Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Located in central Europe at the junction of the Southern Alps and the Dinarides, the ≈ 100 km long Idrija fault, striking N310 and dipping ≈ 80°NE is often considered as the potential source of the historical 1511 earthquake (estimated macroseismic magnitude: Mm 6.8). Using 1/25,000 to 1/5000 topographical maps, satellite images (SPOT5), 12.5 m illuminated DEM and airborne LiDAR data-derived 1-m-DEM, we examined in detail the Idrija fault trace along a 20-km-long swath in the central portion of the fault. Combining topographic and remote sensing data allows characterizing the recent activity along the Idrija fault and estimating its cumulative displacement along strike.Between Tolmin and Godovič, the fault trace is mostly linear but appears divided into three disconnected segments of 11–20-km-long. Morphological evidences such as offset streams and ridges and major drainage abandonments suggest ongoing movement. At three sites, field observations and LiDAR-DEM analysis allow measuring cumulative dextral offsets comprised between 35 and 65 m. We found two larger offsets of ≈ 140 m and ≈ 360 m at the southeasternmost site. The vertical component is significant and revealed by a rake ranging from 0 to 33°. The derived N303–N310 striking slip-vector is in agreement with the motion along this fault as suggested by the geodesy. Assuming that the smallest measured offsets have been recorded after the last glacial maximum (LGM, about 20 ka ago), the minimum slip-rate for the Idrija fault is about 1.5 mm/yr over this period of time.
ISSN: 0040-1951

hal-01115724
https://hal.archives-ouvertes.fr/hal-01115724
DOI : 10.1016/j.tecto.2014.04.043

Éditeur(s) : Turin : Imprimerie Royale
Siècle(s) traité(s) : 19
Provenance : Archives départementales de Guadeloupe
Permalien : http://www.manioc.org/patrimon/ADG18153
ADG18153

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The chronostratigraphy of the lower Miocene deposits of northwestern Sardinia is refined in the Castelsardo Basin. The combination of new 40Ar/39Ar isotopic datings, 19 micropalaeontological datings (calcareous nannofossils, planktonic and large benthic foraminifers) and 16 palaeomagnetic polarity measurements led to a new chronostratigraphic framework. The continental deposits of the first megasequence (Valledoria and Casteldoria members) are possibly Aquitanian. The overlying marine sediments are early Burdigalian (Vaginella depressa Molasse). The marine transgression can be dated to around 19.7 Ma. Marine conditions ceased 18.83 ± 0.13 Ma, the age of the index aerial τ2 ignimbrite. The continental part of the second megasequence (“Lacustre” unit) is early–middle Burdigalian, between 18.8 and 18 Ma. The overlying marine part (Campulandu and Sedini members) is middle–late Burdigalian. The second marine transgression began in the earliest–late Burdigalian, during the Chron C5Dr reversal, at the time of the eustatic Bur 4 event. The Castelsardo basin went through two main extensional tectonic episodes. The first one occurred as the Valledoria Member was deposited and possibly dates back to the Aquitanian. The second one occurred as the uppermost part of the Vaginella depressa Molasse was deposited during the early Burdigalian. The second extensional episode is related to a rapid rotation of Sardinia. Palaeomagnetic results confirm that Corsica and Sardinia acted as a single block which suffered a 28 ± 17° ccw rotation after 19.2 Ma. The Castelsardo basin is held to be an Aquitanian–early Burdigalian intra-arc rift basin that later evolved in a thermally controlled subsident margin of the Ligurian-Provençal Basin during the middle–late Burdigalian.
ISSN: 0031-0182

hal-00498288
https://hal.archives-ouvertes.fr/hal-00498288
DOI : 10.1016/j.palaeo.2010.06.007

