Contemporaneous late cretaceous calc-alkaline and alkaline magmatism in Central Anatolia, Turkey: oxygen isotope constraints on petrogenesis

A wide variety of rock types were produced by the latest Cretaceous magmatism in the Central Anatolian Crystalline Complex. These rocks can be divided into three distinct units: (i) calc-alkaline, (ii) subalkaline/transitional, and (iii) alkaline. The calc-alkaline rocks are mainly metaluminous (I-type) ranging from monzodiorite to granite. The subalkaline/transitional rocks are also metaluminous (I-type) ranging from monzonite to granite. The alkaline rocks are mainly peralkaline (A-type), ranging from feldspathoid-bearing monzosyenite to granite. Whole-rock oxygen isotope data from the complex have a considerable range of δ18O values between 6.5‰ and 14.8‰. Initial 87Sr/86Sr versus 143Nd/144Nd ratios, and both ratios versus δ18O values diagrams show that the intrusive rocks are derived from a subduction-modified mantle and also have experienced fractional crystallisation coupled with crustal assimilation. Delamination of a thermal boundary layer, and/or slab breakoff is the likely mechanisms for the initiation of the diverse magmatism in the complex

Geochemical constraints on petrogenesis of Late Cretaceous alkaline magmatism in east-central Anatolia (Hasancelebi-Basoren, Malatya), Turkey

Late Cretaceous alkali magmatic rocks occur widely in the Hasancelebi and Basoren regions (Malatya). The Hasancelebi and Basoren intrusive rocks are mainly peralkaline and alkaline-oversaturated. The Hasancelebi intrusive rocks are made up of syenite to quartz monzonite. On the other hand the Basoren intrusive rocks mainly contain feldspathoidal syenites that are cut by feldspathoid-bearing dykes. The Hasancelebi intrusive rocks show comparable field, petrographic and geochemical characteristics with A-type rocks. All intrusive rocks show enrichment in LILE and LREE relative to HFSE. The Th/Yb versus Ta/Yb diagram indicates that all magmatic rocks formed from an enriched mantle source region(s). The parental magma for the Basoren rocks has a higher intraplate component than that from the Hasancelebi rocks which could be attributed to mantle source heterogeneity before collision in east-central Anatolia. Either delamination of the thermal boundary layer or slab-breakoff are likely mechanisms for the initiation of post-collisional magmatism in the Hasancelebi-Basoren areas

Petrogenesis of collision-related plutonics in Central Anatolia, Turkey

Central Anatolia exhibits good examples of calc-alkaline and alkaline magmatism of similar age in a collision-related tectonic setting (continent–island arc collision). In the Central Anatolia region, late Cretaceous post-collisional plutonic rocks intrude Palaeozoic–Mesozoic metamorphic rocks overthrust by Upper Cretaceous ophiolitic units to make up the Central Anatolian Crystalline Complex. In the complex, three different intrusive rock types may be recognised based on their geochemical characteristics: (i) calc-alkaline (Behrekdag, Cefalikdag, and Celebi); (ii) subalkaline-transitional (Baranadag); and (ii) alkaline (Hamit). The calc-alkaline and subalkaline plutonic rocks are metaluminous I-type plutons ranging from monzodiorite to granite. The alkaline plutonic rocks are metaluminous to peralkaline plutons, predominantly A-type, ranging from nepheline monzosyenite to quartz syenite. All intrusive rocks show enrichment in LILE and LREE relative to HFSE, and have high 87Sr/86Sr and low 143Nd/144Nd ratios. These characteristics indicate an enriched mantle source region(s) carrying a subduction component inherited from pre-collision subduction events. The tectonic discrimination diagram of Rb vs. (Y+Nb) suggests that the calc-alkaline, subalkaline, and alkaline plutonic rocks have been affected by crustal assimilation combined with fractional crystallisation processes. The coexistence of calc-alkaline and alkaline magmatism in the Central Anatolian Crystalline Complex may be attributed to mantle source heterogeneity before collision. The former carries a smaller intraplate component and pre-subduction enrichment compared to the latter. Either thermal perturbation of the metasomatised lithosphere by delamination of the thermal boundary layer (TBL), or removal of a subducted plate (slab breakoff) is the likely mechanism for the initiation of the post-collisional magmatism in the Complex

