Goldschmidt 2013, Floransa, Italy, 25 - 30 August 2013, vol.77, no.5, pp.2378
The Quaternary Tendürek Volcano is one of the largest eruption centers of the Eastern Anatolia with a summit elevation of 3538 m and a footprint area of 650 km2. It is a shield volcano consisting of lavas ranging in composition from tephrites through benmoreites/phonolites to trachytes. The young volcanism of the region is thought to be related to the continent-continent collision taken place after the closure of the Neo-Tethys Ocean. The Tendürek volcano is of special importance, because it is one of the rare places in Eastern Anatolia where calc-alkaline and potassic alkaline volcanism coexisted. Lavas of the Tendürek volcano are classified on the SiO2 versus K2O diagram as medium K / high K and shoshonitic series. Results of our FC, AFC and EC-AFC modelings indicate that the Tendürek lavas were influenced by crustal contamination and fractional crystallization. Medium to high potassic basalts, trachy-basalts, tephrites and basaltictrachyandesites basically follow a partial melting trend on La vs. La/Yb diagram in contrast to the trachy-andesites, phonotephrites, tephriphonolites, phonolites, and trachytes of the shoshonitic series aligning along a fractional crystallization trend. The high-SiO2 phonolitic lavas have a more pronounced enrichment in incompatible elements, such as Rb, Th, La and Nb, in comparison to those in the other shoshonitic rocks. The aforementioned differences in the chemical compositions of these two groups of shoshonitic rocks may reflect variations in the fractional crystallization process which involved clinopyroxene and plagioclase during the petrogenesis of the potassic rocks. According to our melting model, primitive magma of the Tendürek lavas were derived from mixing of the spinel and garnet peridotite melts with different melting degrees ranging between 1 - 3%.