52 research outputs found
Salses-le-ChĂąteau â Le chĂąteau
Le Centre des Monuments Nationaux, en tant que gestionnaire de la forteresse de Salses, envisage la rĂ©alisation de travaux sous la maĂźtrise dâĆuvre dâO. Weets (ACMH) concernant la rĂ©fection des rĂ©seaux hydraulique et dâassainissement du site. La rĂ©alisation dâinvestigations complĂ©mentaires prĂ©alables Ă lâĂ©laboration du nouveau projet fait suite Ă la phase 1 « raccordements au rĂ©seau dâeau public », rĂ©alisĂ©e en 2010. Ces investigations ont Ă©tĂ© dĂ©finies sur la base des prĂ©conisations du bureau ..
Ionian Abyssal Plain: a window into the Tethys oceanic lithosphere
The nature of the Ionian Sea crust has been the subject
of scientific debate for more than 30Â years, mainly because seismic imaging
of the deep crust and upper mantle of the Ionian Abyssal Plain (IAP) has not
been conclusive to date. The IAP is sandwiched between the Calabrian and
Hellenic subduction zones in the central Mediterranean. A NNEâSSW-oriented
131 km long seismic refraction and wide-angle reflection profile, consisting
of eight ocean bottom seismometers and hydrophones, was acquired in 2014.
The profile was designed to univocally confirm the proposed oceanic nature
of the IAP crust as a remnant of the Tethys and to confute its
interpretation as a strongly thinned part of the African continental crust.
A P-wave velocity model developed from travel-time forward modelling is
refined by gravimetric data and synthetic modelling of the seismic data. A
roughly 6â7 km thick crust with velocities ranging from 5.1 to 7.2 km sâ1, top to bottom, can be traced throughout the IAP. In the vicinity of
the Medina seamounts at the southern IAP boundary, the crust thickens to
about 9 km and seismic velocities decrease to 6.8 km sâ1 at the crustâmantle
boundary. The seismic velocity distribution and depth of the crustâmantle
boundary in the IAP document its oceanic nature and support the
interpretation of the IAP as a remnant of the Tethys lithosphere with the
Malta Escarpment as a transform margin and a Tethys opening in the NNWâSSE
direction.</p
Reply to Comment by A. Argnani on "Geometry of the Deep Calabrian Subduction from WideâAngle Seismic Data and 3âD Gravity Modeling"
Keypoints
This contribution is a reply on a comment submitted by A. Argnani.
The alternate interpretation of the wide-angle seismic model is discussed.
The Alfeo Fault system is proposed to be the current location of STEP fault.
Abstract
Andrea Argnani in his comment on Dellong et al., 2020 (Geometry of the deep Calabrian subduction (Central Mediterranean Sea) from wideâangle seismic data and 3D gravity modeling), proposes an alternate interpretation of the wide-angle seismic velocity models presented by Dellong et al., 2018 and Dellong et al., 2020 and proposes a correction of the literature citations in these paper. In this reply, we discuss in detail all points raised by Andrea Argnani
Deep structure of the Ionian Sea and Sicily Dionysus - Cruise No. M111, October 10 - November 1, 2014, Catania (Italy) â Catania (Italy)
Summary
The origin of the Ionian Sea lithosphere and the deep structure of its margins remain a little
investigated part of the Mediterranean Sea. To shed light on the plate tectonic setting in this
central part of southern Europe, R/V METEOR cruise M111 set out to acquire deep penetrating
seismic data in the Ionian Sea. M111 formed the core of an amphibious investigation covering
the Ionian Sea and island of Sicily. A total of 153 OBS/OBH deployments using French and
German instruments were successfully carried out, in addition to 12 land stations installed on
Sicily, which recorded the offshore air gun shots.