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : In Vietnam, the Triassic Indosinian collision affected coevally the Truong Son belt and the Kontum Massif,which were not independent tectonic units, but parts of the same Gondwana-derived Indochina continental block. This thermotectonic event took place synchronously throughout Vietnam, during the Lower Triassic 250-240-Ma time interval, as demonstrated by numerous geochronological data, combining Ar-Ar and U-Pb dating methods. Structural and kinematic investigations, in the Indosinian metamorphic rocks, reveal that the collisional process resulted from a consistent northwest-striking convergence of Indochina with respect to the adjacent blocks. It is suggested that this motion was taken up by a pair of opposite subduction zones: to the north, beneath South China, and to the west, beneath western Indochina, along the Song Ma and Po Ko sutures, respectively. Tectonic markers, calc-alkaline subduction-related volcanism and granitic intrusions and the generation of high-pressure rocks that have been recently discovered support this geodynamic setting, at least along Po Ko. Along the northwest-trending Song Ma zone, the obliquity of the convergence during subduction and subsequent collision resulted in the development, within the Truong Son Belt, of a set of subparallel dextral mylonitic shear zones, under amphibolite-facies metamorphism. The intermediate segments remained weakly metamorphic or even almost devoid of metamorphism. Along Po Ko, the convergence was near-orthogonal, with a left-lateral strike-slip component; the ongoing continental subduction resulted in the reworking of the Kontum granulitic basement and the development of Indosinian HP granulitic conditions; the subsequent extension-related exhumation operated approximately in the same northwestwards direction. This Indosinian evolution, applied on a continental crust that had been probably affected, as in South China, by a Caledonian-related event, as judged by the general unconformity of the Lower Devonian sediments, the widespread occurrence of magmatic crystallisation ages of ca 450 Ma (Ordovician-Silurian), and by the approximately similar age of the primary granulitic episode in the Kontum Massif. The similarities of the Devonian facies over central, northern Vietnam and South China imply a land connection, possibly as a consequence of a Caledonian collision along Song Ma, but this does not preclude a further oceanic opening and a closure during the Indosinian.
ISSN: 1631-0713

hal-00411591
https://hal.archives-ouvertes.fr/hal-00411591
DOI : 10.1016/j.crte.2007.10.005

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Tsavorite, the vanadian variety of green grossular, is a high value economic gemstone. It is hosted exclusively in the metasedimentary formations from the Neoproterozoic Metamorphic Mozambique Belt. The deposits are mined in Kenya, Tanzania and Madagascar and other occurrences are located in Pakistan and East Antarctica. They are located within metasomatized graphitic rocks such as graphitic gneiss and calc-silicates, intercalated with meta-evaporites. Tsavorite is found as primary deposits either in nodule (type I) or in quartz vein (type II), and in placers (type III). The primary mineralizations (types I and II) are controlled by lithostratigraphy and/or structure. For the African occurrences, the protoliths of the host-rocks were deposited at the beginning of the Neoproterozoic within a marine coastal sabkha environment, located at the margin of the Congo-Kalahari cratons in the Mozambique Ocean. During the East African-Antarctican Orogeny, the rocks underwent high amphibolite to granulite facies metamorphism and the formation of tsavorite deposits occurred between 650 and 550 Ma. The nodules of tsavorite were formed during prograde metamorphism, calcium coming from sulphates and carbonates, whereas alumina, silicates, vanadium and chromium probably came from clays and chlorite. The veins were formed during the deformation of the metasedimentary platform units which experienced shearing, leading to the formation of fault-filled veins. Metasomatism developed during retrograde metamorphism. The metasedimentary sequences are characterized by the presence of evaporitic minerals such as gypsum and anhydrite, and scapolite. Evaporites are essential as they provide calcium and permit the mobilization of all the chemical elements for tsavorite formation. The H2S-S8 metamorphic fluids characterized in primary fluid inclusions of tsavorites and the δ11B values of coeval dravite confirm the evaporitic origin of the fluids. The V2O3 and Cr2O3 contents of tsavorite range respectively from 0.05 to 7.5 wt.%, while their δ18O values are in the range of 9.5-21.1‰. The genetic model proposed for tsavorite is metamorphic, based on chemical reactions developed between an initial assemblage composed of gypsum and anhydrite, carbonates and organic matter deposited in a sabkha-like sedimentary basin.
ISSN: 0169-1368

hal-00853279
https://hal.archives-ouvertes.fr/hal-00853279
DOI : 10.1016/j.oregeorev.2013.01.016

