@misc{JolivetFaccennaHuetetal.2013, author = {Jolivet, Laurent and Faccenna, Claudio and Huet, Benjamin and Labrousse, Loic and Le Pourhiet, Laetitia and Lacombe, Olivier and Lecomte, Emmanuel and Burov, Evguenii and Denele, Yoann and Brun, Jean-Pierre and Philippon, Melody and Paul, Anne and Salaue, Gwenaelle and Karabulut, Hayrullah and Piromallo, Claudia and Monie, Patrick and Gueydan, Frederic and Okay, Aral I. and Oberh{\"a}nsli, Roland and Pourteau, Amaury and Augier, Romain and Gadenne, Leslie and Driussi, Olivier}, title = {Aegean tectonics strain localisation, slab tearing and trench retreat}, series = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth}, volume = {597}, journal = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0040-1951}, doi = {10.1016/j.tecto.2012.06.011}, pages = {1 -- 33}, year = {2013}, abstract = {We review the geodynamic evolution of the Aegean-Anatolia region and discuss strain localisation there over geological times. From Late Eocene to Present, crustal deformation in the Aegean backarc has localised progressively during slab retreat. Extension started with the formation of the Rhodope Metamorphic Core Complex (Eocene) and migrated to the Cyclades and the northern Menderes Massif (Oligocene and Miocene), accommodated by crustal-scale detachments and a first series of core complexes (MCCs). Extension then localised in Western Turkey, the Corinth Rift and the external Hellenic arc after Messinian times, while the North Anatolian Fault penetrated the Aegean Sea. Through time the direction and style of extension have not changed significantly except in terms of localisation. The contributions of progressive slab retreat and tearing, basal drag, extrusion tectonics and tectonic inheritance are discussed and we favour a model (I) where slab retreat is the main driving engine, (2) successive slab tearing episodes are the main causes of this stepwise strain localisation and (3) the inherited heterogeneity of the crust is a major factor for localising detachments. The continental crust has an inherited strong heterogeneity and crustal-scale contacts such as major thrust planes act as weak zones or as zones of contrast of resistance and viscosity that can localise later deformation. The dynamics of slabs at depth and the asthenospheric flow due to slab retreat also have influence strain localisation in the upper plate. Successive slab ruptures from the Middle Miocene to the late Miocene have isolated a narrow strip of lithosphere, still attached to the African lithosphere below Crete. The formation of the North Anatolian Fault is partly a consequence of this evolution. The extrusion of Anatolia and the Aegean extension are partly driven from below (asthenospheric flow) and from above (extrusion of a lid of rigid crust).}, language = {en} } @misc{PourteauSudoCandanetal.2013, author = {Pourteau, Amaury and Sudo, Masafumi and Candan, Osman and Lanari, P. and Vidal, O. and Oberh{\"a}nsli, Roland}, title = {Neotethys closure history of Anatolia - insights from Ar-40-Ar-39 geochronology and P-T estimation in high-pressure metasedimentary rocks}, series = {Journal of metamorphic geology}, volume = {31}, journal = {Journal of metamorphic geology}, number = {6}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0263-4929}, doi = {10.1111/jmg.12034}, pages = {585 -- 606}, year = {2013}, abstract = {The multiple high-pressure (HP), low-temperature (LT) metamorphic units of Western and Central Anatolia offer a great opportunity to investigate the subduction-and continental accretion-related evolution of the eastern limb of the long-lived Aegean subduction system. Recent reports of the HP-LT index mineral Fe-Mg-carpholite in three metasedimentary units of the Gondwana-derived Anatolide-Tauride continental block (namely the Afyon Zone, the Oren Unit and the southern Menderes Massif) suggest a more complicated scenario than the single-continental accretion model generally put forward in previous studies. This study presents the first isotopic dates (white mica Ar-40-Ar-39 geochronology), and where possible are combined with P-T estimates (chlorite thermometry, phengite barometry, multi-equilibrium thermobarometry), on