The aim of this onshore-offshore study is to quantify the deep geometry and architecture of the
Calabria subduction zone and Ionian Sea lithosphere and to shed light on the nature of the Ionian
Sea crust (oceanic crust vs. thinned continental crust). Investigating the structure of the Ionian
crust and lithospheric mantle will contribute to unravel the unknown ocean-continent transition
and Tethys margin. Analyzing the tectonic activity and active deformation zones is essential for
understanding the subduction processes that underlie the neotectonics of the Calabrian
subduction zone and earthquake hazard of the Calabria/Sicily region, especially in the vicinity of
local decoupling zones
Landscape Pattern Detection in Archaeological Remote Sensing
Automated detection of landscape patterns on Remote Sensing imagery has seen virtually no development or application in the archaeological domain, notwithstanding the fact that large portion of cultural landscapes worldwide are characterised by land engineering applications. The current extraordinary availability of remotely sensed data makes it now urgent to envision and develop automatic methods that can simplify the inspection of RS data and the extraction of relevant information from them, as the quantity of data is no longer manageable by traditional âhumanâ visual interpretation. This paper expands on the development of automatic methods for the detection of target landscape features âintended as field system patternsâ in very high spatial resolution images, within the framework of VEiL, a landscape archaeology project based in Italy and focused on the engineered landscape of the Roman city of Aquileia. The targets of interest consist of a variety of similarly oriented objects (such as roads, drainage channels etc.) that concur to demark the current landscape organisation, which reflects the one imposed by Romans from the 2nd cent. BC onward. The proposed workflow exploits the textural and shape properties of real-world elements forming the field patterns using multiscale analysis of dominant oriented response filters. Experiments using remote sensing imagery show that the proposed approach provides accurate localisation of target linear objects and alignments signalled by a wide range of physical entities with very different characteristics
La transformation du paysage narbonnais antique révélé à partir des indices archéologiques
Documents DVD Pourquoi sâintĂ©resser au paysage environnant le centre urbain (urbs) de Narbonne antique ? Parce que le destin de Narbo Martius, ville littorale par excellence, fondĂ©e au carrefour de voies commerciales terrestres, fluviales et maritimes, est intimement liĂ© Ă la configuration de lâenvironnement dans lequel elle sâest dĂ©veloppĂ©e. Comme nous allons le voir, cette configuration, qui est loin dâĂȘtre figĂ©e, est au cĆur de nombreuses prĂ©occupations, quâelles soient dâordre archĂ©ologiq..
Failles actives et structures profondes de la Marge Est-Sicilienne
In the Ionian Sea (central Mediterranean) the slow convergence between Africa and Eurasia results in the formation of a narrow subduction zone. The nature of the crust of the subducting plate remains debated and could represent the last remnants of the Neo-Tethys ocean. The origin of the Ionian basin is also under discussion, especially concerning the rifting mechanisms as the Malta Escarpment could represent a remnant of this opening. This subduction retreats toward the south-east (motion occurring since the last 35 Ma) but is confined to the narrow Ionian basin. A major lateral slab tear fault is required to accommodate the slab rollback.This fault is thought to propagate along the eastern Sicily margin but its precise location remains controversial.This PhD project focussed on the deep sedimentary and crustal structures of the eastern Sicily margin and the Malta Escarpment (ME). Two two-dimensional P wave velocity models were modelled by forward Modelling of wide-angle seismic data, acquired onboard the R/V Meteor during the DIONYSUS cruise in 2014.A 3D gravity model of the region was also performed to constrain the depth of the subducting slab bellow the Calabro-Peloritan backstops. The seismicity of the three structures identified in the velocity models (ME, Alfeo fault System, Ionian Fault System) permits to study their recent activity. The results image an oceanic crust within the Ionian basin as well as the deep structure