Petrology and ⁴⁰Ar-³⁹Ar dating of paragneisses from the Devrekani Massif (Central Pontides, Northern Turkey): Implications for the Jurassic high-T metamorphism in an extensional tectonic environment

The Devrekani Massif in the northern part of the Central Pontides (Northern Turkey) provides important clues to the regional tectonics and geodynamic processes associated with Jurassic high grade metamorphic conditions. This study reports new paragenetic assemblages, mineral compositions, whole-rock geochemistry and 40Ar-39Ar geochronological data from the paragneisses in the massif, and, discusses the P–T conditions and geodynamic implications of the Jurassic metamorphism during continental extension in the Central Pontides. Upper amphibolite to lower granulite facies paragneisses form one of the main lithological units in the massif. Within these, there are five different mineral parageneses with diagnostic mineral assemblages of: quartz, K-feldspar (An0-1Ab4-26Or73-96), plagioclase (An18-35), biotite [(XPhl: 0.28-0.57; Mg/(Mg+Fe2+): 0.33-0.61)], sillimanite, cordierite [(Mg/(Mg+Fe2+): 0.48-0.71)] and garnet (Alm43-80Grs0-18Prp5-23And0-4Sps10-33) with minor hercynite. Based on Na-in-Crd thermometry and GASP barometry results, the peak metamorphic conditions are 775±25°C and 6±1 kbar in the massif. The field relations, petrography and bulk chemical data suggest that the paragneisses, derived from shale-wackestone and pelitic sedimentary protoliths, are typical rock lithologies of an active continental margin. They display enrichments in LILE over HFSE, coupled with negative Nb and Ti anomalies, which are geochemical signatures of subduction-related sources. It is likely that the peak metamorphism took place during the Middle–Upper Jurassic period (ca. 174–156 Ma), suggesting that the metamorphic rocks cooled to 300-350°C at ca. 156 Ma. The mineral assemblages reveal that the prograde history passed from sillimanite zone conditions up to the cordierite-garnet-K-feldspar zone. The petrological and geochronological data indicate that the protoliths are related to multiple sources such as volcano-sedimentary successions. We conclude that the Devrekani Massif represents the products of pre-Jurassic sedimentation, and Permo-Carboniferous continental arc magmatism, overprinted by Jurassic metamorphism

Geochemical Dataset for the accuracy of the ICP-OES and LA-ICP-MS facilities in Istanbul University-Cerrahpaşa, Geological Engineering Department

The dataset presented here includes operating conditions, experimental setups, and geochemical analysis results of the paper entitled "Accurate Whole-Rock Geochemistry Analysis by Combined ICP-OES and LA-ICP-MS Instruments" to the Bulletin of the Mineral Research and Exploration by Gönenç GÖÇMENGİL, Fatma ŞİŞMAN TÜKEL, Fulya UZUN, Marcel GUILLONG, İsak YILMAZ, Namık AYSAL, Nurullah HANİLÇİ Table S1 includes ICP-OES plasma operating conditions Table S2 includes ICP-OES analyte names, spectral wavelengths and limits of detection in Geochronology and Geochemistry Laboratory of Istanbul University-Cerrahpaşa. Table S3 includes Laser Ablation (LA) and ICP-MS operating conditions. Table S4 includes the results of the ICP-OES analysis on USGS standards BCR-2 and AGV-2 which were generated by lithium-tetraborate fusion. Table S5 includes the results of the LA-ICP-MS measurements on the BCR-2g and BCR-2 glass discs. Table S6 includes the results of the LA-ICP-MS measurements on the AGV-2g and fused AGV-2 discs. Table S7 includes the results of the LA-ICP-MS measurements on the NIST SRM 614

Petrogenesis of Early Cenozoic Sarıcakaya–Nallıhan Volcanism in NW Turkey: Implications for the Geodynamic Setting and Source Characterization of the Balkanatolia Magmatic Realm

Sarıcakaya–Nallıhan Volcanism was generated within the Balkanatolia Magmatic Realm between 48 and 44 Ma (by 40Ar–39Ar age determination) and is represented by three different volcanic units all displaying subduction-related geochemical signatures, such as depletion in HFSE and enrichment in LREE and LILE. The first unit (V1) consists of nepheline-normative, olivine basalts with OIB-like affinity. The second (V2) and third (V3) units are represented by more evolved compositions such as basaltic-andesitic, andesitic, and dacitic-rhyolitic lavas. Even the most basic lavas have elevated Mg# values (62–69), and they are far from representing the true mantle melts. Source characterization of Sarıcakaya–Nallıhan Volcanism reveals that there might be two possible mantle sources for the primary melts of the lavas: (i) metasomatized peridotitic mantle fluxed by sedimentary melts, or (ii) accreted mélange. The direct melting of the mélange-like lithologies is a more favorable mechanism for the Middle Eocene (44–40 Ma) magmatism in Balkanatolia since the Hf–Nd trace element, Nd isotopic systematics and petrological modelling efforts supported the latter. Overall, Early Cenozoic magmatism within this realm was characterized, first (58–44 Ma) by contractional and later (44–40 Ma) by extensional tectonics and the late-stage magmatic phase in the area was possibly controlled by melting of accreted mélange-like lithologies. The presented data indicate that mélange melting might be much more common than envisaged for the magmatism in the Alpine–Himalayan orogenic belt