Geochemical and mineralogical characteristics of beach sediments along the coast between Alanya and Silifke (southern Turkey)

WOS: 000362443900007The aim of this work was to determine the distribution of trace metals in the coastal sediments from the area between Silifke and Alanya (Turkey) and to investigate the sources of these elements, based on their mineralogical, petrographical and geochemical characteristics. Forty three samples were analysed for the determination of their water content, grain-size distribution, petrographical features and their chemical and mineralogical compositions. The samples had low water content, in agreement with the large sand grain size. The mineralogical composition reflects the complex geological setting of the area. The most abundant mineral phases are represented by calcite and dolomite, followed by quartz and mica. Chlorite, feldspar and other carbonates are present in lesser amounts, while kaolinite was detected in one sample only. All samples contain hematite, chromite, magnetite and goethite and one sample contained pyrite. Samples with high concentrations of trace metals, contained fragments of metamorphic rocks with pyroxene, amphibole, quartz and feldspar, whereas carbonates and opaque minerals were subordinate. Compared to literature data, the average concentrations of several elements and trace metals were great enough to be considered as possibly toxic, exceeding the Turkish higher acceptable limits. Geochemical data were treated statistically using Principal Component Analysis (PCA) to obtain evidence of their distribution and to identify any correlations. Based on the distribution of mineral phases, the area investigated was divided into different provinces, each characterized by the abundance of one, or more, tracer minerals. In the westernmost areas, between Alanya and Demirtas, the sediments indicate a provenance from dolomites or marbles. In the area between Demirtas and Gazipasa the provenance was from quartzites, clastic and metamorphic rocks and in the sector between Guney and Anamur, the sediments were derived mostly from low-grade metamorphic rocks, in particular metaschists and metabasites. The sediments in the area between Anamur and Ovacik, display variable source rocks and those between Ovacik and Silifke, were derived from limestones and, subordinately, clastic rocks. The trace-metal concentrations in beach sands appear to be related to the abundance of silicate minerals derived from weathering of the metamorphic-rock outcrops in the inland mountainous regions. In contrast, the trace-metal contents of the limestone- and dolomite-bearing beach sands were small.Scientific Research Projects Unit of Akdeniz UniversityThis study was a part of the MSc Thesis prepared by Feridun Karakaya in the Department of Geological Engineering of Nigde University. The authors thank Luigi Marinoni for XRD analyses at the University of Pavia, Italy. The financial support of the Scientific Research Projects Unit of Akdeniz University is gratefully acknowledged. Dr M. Gurhan Yalcin thanks Dr George E. Christidis for editorial handling, review and editing of this article

MULTIVARIATE ANALYSES TO DETERMINE THE ORIGIN OF SOME POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) IN HONEY SAMPLES

WOS: 000381320400029This study tries to reveal the levels of three distinct PAHs (naphthalene, benzo[a]pyrene (BaP) and anthracene on honey samples. They were taken from several different stations from the Nigde City (Central Anatolia, Turkey). The Gas chromatography-mass spectrometry results revealed that twenty-four honey samples having naphthalene residues (for GC-MS limit of detection is 1 ppb and the upper limit 100 ppb in the European Union MRLs). In addition six samples have BaP residues (1.51 +/- 0.47 ng/g) and eight examples have anthracene residues (1.59 +/- 0.85 ng/g). Heavy metals in the honey samples were studied on Pb, Ni, Cr and Cd elements. To get simple and multivariate statistics, the SPSS Statistics 21 software has been used for this work. According to simple statistics, maximum minimum values for Pb are 4286-1998; Ni 9987-5457; Cr 9654-2335 and Cd 3229-1090. However, we get higher statistics values from Cr and Cd. These results could decrease the quality of honey.Scientific Research Projects Unit of Akdeniz UniversityThe financial support of the Scientific Research Projects Unit of Akdeniz University is gratefully acknowledged