carpholite-bearing rocks from these three HP-LT metasedimentary units. It is shown that, in the Afyon Zone, carpholite-bearing assemblages were retrogressed through greenschist-facies conditions at c. 67-62 Ma. Early retrograde stages in the Oren Unit are dated to 63-59 Ma. In the Kurudere-Nebiler Unit (HP Mesozoic cover of the southern Menderes Massif), HP retrograde stages are dated to c. 45 Ma, and post-collisional cooling to c. 26 Ma. These new results support that the Oren Unit represents the westernmost continuation of the Afyon Zone, whereas the Kurudere-Nebiler Unit correlates with the Cycladic Blueschist Unit of the Aegean Domain. In Western Anatolia, three successive HP-LT metamorphic belts thus formed: the northernmost Tavsanli Zone (c. 88-82 Ma), the Oren-Afyon Zone (between 70 and 65 Ma), and the Kurudere-Nebiler Unit (c. 52-45 Ma). The southward younging trend of the HP-LT metamorphism from the upper and internal to the deeper and more external structural units, as in the Aegean Domain, points to the persistence of subduction in Western Anatolia between 93-90 and c. 35 Ma. After the accretion of the Menderes-Tauride terrane, in Eocene times, subduction stopped, leading to continental collision and associated Barrovian-type metamorphism. Because, by contrast, the Aegean subduction did remain active due to slab roll-back and trench migration, the eastern limb (below Southwestern Anatolia) of the Hellenic slab was dramatically curved and consequently teared. It therefore is suggested that the possibility for subduction to continue after the accretion of buoyant (e.g. continental) terranes probably depends much on palaeogeography.}, language = {en} } @misc{OmraniMoazzenOberhaenslietal.2013, author = {Omrani, H. and Moazzen, Mohssen and Oberh{\"a}nsli, Roland and Tsujimori, T. and Bousquet, Romain and Moayyed, M.}, title = {Metamorphic history of glaucophane-paragonite-zoisite eclogites from the Shanderman area, northern Iran}, series = {Journal of metamorphic geology}, volume = {31}, journal = {Journal of metamorphic geology}, number = {8}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0263-4929}, doi = {10.1111/jmg.12045}, pages = {791 -- 812}, year = {2013}, abstract = {The Shanderman eclogites and related metamorphosed oceanic rocks mark the site of closure of the Palaeotethys ocean in northern Iran. The protolith of the eclogites was an oceanic tholeiitic basalt with MORB composition. Eclogite occurs within a serpentinite matrix, accompanied by mafic rocks resembling a dismembered ophiolite. The eclogitic mafic rocks record different stages of metamorphism during subduction and exhumation. Minerals formed during the prograde stages are preserved as inclusions in peak metamorphic garnet and omphacite. The rocks experienced blueschist facies metamorphism on their prograde path and were metamorphosed in eclogite facies at the peak of metamorphism. The peak metamorphic mineral paragenesis of the rocks is omphacite, garnet (pyrope-rich), glaucophane, paragonite, zoisite and rutile. Based on textural relations, post-peak stages can be divided into amphibolite and greenschist facies. Pressure and temperature estimates for eclogite facies minerals (peak of metamorphism) indicate 15-20kbar at similar to 600 degrees C. The pre-peak blueschist facies assemblage yields <11kbar and 400-460 degrees C. The average pressure and temperature of the post-peak amphibolite stage was 5-6kbar, similar to 470 degrees C. The Shanderman eclogites were formed by subduction of Palaeotethys oceanic crust to a depth of no more than 75km. Subduction was followed by collision between the Central Iran and Turan blocks, and then exhumation of the high pressure rocks in northern Iran.