Éditeur(s) : HAL CCSD American Geophysical Union (AGU)
Résumé : International audience
Deciphering Variscan versus Alpine history in the internal Rif system is a key to constraining the tectonic evolution of the Alboran domain and hence the geodynamics of the western Mediterranean system during the Cenozoic. This study focuses on the evolution of the metamorphic envelope of the Beni Bousera massif and its relation to the underlying peridotites. Combining structural geology, metamorphic petrology, and LA-ICP-MS U-Th-Pb dating of monazite, this study contributes to the understanding of the tectonic history of the western internal Rif. The regional foliation (S2) is characterized by LP/HT mineral assemblages and obliterates a former foliation (S1) developed along a barrovian (MP/MT) metamorphic gradient. The dating of some metamorphic monazite grains from a micaschist and a migmatitic gneiss demonstrates that the crustal envelope of the peridotite recorded two distinct tectonometamorphic episodes. Data from monazite inclusions in S1 garnet suggest that the first event, D1, is older than 250-170 Ma and likely related to the Variscan collision, in agreement with the barrovian type of the metamorphic gradient. The second event, D2, is Alpine in age (at circa 21 Ma) and corresponds to a strong lithosphere thinning allowing subsequent subcontinental mantle exhumation. Such a tectonic context provides an explanation for the LP/HT metamorphic gradient that is recorded in the regional foliation of the western Betic-Rif system. This extension is probably related to a subduction slab roll-back in the western end of the Mediterranean realm during the Oligo-Miocene times. No evidences for a Tertiary HP/LT metamorphism have been identified in the studied area
ISSN: 0278-7407

Droits : info:eu-repo/semantics/OpenAccess
insu-01152517
https://hal-insu.archives-ouvertes.fr/insu-01152517
https://hal-insu.archives-ouvertes.fr/insu-01152517/document
https://hal-insu.archives-ouvertes.fr/insu-01152517/file/gueydan-2015.pdf
DOI : 10.1002/2014TC003769

Éditeur(s) : HAL CCSD Elsevier Elsevier Masson
Résumé : New field and micropalaeontological investigations have been conducted in four of the Pliocene rias of the internal zone of the Rif in Morocco, on the southern margin of the Alboran Sea. We found that marine sediments outcropping in these rias were deposited mainly during the Early Zanclean, between 5.04 and 3.8 Ma. After a transgressive episode that led to the deposition of terrestrial to marine conglomerates, dark clays deposited first at shallow palaeo-depths and then at bathyal palaeo-depths. The rias were then infilled with a shallowing upward succession comprising marine clays and sandstone and, locally, terrestrial sediments that indicate their final emersion. No Gilbert-deltas were observed in these rias. The presence of transgressive deposits at the bottom of the rias, also identified in other basins of the external zone of the Rif, and the absence of Gilbert deltas question a catastrophic reflooding after the Messinian Salinity Crisis in this area.
ISSN: 1631-0713

hal-01115243
https://hal.archives-ouvertes.fr/hal-01115243
DOI : 10.1016/j.crte.2014.03.002

