Yazar "Morgan, Ganerod" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • Küçük Resim Yok
    Öğe
    Ar-40/Ar-39 geochronology, elemental and Sr-Nd-Pb isotope geochemistry of the Neogene bimodal volcanism in the Yilkselen area, NW Konya (Central Anatolia, Turkey)
    (PERGAMON-ELSEVIER SCIENCE LTD, 2017) Korkmaz, Gulin Gencoglu; Asan, Kursad; Kurt, Huseyin; Morgan, Ganerod
    Bimodal volcanic suites occur in both orogenic and anorogenic geotectonic settings. Although their formation can be attributed to either fractional crystallization from basaltic parents to felsic derivatives or partial melting of different sources, the origin of bimodal suites is still unclear. By reporting mineral chemistry, Ar-40/Ar-39 geochronology, elemental and Sr-Nd-Pb isotope geochemistry data, this study aims to investigate the genesis of bimodal basalt-dacite association from the Ytikselen area located on the northern end of the Sulutas Volcanic Complex (Konya, Central Anatolia). The Ytikselen area volcanic rocks are represented by basaltic lava flows, and dacitic dome with enclaves and pyroclastics. Basaltic flows and pyroclastic rocks are interlayered with the Neogene fluviolacustrine sedimentary units, while dacitic rocks cut the pre-Neogene basement in the area. A biotite separation from dacites yielded Ar-40/Ar-39 plateau age of 16.11 +/- 0.18 Ma. On the other hand, a whole rock sample from basalts gave two plateau ages of 16.45 +/- 0.76 Ma and 22.37 +/- 0.65 Ma for the first steps and next steps, respectively. The investigated basalts are sodic alkaline, and characterized by ocean island basalt (OIB)-like anorogenic geochemical signatures. However, dacites are calc-alkaline and metaluminous, and carry geochemical signatures of orogenic adakites. Sr-Nd-Pb isotopic systematics suggest that the basalts were derived from an asthenospheric mantle source enriched by recycled crustal rocks. The dacites show more enriched Sr and Pb ratios and more depleted Nd ones relative to the basalts, which at the first glance might be attributed to crustal contamination of the associated basalts. However, trace element features of the dacites rule out cogenetic relationship between the two rock types, and point to an origin by melting of lower crust. On the other hand, enclaves share several elemental and isotopic characteristics with the dacites, and appear to be fragments of sub-volcanic intrusions closely related to the dacitic host magma. Based on the obtained geochemical data combined with the published geological and geophysical data, the investigated bimodal volcanic activity can be explained by slab break-off process in the convergence system between the African and Anatolian plates. (C) 2017 Elsevier Ltd. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Petrogenesis of the late Cretaceous K-rich volcanic rocks from the Central Pontide orogenic belt, North Turkey
    (WILEY, 2014) Asan, Kursad; Kurt, Huseyin; Francis, Don; Morgan, Ganerod
    Subduction-related volcanic rocks are widespread in the Central Pontides of Turkey, and represented by the Hamsaros volcanic succession in the Sinop area to the north. The volcanic rocks display high-K calc-alkaline, shoshonitic and ultra-K affinities. 40Ar/39Ar age data indicate that the rocks occurred during the Late Cretaceous (ca 82Ma), and the volcanic suites were coeval. Primitive mantle-normalized trace element patterns of all the lavas are characterized by strong enrichments in large ion lithophile elements (LILE) (Rb, Ba, K, and Sr), Th, U, Pb, and light rare earth elements (LREE; La, Ce) and prominent negative Nb, Ta, and Ti anomalies, all typical of subduction-related lavas. There is a systematic increase in the enrichment of incompatible trace elements from the high-K calc-alkaline lavas through the shoshonitic to the ultra-K lavas. In addition, the shoshonitic and ultra-K lavas have significantly higher 87Sr/86Sr (0.70666-0.70834) and lower 143Nd/144Nd (0.51227-0.51236) initial ratios than coexisting high-K calc-alkaline lavas (87Sr/86Sr 0.70576-0.70613, 143Nd/144Nd 0.51245-0.51253). Geochemical and isotopic data show that the shoshonitic and ultra-K rocks cannot be derived from the high-K calc-alkaline suite by any shallow level differentiation process, and point to a derivation from distinct mantle sources. The shoshonitic and ultra-K rocks were derived from metasomatic veins related to melting of recycled subducted sediments, but the high-K calc-alkaline rocks from a lithospheric source metasomatized by fluids from subduction zone.