars. Nutrient content assessment was performed on dry matter. The results showed that all studied cultivars are large and heavy lentils, except for the cultivar “Pardina”. They have high protein levels, ranging from 21% to 25%, which is higher than those found in any other pulse, as well as a high carbohydrate content, greater than 59% in all cases. Fiber content was higher than expected in “Armuña” and “Rubia Castellana” cultivars, ranging from 6% to 6.6%, and exceptionally high in the case of the cultivar “Pardina”, which reached 7.8%. Conversely, very low values were found for fat content, varying between 0.5% and 0.9%. Ca, Fe and Mg levels were remarkably higher (from 550 ppm to 851 ppm, from 98 ppm to 139 ppm and from 790 ppm to 989 ppm, respectively) than those found for other lentil cultivars, especially the high Mg content in the cultivars “Jaspeada” and “Microjaspeada”, both above 955 ppm. Clear differentiation was found between the cultivars “Rubia Castellana”, “Pardina” and those included in the Protected Geographical Indication (PGI) “Lenteja de la Armuña”. Overall, lentil cultivars included in the PGI “Lenteja de la Armuña” showed better morphometric and nutritional characteristics than cultivars “Pardina” or “Rubia Castellana”.

scholarly journals Inverted Basins by Africa–Eurasia Convergence at the Southern Back-Arc Tyrrhenian Basin

Geosciences ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 117
Author(s):  
Maria Filomena Loreto ◽  
Camilla Palmiotto ◽  
Filippo Muccini ◽  
Valentina Ferrante ◽  
Nevio Zitellini
Keyword(s):  
Seismic Reflection ◽  
Magnetic Data ◽  
Normal Faults ◽  
Sedimentary Sequence ◽  
Initiation Zone ◽  
Arc Setting ◽  
Seismic Reflection Profiles ◽  
Back Arc ◽  
Flower Structures ◽  
Tyrrhenian Basin

The southern part of Tyrrhenian back-arc basin (NW Sicily), formed due to the rifting and spreading processes in back-arc setting, is currently undergoing contractional tectonics. The analysis of seismic reflection profiles integrated with bathymetry, magnetic data and seismicity allowed us to map a widespread contractional tectonics structures, such as positive flower structures, anticlines and inverted normal faults, which deform the sedimentary sequence of the intra-slope basins. Two main tectonic phases have been recognised: (i) a Pliocene extensional phase, active during the opening of the Vavilov Basin, which was responsible for the formation of elongated basins bounded by faulted continental blocks and controlled by the tear of subducting lithosphere; (ii) a contractional phase related to the Africa-Eurasia convergence coeval with the opening of the Marsili Basin during the Quaternary time. The lithospheric tear occurred along the Drepano paleo-STEP (Subduction-Transform-Edge-Propagator) fault, where the upwelling of mantle, intruding the continental crust, formed a ridge. Since Pliocene, most of the contractional deformation has been focused along this ridge, becoming a good candidate for a future subduction initiation zone.

Amphibole and mica 40Ar/39Ar ages from the Kaipokok and Aillik domains, Makkovik Province, Labrador: towards a characterization of back-arc processes in the Paleoproterozoic

2002 ◽  
Vol 39 (5) ◽  
pp. 749-764 ◽  
Author(s):  
Nicholas Culshaw ◽  
Peter Reynolds ◽  
Gavin Sinclair ◽  
Sandra Barr
Keyword(s):  
Thermal Effect ◽  
Shear Zone ◽  
Second Order ◽  
Greenschist Facies ◽  
Metamorphic Rocks ◽  
Arc Magmatism ◽  
First Order ◽  
Back Arc ◽  
Order Pattern