of the Malta Escarpment, which presents characteristics of a transform margin. A deep and asymmetrical sedimentary basin is imaged south of the Messina strait and seems to have opened between the Calabrian and Peloritan continental terranes. In the western lobe of the Calabrian accretionary prism, the southern velocity model allows to observe the indentation of the internal clastic wedge into the external evaporitic wedge, thus showing the recent activity of this lobe. The interpretation of the velocity models suggests that the major STEP fault is located east of the Malta Escarpment, along the Alfeo Fault System.Le bassin Ionien, en MĂ©diterranĂ©e centrale, abrite une zone de subduction Ă vergence Nord-Ouest oĂč la plaque Afrique plonge sous les blocs Calabro-PĂ©loritain au Nord-Est de la Sicile. Cette subduction rĂ©sulte de la lente convergence entre les plaques tectoniques Afrique et Eurasiatique. Bien que de nombreuses campagnes dâexploration scientifique ont Ă©tĂ© menĂ©es dans cette zone particuliĂšre, plusieurs questions gĂ©odynamiques restent dĂ©battues. Tout dâabord la croĂ»te pavant le bassin Ionien pourrait ĂȘtre soit de nature continentale amincie et reprĂ©senter une extension de la plaque Afrique, soit ocĂ©anique (NĂ©o-TĂ©thys) faisant de ce bassin lâun des plus anciens domaines ocĂ©aniques au monde. Lâescarpement de Malte reprĂ©sente un vestige de lâouverture du bassin, mais les mĂ©canismes de rifting et notamment la gĂ©omĂ©trie dâouverture du bassin restent dĂ©battus. Cette subduction est en retrait vers le Sud-Est depuis les derniers 35 Ma, mais est aujourdâhui confinĂ©e Ă lâĂ©troit bassin Ionien. Afin dâaccommoder ce retrait de la plaque plongeante dans le bassin, une grande faille de dĂ©chirure lithosphĂ©rique de bord de subduction (STEP fault en anglais pour « subduction Transform Edge Propagator ») doit se propager le long de la marge Est-Sicilienne. Cependant, sa position en surface reste difficile Ă dĂ©terminer dans lâĂ©pais prisme dâaccrĂ©tion recouvrant le bassin. Ces questions ont Ă©tĂ© explorĂ©es par modĂ©lisation des donnĂ©es de sismique grand angle de la campagne DIONYSUS (Octobre 2014, R/V Meteor) le long de deux profils perpendiculaires Ă la marge Est-Sicilienne. Des modĂ©lisations gravimĂ©triques en 3D ont aussi Ă©tĂ© rĂ©alisĂ©es dans le but de localiser la plaque plongeante en profondeur sous les blocs Calabro-PĂ©loritains. La sismicitĂ© des trois structures majeures du bassin : lâescarpement de Malte, lâAFS (Alfeo Fault System), et lâIFS (Ionian Fault System) a permis dâĂ©tudier leurs activitĂ©s Ă lâactuel. Les rĂ©sultats obtenus permettent dâobserver une croĂ»te ocĂ©anique au fond du bassin. La structure profonde de lâescarpement de Malte est observĂ©e comme une zone dâamincissement crustal abrupt, ce qui est caractĂ©ristique des marges transformantes. Un profond bassin sĂ©dimentaire asymĂ©trique (11 km) est observĂ© au Sud du dĂ©troit de Messine. Il sâest probablement ouvert rĂ©cemment entre les blocs continentaux PĂ©loritain et Calabre. Dans le lobe Ouest du prisme dâaccrĂ©tion Calabrais, le modĂšle de vitesse permet dâobserver lâindentation du prisme clastique interne dans le prisme Ă©vaporitique externe. Des modĂ©lisations analogiques utilisant sable et silicone ont permis de dĂ©montrer la rĂ©cente activitĂ© de ce lobe. LâinterprĂ©tation des modĂšles de vitesse permet de localiser la faille STEP le long de lâAFS sur les deux profils
Active faulting and deep crustal structure of the Eastern Sicily Margin
Le bassin Ionien, en MĂ©diterranĂ©e centrale, abrite une zone de subduction Ă vergence Nord-Ouest oĂč la plaque Afrique plonge sous les blocs Calabro-PĂ©loritain au Nord-Est de la Sicile. Cette subduction rĂ©sulte de la lente convergence entre les plaques tectoniques Afrique et Eurasiatique. Bien que de nombreuses campagnes dâexploration scientifique ont Ă©tĂ© menĂ©es dans cette zone particuliĂšre, plusieurs questions gĂ©odynamiques restent dĂ©battues. Tout dâabord la croĂ»te pavant le bassin Ionien pourrait ĂȘtre soit de nature continentale amincie et reprĂ©senter une extension de la plaque Afrique, soit ocĂ©anique (NĂ©o-TĂ©thys) faisant de ce bassin lâun des plus anciens domaines ocĂ©aniques au monde. Lâescarpement de Malte reprĂ©sente un vestige de lâouverture du bassin, mais les mĂ©canismes de rifting et notamment la gĂ©omĂ©trie dâouverture du bassin restent dĂ©battus. Cette subduction est en retrait vers le Sud-Est depuis les