TY - JOUR A1 - Akal, Cuneyt A1 - Koralay, O. Ersin A1 - Candan, Osman A1 - Oberhänsli, Roland A1 - Chen, Fukun T1 - Geodynamic significance of the early triassic karaburun granitoid (Western Turkey) for the opening history of Neo-Tethys JF - Turkish journal of earth sciences = Türk yerbilimleri dergisi N2 - The Karaburun Peninsula, which is considered part of the Anatolide-Tauride Block of Turkey, contains clastic and carbonate sequences deposited on the northern margin of Gondwana. The Palaeozoic clastic sequence, which is intruded by the Early Triassic granitoid and tectonically overlies a Mesozoic melange sequence, can be divided into three subunits: a lower clastic subunit consisting of a sandstone-shale alternation, an upper clastic subunit consisting of black chert-bearing shales, sandstone and conglomerate, and a Permo-Carboniferous carbonate subunit. The lower Triassic Karaburun I-type granitoid has a high initial Sr-87/Sr-86 ratio (0.709021-0.709168), and low Nd-143/Nd-144 ratio (0.512004-0.512023) and epsilon Nd (-5.34 to -5.70) isotopic values. Geochronological data indicate a crystallization (intrusion) age of 247.1 +/- 2.0 Ma (Scythian). Geochemically, the acidic magmatism reflects a subduction-related continental-arc basin tectonic setting, which can be linked to the opening of the northern branch of Neo-Tethys as a continental back-arc rifting basin on the northern margin of Gondwana. This can be related to the closure through southward subduction of the Palaeotethys Ocean beneath Gondwana. KW - Karaburun KW - Neo-Tethys KW - Palaeo-Tethys KW - diorite KW - Triassic KW - magmatism Y1 - 2011 U6 - https://doi.org/10.3906/yer-1008-1 SN - 1300-0985 VL - 20 IS - 3 SP - 255 EP - 271 PB - Tübitak CY - Ankara ER - TY - JOUR A1 - Akal, Cüneyt A1 - Candan, Osman A1 - Koralay, O. Ersin A1 - Oberhänsli, Roland A1 - Chen, Fukun A1 - Prelevic, Dejan T1 - Early Triassic potassic volcanism in the Afyon Zone of the Anatolides/Turkey - implications for the rifting of the Neo-Tethys JF - International journal of earth sciences N2 - Afyon Zone, which was derived from the Anatolide-Tauride platform during closure of the Neo-Tethys, is made up of pre-Mesozoic basement and unconformably overlying Triassic-Early Tertiary cover series. The Afyon Zone contains widespread metavolcanic rocks, which are dominated by rhyolite, dacite, and trachyandesite. They form a distinct volcanic succession, which is separated from the underlying Silurian-Lower Carboniferous metacarbonates and meta-siliciclastics by a regional unconformity. Trachyandesitic metavolcanics are made up of massive lava flows, pyroclastics and epiclastics, less frequently, domes and dikes, which were developed on a deeply eroded subaerial landmass. U/Pb and Pb/Pb zircon geochronology yielded Lower Triassic (similar to 250 Ma) ages, which are interpreted as extrusion age of trachyandesitic volcanics. Based on the stratigraphic, geochronological, and geochemical data, we suggest that these Lower Triassic magmatic rocks represent an extensional tectonic setting on the northern active margin of the Gondwana, which led to the development of the northern branch of the Neo-Tethys. KW - Meta-trachyandesite KW - Afyon Zone KW - Turkey KW - Neo-Tethys KW - Paleo-tethys Y1 - 2012 U6 - https://doi.org/10.1007/s00531-011-0654-2 SN - 1437-3254 VL - 101 IS - 1 SP - 177 EP - 194 PB - Springer CY - New York ER - TY - JOUR A1 - Ali, Saleem H. A1 - Giurco, Damien A1 - Arndt, Nicholas A1 - Nickless, Edmund A1 - Brown, Graham A1 - Demetriades, Alecos A1 - Durrheim, Ray A1 - Enriquez, Maria Amelia A1 - Kinnaird, Judith A1 - Littleboy, Anna A1 - Meinert, Lawrence D. A1 - Oberhänsli, Roland A1 - Salem, Janet A1 - Schodde, Richard A1 - Schneider, Gabi A1 - Vidal, Olivier A1 - Yakovleva, Natalia T1 - Mineral supply for sustainable development requires resource governance JF - Nature : the international weekly journal of science N2 - Successful delivery of the United Nations sustainable development goals and implementation of the Paris Agreement requires technologies that utilize a wide range of minerals in vast quantities. Metal recycling and technological change will contribute to sustaining supply, but mining must continue and grow for the foreseeable future to ensure that such minerals remain available to industry. New links are needed between existing institutional frameworks to oversee responsible sourcing of minerals, trajectories for mineral exploration, environmental practices, and consumer awareness of the effects of consumption. Here we present, through analysis of a comprehensive set of data and demand forecasts, an interdisciplinary perspective on how best to ensure ecologically viable continuity of global mineral supply over the coming decades. Y1 - 2017 U6 - https://doi.org/10.1038/nature21359 SN - 0028-0836 SN - 1476-4687 VL - 543 SP - 367 EP - 372 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Altenberger, Uwe A1 - Mejia Jimenez, D. M. A1 - Günter, C. A1 - Sierra Rodriguez, G. I. A1 - Scheffler, F. A1 - Oberhänsli, Roland T1 - The Garzn Massif, Colombia-a new ultrahigh-temperature metamorphic complex in the early Neoproterozoic of northern South America JF - Mineralogy and petrology N2 - The Garzn Complex of the Garzn Massif in SW Colombia is composed of the Vergel Granulite Unit (VG) and the Las Margaritas Migmatite Unit (LMM). Previous studies reveal peak temperature conditions for the VG of about 740 A degrees C. The present study considers the remarkable exsolution phenomena in feldspars and pyroxenes and titanium-in-quartz thermometry. Recalculated ternary feldspar compositions indicate temperatures around 900-1,000 A degrees C just at or above the ultra-high temperature-metamorphism (UHTM) boundary of granulites. The calculated temperatures range of exsolved ortho- and clinopyroxenes also supports the existence of an UHTM event. In addition, titanium-in-quartz thermometry points towards ultra-high temperatures. It is the first known UHTM crustal segment in the northern part of South America. Although a mean geothermal gradient of ca 38 A degrees C km(-1) could imply additional heat supply in the lower crust controlling this extreme of peak metamorphism, an alternative model is suggested. The formation of the Vergel Granulite Unit is supposed to be formed in a continental back-arc environment with a thinned and weakened crust behind a magmatic arc (Guapotn-Mancagua Gneiss) followed by collision. In contrast, rocks of the adjacent Las Margaritas Migmatite Unit display "normal" granulite facies temperatures and are formed in a colder lower crust outside the arc, preserved by the Guapotn-Mancagu Gneiss. Back-arc formation was followed by inversion and thickening of the basin. The three units that form the modern-day Garzn Massif, were juxtaposed upon each other during collision (at ca. 1,000 Ma) and exhumation. The collision leading to the deformation of the studied area is part of the Grenville orogeny leading to the amalgamation of Rodinia. Y1 - 2012 U6 - https://doi.org/10.1007/s00710-012-0202-1 SN - 0930-0708 VL - 105 IS - 3-4 SP - 171 EP - 185 PB - Springer CY - Wien ER - TY - JOUR A1 - Altenberger, Uwe A1 - Oberhänsli, Roland A1 - Stein, Eckehard A1 - Moghni, Mohsen T1 - Geochemistry, tectonic setting and geodynamic position of late orogenic dikes in the Melibocus Massiv, Bergstraesser Odenwald Y1 - 2001 ER - TY - JOUR A1 - Armbruster, Thomas A1 - Bermance, V. A1 - Zebec, M. A1 - Oberhänsli, Roland T1 - Titanium and iron poor zincohögbomite-16H, Zn14(al,Fe3+,Ti,Mg)8Al24O62(OH)2, from Nezilovo, Macedonia: occurrence and crystal structure of a new polysome Y1 - 1998 ER - TY - JOUR A1 - Aygül, Mesut A1 - Oberhänsli, Roland T1 - Tectonic Stacking of HP/LT Metamorphic Rocks in Accretionary Wedges and the Role of Shallowing Slab-Mantle Decoupling JF - Tectonics N2 - High-pressure/low-temperature (HP/LT) chloritoid-bearing micaschists crop out widely in the central part of northern Turkey and represent deep-seated subduction-accretionary complexes. Three peak metamorphic assemblages are identified in the area studied: (1) garnet-chloritoid-glaucophane with pseudomorphs after lawsonite; (2) chloritoid with pseudomorphs after glaucophane; and (3) chloritoid with pseudomorphs after jadeite in addition to