We report amphibole and mica 40Ar/39Ar ages from the Makkovik Province. Amphibole ages from metamorphic rocks decrease towards the interior of the province, indicating a first-order pattern of monotonic cooling with progressive migration of the province into a more distal back-arc location. The amphibole data, in combination with muscovite ages, reveal a second-order pattern consisting of four stages corresponding to changing spatial and temporal configurations of plutonism and deformation. (1) The western Kaipokok domain cooled through muscovite closure by 1810 Ma, long after the cessation of arc magmatism. (2) The Kaipokok Bay shear zone, bounding the Kaipokok and Aillik domains, cooled through amphibole closure during 1805–1780 Ma, synchronous with emplacement of syn-tectonic granitoid plutons. (3) Between 1740 and 1700 Ma, greenschist-facies shearing occurred along the boundary between the Kaipokok domain and Nain Province synchronous with A-type plutonism and localized shearing in the western Kaipokok domain, cooling to muscovite closure temperatures in the Kaipokok Bay shear zone, and A-type plutonism and amphibole closure or resetting in the Aillik domain. (4) In the period 1650–1640 Ma, muscovite ages, an amphibole age from a shear zone, and resetting of plutonic amphibole indicate a thermal effect coinciding in part with Labradorian plutonism in the Aillik domain. Amphibole ages from dioritic sheets in the juvenile Aillik domain suggest emplacement between 1715 and 1685 Ma. Amphibole ages constrain crystallization of small mafic plutons in the Kaipokok domain (reworked Archean foreland) to be no younger than 1670–1660 Ma. These ages are the oldest yet obtained for Labradorian plutonism in the Makkovik Province.

scholarly journals Monazite U–Th–Pb geochronology of the Central Metasedimentary Belt Boundary Zone (CMBbz), Grenville Province, Ontario Canada

2018 ◽  
Vol 55 (9) ◽  
pp. 1063-1078 ◽  
Author(s):  
Michelle J. Markley ◽  
Steven R. Dunn ◽  
Michael J. Jercinovic ◽  
William H. Peck ◽  
Michael L. Williams
Keyword(s):  
Shear Zone ◽  
Crustal Thickening ◽  
Boundary Zone ◽  
Grenville Province ◽  
Metamorphic History ◽  
Crustal Thinning ◽  
Tectonic Significance ◽  
History Of ◽  
Central Gneiss Belt ◽  
Scale Shear

The Central Metasedimentary Belt boundary zone (CMBbz) is a crustal-scale shear zone that juxtaposes the Central Gneiss Belt and the Central Metasedimentary Belt of the Grenville Province. Geochronological work on the timing of deformation and metamorphism in the CMBbz is ambiguous, and the questions that motivate our study are: how many episodes of shear zone activity did the CMBbz experience, and what is the tectonic significance of each episode? We present electron microprobe data from monazite (the U–Th–Pb chemical method) to directly date deformation and metamorphism recorded in five garnet–biotite gneiss samples collected from three localities of the CMBbz of Ontario (West Guilford, Fishtail Lake, and Killaloe). All three localities yield youngest monazite dates ca. 1045 Ma; most of the monazite domains that yield these dates are high-Y rims. In comparison with this common late Ottawan history, the earlier history of the three CMBbz localities is less clearly shared. The West Guilford samples have monazite grain cores that show older high-Y domains and younger low-Y domains; these cores yield a prograde early Ottawan (1100–1075 Ma) history. The Killaloe samples yield a well-defined prograde, pre- to early Shawinigan history (i.e., 1220–1160 Ma) in addition to some evidence for a second early Ottawan event. In other words, the answers to our research questions are: three events; a Shawinigan event possibly associated with crustal thickening, an Ottawan event possibly associated with another round of crustal thickening, and a late Ottawan event that resists simple interpretation in terms of metamorphic history but that coincides chronologically with crustal thinning at the base of an orogenic lid.

scholarly journals Biochemical Characterization of Cassiopea andromeda (Forsskål, 1775), Another Red Sea Jellyfish in the Western Mediterranean Sea

Marine Drugs ◽  
2021 ◽  
Vol 19 (9) ◽  
pp. 498
Author(s):  
Gianluca De De Rinaldis ◽  
Antonella Leone ◽  
Stefania De De Domenico ◽  
Mar Bosch-Belmar ◽  
Rasa Slizyte ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Biochemical Characterization ◽  
Biological Activities ◽  
Enzymatic Digestion ◽  
Western Mediterranean ◽  
Western Mediterranean Sea ◽  
Blue Growth ◽  
Jellyfish Species ◽  
Italian Coasts