derniers 35 Ma, mais est aujourdâhui confinĂ©e Ă lâĂ©troit bassin Ionien. Afin dâaccommoder ce retrait de la plaque plongeante dans le bassin, une grande faille de dĂ©chirure lithosphĂ©rique de bord de subduction (STEP fault en anglais pour « subduction Transform Edge Propagator ») doit se propager le long de la marge Est-Sicilienne. Cependant, sa position en surface reste difficile Ă dĂ©terminer dans lâĂ©pais prisme dâaccrĂ©tion recouvrant le bassin. Ces questions ont Ă©tĂ© explorĂ©es par modĂ©lisation des donnĂ©es de sismique grand angle de la campagne DIONYSUS (Octobre 2014, R/V Meteor) le long de deux profils perpendiculaires Ă la marge Est-Sicilienne. Des modĂ©lisations gravimĂ©triques en 3D ont aussi Ă©tĂ© rĂ©alisĂ©es dans le but de localiser la plaque plongeante en profondeur sous les blocs Calabro-PĂ©loritains. La sismicitĂ© des trois structures majeures du bassin : lâescarpement de Malte, lâAFS (Alfeo Fault System), et lâIFS (Ionian Fault System) a permis dâĂ©tudier leurs activitĂ©s Ă lâactuel. Les rĂ©sultats obtenus permettent dâobserver une croĂ»te ocĂ©anique au fond du bassin. La structure profonde de lâescarpement de Malte est observĂ©e comme une zone dâamincissement crustal abrupt, ce qui est caractĂ©ristique des marges transformantes. Un profond bassin sĂ©dimentaire asymĂ©trique (11 km) est observĂ© au Sud du dĂ©troit de Messine. Il sâest probablement ouvert rĂ©cemment entre les blocs continentaux PĂ©loritain et Calabre. Dans le lobe Ouest du prisme dâaccrĂ©tion Calabrais, le modĂšle de vitesse permet dâobserver lâindentation du prisme clastique interne dans le prisme Ă©vaporitique externe. Des modĂ©lisations analogiques utilisant sable et silicone ont permis de dĂ©montrer la rĂ©cente activitĂ© de ce lobe. LâinterprĂ©tation des modĂšles de vitesse permet de localiser la faille STEP le long de lâAFS sur les deux profils.In the Ionian Sea (central Mediterranean) the slow convergence between Africa and Eurasia results in the formation of a narrow subduction zone. The nature of the crust of the subducting plate remains debated and could represent the last remnants of the Neo-Tethys ocean. The origin of the Ionian basin is also under discussion, especially concerning the rifting mechanisms as the Malta Escarpment could represent a remnant of this opening. This subduction retreats toward the south-east (motion occurring since the last 35 Ma) but is confined to the narrow Ionian basin. A major lateral slab tear fault is required to accommodate the slab rollback.This fault is thought to propagate along the eastern Sicily margin but its precise location remains controversial.This PhD project focussed on the deep sedimentary and crustal structures of the eastern Sicily margin and the Malta Escarpment (ME). Two two-dimensional P wave velocity models were modelled by forward Modelling of wide-angle seismic data, acquired onboard the R/V Meteor during the DIONYSUS cruise in 2014.A 3D gravity model of the region was also performed to constrain the depth of the subducting slab bellow the Calabro-Peloritan backstops. The seismicity of the three structures identified in the velocity models (ME, Alfeo fault System, Ionian Fault System) permits to study their recent activity. The results image an oceanic crust within the Ionian basin as well as the deep structure of the Malta Escarpment, which presents characteristics of a transform margin. A deep and asymmetrical sedimentary basin is imaged south of the Messina strait and seems to have opened between the Calabrian and Peloritan continental terranes. In the western lobe of the Calabrian accretionary prism, the southern velocity model allows to observe the indentation of the internal clastic wedge into the external evaporitic wedge, thus showing the recent activity of this lobe. The interpretation of the velocity models suggests that the major STEP fault is located east of the Malta Escarpment, along the Alfeo Fault System
Active faulting and deep crustal structure of the Eastern Sicily Margin