}, language = {en} } @misc{SodoudiYuanKindetal.2013, author = {Sodoudi, Forough and Yuan, Xiaohui and Kind, Rainer and Lebedev, Sergei and Adam, Joanne M-C. and K{\"a}stle, Emanuel and Tilmann, Frederik}, title = {Seismic evidence for stratification in composition and anisotropic fabric within the thick lithosphere of Kalahari Craton}, series = {Geochemistry, geophysics, geosystems}, volume = {14}, journal = {Geochemistry, geophysics, geosystems}, number = {12}, publisher = {American Geophysical Union}, address = {Washington}, issn = {1525-2027}, doi = {10.1002/2013GC004955}, pages = {5393 -- 5412}, year = {2013}, abstract = {Based on joint consideration of S receiver functions and surface-wave anisotropy we present evidence for the existence of a thick and layered lithosphere beneath the Kalahari Craton. Our results show that frozen-in anisotropy and compositional changes can generate sharp Mid-Lithospheric Discontinuities (MLD) at depths of 85 and 150-200 km, respectively. We found that a 50 km thick anisotropic layer, containing 3\% S wave anisotropy and with a fast-velocity axis different from that in the layer beneath, can account for the first MLD at about 85 km depth. Significant correlation between the depths of an apparent boundary separating the depleted and metasomatised lithosphere, as inferred from chemical tomography, and those of our second MLD led us to characterize it as a compositional boundary, most likely due to the modification of the cratonic mantle lithosphere by magma infiltration. The deepening of this boundary from 150 to 200 km is spatially correlated with the surficial expression of the Thabazimbi-Murchison Lineament (TML), implying that the TML isolates the lithosphere of the Limpopo terrane from that of the ancient Kaapvaal terrane. The largest velocity contrast (3.6-4.7\%) is observed at a boundary located at depths of 260-280 km beneath the Archean domains and the older Proterozoic belt. This boundary most likely represents the lithosphere-asthenosphere boundary, which shallows to about 200 km beneath the younger Proterozoic belt. Thus, the Kalahari lithosphere may have survived multiple episodes of intense magmatism and collisional rifting during the billions of years of its history, which left their imprint in its internal layering.}, language = {en} } @misc{MechieBenAvrahamWeberetal.2013, author = {Mechie, James and Ben-Avraham, Zvi and Weber, Michael H. and G{\"o}tze, Hans-J{\"u}rgen and Koulakov, Ivan and Mohsen, A. and Stiller, M.}, title = {The distribution of Moho depths beneath the Arabian plate and margins}, series = {TECTONOPHYSICS}, volume = {609}, journal = {TECTONOPHYSICS}, publisher = {ELSEVIER SCIENCE BV}, address = {AMSTERDAM}, issn = {0040-1951}, doi = {10.1016/j.tecto.2012.11.015}, pages = {234 -- 249}, year = {2013}, abstract = {In this study three new maps of Moho depths beneath the Arabian plate and margins are presented. The first map is based on the combined gravity model, EIGEN 06C, which includes data from satellite missions and ground-based studies, and thus covers the whole region between 31 degrees E and 60 inverted perpendicular E and between 12 degrees N and 36 degrees N. The second map is based on seismological and ground-based gravity data while the third map is based only on seismological data. Both these maps show gaps due to lack of data coverage especially in the interior of the Arabian plate. Beneath the interior of the Arabian plate the Moho lies between 32 and 45 km depth below sea level. There is a tendency for higher Pn and Sn velocities beneath the northeastern parts of the plate interior with respect to the southwestern parts of the plate interior. Across the northern, destructive margin with the Eurasian plate, the Moho depths increase to over 50 km beneath the Zagros mountains. Across the conservative western margin, the Dead Sea Transform (DST). Moho depths decrease from almost 40 km beneath the highlands east of the DST to about 21-23 km under the southeastern Mediterranean Sea. This decrease seems to be modulated by a slight depression in the Moho beneath the southern DST. The constructive southwestern and southeastern margins of the Arabian plate also show the Moho shallowing from the plate interior towards the plate boundaries. A comparison of the abruptness of the Moho shallowing between the margins of the Arabian plate, the conjugate African margin at 26 degrees N and several Atlantic margins shows a complex picture and suggests that the abruptness of the Moho shallowing may reflect fundamental differences in the original structure of the margins. (C) 2012 Elsevier B.V. All rights reserved.}, language = {en} }