Geochemistry And Tectonic Setting Of Tertiary Volcanism In The Guvem Area, Anatolia, Turkey

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Journal Article: Geochemistry And Tectonic Setting Of Tertiary Volcanism In The Guvem Area, Anatolia, Turkey

Abstract
Detailed field mapping in the Guvem area in the Galatia province of NW Central Anatolia, Turkey, combined with K-Ar dating, has established the existence of two discrete Miocene volcanic phases, separated by a major unconformity. The magmas were erupted in a post-collisional tectonic setting and it is possible that the younger phase could be geodynamically linked to the onset of transtensional tectonics along the North Anatolian Fault zone. The Early Miocene phase (18-20 Ma; Burdigalian) is the most voluminous, comprising of over 1500 m of potassium-rich intermediate-acid magmas. In contrast, the Late Miocene volcanic phase (ca. 10 Ma; Tortonian) comprises a single 70-m-thick flow unit of alkali basalt. The major and trace element and Sr-Nd isotope compositions of the volcanics suggest that the Late Miocene basalts and the parental mafic magmas to the Early Miocene series were derived from different mantle sources. Despite showing some similarities to high-K calc-alkaline magma series from active continental margins, the Early Miocene volcanics are clearly alkaline with higher abundances of high field strength elements (Zr, Nb, Ti, Y). Crustal contamination appears to have enhanced the effects of crystal fractionation in the petrogensis of this series and some of the most silica-rich magmas may be crustal melts. The mantle source of the most primitive mafic magmas is considered to have been an asthenospheric mantle wedge modified by crustally-derived fluids rising from a Late Cretaceous-Early Tertiary Tethyan subduction zone dipping northwards beneath the Galatia province. The Late Miocene basalts, whilst still alkaline, have a Sr-Nd isotope composition indicating partial melting of a more depleted mantle source component, which most likely represents the average composition of the asthenosphere beneath the region.

Authors 
Ayla Tankut, Marjorie Wilson and Tadesse Yihunie








Published Journal 
Journal of Volcanology and Geothermal Research, 1998





DOI 
Not Provided
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Citation

Ayla Tankut,Marjorie Wilson,Tadesse Yihunie. 1998. Geochemistry And Tectonic Setting Of Tertiary Volcanism In The Guvem Area, Anatolia, Turkey. Journal of Volcanology and Geothermal Research. (!) .