Éditeur(s) : HAL CCSD
Résumé : 22 pages; 20 figures
Rock foundations of the Kephren and Kheops pyramids are examined in comparison with other Fourth Dynasty monuments: the Sphinx, Queen Kentkawes' mastaba and the Abu Rawash pyramid. This study is based on geological and geomorphological observations, visual observation, and photomontages. Results, correlated with those of former studies, demonstrate the existence of natural hills used as substrata in the construction of the two great pyramids. The minimum volume of these hills can be estimated at 12% and 23% respectively of the volumes of the Kephren and Kheops pyramids. The use of worked rock hills appears to be a characteristic of the construction methods under the Fourth Dynasty.
Le substratum rocheux des pyramides de Kheops et Khephren est étudié en comparaison avec celui d'autres monuments de la quatrième dynastie de l'ancienne Egypte : le Sphinx, le mastaba de la reine Kentkawes et la pyramide d'Abu Rawash. Cette étude est basée sur des observations géologiques et géomorphologiques, l'observation visuelle et des photomontages, ainsi que des mesures réalisées sur le terrain. Les résultats, corrélés avec ceux d'études antérieures, démontrent l'existence de collines naturelles utilisées comme assises pour la construction des deux grandes pyramides. Le volume minimum de ces collines peut être estimé par rapport au volume total à 12% pour Khephren et 23% pour Kheops. L'utilisation de collines rocheuses pour asseoir la construction d'un monument apparaît être caractéristique des méthodes de construction utilisées sous la quatrième dynastie.
https://hal.archives-ouvertes.fr/hal-00319586

hal-00319586
https://hal.archives-ouvertes.fr/hal-00319586
https://hal.archives-ouvertes.fr/hal-00319586/document
https://hal.archives-ouvertes.fr/hal-00319586/file/PyramidsSR.pdf

Éditeur(s) : HAL CCSD Wiley/Blackwell
Résumé : 4 pages
International audience
This article documents the addition of 268 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Alburnoides bipunctatus, Chamaerops humilis, Chlidonias hybrida, Cyperus papyrus, Fusarium graminearum, Loxigilla barbadensis, Macrobrachium rosenbergii, Odontesthes bonariensis, Pelteobagrus vachelli, Posidonia oceanica, Potamotrygon motoro, Rhamdia quelen, Sarotherodon melanotheron heudelotii, Sibiraea angustata, Takifugu rubripes, Tarentola mauritanica, Trimmatostroma sp. and Wallago attu. These loci were cross-tested on the following species: Alburnoides fasciatus, Alburnoides kubanicus, Alburnoides maculatus, Alburnoides ohridanus, Alburnoides prespensis, Alburnoides rossicus, Alburnoides strymonicus, Alburnoides thessalicus, Alburnoides tzanevi, Carassius carassius, Fusarium asiaticum, Leucaspius delineatus, Loxigilla noctis dominica, Pelecus cultratus, Phoenix canariensis, Potamotrygon falkneri, Trachycarpus fortune and Vimba vimba.
ISSN: 1755-098X

hal-00823716
https://hal.archives-ouvertes.fr/hal-00823716
DOI : 10.1111/1755-0998.12095
PUBMED : 23521844

Éditeur(s) : HAL CCSD Elsevier
Résumé : We present comparative field studies in folded areas (Southern France. Moroccan Western Atlas and Abruzzo, Italy) giving new insights into fracture distribution within folded rocks of the shallow brittle crust. We show that the curvature in folds formed in brittle mechanical units is usually accommodated by multiple "dip-domain boundaries" (appearing as curvature discontinuities at fold scale) corresponding to relatively narrow and dense fracture zones, striking parallel or slightly oblique to the fold axis. They separate "dip-domains" where curvature is absent or moderate. It is shown that the dip-domain boundaries (which are obvious in the case of kink folds or box-fold anticlines) are currently present as multiple subtle hinges even when the curvature appears continuous at first sight. The nature of dip-domain boundaries is studied, they often cut through the whole thickness of the mechanical units Their internal structure varies, and a non-exhaustive typology is proposed For each type, an interpretative kinematic scenario shows how the dip-domain boundaries could initiate and develop. We suggest two kinds of origins (1) they could correspond to the reactivation of inherited, along-strike fracture zones (opening-mode fracture concentrations such as big joints, fracture corridors. Inherited faults, etc), (2) they could be created as mechanical instabilities during the fold formation (syn-folding origin), in particular through small reverse faults. In both cases, early zones of weakness localize the dip-domain boundaries, and control the Increase in curvature in association with increasing fracture density within the boundary. Because they represent well-defined vertically and axially persistent sub-seismic fracture zones generally limited to the thickness of the folded unit, dip-domain boundaries could enhance the axial permeability of folded and fractured reservoirs.
ISSN: 0191-8141

hal-00512651
https://hal.archives-ouvertes.fr/hal-00512651
DOI : 10.1016/j.jsg.2010.03.002

