Tracking the timing of Neotethyan oceanic slab break-off: Geochronology and geochemistry of the quartz diorite porphyries, NE Turkey

The initiation of the break-off of the northern branch of the Neotethyan oceanic lithosphere is an important but poorly understood event in the geology of the Sakarya Zone (SZ) in northeastern Turkey. Although it is well-known that Latest Cretaceous intrusives (~70 Ma) and early Eocene adakitic magmatic rocks are present in the eastern SZ, the outcrops of the early Eocene non-adakitic rocks are very limited, and their tectono-magmatic evolution has not been studied. We describe a small outcrop of non-adakitic quartz diorite porphyry in the Kov area of the Gümüşhane region in northeastern Turkey. The genesis of these porphyries is significant in evaluating the syn- to post-collision-related magmatism. The LA-ICP-MS zircon U-Pb dating revealed that the Kov quartz diorite porphyries (KQDP) formed at ca. 50 Ma, coeval with adakitic rocks, and ~20 Myr later than the slab roll-back-related intrusive rocks. The KQDPs are calc-alkaline in composition and enriched in large ion lithophile elements (LILEs) and light rare earth elements (LREEs) and depleted in high field strength elements (HFSEs; e.g., Nb, Ta, Ti), with significant negative anomalies of Nb, Ta, and Ti but positive anomalies of Th, U, and Pb. Isotopic compositions of the samples show limited range of variation and slight enrichment of 87Sr/86Sr(t) (0.70489 to 0.70555), εNd(t) (−1.4 to −1.2) with TDM of 1.11 to 1.61 Ga. Pb isotopic ratios of the samples point to an enriched mantle source. They were likely crystallized from the melt that originated from an EM2-type spinel-facies subcontinental lithospheric mantle (SCLM), followed by the fractionation with insignificant crustal assimilation. The SCLM was metasomatically enriched, and the metasomatic agent was likely H2O-rich fluids rather than sediments released from subducting oceanic crust during the Late Cretaceous closure of the Neotethyan oceanic lithosphere. In conjunction with the geological background and previous data, we propose that the generation of the KQDPs resulted from a slab break-off event that caused ascending or infiltration of hot asthenosphere, triggering mantle melting. Such sporadic occurrences of the KQDPs, with coeval adakitic rocks in the SZ, are likely associated with the onset of extensional tectonics due to the earlier stage of slab break-off along the region during the early Eocene period.publishe

Relative contributions of crust and mantle to generation of Campanian high-K calc-alkaline I-type granitoids in a subduction setting, with special reference to the Harsit Pluton, Eastern Turkey

We present elemental and Sr-Nd-Pb isotopic data for the magmatic suite (similar to 79 Ma) of the Harsit pluton, from the Eastern Pontides (NE Turkey), with the aim of determining its magma source and geodynamic evolution. The pluton comprises granite, granodiorite, tonalite and minor diorite (SiO(2) = 59.43-76.95 wt%), with only minor gabbroic diorite mafic microgranular enclaves in composition (SiO(2) = 54.95-56.32 wt%), and exhibits low Mg# (<46). All samples show a high-K calc-alkaline differentiation trend and I-type features. The chondrite-normalized REE patterns are fractionated [(La/Yb)(n) = 2.40-12.44] and display weak Eu anomalies (Eu/Eu* = 0.30-0.76). The rocks are characterized by enrichment of LILE and depletion of HFSE. The Harsit host rocks have weak concave-upward REE patterns, suggesting that amphibole and garnet played a significant role in their generation during magma segregation. The host rocks and their enclaves are isotopically indistinguishable. Sr-Nd isotopic data for all of the samples display I(Sr) = 0.70676-0.70708, epsilon(Nd)(79 Ma) = -4.4 to -3.3, with T(DM) = 1.09-1.36 Ga. The lead isotopic ratios are ((206)Pb/(204)pb) = 18.79-18.87, ((207)Pb/(204)Pb) = 15.59-15.61 and ((208)Pb/(204)Pb) = 38.71-38.83. These geochemical data rule out pure crustal-derived magma genesis in a post-collision extensional stage and suggest mixed-origin magma generation in a subduction setting. The melting that generated these high-K granitoidic rocks may have resulted from the upper Cretaceous subduction of the Izmir-Ankara-Erzincan oceanic slab beneath the Eurasian block in the region. The back-arc extensional events would have caused melting of the enriched subcontinental lithospheric mantle and formed mafic magma. The underplating of the lower crust by mafic magmas would have played a significant role in the generation of high-K magma. Thus, a thermal anomaly induced by underplated basic magma into a hot crust would have caused partial melting in the lower part of the crust. In this scenario, the lithospheric mantle-derived basaltic melt first mixed with granitic magma of crustal origin at depth. Then, the melts, which subsequently underwent a fractional crystallization and crustal assimilation processes, could ascend to shallower crustal levels to generate a variety of rock types ranging from diorite to granite. Sr-Nd isotope modeling shows that the generation of these magmas involved similar to 65-75% of the lower crustal-derived melt and similar to 25-35% of subcontinental lithospheric mantle. Further, geochemical data and the Ar-Ar plateau age on hornblende, combined with regional studies, imply that the Harsit pluton formed in a subduction setting and that the back-arc extensional period started by least similar to 79 Ma in the Eastern Pontides.Geochemistry & GeophysicsMineralogySCI(E)33ARTICLE4467-48716