Increasing frequency of native jellyfish proliferations and massive appearance of non-indigenous jellyfish species recently concur to impact Mediterranean coastal ecosystems and human activities at sea. Nonetheless, jellyfish biomass may represent an exploitable novel resource to coastal communities, with reference to its potential use in the pharmaceutical, nutritional, and nutraceutical Blue Growth sectors. The zooxanthellate jellyfish Cassiopea andromeda, Forsskål, 1775 (Cnidaria, Rhizostomeae) entered the Levant Sea through the Suez Canal and spread towards the Western Mediterranean to reach Malta, Tunisia, and recently also the Italian coasts. Here we report on the biochemical characterization and antioxidant activity of C. andromeda specimens with a discussion on their relative biological activities. The biochemical characterization of the aqueous (PBS) and hydroalcoholic (80% ethanol) soluble components of C. andromeda were performed for whole jellyfish, as well as separately for umbrella and oral arms. The insoluble components were hydrolyzed by sequential enzymatic digestion with pepsin and collagenase. The composition and antioxidant activity of the insoluble and enzymatically digestible fractions were not affected by the pre-extraction types, resulting into collagen- and non-collagen-derived peptides with antioxidant activity. Both soluble compounds and hydrolyzed fractions were characterized for the content of proteins, phenolic compounds, and lipids. The presence of compounds coming from the endosymbiont zooxanthellae was also detected. The notable yield and the considerable antioxidant activity detected make this species worthy of further study for its potential biotechnological sustainable exploitation.

scholarly journals Molecular characterization of gaseous and particulate oxygenated compounds at a remote site in Cape Corsica in the western Mediterranean Basin

2021 ◽  
Vol 21 (10) ◽  
pp. 8067-8088
Author(s):  
Vincent Michoud ◽  
Elise Hallemans ◽  
Laura Chiappini ◽  
Eva Leoz-Garziandia ◽  
Aurélie Colomb ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carboxylic Acids ◽  
Organic Aerosol ◽  
Western Mediterranean ◽  
Water Soluble ◽  
Molecular Composition ◽  
Particle Phase ◽  
Western Mediterranean Basin ◽  
Partitioning Coefficients

Abstract. The characterization of the molecular composition of organic carbon in both gaseous and aerosol is key to understanding the processes involved in the formation and aging of secondary organic aerosol. Therefore a technique using active sampling on cartridges and filters and derivatization followed by analysis using a thermal desorption–gas chromatography–mass spectrometer (TD–GC–MS) has been used. It is aimed at studying the molecular composition of organic carbon in both gaseous and aerosol phases (PM2.5) during an intensive field campaign which took place in Corsica (France) during the summer of 2013: the ChArMEx (Chemistry and Aerosol Mediterranean Experiment) SOP1b (Special Observation Period 1B) campaign. These measurements led to the identification of 51 oxygenated (carbonyl and or hydroxyl) compounds in the gaseous phase with concentrations between 21 and 3900 ng m−3 and of 85 compounds in the particulate phase with concentrations between 0.3 and 277 ng m−3. Comparisons of these measurements with collocated data using other techniques have been conducted, showing fair agreement in general for most species except for glyoxal in the gas phase and malonic, tartaric, malic and succinic acids in the particle phase, with disagreements that can reach up to a factor of 8 and 20 on average, respectively, for the latter two acids. Comparison between the sum of all compounds identified by TD–GC–MS in the particle phase and the total organic matter (OM) mass reveals that on average 18 % of the total OM mass can be explained by the compounds measured by TD–GC–MS. This number increases to 24 % of the total water-soluble OM (WSOM) measured by coupling the Particle Into Liquid Sampler (PILS)-TOC (total organic carbon) if we consider only the sum of the soluble compounds measured by TD–GC–MS. This highlights the important fraction of the OM mass identified by these measurements but also the relative important fraction of OM mass remaining unidentified during the campaign and therefore the complexity of characterizing exhaustively the organic aerosol (OA) molecular chemical composition. The fraction of OM measured by TD–GC–MS is largely dominated by di-carboxylic acids, which represent 49 % of the PM2.5 content detected and quantified by this technique. Other contributions to PM2.5 composition measured by TD–GC–MS are then represented by tri-carboxylic acids (15 %), alcohols (13 %), aldehydes (10 %), di-hydroxy-carboxylic acids (5 %), monocarboxylic acids and ketones (3 % each), and hydroxyl-carboxylic acids (2 %). These results highlight the importance of polyfunctionalized carboxylic acids for OM, while the chemical processes responsible for their formation in both phases remain uncertain. While not measured by the TD–GC–MS technique, humic-like substances (HULISs) represent the most abundant identified species in the aerosol, contributing for 59 % of the total OM mass on average during the campaign. A total of 14 compounds were detected and quantified in both phases, allowing the calculation of experimental partitioning coefficients for these species. The comparison of these experimental partitioning coefficients with theoretical ones, estimated by three different models, reveals large discrepancies varying from 2 to 7 orders of magnitude. These results suggest that the supposed instantaneous equilibrium being established between gaseous and particulate phases assuming a homogeneous non-viscous particle phase is questionable.

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