Durmuş Boztuğ

Space and Time Relations of Three Plutonic Phases in the Eastern Pontides, Turkey

Granitoid plutons located between the towns of Dereli and Sebinkarahisar are differentiated into three groups, representing the products of three distinct phases; each of these phases is subdivided into several subunits. The first plutonic phase, intruding into the Santonian-Campanian volcanics, is composed of the Maastrichtian Tamdere quartz monzonite, Surmen granodiorite, and Aksu biotite monzogranite. It appears to have formed as differentiation products of a single hybrid magma source. The subunits of the second plutonic phase consist of the Paleocene Gokcebel syenite and Sebinkarahisar quartz syenite, which are intruded into the Aksu biotitemonzogranite to the north and the Santonian-Campanian volcanics to the south. The third plutonic phase consists solely of the Eocene-age Yucedere diorite/gabbro, which intrudes the subunits of the first plutonic phase. The first and second plutonic phases include microgranular mafic magmatic enclaves and display special microscopic textures, the former indicating ...

Comparative petrogenetic investigation of Composite Kaçkar Batholith granitoids in Eastern Pontide magmatic arc—Northern Turkey

The Pontides are an east-west trending orogenic belt which is subdivided into west, middle and eastern sectors according to their different tectonostratigraphy. The Eastern Pontides are represented by west-east-trending tectonic zones resulted from a common Mesozoic-Tertiary history, comprises dominantly of magmatic rocks. The magmatic belt in the Eastern Pontides includes a large batholith, termed the Composite Kaçkar Batholith (CKB) in which there are various granitic facies. The emplacement of CKB occurred in pulses between the Early Cretaceous and Eocene period during the development of the eastern Pontide magmatic arc and following collisional events. The members of the CKB are Dereli-Şebinkarahisar (Giresun) in the west, southern Araklı (Trabzon) in the middle and Kaçkar Mountain and its surrounding area (Rize) in the east. The plutons ranging from syenite through monzonite to granite are typically medium-high K calc-alkaline rarely tholeiitic and metaluminous I-type. The studied members of the CKB intrudes into the Late Cretaceous arc volcanics and are determined to be Late Cretaceous-Eocene (75.7 ± 1.55; 41.2 ± 0.89) in K-Ar age. The tectono-magmatic setting of the granitoids has been interpreted as an arc-related granitic suite, a post-collisional granitic suite and a post-orogenic granitic suite. Some plutons including mafic magmatic enclaves (MME) and K-feldspar megacrystals suggest magma mixing/mingling. HFS and LIL element geochemistry of the granitic intrusions also suggest that fractional crystallization, magma mixing/mingling and crustal contamination played an important role in the evolution of the CKB. All the data mentioned above show that the granitoids in the three different regions may have been derived from an arc, developed in response to the northward subduction of the northern branch of neo-Tethyan oceanic crust beneath the Eurasian plate in Late Cretaceous and a collision between the Pontide arc and the Anatolide-Tauride platform in Paleocene.

Geochemical and Pb-Sr-Nd Isotopic Constraints Indicating an Enriched-Mantle Source for Late Cretaceous to Early Tertiary Volcanism, Central Anatolia, Turkey

Bulk-rock major, trace, and REE geochemistry and Pb-Sr-Nd isotopic compositions identify mantle sources involved in the genesis of volcanic rocks of the Upper Cretaceous-Lower Tertiary Ulukişla Formation, Çamard-Ulukişla Basin, Nigde Province, central Anatolia. Incompatible trace-element patterns exhibit a large Nb-Ta trough and strong enrichment of LILE such as Ba, Th and U, and LREE, which indicate a subduction-zone signature. Trace-element ratios are compatible with a subcontinental lithospheric source. Isotopic data demonstrate the presence of an EMII-like protolith (87Sr/86Sr = 0.707242-0.707582, 143Nd/144Nd = 0.512336-0.512390, 206Pb/204Pb = 18.70-18.917, 207Pb/204Pb = 15.716-15.796, 208Pb/204Pb = 39.157-39.45). These geochemical and isotopic data indicate the derivation of the studied volcanic rocks from an enriched subcontinental mantle source, modified by earlier subduction events. This petrogenetic conclusion is compatible with a geodynamic setting of post-collisional extension for the Çamard-Ulukişla Basin.

Geology, Geochemistry, and Petrology of the Alkaline Subvolcanic Trachyte-Hosted Iron Deposit in the Karakuz Area, Northwestern Hekimhan-Malatya, Turkey

The Karakuz iron deposit is hosted by Maastrichtian subvolcanic trachyte-trachyandesite, which has a total alkali content of 9-13 wt%, with Na2O less than 1% of the total alkalies. SiO2, Al2O3, and Fe2O3, in order of relative abundance, are other common oxides, whereas the P2O5 concentration is less than 0.5% in all of the host-rock samples. The trachytic host rock has an indistinct flow structure in the field and a subvolcanic porphyritic texture in thin sections. The tectonomagmatic environment of the trachytic subvolcanic host rock is intraplate and is derived from alkaline basaltic magma in the Hasancelebi-Hekimhan area. The iron deposit at Karakuz occurs as stringers, stockworks, lenses, and less disseminated ores. A characteristic feature of the deposit is martitization. Dominant iron minerals in the paragenetic sequence are magnetite-hematite-martite-goethite ± lepidocrocite ± limonite. Quartz, calcite, and barite are the main gangue minerals in the ore zone. The ore zone proper is characterized by...