Data for: Jurassic acidic magmatism in a back-arc setting, eastern Sakarya Zone, Turkey: Geochemical constraints and an evolutionary model

The raw and processed whole-rock major oxides and trace elements along with CIPW normatives, molar ratios and modal mineral compositions are included in the table. Data used for the comparion are also included

FAST SS-ILM: A COMPUTATIONALLY EFFICIENT ALGORITHM TO DISCOVER SOCIALLY IMPORTANT LOCATIONS

Socially important locations are places which are frequently visited by social media users in their social media lifetime. Discovering socially important locations provide several valuable information about user behaviours on social media networking sites. However, discovering socially important locations are challenging due to data volume and dimensions, spatial and temporal calculations, location sparseness in social media datasets, and inefficiency of current algorithms. In the literature, several studies are conducted to discover important locations, however, the proposed approaches do not work in computationally efficient manner. In this study, we propose Fast SS-ILM algorithm by modifying the algorithm of SS-ILM to mine socially important locations efficiently. Experimental results show that proposed Fast SS-ILM algorithm decreases execution time of socially important locations discovery process up to 20 %

Sentiment Analysis of Posts of Social Media Users in Their Socially Important Locations

2018 International Conference on Artificial Intelligence and Data Processing, IDAP 2018 -- 28 September 2018 through 30 September 2018 -- -- 144523Socially important locations are frequently visited locations of social media users in their social media lifetime. Socially important locations reveal spatial preferences of social media users in a social media user group. Discovering socially important locations is important for recommending locations, marketing, urban planning, etc. However, the motivation of preferring these locations is unclear. This study is performed to reveal the motivation of location preferences of social media users. Polarity of socially important locations of social media users are detected using two popular document classification methods namely, SVM and Naïve Bayes. The results showed that SVM algorithm is more efficient than Naïve Bayes algorithm on detecting tweet polarities. Also, the location preference motivations could be revealed based on dominant polarity ratio. © 2018 IEEE

Data for: Jurassic acidic magmatism in a back-arc setting, eastern Sakarya Zone, Turkey: Geochemical constraints and an evolutionary model

The raw and processed whole-rock major oxides and trace elements along with CIPW normatives, molar ratios and modal mineral compositions are included in the table. Data used for the comparion are also included.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

ASSOCIATIONS BETWEEN STREAM FLOW AND CLIMATIC VARIABLES AT KIZILIRMAK RIVER BASIN IN TURKEY

This study aims to demonstrate the use of association analysis for discovering the relationships between stream flow and climatic variables in the Kizilirmak River Basin in Turkey. Association analysis is a data mining technique that aims to discover rules in the form of A -> B that may occur in large datasets with frequency above a given threshold. A and B can be defined as events of a certain type, with the rule if A occurs then B occurs. In this study, A refers to climatic variable(s) (i.e., precipitation, temperature, wind speed, relative humidity) of certain magnitude, and B refers to the magnitude of stream flow. The interesting rules were quantified using support and confidence measures. Stream-flow data from three gauging stations in the Kizilirmak River Basin and climate data from three weather stations in the same basin were included in the analyses. All data were first segregated into three groups that were named as low, medium, and high. Low and high ranges of stream-flow data were further divided into three to increase our focus on extreme events. The analyses were conducted at the annual and seasonal timescales. The analyses indicated that the relationships between precipitation and temperature and stream flow are most prevalent but, relative humidity and wind speed are also important determinants of stream flow in the Kizilirmak River Basin

