Cooper, Alan F.; Boztug, Durmus; Palin, J. Michael; Martin, Candace E.; Numata, Mihoko

The late Cretaceous A-type Kara double dagger ayA +/- r pluton in Central Anatolia, Turkey, intrudes and entrains xenoliths of Palaeozoic limestone. Carbonatitic magmatic rocks within the syenite have been previously interpreted (Schuiling in Nature, 192:1280, 1961) to result from metasomatic alteration and syntectic melting of marble. Carbonatites and associated calcite-syenites exhibit mineralogical characteristics (Ab-rich plagioclase, Ba-rich K-feldspar, low-Mg# biotite) that are petrogenetically more evolved than the host syenitic suite. Geochemically, carbonate-rich magmatic rocks are greatly enriched in Sr, Ba, Th, and REE and have higher LREE/HREE ratios than either syenites or marbles. In terms of O-C-Sr-Pb isotope ratios, the carbonatite/calcite-syenite suite form a consistent and geochemically coherent group that is distinct from the marble country rock and xenolith population, but similar to some of the syenitic, and particularly the nepheline syenite components of the Kara double dagger ayA +/- r pluton. Other silicate magmatic rocks are geochemically, isotopically, and geochronologically different, suggesting the pluton is composite. Overall, the mineralogical and geochemical characteristics of the carbonatites are incompatible with binary mixing of syenite and marble but are consistent with derivation of carbonatite from petrogenetically evolved foid syenite. Carbonate-silicate rock types have modal variations compatible with an origin by fractional crystallisation, rather than by liquid immiscibility.

AtıfWoS17·OpenAlex17

İncele

Yilmaz, Ali; Yilmaz, Huseyin; Kaya, Cemal; Boztug, Durmus

The Eastern Anatolian Plateau (EAP) of Turkey, with an elevation ranging from 1700 to 2000 m, is located between the Eastern Pontide Arc to the north and the Arabian Platform to the south. In this region, pre-Maastrichtian tectonic units representing the crust crop out in only a few localities. As they are covered by Maastrichtian-Quaternary rock units, it is difficult to study the nature and mutual relationships of these pre-Maastrichtian tectonic units. The palaeotectonic units of the EAP comprise two different levels in the present study: (1) The lower level consists of platform-type carbonates and their metamorphic equivalents. These units may represent the Taurus Platform and its metamorphic equivalents. (2) The upper level consists of an ophiolitic-melange prism which is made up mainly of oceanic crust; the prism comprises a complex of ophiolite, ophiolitic melange, and fore-arc deposits. This upper unit represents a subduction-accretion prism and may have originated partly from the North Anatolian Suture to the north, and partly from the South-eastern Anatolian Suture to the south. Continental crustal rocks were thrust over by the ophiolitic melange prism; thus outcrops of them are scarce in the region as they are exposed in tectonic windows through the ophiolitic thrust sheets. The pre-Maastrichtian tectonic units of the EAP are blanketed by Maastrichtian to Quaternary volcanic and sedimentary rock units; these sequences include successive transgressive and regressive intervals and overlie the palaeotectonic units along a pronounced unconformity. Olistostromal units are abundant in the Eocene sedimentary units and were derived from the ophiolites and ophiolitic melange. The Maastrichtian-Quaternary cover is made up of collisional and post-collisional deposits across the whole region. Although the EAP has been experiencing considerable N-S compression, it has not been affected by significant crustal thickening because of the strike-slip tectonic regime that is dominant in the region. (C) 2010 Lavoisier SAS. All rights reserved

AtıfWoS33·OpenAlex28

İncele

Boztug, Durmus; Güney, Ozlem; Heizler, Matt; Jonckheere, Raymond C.; Tichomirowa, Marion; Otlu, Nazmi