phengite, paragonite, quartz, chlorite, rutile, and apatite. The latter is interpreted as transformation of a chloritoid + glaucophane assemblage to chloritoid + jadeite with increasing pressure; PT modeling indicates similar to 17 and 22-25 kbars for the two peak parageneses. The diversity of peak metamorphic assemblages and the PT estimates suggest that basal accretion occurred at different depths within the wedge. The depth of the basal accretion is possibly controlled by the slab-mantle decoupling depth. Stretching and thinning of the lithospheric fore arc induced by the slab rollback possibly caused shallowing of the slab-mantle decoupling depth which limited depth of the basal accretion from 70-80km to similar to 55km within the subduction channel. A slab-mantle coupling depth-controlled basal accretion may also explain the scarcity of eclogite and high-grade blueschist facies metamorphic rocks in active intraoceanic subduction zones. Because the overriding plate is young and hot in intraoceanic subductions, the slab and mantle are coupled at a relatively shallow depth before eclogitization of the oceanic crust. This prevents accretion and exhumation of eclogite along the subduction channel. KW - chloritoid micaschist KW - accretionary complex KW - slab-mantle decoupling KW - basal accretion Y1 - 2017 U6 - https://doi.org/10.1002/2017TC004689 SN - 0278-7407 SN - 1944-9194 VL - 36 SP - 2332 EP - 2346 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Aygül, Mesut A1 - Okay, Aral I. A1 - Oberhänsli, Roland A1 - Schmidt, Alexander A1 - Sudo, Masafumi T1 - Late Cretaceous infant intra-oceanic arc volcanism, the Central Pontides, Turkey: Petrogenetic and tectonic implications JF - Journal of Asian earth sciences N2 - A tectonic slice of an arc sequence consisting of low-grade metavolcanic rocks and overlying metasedimentary succession is exposed in the Central Pontides north of the Izmir-Ankara-Erzincan suture separating Laurasia from Gondwana-derived terranes. The metavolcanic rocks mainly consist of basaltic andesite/andesite and mafic cognate xenolith-bearing rhyolite with their pyroclastic equivalents, which are interbedded with recrystallized pelagic limestone and chert. The metasedimentary succession comprises recrystallized micritic limestone with rare volcanogenic metaclastic rocks and stratigraphically overlies the metavolcanic rocks. The geochemistry of the metavolcanic rocks indicates an arc setting evidenced by depletion of HFSE (Ti, P and Nb) and enrichment of fluid mobile LILE. Identical trace and rare earth elements compositions of basaltic andesites/andesites and rhyolites suggest that they are cogenetic and derived from a common parental magma. The arc sequence crops out between an Albian-Turonian subduction-accretionary complex representing the Laurasian active margin and an ophiolitic melange. Absence of continent derived detritus in the arc sequence and its tectonic setting in a wide Cretaceous accretionary complex suggest that the Kosdag Arc was intra-oceanic. Zircons from two metarhyolite samples give Late Cretaceous (93.8 +/- 1.9 and 94.4 +/- 1.9 Ma) U/Pb ages. These ages are the same as the age of the supra-subduction ophiolites in western Turkey, which implies that that the Kosdag Arc may represent part of the incipient arc formed during the generation of the supra-subduction ophiolites. The low-grade regional metamorphism in the Kosdag Arc is constrained to 69.9 +/- 0.4 Ma by Ar-40/Ar-39 muscovite dating indicating that the arc sequence became part of a wide Tethyan Cretaceous accretionary complex by the latest Cretaceous. Non-collisional cessation of the arc volcanism is possibly associated with southward migration of the magmatism as in the Izu-Bonin-Mariana arc system. (c) 2015 Elsevier Ltd. All rights reserved. KW - Intra-oceanic subduction KW - Felsic volcanism KW - Arc accretion KW - Ophiolite obduction Y1 - 2015 U6 - https://doi.org/10.1016/j.jseaes.2015.07.005 SN - 1367-9120 SN - 1878-5786 VL - 111 SP - 312 EP - 327 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Aygül, Mesut A1 - Okay, Aral I. A1 - Oberhänsli, Roland A1 - Ziemann, Martin Andreas T1 - Thermal structure of low-grade accreted Lower Cretaceous distal turbidites, the Central Pontides, Turkey: insights for tectonic thickening of an accretionary wedge JF - Turkish journal of earth sciences = Türk yerbilimleri dergisi N2 - Albian-Turonian subduction-accretionary complexes are exposed widely in the Central Pontides. A major portion of the accretionary complexes is made up of a metaflysch sequence consisting of slate/phyllite and metasandstone intercalation with blocks of marble, Na-amphibole bearing metabasite, and serpentinite. The metaflysch sequence represents distal parts of a large Lower Cretaceous submarine turbidite fan deposited on the Laurasian active continental margin that was subsequently accreted and metamorphosed during the Albian. Raman spectra of carbonaceous material of the metapelitic rocks revealed that the metaflysch consists of metamorphic packets with distinct peak metamorphic temperatures. The majority of the metapelites are low-temperature (ca. 330 degrees C) slates characterized by lack of differentiation of the graphite (G) and D2 defect bands. They possibly represent offscraped distal turbidites along the toe of the Albian accretionary wedge. Other phyllites are characterized by a slightly pronounced G band with a D2 defect band occurring on its shoulder. Peak metamorphic temperatures of these phyllites are constrained to 370-385 degrees C. The phyllites are associated with a strip of incipient blueschist facies metabasites and are found as a sliver within the offscraped distal turbidites. We interpret the phyllites as underplated continental sediments together with oceanic crustal basalt along the basal decollement. Tectonic emplacement of the underplated rocks into the offscraped distal turbidites was possibly achieved by out-of-sequence thrusting causing tectonic thickening and uplift of the wedge. KW - Pontides KW - distal turbidites KW - offscraping KW - underplating KW - low-grade metamorphism KW - graphitization KW - Raman microspectroscopy Y1 - 2015 U6 - https://doi.org/10.3906/yer-1504-4 SN - 1300-0985 VL - 24 IS - 5 SP - 461 EP - 474 PB - Tübitak CY - Ankara ER - TY - JOUR A1 - Bazylev, B. A. A1 - Zakariadze, G. S. A1 - Zhelyazkova-Panayotova, M. D. A1 - Kolcheva, K. A1 - Oberhänsli, Roland A1 - Solov'eva, N. V. T1 - Petrology of ultramafic rocks from the ophiolithe association in the crystalline basement of the Rhodope massif Y1 - 1999 ER - TY - JOUR A1 - Bazylev, B. A. A1 - Zakariadze, G. S. A1 - Zhelyazkova-Panayotova, M. D. A1 - Solov'eva, N. V. A1 - Oberhänsli, Roland T1 - Genetic diversity of ophiolite ultramafics from the crystalline basement of Rhodope massif Y1 - 1998 ER - TY - JOUR A1 - Bianchi, Gianphino Walter A1 - Martinotti, G. A1 - Oberhänsli, Roland T1 - Metasedimentary cover sequences and associated metabasites in the Sabbione Lake zone, Formazza Valley, Italy Y1 - 1998 ER - TY - JOUR A1 - Bousquet, Romain A1 - Oberhänsli, Roland T1 - Distribution of HP-LT metamorphism and extensional deformation in the "Bündnerschiefer" of the Engadine window (eastern Central Alps) : Implication of regional evolution Y1 - 1997 ER - TY - JOUR A1 - Bousquet, Romain A1 - Oberhänsli, Roland T1 - High-pressure-low-temperature metamorphism and deformation in the "Bündnerschiefer" of the Engadine window : implications for the regional evolution of the eastern Central Alps Y1 - 1998 ER - TY - JOUR A1 - Candan, O. A1 - Akal, C. A1 - Koralay, O. E. A1 - Okay, A. I. A1 - Oberhänsli, Roland A1 - Prelevic, D. A1 - Mertz-Kraus, R. T1 - Carboniferous granites on the northern margin of Gondwana, Anatolide-Tauride Block, Turkey - Evidence for southward subduction of Paleotethys JF - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth N2 - Carboniferous metagranites with U-Pb zircon crystallization ages of 331-315 Ma crop out in the Afyon zone in the northern margin of the Anatolide-Tauride Block, which is commonly regarded as part of Gondwana during the Late Palaeozoic. They are peraluminous, calc-alkaline and are characterized by increase in Rb and Ba, decrease in Nb-Ta, and enrichment in Sr and high LILE/HFSE ratios compatible with a continental arc