In the Ionian Sea (central Mediterranean) the slow convergence between Africa and Eurasia results in the formation of a narrow subduction zone. The nature of the crust of the subducting plate remains debated and could represent the last remnants of the Neo-Tethys ocean. The origin of the Ionian basin is also under discussion, especially concerning the rifting mechanisms as the Malta Escarpment could represent a remnant of this opening. This subduction retreats toward the south-east (motion occurring since the last 35 Ma) but is confined to the narrow Ionian basin. A major lateral slab tear fault is required to accommodate the slab rollback.This fault is thought to propagate along the eastern Sicily margin but its precise location remains controversial.This PhD project focussed on the deep sedimentary and crustal structures of the eastern Sicily margin and the Malta Escarpment (ME). Two two-dimensional P wave velocity models were modelled by forward Modelling of wide-angle seismic data, acquired onboard the R/V Meteor during the DIONYSUS cruise in 2014.A 3D gravity model of the region was also performed to constrain the depth of the subducting slab bellow the Calabro-Peloritan backstops. The seismicity of the three structures identified in the velocity models (ME, Alfeo fault System, Ionian Fault System) permits to study their recent activity. The results image an oceanic crust within the Ionian basin as well as the deep structure of the Malta Escarpment, which presents characteristics of a transform margin. A deep and asymmetrical sedimentary basin is imaged south of the Messina strait and seems to have opened between the Calabrian and Peloritan continental terranes. In the western lobe of the Calabrian accretionary prism, the southern velocity model allows to observe the indentation of the internal clastic wedge into the external evaporitic wedge, thus showing the recent activity of this lobe. The interpretation of the velocity models suggests that the major STEP fault is located east of the Malta Escarpment, along the Alfeo Fault System.Le bassin Ionien, en MĂ©diterranĂ©e centrale, abrite une zone de subduction Ă vergence Nord-Ouest oĂč la plaque Afrique plonge sous les blocs Calabro-PĂ©loritain au Nord-Est de la Sicile. Cette subduction rĂ©sulte de la lente convergence entre les plaques tectoniques Afrique et Eurasiatique. Bien que de nombreuses campagnes dâexploration scientifique ont Ă©tĂ© menĂ©es dans cette zone particuliĂšre, plusieurs questions gĂ©odynamiques restent dĂ©battues. Tout dâabord la croĂ»te pavant le bassin Ionien pourrait ĂȘtre soit de nature continentale amincie et reprĂ©senter une extension de la plaque Afrique, soit ocĂ©anique (NĂ©o-TĂ©thys) faisant de ce bassin lâun des plus anciens domaines ocĂ©aniques au monde. Lâescarpement de Malte reprĂ©sente un vestige de lâouverture du bassin, mais les mĂ©canismes de rifting et notamment la gĂ©omĂ©trie dâouverture du bassin restent dĂ©battus. Cette subduction est en retrait vers le Sud-Est depuis les derniers 35 Ma, mais est aujourdâhui confinĂ©e Ă lâĂ©troit bassin Ionien. Afin dâaccommoder ce retrait de la plaque plongeante dans le bassin, une grande faille de dĂ©chirure lithosphĂ©rique de bord de subduction (STEP fault en anglais pour « subduction Transform Edge Propagator ») doit se propager le long de la marge Est-Sicilienne. Cependant, sa position en surface reste difficile Ă dĂ©terminer dans lâĂ©pais prisme dâaccrĂ©tion recouvrant le bassin. Ces questions ont Ă©tĂ© explorĂ©es par modĂ©lisation des donnĂ©es de sismique grand angle de la campagne DIONYSUS (Octobre 2014, R/V Meteor) le long de deux profils perpendiculaires Ă la marge Est-Sicilienne. Des modĂ©lisations gravimĂ©triques en 3D ont aussi Ă©tĂ© rĂ©alisĂ©es dans le but de localiser la plaque plongeante en profondeur sous les blocs Calabro-PĂ©loritains. La sismicitĂ© des trois structures majeures du bassin : lâescarpement de Malte, lâAFS (Alfeo Fault System), et lâIFS (Ionian Fault System) a permis dâĂ©tudier leurs activitĂ©s Ă lâactuel. Les rĂ©sultats obtenus permettent dâobserver une croĂ»te ocĂ©anique au fond du bassin. La structure profonde de lâescarpement de Malte est observĂ©e comme une zone dâamincissement crustal abrupt, ce qui est caractĂ©ristique des marges transformantes. Un profond bassin sĂ©dimentaire asymĂ©trique (11 km) est observĂ© au Sud du dĂ©troit de Messine. Il sâest probablement ouvert rĂ©cemment entre les blocs continentaux PĂ©loritain et Calabre. Dans le lobe Ouest du prisme dâaccrĂ©tion Calabrais, le modĂšle de vitesse permet dâobserver lâindentation du prisme clastique interne dans le prisme Ă©vaporitique externe. Des modĂ©lisations analogiques utilisant sable et silicone ont permis de dĂ©montrer la rĂ©cente activitĂ© de ce lobe. LâinterprĂ©tation des modĂšles de vitesse permet de localiser la faille STEP le long de lâAFS sur les deux profils
- âŠ