Generation of the Early Cenozoic adakitic volcanism by partial melting of mafic lower crust, Eastern Turkey: Implications for crustal thickening to delamination

Early Cenozoic (48-50 Ma) adakitic volcanic rocks from the Eastern Pontides, NE Turkey, consist of calc-alkaline and high-K calc-alkaline andesite and dacite, with Si

Deciphering the shoshonitic monzonites with I-type characteristic, the Sisda?i pluton, NE Turkey: Magmatic response to continental lithospheric thinning

Large-scale late Mesozoic to early Cenozoic plutons in the Eastern Pontide orogenic belt mostly show calc-alkaline and I-type geochemical features. However, we identify the Sisda?i pluton that has shoshonitic affinity and I-type character in the region. The pluton was emplaced at shallow depths (<5km), revealed by Al-in hornblende barometry, in the northern margin of the orogenic belt, with SHRIMP zircon U-Pb age of 41.55±0.31Ma, interpreted as dating magma crystallization. It is composed of monzonite, monzodiorite and monzogabbro. The samples show low zircon saturation temperature (T Zr) ranging from 603 to 769°C compared to A-type rocks. They exhibit SiO 2 contents of 47.6-61.4wt.%, and high K 2O+Na 2O (5.0-8.8wt.%) and K 2O/Na 2O (0.8-1.8). All the samples are characterized by low Mg# (<47) and relatively high but variable Al 2O 3 content (16.9-22.2wt.%). They are also enriched in light rare earth elements (LREE), large ion lithophile elements (LILE) and depleted in high field strength elements (HFSE), with a weak negative Eu anomaly (Eu/Eu *=0.58-1.26) in mantle-normalized trace element patterns.The samples possess homogeneous initial Sr and Nd isotopic compositions, marked with low I Sr=0.70376-0.70408 and ? Nd (42Ma)=+1.3 to +2.4. T DM ages of the samples range from 0.70 to 0.85Ga. The Pb isotopic ratios are ( 206Pb/ 204Pb)=18.64-18.72, ( 207Pb/ 204Pb)=15.51-15.58 and ( 208Pb/ 204Pb)=38.31-38.65. These geochemical features imply that the parental magma resulted from melting of chemically enriched lithospheric mantle source. In such a case, a hot upwelling asthenosphere is necessary to partially melt the lithospheric mantle in order to form the parental magma. The pluton is considered to be a post-orogenic intrusion that was emplaced in an environment of lithospheric extension, triggering asthenospheric upwelling. The thermal anomaly induced by asthenospheric upwelling resulted in partial fusion of chemically enriched subcontinental lithospheric mantle beneath the region. Then, the shoshonitic melt, which subsequently underwent fractional crystallization with minor crustal contamination, ascent to shallower crustal levels to generate a monzonitic rock series ranging from monzogabbro to monzonite. All these data combined with the regional geology suggest that the crustal thickening as a consequence of regional compression during the Paleocene changed into a lithospheric extension and thinning throughout the early Cenozoic (at ?42Ma) in the Eastern Pontides. Hence, the middle Eocene shoshonitic I-type magmatism is a unique pluton, signifying initiation of lithospheric thinning and thus of hot asthenospheric upwelling in the region. These interpretations also argue against the presence of an early Cenozoic subduction of oceanic slab in the Eastern Pontides. © 2012 Elsevier Ltd.Türkiye Bilimsel ve Teknolojik Araştirma Kurumu: 107Y177 Türkiye Bilimsel ve Teknolojik Araştirma KurumuThis study was jointly supported by the Scientific and Technological Research Council of Turkey (TÜBITAK) with Grant #107Y177. The authors are also grateful to Faruk Aydin for his critical and constructive comments. Dane Müller is gratefully acknowledged for his English editing of the earlier draft. We thank to Bor-ming Jahn for his constructive comments and editorial handlings. Constructive reviews by K.N. Pang and an anonymous referee are greatly appreciated. Many thanks are also due to Berke Karsli, who is son of corresponding author, for his lively accommodations in the fieldtrip