setting. The metagranites intrude a metasedimentary sequence of phyllite, metaquartzite and marble; both the Carboniferous metagranites and metasedimentary rocks are overlain unconformably by Lower Triassic metaconglomerates, metavolcanics and Upper Triassic to Cretaceous recrystallized limestones. The low-grade metamorphism and deformation occurred at the Cretaceous-Tertiary boundary. There is no evidence for Carboniferous deformation and metamorphism in the region. Carboniferous arc-type granites and previously described Carboniferous subduction-accretion complexes on the northern margin of the Anatolide-Tauride Block suggest southward subduction of Paleotethys under Gondwana during the Carboniferous. Considering the Variscan-related arc granites in Pelagonian and Sakarya zones on the active southern margin of Laurasia, a dual subduction of Paleotethys can be envisaged between Early Carboniferous and Late Permian. However, the southward subduction was short-lived and by the Late Permian the Gondwana margin became passive. (C) 2016 Elsevier B.V. All rights reserved. KW - Carboniferous magmatism KW - Paleotethys KW - Gondwana KW - Afyon zone KW - Anatolide-Tauride Block Y1 - 2016 U6 - https://doi.org/10.1016/j.tecto.2016.06.030 SN - 0040-1951 SN - 1879-3266 VL - 683 SP - 349 EP - 366 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Candan, O. A1 - Cetinkaplan, Mete A1 - Oberhänsli, Roland A1 - Rimmele, Gaetan A1 - Akal, Cemal B. T1 - Alpine high-P/low-T metamorphism of the Afyon Zone and implications for the metamorphic evolution of Western Anatolia, Turkey N2 - Carpholite+chloritoid+pyrophyllite association occurs widely in the Triassic metaclastic rocks of the Afyon Zone in west-central Turkey. Fe-Mg-carpholite is associated with rare aragonite pseudomorphs and glaucophane in marbles and metabasites, respectively. The Afyon Zone consists stratigraphically of a Pan-African basement and an overlying Mesozoic cover sequence. The Pan-African basement, which shows Barrovian-type amphibolite-facies metamorphism, comprises garnet-mica schists, intruded by sodic amphibole-bearing metagabbros and leucocratic metagranites. It is unconformably overlain by a continuous metasedimentary sequence extending from Triassic to early Palaeocene. This cover sequence begins with metaconglomerates, which pass upwards into phyllites. Fe-Mg-carpholite occurs within this metaclastic sequence as rosette-like crystals in metapelites and fibres in quartz segregations. The metaclastic rocks are succeeded by metamorphosed platform carbonates, grading into Latest Mesozoic metamorphosed pelagic limestones, which in turn progress up to a Late Mesozoic-Early Tertiary olistostrome. This sequence is tectonically overlain by the blueschists of the Tavsanh Zone. Fe-Mg-carpholite-bearing assemblages imply temperatures of about 350 degrees C and minimum pressures of 6-9 kbar, corresponding to burial depths of about 30 km for the Mesozoic passive continental margin sediments and the underlying Pan-African supracrustal metasediments and metaintrusives. The metamorphic rocks of the Afyon Zone are unconformably overlain by Upper Palaeocene-Lower Eocene sedimentary rocks, indicating a Paleocene age for the regional HP/LT metamorphism. This implies continuous younging of HP/LT metamorphism in the Anatolides related to northward subduction of the Anatolide-Tauride platform beneath the Sakarya Zone. From north to south this involved the Tavsanh Zone (Campanian, 80 +/- 5 Ma), the Afyon Zone (Palaeocene?), the Menderes Massif (Middle Eocene) and the Lycian Nappes (Late Cretaceous-Eocene?), all of which were probably derived from the frontal part of the Anatolide-Tauride platform. (c) 2005 Elsevier B.V. All rights reserved Y1 - 2005 SN - 0024-4937 ER - TY - JOUR A1 - Candan, O. A1 - Dora, O. A1 - Oberhänsli, Roland A1 - Cetinkaplan, Mete A1 - Partzsch, Julius A1 - Warkus, Friederike C. A1 - Dürr, S. T1 - Pan-African high-pressure metamorphism in the Precambrian basement of the Menderes massif, Western Anatolia, Turkey Y1 - 2000 ER - TY - JOUR A1 - Candan, O. A1 - Dora, O. A1 - Oberhänsli, Roland A1 - Ölsner, F. A1 - Dürr, S. T1 - Blueschist relics in the Mesozoic cover series of the Menderes Massif and correlations with Samos Island, Cyclades Y1 - 1997 ER - TY - JOUR A1 - Candan, O. A1 - Koralay, O. E. A1 - Topuz, G. A1 - Oberhänsli, Roland A1 - Fritz, H. A1 - Collins, A. S. A1 - Chen, F. T1 - Late Neoproterozoic gabbro emplacement followed by early Cambrian eclogite-facies metamorphism in the Menderes Massif (W. Turkey): Implications on the final assembly of Gondwana JF - Gondwana research : international geoscience journal ; official journal of the International Association for Gondwana Research N2 - Numerous (meta-)gabbroic dikes or stocks occur within the latest Neoproterozoic-early Cambrian series of the Menderes Massif (Anatolide-Tauride Block, western Turkey). These well-preserved rocks were locally converted into eclogitic metagabbros and garnet amphibolites along the contacts or shear zones. Both bulk-rock composition and compositions of igneous clinopyroxenes suggest continental tholeiitic affinity. U-Pb dating of igneous zircons from gabbroic rocks yielded a mean age of 563 +/- 1 Ma (2 sigma), indicating emplacement during the latest Neoproterozoic (Ediacaran). On the other hand, rims of zircons from eclogitic metagabbro gave 535 +/- 3 Ma (2 sigma) (early Cambrian), in addition to 558 +/- 3 Ma (2 sigma) obtained from the igneous core of zircons. These ages are interpreted as the time of high-P metamorphism and crystallization age of gabbroic protolith, respectively. Given the estimated paleogeographic position of the Anatolide-Tauride Block during the late Neoproterozoic and early Cambrian, this orogenic event can be spatially and temporally related to the northward continuity of 600-500 Ma orogenic event (Malagasy/Kuunga orogeny) extending from western margin of India, Madagascar, via Arabia up to northern margin of Gondwana beneath thick Phanerozoic cover series in Arabian Peninsula. Therefore, the high-P evolution of the basement of the Menderes Massif and associated basic intrusions can be interpreted to mark the latest stages of consumption of the basin/oceanic branches and final amalgamation of the Gondwana during the late Neoproterozoic-early Cambrian around the Arabian region. (C) 2015 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved. KW - Gabbro KW - Eclogite KW - Malagasy/Kuunga orogeny KW - Menderes Massif KW - Turkey Y1 - 2016 U6 - https://doi.org/10.1016/j.gr.2015.02.015 SN - 1342-937X SN - 1878-0571 VL - 34 SP - 158 EP - 173 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Candan, Osman A1 - Koralay, O. E. A1 - Akal, Cemal B. A1 - Kaya, O. A1 - Oberhänsli, Roland A1 - Dora, O. O. A1 - Konak, N. A1 - Chen, F. T1 - Supra-Pan-African unconformity between core and cover series of the Menderes Massif/Turkey and its geological implications JF - Precambrian research N2 - Well-preserved primary contact relationships between a Late Proterozoic metasedimentary and the metagranitic core and Palaeozoic cover series of the Menderes Massif have been recognized in the eastern part of the Cine submassif on a regional-scale. Metaconglomerates occur as laterally discontinuous channel-fill bodies close the base of the metaquartzarenite directly above the basement. The pebbles in the metaconglomerates consist mainly of different types of tourmaline-rich leucocratic granitoids, tourmalinite and schist in a sandy matrix. Petrographic features, geochemical compositions and zircon radiometric ages (549.6 +/- 3.7-552.3 +/- 3.1 Ma) of the diagnostic clasts of the metaconglomerates (e.g. leucocratic granitoids and tourmalinites) show excellent agreement with their in situ equivalents (549.0 +/- 5.4 Ma) occurring in the Pan-African basement as stocks and veins. The correlation between clasts in the metaconglomerates and granitoids of the basement suggests that the primary contact between the basement and cover series is a regional unconformity (supra-Pan-African Unconformity) representing deep erosion of the Pan-African basement followed by the deposition of the cover series. Hence the usage of 'core-cover' terminology in the Menderes Massif is valid. Consequently, these new data preclude the views that