Crustal homogenization revealed by U–Pb zircon ages and Hf isotope evidence from the Late Cretaceous granitoids of the Agaçören intrusive suite (Central Anatolia/Turkey)

Geochemical and isotopic evidence from the Agacoren Igneous Association in central Anatolia-Turkey indicates that this suite of calc-alkaline granitic rocks have undergone crustal homogenization during regional metamorphic and related magmatic events. Whole-rock chemical and Sr-Nd isotopic data of the granitoids reveal crustal affinity with an earlier subduction component. Zircons show inherited cores and subsequent magmatic overgrowths. The laser ablation ICP-MS Pb-206/U-238 zircon ages are determined as 84.1 +/- 1.0 Ma for the biotite-muscovite granite, 82.3 + 0.8/-1.1 Ma for the hornblende-biotite granite, 79.1 + 2.1/-1.5 Ma for the granite porphyry dyke, 75.0 + 1.0/-1.0 Ma for the alkali feldspar dyke, and 73.6 +/- 0.4 Ma for the monzonite. This is interpreted as continuous magma generation, possibly from heterogeneous sources, from ca. 84 to 74 Ma during the closure of the northern branch of the Neotethyan Ocean. The oldest granitoids (84-82 Ma) were probably formed due to crustal thickening after obduction of the MORB-type oceanic crust onto the Tauride-Anatolide microplate. The younger granitoids are interpreted to be related to the subsequent post-collisional extension after lithospheric delamination. Combination of the laser ablation ICP-MS zircon Lu-Hf isotope data with the U-Pb ages of inherited cores suggests that Cretaceous granitoids formed by melting of heterogeneous crustal protoliths, which results in significant variation in epsilon Hf-(t) data (from -12.9 to +2.2). These protoliths were probably composed of reworked Early Proterozoic crust, minor juvenile Late Proterozoic magmatic components, and Paleozoic to pre-Late Cretaceous recycled crustal material. Moreover, the Late Cretaceous zircon domains of the different granitoids are characterized by a crustal signature, with a relatively restricted zircon epsilon Hf-(t) data ranging from -4.1 to -8.8. This variation is only about twice the reproducibility (ca. +/- 1 epsilon Hf) of the data, bu

Kinematics of a former oceanic plate of the Neotethys revealed by deformation in the Ulukışla basin (Turkey)

Kinematic reconstruction of modern ocean basins shows that since Pangea breakup a vast area in the Neotethyan realm was lost to subduction. Here we develop a first-order methodology to reconstruct the kinematic history of the lost plates of the Neotethys, using records of subducted plates accreted to (former) overriding plates, combined with the kinematic analysis of overriding plate extension and shortening. In Cretaceous-Paleogene times, most of Anatolia formed a separate tectonic plate—here termed “Anadolu Plate”—that floored part of the Neotethyan oceanic realm, separated from Eurasia and Africa by subduction zones. We study the sedimentary and structural history of the Ulukışla basin (Turkey); overlying relics of this plate to reconstruct the tectonic history of the oceanic plate and its surrounding trenches, relative to Africa and Eurasia. Our results show that Upper Cretaceous-Oligocene sediments were deposited on the newly dated suprasubduction zone ophiolites (~92 Ma), which are underlain by mélanges, metamorphosed and nonmetamorphosed oceanic and continental rocks derived from the African Plate. The Ulukışla basin underwent latest Cretaceous-Paleocene N-S and E-W extension until ~56 Ma. Following a short period of tectonic quiescence, Eo-Oligocene N-S contraction formed the folded structure of the Bolkar Mountains, as well as subordinate contractional structures within the basin. We conceptually explain the transition from extension, to quiescence, to shortening as slowdown of the Anadolu Plate relative to the northward advancing Africa-Anadolu trench resulting from collision of continental rocks accreted to Anadolu with Eurasia, until the gradual demise of the Anadolu-Eurasia subduction zone