@article{SchefflerImmenhauserPourteauetal.2019, author = {Scheffler, Franziska and Immenhauser, Adrian and Pourteau, Amaury and Natalicchio, Marcello and Candan, Osman and Oberh{\"a}nsli, Roland}, title = {A lost Tethyan evaporitic basin}, series = {Sedimentology : the journal of the International Association of Sedimentologists}, volume = {66}, journal = {Sedimentology : the journal of the International Association of Sedimentologists}, number = {7}, publisher = {Wiley}, address = {Hoboken}, issn = {0037-0746}, doi = {10.1111/sed.12606}, pages = {2627 -- 2660}, year = {2019}, abstract = {Ancient evaporite deposits are geological archives of depositional environments characterized by a long-term negative precipitation balance and bear evidence for global ocean element mass balance calculations. Here, Cretaceous selenite pseudomorphs from western Anatolia ('Rosetta Marble') — characterized by their exceptional morphological preservation — and their 'marine' geochemical signatures are described and interpreted in a process-oriented context. These rocks recorded Late Cretaceous high-pressure/low-temperature, subduction-related metamorphism with peak conditions of 1·0 to 1·2 GPa and 300 to 400°C. Metre-scale, rock-forming radiating rods, now present as fibrous calcite marble, clearly point to selenitic gypsum as the precursor mineral. Stratigraphic successions are recorded along a reconstructed proximal to distal transect. The cyclical alternation of selenite beds and radiolarian ribbon-bedded cherts in the distal portions are interpreted as a two type of seawater system. During arid intervals, shallow marine brines cascaded downward into basinal settings and induced precipitation. During more humid times, upwelling-induced radiolarian blooms caused the deposition of radiolarite facies. Interestingly, there is no comparable depositional setting known from the Cenozoic world. Meta-selenite geochemical data (δ13C, δ18O and 87Sr/86Sr) plot within the range of reconstructed middle Cretaceous seawater signatures. Possible sources for the 13C-enriched (mean 2·2 per mille) values include methanogenesis, gas hydrates and cold seep fluid exhalation. Spatially resolved component-specific analysis of a rock slab displays isotopic variances between meta-selenite crystals (mean δ13C 2·2 per mille) and host matrix (mean δ13C 1·3 per mille). The Cretaceous evaporite-pseudomorphs of Anatolia represent a basin wide event coeval with the Aptian evaporites of the Proto-Atlantic and the pseudomorphs share many attributes, including lateral distribution of 600 km and stratigraphic thickness of 1·5 to 2·0 km, with the evaporites formed during the younger Messinian salinity crisis. The Rosetta Marble of Anatolia may represent the best-preserved selenite pseudomorphs worldwide and have a clear potential to act as a template for the study of meta-selenite in deep time.}, language = {en} } @misc{PourteauOberhaensliCandanetal.2016, author = {Pourteau, Amaury and Oberh{\"a}nsli, Roland and Candan, Osman and Barrier, Eric and Vrielynck, Bruno}, title = {Neotethyan closure history of western Anatolia: a geodynamic discussion}, series = {International journal of earth sciences}, volume = {105}, journal = {International journal of earth sciences}, publisher = {Springer}, address = {New York}, issn = {1437-3254}, doi = {10.1007/s00531-015-1226-7}, pages = {203 -- 224}, year = {2016}, abstract = {This paper addresses the lithosphere-scale subduction-collision history of the eastern termination of the Aegean retreating subduction system, i.e. western Anatolia. Although there is some general consensus on the protracted subduction evolution of the Aegean since the early Cenozoic at least, correlation with western Anatolia has been widely debated for more than several decades. In western Anatolia, three main tectonic configurations have been envisaged in the past years to reconstruct slab dynamics during the closure of the Neotethyan oceanic realm since the Late Cretaceous. Some authors have suggested an Aegean-type scenario, with the continuous subduction of a single lithospheric slab, punctuated by episodic slab roll-back and trench retreat, whereas others assumed a discontinuous subduction history marked by intermittent slab break-off during either the Campanian (ca. 75 Ma) or the Early Eocene (ca. 55-50 Ma). The third view implies three partly contemporaneous subduction zones. Our review of these models points to key debated aspects that can be re-evaluated in the light of multidisciplinary constraints from the literature. Our discussion leads us to address the timing of subduction initiation, the existence of hypothetical ocean basins, the number of intervening subduction zones between the Taurides and the Pontides, the palaeogeographic origin of tectonic units and the possibility for slab break-off during either the Campanian or the Early Eocene. Thence, we put forward a favoured tectonic scenario featuring two successive phases of subduction of a single lithospheric slab and episodic accretion of two continental domains separated by a continental trough, representing the eastern end of the Cycladic Ocean of the Aegean. The lack of univocal evidence for slab break-off in western Anatolia and southward-younging HP/LT metamorphism in continental tectonic units (from similar to 85, 70 to 50 Ma) in the Late Cretaceous-Palaeogene period suggests continuous subduction since similar to 110 Ma, marked by roll-back episodes in the Palaeocene and the Oligo-Miocene, and slab tearing below western Anatolia during the Miocene.}, language = {en} }