the granitic precursors of the leucocratic orthogneisses are Tertiary intrusions. KW - Menderes Massif KW - Pan-African KW - Zircon age KW - Core complex KW - Turkey Y1 - 2011 U6 - https://doi.org/10.1016/j.precamres.2010.09.010 SN - 0301-9268 VL - 184 IS - 1-4 SP - 1 EP - 23 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Cetinkaplan, Mete A1 - Pourteau, Amaury A1 - Candan, Osman A1 - Koralay, O. Ersin A1 - Oberhänsli, Roland A1 - Okay, Aral I. A1 - Chen, Fukun A1 - Kozlu, Huseyin A1 - Sengun, Firat T1 - P-T-t evolution of eclogite/blueschist facies metamorphism in Alanya Massif: time and space relations with HP event in Bitlis Massif, Turkey JF - International journal of earth sciences N2 - The Alanya Massif, which is located to the south of central Taurides in Turkey, presents a typical nappe pile consisting of thrust sheets with contrasting metamorphic histories. In two thrust sheets, Sugozu and GundogmuAY nappes, HP metamorphism under eclogite (550-567 A degrees C/14-18 kbar) and blueschist facies (435-480 A degrees C/11-13 kbar) conditions have been recognized, respectively. Whereas the rest of the Massif underwent MP metamorphism under greenschist to amphibolite facies (525-555 A degrees C/6.5-7.5 kbar) conditions. Eclogite facies metamorphism in Sugozu nappe, which consists of homogeneous garnet-glaucophane-phengite schists with eclogite lenses is dated at 84.8 +/- A 0.8, 84.7 +/- A 1.5 and 82 +/- A 3 Ma (Santonian-Campanian) by Ar-40/Ar-39 phengite, U/Pb zircon and rutile dating methods, respectively. Similarly, phengites in GundogmuAY nappe representing an accretionary complex yield 82-80 Ma (Campanian) ages for blueschist facies metamorphism. During the exhumation, the retrograde overprint of the HP units under greenschist-amphibolite facies conditions and tectonic juxtaposition with the Barrovian units occurred during Campanian (75-78 Ma). Petrological and geochronological data clearly indicate a similar Late Cretaceous tectonometamorphic evolution for both Alanya (84-75 Ma) and Bitlis (84-72 Ma) Massifs. They form part of a single continental sliver (Alanya-Bitlis microcontinent), which was rifted from the southern part of the Anatolide-Tauride platform. The P-T-t coherence between two Massifs suggests that both Massifs have been derived from the closure of the same ocean (Alanya-Bitlis Ocean) located to the south of the Anatolide-Tauride block by a northward subduction. The boundary separating the autochthonous Tauride platform to the north from both the Alanya and Bitlis Massifs to the south represents a suture zone, the Pamphylian-Alanya-Bitlis suture. KW - Tauride KW - Eclogite KW - Alanya KW - Blueschist KW - Metamorphism Y1 - 2016 U6 - https://doi.org/10.1007/s00531-014-1092-8 SN - 1437-3254 SN - 1437-3262 VL - 105 SP - 247 EP - 281 PB - Springer CY - New York ER - TY - JOUR A1 - Dorani, Maryam A1 - Arvin, Mohsen A1 - Oberhänsli, Roland A1 - Dargahi, Sara T1 - P-T evolution of metapelites from the Bajgan complex in the Makran accretionary prism, south eastern Iran JF - Chemie der Erde : interdisciplinary journal for chemical problems of the geo-sciences and geo-ecology = Geochemistry N2 - The Bajgan Complex, one of the basement constituents of the arc massif in Iranian Makran forms a rugged, deeply incised terrain. The complex consists of pelitic schists with minor psammitic and basic schists, calc silicate rocks, amphibolites, marbles, metavolcanosediments, mafic and felsic intrusives as well as ultramafic rocks. Metapelitic rocks show an amphibolite facies regional metamorphism and contain garnet, biotite, white mica, quartz, albite ± rutile ± apatite. Thermobarometry of garnet schist yields pressure of more than 9 kbar and temperatures between 560 and 675 °C. The geothermal gradient obtained for the peak of regional metamorphism is 19 °C/km, corresponding to a depth of ca. 31 km. Replacement of garnet by chlorite and epidote suggest greenschist facies metamorphism due to a decrease in temperature and pressure through exhumation and retrograde metamorphism (370–450 °C and 3–6 kbar). The metapelitic rocks followed a ‘clockwise’ P–T path during metamorphism, consistent with thermal decline following tectonic thickening. The formation of medium-pressure metamorphic rocks is related to presence of active subduction of the Neotethys Oceanic lithosphere beneath Eurasia in the Makran. KW - Bajgan Complex KW - Makran KW - Metapelitic rock KW - Garnet schist KW - Thermobarometry KW - Clockwise P-T path Y1 - 2017 U6 - https://doi.org/10.1016/j.chemer.2017.07.004 SN - 0009-2819 SN - 1611-5864 VL - 77 IS - 3 SP - 459 EP - 475 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Duesterhoeft, Erik A1 - Quinteros, Javier A1 - Oberhänsli, Roland A1 - Bousquet, Romain A1 - de Capitani, Christian T1 - Relative impact of mantle densification and eclogitization of slabs on subduction dynamics: A numerical thermodynamic/thermokinematic investigation of metamorphic density evolution JF - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth N2 - Understanding the relationships between density and spatio-thermal variations at convergent plate boundaries is important for deciphering the present-day dynamics and evolution of subduction zones. In particular, the interaction between densification due to mineralogical phase transitions and slab pull forces is subject to ongoing investigations. We have developed a two-dimensional subduction zone model that is based on thermodynamic equilibrium assemblage calculations and includes the effects of melting processes on the density distribution in the lithosphere. Our model calculates the "metamorphic density" of rocks as a function of pressure, temperature and chemical composition in a subduction zone down to 250 km. We have used this model to show how the hydration, dehydration, partial melting and fractionation processes of rocks all influence the metamorphic density and greatly depend on the temperature field within the subduction system. These processes are largely neglected by other approaches that reproduce the density distribution within this complex tectonic setting. Our model demonstrates that the initiation of edogitization (i.e., when crustal rocks reach higher densities than the ambient mantle) of the slab is not the only significant process that makes the descending slab denser and generates the slab pull force. Instead, the densification of the lithospheric mantle of the sinking slab starts earlier than eclogitization and contributes significantly to slab pull in the early stages of subduction. Accordingly, the complex metamorphic structure of the slab and the mantle wedge has an important impact on the development of subduction zones. (C) 2014 Elsevier B.V. All rights reserved. KW - Density KW - Melt KW - Metamorphism KW - Subduction KW - Thermodynamic modeling KW - Thermo-mechanical modeling Y1 - 2014 U6 - https://doi.org/10.1016/j.tecto.2014.09.009 SN - 0040-1951 SN - 1879-3266 VL - 637 SP - 20 EP - 29 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Düsterhöft, Erik A1 - Bousquet, Romain A1 - Wichura, Henry A1 - Oberhänsli, Roland T1 - Anorogenic plateau formation The importance of density changes in the lithosphere JF - Journal of geophysical research : Solid earth N2 - Away from active plate boundaries the relationships between spatiotemporal variations in density and geothermal gradient are important for understanding the evolution of topography in continental interiors. In this context the classic concept of the continental lithosphere as comprising three static layers of different densities (upper crust, lower crust, and upper mantle) is not adequate to assess long-term changes in topography and relief in regions associated with pronounced thermal anomalies in the mantle. We have therefore developed a one-dimensional model, which is based on thermodynamic equilibrium assemblage computations and deliberately excludes the effects of melting processes like intrusion or extrusions. Our model calculates the "metamorphic density" of rocks as a function of pressure, temperature, and chemical composition. It not only provides a useful tool for quantifying the influence of petrologic characteristics on density, but also allows the modeled "metamorphic" density to be adjusted to variable geothermal