The Kaman-Kirsehir region intrusions were generated in a post-collisional extensional setting following Cenomanian-Turonian docking of an oceanic island arc, comprising the supra-subduction zone (SSZ) Central Anatolian ophiolite (CAO), onto the Tauride-Anatolide Platform (TAP). These granitoids have been named, from N to S, the Camsari quartz syenite, Hamit quartz syenite, Bayindir nepheline-cancrinite syenite, Durmuslu nepheline-nosean-melanite syenite porphyry and Baranadag quartz monzonite. They intrude the crustal metasediments of the Central Anatolian Crystalline Complex (CACC) and CAO and are unconformably overlain by Upper Paleocene to Lower-Middle Eocene sediments. The single-zircon Pb-207-Pb-206 evaporation age of the Camsari unit is 95.7 +/- 5.1 Ma; those of the Hamit and Baranadag units are indistinguishable with a weighted mean of 74.3 +/- 4.5 Ma. The amphibole 40Ar-39Ar ages of the Hamit and Baranadag units are almost identical with a weighted mean of 72.7 +/- 0.1 Ma. The apatite fission-track age vs elevation plot for the Camsari, Hamit, Durmuslu and Baranadag samples reveals rapid exhumation (>1 km/Ma) between similar to 57 and similar to 61 Ma, consistent with the results of track-length modelling. This Early-Middle Paleocene rapid exhumation is thought to result from uplift triggered by continent (TAP) - continent (Eurasian plate; EP) collision following the closure of Izmir-Ankara-Erzincan (IAE) ocean that also initiated the formation of peripheral foreland basins in central Anatolia. The Kaman-Kirsehir region intrusions were generated in a post-collisional extensional setting following Cenomanian-Turonian docking of an oceanic island arc, comprising the supra-subduction zone (SSZ) Central Anatolian ophiolite (CAO), onto the Tauride-Anatolide Platform (TAP). These granitoids have been named, from N to S, the Camsari quartz syenite, Hamit quartz syenite, Bayindir nepheline-cancrinite syenite, Durmuslu nepheline-nosean-melanite syenite porphyry and Baranadag quartz monzonite. They intrude the crustal metasediments of the Central Anatolian Crystalline Complex (CACC) and CAO and are unconformably overlain by Upper Paleocene to Lower-Middle Eocene sediments. The single-zircon Pb-207-Pb-206 evaporation age of the Camsari unit is 95.7 +/- 5.1 Ma; those of the Hamit and Baranadag units are indistinguishable with a weighted mean of 74.3 +/- 4.5 Ma. The amphibole 40Ar-39Ar ages of the Hamit and Baranadag units are almost identical with a weighted mean of 72.7 +/- 0.1 Ma. The apatite fission-track age vs elevation plot for the Camsari, Hamit, Durmuslu and Baranadag samples reveals rapid exhumation (>1 km/Ma) between similar to 57 and similar to 61 Ma, consistent with the results of track-length modelling. This Early-Middle Paleocene rapid exhumation is thought to result from uplift triggered by continent (TAP) - continent (Eurasian plate; EP) collision following the closure of Izmir-Ankara-Erzincan (IAE) ocean that also initiated the formation of peripheral foreland basins in central Anatolia.

AtıfWoS23

İncele

Boztug, Durmus; Türksever, Esra; Heizler, Matt; Jonckheere, Raymond C.; Tichomirowa, Marion

The Karacayir syenite, intruding the Palaeozoic crustal metamorphics and unconformably overlain by Upper Paleocene to Eocene Tokus formation in the north of Sivas (east-central Anatolia), has been studied with respect to Pb-207-Pb-206 single zircon evaporation, biotite 40Ar-39Ar, and apatite fission-track geothermochronology. Pb-207-Pb-206 single zircon evaporation dating yields an age of 99.0 +/- 11.0 Ma (Cenomanian-Turonian) which is considered to be the intrusion age. Biotite 40Ar-39Ar age determination gives a cooling age of ca. 65 Ma. Apatite fission-track dating, combined with T-t modeling based on track-length distribution data, determines a fast tectonic exhumation with an uplift rate of > 1 mm/a which occurred 58-61 Ma ago. This Middle Paleocene fast tectonic uplift is considered to have resulted from a compressional regime induced by the collision between the Tauride-Anatolide platform (TAP) and the Eurasian plate (EP) along the Izmir-Ankara-Erzincan (IAE) suture zone following the closure of the north-dipping subducted IAE ocean which belongs to northern Neo-Tethyan realm. This compressional regime has also formed the peripheral foreland basins in central Anatolia.

AtıfWoS14

İncele