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Mediterranean. All the rock groups have similar and high abundances of incompatible trace elements, and radiogenic Sr. Geochemical modeling of the trace element and isotopic ratios of the samples reveals that both the SHO-UK and HKCA groups were derived from a common mantle source which had been highly metasomatized and enriched by continental materials during partial subduction of the crustal metamorphic slices in a continental collision setting. The geochemical variations of these rocks were mainly controlled by source characteristics (such as heterogeneity) and variable degrees of partial melting and subsequent effects of fractional crystallization, with low degrees of crustal contamination. The HKCA series were derived by higher degrees of partial melting of the lithospheric mantle source than the SHO-UK rocks. The HKCA rocks then underwent two-stage fractional crystallization (clinopyroxene-dominated followed by feldspar-dominated fractionating mineral assemblages) to form the high-K calc-alkaline basalt to rhyolite series, whereas the SHO-UK rocks experienced comparatively little fractional crystallization. A tectonic scenario involving the rapidly extending and thinning of orogenic crust is compatible with the time-dependent compositional variation of the magmatic rocks.

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The study area is located between Balikesir-Dursunbey and Kutahya-Simav districts.According to the field studies and petrographic studies on Civanadag tuffs, it is determined that this unit is formed by two different facies as Upper (fine-grained laminated facies) and Lower

Geologic mapping and crystal-chemical analysis of Middle-Upper Miocene volcanics in the Sandıklı-Afyonkarahisar region of Turkey, coupled with published zeolite analyses has revealed that western Turkey hosts unique zeolitic mineral assemblages with distinct paragenetic sequences. The present investigation focused on pyroclastic deposits, including low to intermediate potassic trachytic/trachyandesitic tuffs (LPT) and high potassic tephriphonolitic, tephritic, and trachybasaltic tuffs (HPT), each of which contains various styles of zeolites. Optical petrography, X-ray powder diffraction, and chemical analyses have revealed varying degrees of lithification, probably related to differences in initial emplacement temperature, depositional mechanism and thickness, chilling rate, and extent of mafic composition. Zeolitization was further influenced by meteoric flushing in a hydrologically open system. Chabazite in the LPT from the Selçik area occurs extensively as coatings and infillings of pores. Phillipsite in the HPT found in the Ballık, Küfeke, and Ömerkuyu areas dominates the assemblage and is accompanied by chabazite and minor amounts of analcime. Analcime was probably generated by alteration of leucite which is found as a pyrogene mineral. Alkali zeolites or Ca-bearing zeolites formed as a consequence of the addition of Ca and/or the removal of Na (i.e. dissolution of analcime). The paragenetic sequence may be described as: analcime/phillipsite → chabazite → calcite. The characterization of these assemblages may lead to better exploitation strategies for natural zeolitic resources in the region.