gradients and applied to different geodynamic environments. We have used this model to simulate a scenario in which the lithosphere-asthenosphere boundary is subjected to continuous heating over a long period of time (130 Ma), and demonstrate how an anorogenic plateau with an elevation of 1400 m can be formed solely as a result of heat transfer within the continental lithosphere. Our results show that, beside dynamic topography (of asthenospheric origin), density changes within the lithosphere have an important impact on the evolution of anorogenic plateaus. Y1 - 2012 U6 - https://doi.org/10.1029/2011JB009007 SN - 2169-9313 SN - 2169-9356 VL - 117 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Förster, Hans-Jürgen A1 - Förster, Andrea A1 - Oberhänsli, Roland A1 - Stromeyer, Dietrich T1 - Lithospheric composition and thermal structure of the Arabian Shield in Jordan N2 - In this paper, a unique set of samples from the uppermost crust down to the lithospheric mantle of Jordan is analyzed for composition and petrophysical properties (density. thermal conductivity, radiogenic heat production) These data, covering a vertical section of almost 65 km. are used in conjunction with surface heat flow to generate a detailed and comprehensive lithospheric thermal model that reflects the conditions of the Arabian Shield (AS) prior to the post- Oligocene onset of lithosphere thinning and Voluminous basaltic volcanism. The pre-Miocene model geotherms, based on conductive surface heat flows of 55 and 60 mW m(-2). (a) meet the range of lithosphere-asthenosphere boundary depths of 110-160 km known from seismology, (b) conform to results of thermomechanical models on the on.-in of the Dead Sea basin that started in Miocene time. and (c) are consistent with typical xenolith-derived geotherms for terranes of similar age and lithospheric thickness. Moho temperatures (at depths between 35 and 40 km) of the AS in pre-Miocene times were most likely in the order of 530-650 degrees C, with mantle heat flows averaging between 24 and 29 mW m(-2) Results contradict former views of the late Proterozoic/early Cambrian-stabilized AS being an anomalously cold terrane A "cold" thermal structure inferred from previously measured low surface heat flows (generally <= 45 mW m(-2)) is inconsistent with the thickness, composition, and petrophysical properties of the stable lithosphere of the shield. Y1 - 2010 UR - http://www.sciencedirect.com/science/journal/00401951 U6 - https://doi.org/10.1016/j.tecto.2008.11.014 SN - 0040-1951 ER - TY - JOUR A1 - Hajialioghli, Robab A1 - Moazzen, Mohssen A1 - Jahangiri, Ahmad A1 - Oberhänsli, Roland A1 - Mocek, Beate A1 - Altenberger, Uwe T1 - Petrogenesis and tectonic evolution of metaluminous sub-alkaline granitoids from the Takab Complex, NW Iran JF - Geological magazine N2 - The Takab complex is composed of a variety of metamorphic rocks including amphibolites, metapelites, mafic granulites, migmatites and meta-ultramafics, which are intruded by the granitoid. The granitoid magmatic activity occurred in relation to the subduction of the Neo-Tethys oceanic crust beneath the Iranian crust during Tertiary times. The granitoids are mainly granodiorite, quartz monzodiorite, monzonite and quartz diorite. Chemically, the magmatic rocks are characterized by ASI < 1.04, AI < 0.87 and high contents of CaO (up to similar to 14.5 wt %), which are consistent with the I-type magmatic series. Low FeO(t)/(FeO(t)+MgO) values (< 0.75) as well as low Nb, Y and K(2)O contents of the investigated rocks resemble the calc-alkaline series. Low SiO(2), K(2)O/Na(2)O and Al(2)O(3) accompanied by high CaO and FeO contents indicate melting of metabasites as an appropriate source for the intrusions. Negative Ti and Nb anomalies verify a metaluminous crustal origin for the protoliths of the investigated igneous rocks. These are comparable with compositions of the associated mafic migmatites, in the Takab metamorphic complex, which originated from the partial melting of amphibolites. Therefore, crustal melting and a collision-related origin for the Takab calc-alkaline intrusions are proposed here on the basis of mineralogy and geochemical characteristics. The P-T evolution during magmatic crystallization and subsolidus cooling stages is determined by the study of mineral chemistry of the granodiorite and the quartz diorite. Magmatic crystallization pressure and temperature for the quartz-diorite and the granodiorite are estimated to be P similar to 7.8 +/- 2.5 kbar, T similar to 760 +/- 75 degrees C and P similar to 5 +/- 1 kbar, T similar to 700 degrees C, respectively. Subsolidus conditions are consistent with temperatures of similar to 620 degrees C and similar to 600 degrees C, and pressures of similar to 5 kbar and similar to 3.5 kbar for the quartz-diorite and the granodiorite, respectively. KW - granitoids KW - partial melting KW - Neo-Tethys KW - Takab KW - NW Iran Y1 - 2011 U6 - https://doi.org/10.1017/S0016756810000683 SN - 0016-7568 VL - 148 IS - 2 SP - 250 EP - 268 PB - Cambridge Univ. Press CY - New York ER - TY - JOUR A1 - Hofer, H. E. A1 - Brey, G. P. A1 - Oberhänsli, Roland T1 - The determination of the oxidation state of iron in synthetic garnets by X-ray spectroscopy with the electron microprobe Y1 - 1996 ER - TY - JOUR A1 - Jolivet, L. A1 - Goffe, B. A1 - Bousquet, Romain A1 - Oberhänsli, Roland A1 - Michard, Andre T1 - Detachments in high-pressure mountain belts, Tethyan examples Y1 - 1998 ER - TY - JOUR A1 - Jolivet, L. A1 - Rimmele, Gaetan A1 - Oberhänsli, Roland A1 - Goffe, B. A1 - Candan, O. T1 - Correlation of syn-orogenic tectonic and metamorphic events in the Cyclades, the Lycian nappes and the Menderes massif : Geodynamic implications N2 - The recent discovery of HP-LT parageneses in the basal unit of the Lycian nappes and in the Mesozoic cover of the Menderes massif leads us to reconsider and discuss the correlation of this region with the nearby collapsed Hellenides in the Aegean domain. Although similarities have long been pointed Out by various authors, a clear correlation has not yet been proposed and most authors insist more on differences than similarities. The Menderes massif is the eastern extension of the Aegean region but it has been less severely affected by the Aegean extension during the Oligo-Miocene. It would thus be useful to use the structure of the Menderes massif as an image of the Aegean region before a significant extension has considerably reduced its crustal thickness. But the lack of correlation between the two regions has so far hampered Such comparisons. We describe the main tectonic units and metamorphic events in the two regions and propose a correlation. We then show possible sections of the two regions before the Aegean extension and discuss the involvement of continental basement in the Hellenic accretionary complex. In our interpretation the Hellenic- Tauric accretionary complex was composed of stacked basement and cover units which underwent variable P-T histories. Those which were not exhumed early enough later followed a high-T evolution which led to partial melting in the Cyclades during post-orogenic extension. Although the Menderes massif contains a larger volume of basement units it does not show significant evidence for the Oligo-Miocene migmatites observed in the center of the Cyclades suggesting that crustal partial melting is strictly related to post-orogenic extension in this case Y1 - 2004 SN - 0037-9409 ER - TY - JOUR A1 - Jolivet, Laurent A1 - Faccenna, Claudio A1 - Huet, Benjamin A1 - Labrousse, Loic A1 - Le Pourhiet, Laetitia A1 - Lacombe, Olivier A1 - Lecomte, Emmanuel A1 - Burov, Evguenii A1 - Denele, Yoann A1 - Brun, Jean-Pierre A1 - Philippon, Melody A1 - Paul, Anne A1 - Salaue, Gwenaelle A1 - Karabulut, Hayrullah A1 - Piromallo, Claudia A1 - Monie, Patrick A1 - Gueydan, Frederic A1 - Okay, Aral I. A1 - Oberhänsli, Roland A1 - Pourteau, Amaury A1 - Augier, Romain A1 - Gadenne, Leslie A1 - Driussi, Olivier T1 - Aegean tectonics strain localisation, slab tearing and trench retreat JF - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth N2 - 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). KW - Backarc extension KW - Slab retreat KW - Asthenospheric flow KW - Strain localisation KW - Aegean Sea KW - Metamorphic core complex Y1 - 2013 U6 - https://doi.org/10.1016/j.tecto.2012.06.011 SN - 0040-1951 VL - 597 SP - 1 EP - 33 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Karo, Nihad M. A1 - Oberhänsli, Roland A1 - Aqrawi, Ahmed M. A1 - Elias, Elias M. A1 - Aswad, Khalid J. A1 - Sudo, Masafumi T1 - New Ar-40/Ar-39 age constraints on cooling and unroofing history of the metamorphic host rocks (and igneous intrusion associates) from the Bulfat Complex (Bulfat area), NE-Iraq JF - Arabian journal of geosciences N2 - The Northern Zagros Suture Zone (NZSZ), formed as a result of the collision between Arabian and Sanandaj-Sirjan microplate, is considered as part of the Zagros orogenic belt. NZSZ is marked by two allochthonous thrust sheets in upward stacking order: lower and upper allochthon. The Bulfat complex is a part of the upper allochthon or "Ophiolite-bearing terrane" of Albian-Cenomenion age (97-105 Ma). Voluminous highly sheared serpentinites associated with ophiolites occur within this upper allochthon. In addition, the Gemo-Qandil Group is characterized by gabbroic to dioritic Bulfat intrusion with a crystallization age spanning from similar to 45 to similar to 40 Ma, as well as extensive metapelites with contact to the Walash-Naupurdam metavolcanic rocks. Due to the deformation in the Sanandaj-Sirjan Zone along the eastern side of the Iraqi segment of NZSZ, the Gemo-Qandil Group was regionally metamorphosed during late Cretaceous (similar to 80 Ma). This tectono-compressional dynamics ultimately caused an oscillatory deformation against Arabian continental margin deposits as well. During these events, gabbro-diorite intrusion with high-grade contact metamorphic aureoles occurred near Bulfat. Thus, there is an overlap between regional and contact metamorphic conditions in the area. The earlier metamorphic characteristic can be seen only in places where the latter contact influence was insignificant. Generally, this can only observed at a distance of more than 2.5 km from the contact. According to petrographic details and field observations, the thermally metamorphosed metapelitic units of the metasediment have been completely assimilated, with only some streaks of biotite and relicts of initial foliation. They strongly resemble amphibolite-grade slices from the regional metamorphic rocks in the region. Metapelitic samples far from the intrusion give similar biotite cooling ages as the intrusive rocks. Thus, they may be affected by the same thermal event. Ar-40/Ar-39 dating of biotite in metapelite rocks of Bulfat by step-wise heating with laser gave average weighted isotopic ages of 34.78 +/- 0.06 Ma. This is interpreted as crystallization/recrystallization age of biotite possibly representing the time of cooling and uplift history of the Bulfat intrusion. Cooling and exhumation rates for the Bulfat gabbro-diorite rocks were estimated as similar to 400 A degrees C/Ma and similar to 3.3 mm/year respectively. According to petrographic details, field observations and Ar/Ar dating concerning the contact metamorphism near Bulfat due to the gabbro-diorite intrusion, no significant deformation is visible during exhumation processes after the Paleogene tectono-thermal event, indicating that isotopic ages of 34.78 +/- 0.06 Ma could mark the timing of termination of the island arc activity in the Ophiolite-bearing terrane (upper allochthon). KW - Iraq KW - Bulfat KW - Metapelites KW - Northern Zagros Suture Zone (NZSZ) KW - Ar-40/Ar-39 KW - Cooling and unroofing history Y1 - 2018 U6 - https://doi.org/10.1007/s12517-018-3571-x SN - 1866-7511 SN - 1866-7538 VL - 11 IS - 10 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Keyser, William A1 - Tsai, Chin-Ho A1 - Iizuka, Yoshiyuki A1 - Oberhänsli, Roland A1 - Ernst, W. G. T1 - High-pressure metamorphism in the Chinshuichi area, Yuli belt, eastern Taiwan JF - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth N2 - Tectonic blocks and slabs of mafic-ultramafic rocks are distributed discontinuously in the Yuli metamorphic belt of Taiwan. The blocks include rare omphacite metagabbros and gamet-epidote blueschists in the Wanjung and Juisui (Tamayen) areas, respectively. Such high-pressure (HP) mineral assemblages have been attributed to a mid-Miocene subduction event. However, the surrounding psammitic, pelitic and chloritic schists are the dominant greenschist-facies lithologies of the Yuli belt. In the Chinshuichi area, tectonic blocks are enclosed in garnet-bearing metapelites, suggesting elevated pressures. In this area, we recently discovered meta-plagiogranite containing the assemblage glaucophane + omphacite (X-Jd up to 039) + rutile + quartz, indicating P-T conditions near 13 kbar/550 degrees C. New equilibrium phase modeling of a garnet-paragonite mica schist and compositional isopleths for peak assemblage minerals garnet and phengite (Si = 3.33-3.37 pfu) indicate metamorphic conditions of 15.5-17 kbar/530-550 degrees C. These P-T estimates are higher than previously reported in the Yuli belt and suggest that both tectonic blocks and host metapelites underwent HP metamorphism. The juxtaposition of tectonic blocks and metapelites apparently occurred during the formation of a subduction-accretionary complex, followed by exhumation facilitated by a collisional event. These new findings imply that HP metamorphism was not limited to tectonic blocks, and instead played a significant role attending orogenesis in eastern Taiwan. (C) 2015 Elsevier B.V. All rights reserved. KW - Equilibrium phase modeling KW - Omphacite KW - Glaucophane KW - Meta-plagiogranite KW - High-pressure metamorphism KW - Yuli belt KW - Tananao Complex Y1 - 2016 U6 - https://doi.org/10.1016/j.tecto.2015.09.012 SN - 0040-1951 SN - 1879-3266 VL - 692 SP - 191 EP - 202 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Koralay, O. E. A1 - Candan, Osman A1 - Chen, F. A1 - Akal, Cemal B. A1 - Oberhänsli, Roland A1 - Satir, M. A1 - Dora, O. O. T1 - Pan-African magmatism in the Menderes Massif - geochronological data from leucocratic tourmaline orthogneisses in western Turkey JF - International journal of earth sciences N2 - The Menderes Massif, exposed in western Anatolia, is a metamorphic complex cropping out in the Alpine orogenic belt. The metamorphic rock succession of the Massif is made up of a Precambrian basement and overlying Paleozoic-early Tertiary cover series. The Pan-African basement is composed of late Proterozoic metasedimentary rocks consisting of partially migmatized paragneisses and conformably overlying medium- to high-grade mica schists, intruded by orthogneisses and metagabbros. Along the southern flank of the southern submassif, we recognized well-preserved primary contact relationship between biotite and leucocratic tourmaline orthogneisses and country rocks as the orthogneisses represent numerous large plutons, stocks and vein rocks intruded into a basement of garnet mica schists. Based on the radiometric data, the primary deposition age of the precursors of the country rocks, garnet mica schist, can be constrained between 600 and 550 Ma (latest Neoproterozoic). The North Africa-Arabian-Nubian Shield in the Mozambique Belt can be suggested as the possible provenance of these metaclastics. The intrusion ages of the leucocratic tourmaline orthogneisses and biotite orthogneisses were dated at 550-540 Ma (latest Neoproterozoic-earliest Cambrian) by zircon U/Pb and Pb/Pb geochronology. These granitoids represent the products of the widespread Pan-African acidic magmatic activity, which can be attributed to the closure of the Mozambique Ocean during the final collision of East and West Gondwana. Detrital zircon ages at about 550 Ma in the Paleozoic muscovite-quartz schists show that these Pan-African granitoids in the basement form the source rocks of the cover series of the Menderes Massif. KW - Menderes Massif KW - Leucocratic tourmaline orthogneisses KW - Pan-African magmatism KW - Zircon U/Pb and Pb-Pb ages KW - Mozambique Ocean KW - Gondwanaoberh Y1 - 2012 U6 - https://doi.org/10.1007/s00531-012-0775-2 SN - 1437-3254 VL - 101 IS - 8 SP - 2055 EP - 2081 PB - Springer CY - New York ER - TY - JOUR A1 - Kroner, Alfred A1 - Oberhänsli, Roland A1 - Mezger, Klaus A1 - Teklay, M. T1 - Geochemistry, Pb-Pb single zircon ages and Nd-Sr