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The Souttoufide belt is situated between the High-Atlas in the north, the Mauritanides in the south and the West African Craton as well as the Tindouf basin in the east. Thus, this belt is a part of the West African fold belt system which surrounds the West African Craton. Outcrops occur only in three areas, while the rest of the Souttoufide belt is covered by Meso- to Cenozoic sediments. These areas are, from the south to the north, the Adrar Souttouf Massif, the Smara Zemmour area, and the western part of the Anti-Atlas. Because of the continuing processing and numerous publications, the Anti-Atlas cannot be dealt with in detail. Fundamental geological work in both of the other areas was mainly done during the second third of the 20th century, followed by several decades of inactivity. Numerous studies were done in the Adrar Souttouf massif during the last decade, while the Smara-Zemmour area still remains poorly investigated. Most of them were focused on geochronological analyses and geochemistry. Accordingly, the obtained data led to a new interpretation. The Adrar Souttouf is interpreted as a Pan-African belt exhibiting a Neoproterozoic island arc reworked by the Variscan collision between the North American Craton (NAC) and the West African Craton (WAC). The Smara-Zemmour area is considered as the external part of this Variscan belt thrusted onto the Palaeozoic Tindouf basin. The western Anti-Atlas as considered as a Pan-African active margin reworked during the Variscan orogen. Together, these three areas, lead to the hypothesis of a Late Pan-African belt capped by the Early and Middle Palaeozoic covers and then affected by the Middle Carboniferous tectonic event (330 Ma) related to the Pangaean assembly. Correlations with adjacent belts (Mauritanides and Anti-Atlas) are considered.
ISSN: 0899-5362

hal-01382815
https://hal.archives-ouvertes.fr/hal-01382815
DOI : 10.1016/j.jafrearsci.2015.04.016

Éditeur(s) : Paris : Imprimerie Pradier
Siècle(s) traité(s) : 20
Provenance : Archives départementales de Guadeloupe
Permalien : http://www.manioc.org/patrimon/ADG18191
ADG18191

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
New investigations in the Neogene Boudinar basin (Morocco) provide new information about the Messinian Salinity Crisis (MSC) and Zanclean reflooding in the southern part of the Alboran realm (westernmost Mediterranean). Based on a new field, sedimentological and palaeontological analyses, the age and the geometry of both the Messinian erosional surface (MES) and the overlying deposits have been determined. The MES is of late Messinian age and was emplaced in subaerial settings. In the Boudinar basin, a maximum of 200 m of Miocene sediments was eroded, including late Messinian gypsum blocks. The original geometry of the MES is preserved only when it is overlain by late Messinian continental deposits, conglomeratic alluvial fans or lacustrine marly sediments. These sediments are interpreted as indicators of the sea-level fall during the MSC. Elsewhere in the basin, the contact between late Messinian and early Pliocene deposits is a low-angle dipping, smooth surface that corresponds to the early Pliocene transgression surface that subsequently re-shaped the regressive MES. The early Pliocene deposits are characterized by: (i) their onlap onto either the basement of the Rif chain or the late Miocene deposits; (ii) lagoonal deposits at the base to offshore marls and sands at the top (earliest Pliocene; 5.33–5.04 Ma interval; foraminifer zone PL1); (iii) marine recovery occurring in the 5.32–5.26 Ma interval; and (iv) the change from lagoonal to offshore environments occurring within deposits tens of metres thick. This information indicates that at least the end of the reflooding period was progressive, not catastrophic as previously thought.
ISSN: 0037-0738

hal-01306672
https://hal.archives-ouvertes.fr/hal-01306672
DOI : 10.1016/j.sedgeo.2015.12.014