isotope composition of Precambrian rocks from southern and eastern Ethiopia: implications for crustal evolution in east Africa Y1 - 1998 ER - TY - JOUR A1 - Lambert, Ian A1 - Durrheim, Ray A1 - Godoy, Marcio A1 - Kota, Mxolisi A1 - Leahy, Pat A1 - Ludden, John A1 - Nickless, Edmund A1 - Oberhänsli, Roland A1 - Anjian, Wang A1 - Williams, Neil T1 - Resourcing future generations a proposed new IUGS initiative JF - Episodes : journal of international geosciences Y1 - 2013 SN - 0705-3797 VL - 36 IS - 2 SP - 82 EP - 86 PB - Geological Society of India CY - Bangalore ER - TY - JOUR A1 - Lambert, Ian A1 - Oberhänsli, Roland T1 - Towards more effective risk reduction: Catastrophic tsunami JF - Episodes : journal of international geosciences N2 - The International Union of Geological Sciences (JUGS) is evaluating whether there are additional geoscientific activities that would be beneficial in helping mitigate the impacts of tsunami. Public concerns about poor decisions and inaction, and advances in computing power and data mining call for new scientific approaches. Three fundamental requirements for mitigating impacts of natural hazards are defined. These are: (1) improvement of process-oriented understanding, (2) adequate monitoring and optimal use of data, and (3) generation of advice based on scientific, technical and socio-economic expertise. International leadership/coordination is also important. To increase the capacity to predict and mitigate the impacts of tsunami and other natural hazards a broad consensus is needed. The main needs include the integration of systematic geological inputs - identifying and studying paleo-tsunami deposits for all subduction zones; optimising coverage and coordination of geodetic and seismic monitoring networks; underpinning decision making at national and international scales by developing appropriate mechanisms for gathering, managing and communicating authoritative scientific and technical advice information; international leadership for coordination and authoritative statements of best approaches. All these suggestions are reflected in the Sendai Agreement, the collective views of the experts at the International Workshop on Natural Hazards, presented later in this volume. Y1 - 2014 SN - 0705-3797 VL - 37 IS - 4 SP - 229 EP - 233 PB - Geological Society of India CY - Bangalore ER - TY - JOUR A1 - Liu, Xiaochun A1 - Jahn, Bor-Ming A1 - Dong, Shuwen A1 - Li, Huimin A1 - Oberhänsli, Roland T1 - Neoproterozoic granitoid did not record ultrahigh-pressure metamorphism from the Southern Dabieshan of China N2 - It has been often debated whether all granitic gneisses associated with coesite-bearing eclogites in southern Dabieshan, China, have also been subjected to ultrahigh-pressure (UHP) metamorphism. We show here that a metagranitoid adjacent to the Bixiling eclogite-ultramafic complex has preserved primary granitic textures and an igneous mineral assemblage of biotite + plagioclase + microcline + quartz + allanite +/- amphibole. The absence of UPH recrystallization for the metagranitoid is particularly manifested by the conservation of euhedral-zoned plagioclase phenocrysts, the lack of corona garnets around igneous biotite, and the presence of an igneous mineral assemblage in zircons. The only metamorphic overprint was the epidote-amphibolite facies metamorphism characterized by the assemblage of biotite + phengiticmica + epidote + albite + K-feldspar + quartz +/- amphibole Metamorphic conditions are estimated at ca. 550degrees-680degreesC and 6-13 kbar for the metagranitoid and its amphibolitic enclave. Geochemically, the metagranitoid is similar to its country gneiss and shows an affinity to volcanic arc granitoid. Zircon U-Pb dating suggests that the Bixiling metagranitoid was emplaced during the Neoproterozoic (729+/-4 Ma), when most other granitic rocks and the protoliths of eclogite were also formed in Dabieshan. Taking into account the discovery of non-UHP granitic gneisses in other places, we argue that part of Neoproterozoic granitic rocks in the Dabieshan and Sulu terranes have escaped UHP metamorphism during the Triassic deep subduction of the continental crust as a consequence of a lack of penetrative deformation and fluid-rock interaction Y1 - 2003 SN - 0022-1376 ER - TY - JOUR A1 - Mesbahi, Fatemeh A1 - Mohajjel, Mohammad A1 - Oberhänsli, Roland A1 - Moazzen, Mohsen T1 - The mafic rocks along the North Tabriz Fault, possible remnants of Neo-Tethys oceanic crust in NW Iran JF - Geopersia N2 - The North Tabriz Fault is seismologically an active fault with current right lateral strike-slip movements. Restricted mafic to intermediate Fate Cretaceous igneous rocks are exposed along the North Tabriz Fault. Whole rock and clinopyroxene phenocrysts geochemistry were studied in order to characterize the petrogenesis of these mafic rocks and their possible relation to an oceanic crust. The results indicate a tholeiitic parental magma that formed in an evolved mid-ocean ridge tectonic setting similar to the Iceland mid-Atlantic ridge basalts. The ocean floor basalt characteristics give evidence of an oceanic crust along the North Tabriz Fault. Therefore, the trend of the North Tabriz Fault more likely marks a suture zone related to the closure of a branch of the Neo-Tethys Ocean in the NW Iran. This fault, in addition to the Caucasus and Zagros suture zones, compensates an important part of the convergence between the Arabian and Eurasian plates resulting from the Red Sea divergence. It is concluded that the North Tabriz Fault appears to be possible southeastern continuation of the North Anatolian suture zone. KW - North Tabriz Fault KW - Mafic Rocks KW - Tholeiite KW - Late Cretaceous Y1 - 2017 U6 - https://doi.org/10.22059/geope.2017.232747.648323 SN - 2228-7817 VL - 7 SP - 301 EP - 311 PB - Graduate Faculty of Environment, University of Theran CY - Tehran ER - TY - JOUR A1 - Moazzen, Mohssen A1 - Oberhänsli, Roland A1 - Hajialioghli, Robab A1 - Moeller, Andreas A1 - Bousquet, Romain A1 - Droop, Giles A1 - Jahangiri, Ahmad T1 - Peak and post-peak P-T conditions and fluid composition for scapolite-clinopyroxene-garnet calc-silicate rocks from the Takab area, NW Iran N2 - The Takab calcareous rocks of northwest Iran crop out in association with a variety of metamorphic rocks including mafic granulites, amphibolites, granitic gneisses, pelitic schists and meta-ultramafic rocks. They can be divided into marbles and calc-silicate rocks on the basis of the dominance of calcite/dolomite and silicate minerals. Dominant peak metamorphic granulite facies assemblage of calc-silicate rocks is Scp + Grt(I) + Cpx + Cal + Qtz +/- Hbl(I). The decrease of temperature and pressure during exhumation produced post-peak metamorphic assemblages. Coronal garnet (Grt II) in the calc-silicate rocks was produced by retrograde reactions consuming plagioclase and clinopyroxene, while peak metamorphic garnet (Grt I) occurs as preserved xenoblastic grains in calcite and/or plagioclase (Pl II). Regional metamorphism took place at 740 degrees C and X-CO2 similar to 0.9. Garnet-clinopyroxene-plagioclase-quartz (GADS) barometry yields a pressure of 8-9 kbar, corresponding to a depth of ca. 24-27 km. This was followed by decompression and hydration during exhumation of the crustal rocks up to the surface. Secondary phases such as garnet (II) hornblende (II), plagioclase (II), zoisite and titanite (II) constrain the temperature and pressure of post-peak metamorphism as similar to 600 degrees C and similar to 6 kbar respectively and a fluid with XCO2 as low as 0.4. Halogens were near-absent during the peak metamorphic stage. The scapolite and hornblende crystallized underpeak metamorphic conditions contain very low fluorine and chlorine, whereas relatively high fluorine (similar to 0.8 wt%) in the titanite (II) and hornblende (II) suggests a possible infiltration of F-rich fluids into the calc-silicate rocks during retrogression. It is interpreted to be related to external fluids released during crystallisation of granitoid magmas and/or leucosome patches in the adjacent migmatites. Y1 - 2009 UR - http://eurjmin.geoscienceworld.org/ U6 - https://doi.org/10.1127/0935-1221/2009/0021-1887 SN - 0935-1221 ER - TY - JOUR A1 - Oberhänsli, Roland T1 - Deep-time Digital Earth (DDE) the first IUGS big science program JF - Journal of the Geological Society of India Y1 - 2020 U6 - https://doi.org/10.1007/s12594-020-1420-5 SN - 0016-7622 SN - 0974-6889 VL - 95 IS - 3 SP - 223 EP - 226 PB - Springer India CY - New Delhi ER - TY - JOUR A1 - Oberhänsli, Roland T1 - High-Pressure - Low-temperature evolution in the Indus-Tsangpo suture along the Kohistan Arc (Kaghan Valley, NE Pakistan) JF - Episodes : journal of international geosciences N2 - North of Naran in the Kaghan Valley (NE Pakistan), the metabasites of the melange units lying below the Kohistan Arc, contain glaucophane. Typically they reflect blueschist-metamorphic conditions (0.7 GPa, 400 degrees C). Associated graphite-rich metapelites with quartz veins underwent upper greenschist to amphibolite conditions. Near Naran we observed in quartz grains of type 3 veins first minute relics of Fe-Mg carpholite indicating earlier blueschist metamorphic conditions. P-T estimates indicate 1.2-1.6 GPa at 380-410 degrees C, pressure and temperature values typical for blueschist metamorphic conditions. Changes in mineral assemblages and abundant sudoite component in associated chlorite point to a pressure drop after peak I conditions. We assign the observed changes to peak I conditions occurring during a Cretaceous subduction event. Temperatures estimated with Raman graphite-thermometry clearly indicate a significant subsequent rise of post-peak I temperatures up to 500 degrees C. This is compatible with the amphibolite peak II assigned to the Tertiary continental collision that leads to subduction of the Indian Plate and ultra-high-pressure metamorphism. During subduction the blueschist metamorphic metapelites underwent dehydration, which caused alteration in the overlying lithospheric mantle. In a hydrated lithospheric mantle density is significantly reduced which enhanced subduction of continental crust in the Higher Himalaya. This P-T evolution is typical for a collision orogen with a high plateau but remarkably contrasting findings from Eastern Anatolia, where plateau building is in "statu nascendi" (e.g., Oberhänsli et al., 2010). Y1 - 2013 SN - 0705-3797 VL - 36 IS - 2 SP - 87 EP - 93 PB - Geological Society of India CY - Bangalore ER - TY - JOUR A1 - Oberhänsli, Roland T1 - The age of blueschist metamorphiosm ion the Mesozoic cover series of the Menderes massif Y1 - 1998 ER - TY - JOUR A1 - Oberhänsli, Roland T1 - The tectono-metamorphic signature of detachments in high-pressure mountain belts, Tethyan examples Y1 - 1998 ER - TY - JOUR A1 - Oberhänsli, Roland A1 - Bousquet, Romain A1 - Candan, Osman A1 - Okay, Aral I. T1 - Dating subduction events in East Anatolia, Turkey JF - Turkish journal of earth sciences = Türk yerbilimleri dergisi N2 - Metamorphic studies in the cover sequences of the Bitlis complex allow the thermal evolution of the massif to be constrained using metamorphic index minerals. Regionally distributed metamorphic index minerals such as glaucophane, carpholite, relics of carpholite in chloritoid-bearing schists and pseudomorphs after aragonite in marbles record a LT-HP evolution:This demonstrates that the Bitlis complex was subducted and stacked to form a nappe complex during the closure of the Neo-Tethys. During late Cretaceous to Cenozoic evolution the Bitlis complex experienced peak metamorphism of 1.0-1.1 GPa at 350-400 degrees C. During the retrograde evolution temperatures remained below 460 degrees C. Ar-39/Ar-40 dating of white mica in different parageneses from the Bitlis complex reveals a 74-79 Ma (Campanian) date of peak metamorphism and rapid exhumation to an almost isothermal greenschist stage at 67-70 Ma (Maastrichtian). The HP Eocene flysch escaped the greenschist facies stage and were exhumed under very cold conditions. These single stage evolutions contrast with the multistage evolution reported further north from the Amassia-Stepanavan Suture in Armenia. Petrological investigations and isotopic dating show that the collision of Arabia with Eurasia resulted in an assemblage of different blocks derived from the northern as well as from the southern plate and a set of subduction zones producing HP rocks with diverse exhumation histories. KW - Bitlis complex KW - HP metamorphism KW - Ar dating KW - geodynamic evolution of SE Anatolia KW - subduction history Y1 - 2012 U6 - https://doi.org/10.3906/yer-1006-26 SN - 1300-0985 VL - 21 IS - 1 SP - 1 EP - 17 PB - Tübitak CY - Ankara ER - TY - JOUR A1 - Oberhänsli, Roland A1 - Bousquet, Romain A1 - Goffe, B. T1 - Comment to "Chloritoid composition and formation in the eastern Central Alps : a comparison between Penninic and Helvetic occurrences" by M. Rahn, M. Steinmann and M. Frey Y1 - 2003 SN - 0036-7699 ER - TY - JOUR A1 - Oberhänsli, Roland A1 - Candan, O. A1 - Dora, O. A1 - Dürr, S. T1 - Eclogites within the Menderes Massif / western Turkey Y1 - 1997 ER - TY - JOUR A1 - Oberhänsli, Roland A1 - Goffe, B. A1 - Bousquet, Romain T1 - Record of a HP-LT metamorphic evolution in the Valais zone : Geodynamics implications Y1 - 1995 SN - 0392 - 758X ER - TY - JOUR A1 - Oberhänsli, Roland A1 - Koralay, E. A1 - Candan, Osman A1 - Pourteau, Amaury A1 - Bousquet, Romain T1 - Late cretaceous eclogitic high-pressure relics in the Bitlis Massif JF - Geodinamica acta : revue de géologie dynamique et de géographie physique N2 - A new occurrence of eclogites was found in the Kesandere valley in the eastern most part of the Bitlis complex, SE Anatolia. These high-pressure (HP) relics were preserved in calc-arenitic metasediments within the high-grade metamorphic basement of the Bitlis complex. The eclogitic parageneses were strongly overprinted during decompression and heating. These new eclogites locality complements the evidence of blueschist-facies metamorphism documented recently in the meta-sedimentary cover sequence of this part of the Bitlis complex. Thermodynamic calculations suggest peak conditions of ca. 480-540 degrees C/1.9-2.4GPa. New U/Pb dates of 84.4 +/-.9 and 82.4 +/-.9Ma were obtained on zircons from two Kesandere eclogite samples. On the basis of geochemical criteria, these dates are interpreted to represent zircon crystallization during the eclogitic peak stage. Kesandere eclogites differ from those previously described in the western Bitlis complex (Mt. Gablor locality) in terms of lithologic association, protolithic origin, and peak P-T conditions (600-650 degrees C/1.0-2.0GPa, respectively). On the other hand, eclogitic metamorphism of Kesandere metasediments occurred shortly before blueschist-facies metamorphism of the sedimentary cover (79-74Ma Ar-40/Ar-39 white mica). Therefore, the exhumation of Kesandere eclogites started between ca. 82 and 79Ma, while the meta-sedimentary cover was being buried. During this short time span, Kesandere eclogite were likely uplifted from similar to 65 to 35km depth, indicating a syn-subduction exhumation rate of similar to 4.3mm/a. Subsequently, eclogite- and blueschist-facies rocks were likely retrogressed contemporarily during collision-type metamorphism (around 72-69Ma). The Bitlis HP rocks thus sample a subduction zone that separated the Bitlis-Puturge (Bistun?) block from the South-Armenian block, further north. To the south, Eocene metasediments of the Urse formation are imbricated below the Bitlis complex. They contain (post Eocene) blueschists, testifying separation from the Arabian plate and southward migration of the subduction zone. The HT overprint of Kesandere eclogites can be related to the asthenospheric flow provoked by subducting slab retreat or break off. KW - eclogites KW - zircon KW - U KW - Pb ages KW - E Anatolia KW - subduction-collision Y1 - 2013 U6 - https://doi.org/10.1080/09853111.2013.858951 SN - 0985-3111 SN - 1778-3593 VL - 26 IS - 3-4 SP - 175 EP - 190 PB - Routledge, Taylor & Francis Group CY - Abingdon ER - TY - JOUR A1 - Oberhänsli, Roland A1 - Negendank, Jörg F. W. T1 - Natural and anthropogenic influences on the geochemistry of Quaternary lake sediments from Holzmaar, Germany Y1 - 1997 ER - TY - JOUR A1 - Oberhänsli, Roland A1 - Partzsch, Julius A1 - Candan, O. A1 - Cetinkaplan, Mete T1 - First occurrence of Fe-Mg-carpholite documenting a high pressure metamorphism in the metasediments of the Lycian nappes, SW Turkey Y1 - 2000 ER -