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The morphogenetic evolution of the Lesser Caucasus has been strongly influenced by Plio-Quaternary volcanic and tectonic events and Pleistocene glaciations. Fluvio-lacustrine environments, indicated by diatomaceous deposits, prevailed in the Syunik region of southern Armenia during the Pliocene and Pleistocene. The Pleistocene diatomaceous deposits studied contain leaf impressions and pollen, allowing local palaeoclimatic reconstructions. The chronology of morphogenetic events has been determined by 17 radiometric dates (K/Ar, Ar/Ar, U/Th), palaeomagnetic investigations and is placed in a spatial context by a detailed geomorphological map and a 24-km geological transect of the Vorotan valley, the main area studied. Before 1.21 Ma, tectonic movements (antecedents of the lower part of the Vorotan valley) generated extensive lake formations with diatomaceous deposits. From 993 ka, volcanic eruptions produced lava flows that covered the fluvio-lacustrine accumulations. During Marine Isotopic Stages 12, 6 and 4, glaciers and fluvio-glacial deposits were probably present overall the principal uplands and valleys of southern Armenia. At 53.68 ka (MIS 3), 12.6 ka, 10.78 ka and 4.14 ka (MIS 1), the development of travertines on some slopes and in some valleys highlights temperate and humid climatic phases. Palaeobotanical studies of leaf and pollen floras show that the vegetation changed several times from forested to steppic phases in response to the climate oscillations of the Lower Pleistocene. This work proposes a first morphogenic and palaeoclimatic reconstruction from the lower Pleistocene to the Postglacial period, when the first settlements of the population in the Lesser Caucasus were influenced by tectono-volcanic events, lake level changes and glacialeinterglacial oscillations forced by the obliquity orbital parameter (41 ky cycles).
ISSN: 1040-6182

hal-00481939
https://hal.archives-ouvertes.fr/hal-00481939
DOI : 10.1016/j.quaint.2010.02.008

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Located on the margin of the west Alboran basin, the Gibraltar Arc (Betic-Rif mountain belt) displays post-Pliocene vertical movements evidenced by uplifted marine sedimentary basins and marine terraces. Quantification of vertical movements is an important clue to understand the origin of present-day relief generation in the Betic-Rif mountain chain together with the causes of the Messinian Salinity Crisis. In this paper, we present the results of a pluridisciplinary study combining an analysis of low temperature thermochronology and Pliocene basins evolution to constrain the exhumation history and surface uplift of internals units of the Rif belt (Northern Morocco). The mean (U-Th)/He apatite ages obtained from 11 samples are comprised between 14.1 and 17.8 Ma and display a wide dispersion, which could be explained by a great variability of apatite chemistries in the analyzed samples. No correlations between altitude and age have been found along altitudinal profile suggesting a rapid exhumation during this period. Thermal modeling using our (U-Th)/He apatite ages and geochronological data previously obtained in the same area (40Ar/39Ar and K/Ar data on biotite, zircon and apatite fission track) allow us to propose a cooling history. The rocks suffered a rapid cooling at 60-100 °C/Ma between 22.5 and 19 Ma, then cooled to temperatures around 40 °C between 19 and 18 Ma. They were re-heated at around 110 °C between 18 and 15 Ma then rapidly cooled and exhumed to reach the surface temperature at around 13 Ma. The re-heating could be related to a renewal in thrusting and burying of the inner zones. Between 15 and 13 Ma the cooling resumed at a rate of 50 °C/Ma indicating an exhumation rate of 0.8 mm/y considering an average 40 °C/km geothermal gradient. This exhumation may be linked to the extension in the Alboran Sea. Otherwise biostratigraphic and sedimentological analysis of Pliocene basins of the internal Rif provided informations on the more recent events and vertical movements. Pliocene deposits of the Rifian coast represent the passive infilling of palaeo-rias between 5.33 and 3.8 Ma. The whole coastal area was uplifted at slow average rates (0.01-0.03 mm/y) in relation with a northeastward tilting of 0.2-0.3° since the Lower-Pliocene. A late Pliocene to present extensional tectonics associated to uplift has been identified all along the coastal ranges of the Internal Zone of the Rif chain. This extension was coeval with the major late Pliocene to Pleistocene extensional episode of the Alboran Sea and appears to be still active nowadays. No significant late Messinian uplift was evidenced, thus calling into question the geodynamic models relating the closure of the marine gateways and the MSC to slab roll back.
ISSN: 0264-3707

hal-01053531
https://hal.archives-ouvertes.fr/hal-01053531
DOI : 10.1016/j.jog.2014.01.006

Éditeur(s) : Londres : P. S. King and Son
Siècle(s) traité(s) : 19
Provenance : Université Caen Normandie. Service commun de la documentation
Permalien : http://www.manioc.org/patrimon/CAE19037
CAE19037

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The continental South Armenian Block – part of the Anatolide–Tauride South Armenian microplate – of Gondwana origin rifted from the African margin after the Triassic and collided with the Eurasian margin after the Late Cretaceous. During the Late Cretaceous, two northward dipping subduction zones were simultaneously active in the northern Neo-Tethys between the South Armenian Block in the south and the Eurasian margin in the north: oceanic subduction took place below the continental Eurasian margin and intra-oceanic subduction resulted in ophiolite obduction onto the South Armenian Block in the Late Cretaceous.The paleolatitude position of the South Armenian Block before its collision with Eurasia within paleogeographic reconstructions is poorly determined and limited to one study. This earlier study places the South Armenian Block at the African margin in the Early Jurassic. To reconstruct the paleolatitude history of the South Armenian Block, we sampled Upper Devonian–Permian and Cretaceous sedimentary rocks in Armenia. The sampled Paleozoic rocks have likely been remagnetized. Results from two out of three sites sampled in Upper Cretaceous strata pass fold tests and probably all three carry a primary paleomagnetic signal. The sampled sedimentary rocks were potentially affected by inclination shallowing. Therefore, two sites that consist of a large number of samples (> 100) were corrected for inclination shallowing using the elongation/inclination method.These are the first paleomagnetic data that quantify the South Armenian Block's position in the Tethys ocean between post-Triassic rifting from the African margin and post-Cretaceous collision with Eurasia. A locality sampled in Lower Campanian Eurasian margin sedimentary rocks and corrected for inclination shallowing, confirms that the corresponding paleolatitude falls on the Eurasian paleolatitude curve. The north–south distance between the South Armenian Block and the Eurasian margin just after Coniacian–Santonian ophiolite obduction was at most 1000 km.
ISSN: 0040-1951

hal-01365871
https://hal.archives-ouvertes.fr/hal-01365871
DOI : 10.1016/j.tecto.2015.01.012

Droits : Domaine public
Provenance : Collectivité territoriale de Guyane. Bibliothèque Alexandre-Franconie
Permalien : http://www.manioc.org/patrimon/FRA11274-3
FRA11274-3

Éditeur(s) : Paris : Société de Géographie
Siècle(s) traité(s) : 19
Droits : Domaine public
Provenance : Collectivité territoriale de Guyane. Bibliothèque Alexandre-Franconie
Permalien : http://www.manioc.org/patrimon/FRA11061
FRA11061

Description : Récit de voyage en Amérique avec une partie sur plateau des Guyanes et sur le Brésil. Gravures
Siècle(s) traité(s) : 19
Droits : Domaine public
Provenance : Philippe Batrosse - Libraire à Cayenne
Permalien : http://www.manioc.org/patrimon/HASH017ff277fc4ae32658ca07cf
HASH017ff277fc4ae32658ca07cf