Thermobarometric Constraints on the Evolution of the Menderes Massif (Western Turkey): Insights into the Metamorphic History of a Complexlydeformed Region

Abstract

The purpose of the thesis is to establish the Pressure Temperature (P-T) histories of rocks collected near the Kuzey detachment of the central Menderes Massif as a means to identify if garnets record a polymetamorphic history. During the summer of 2003, rocks were collected from the central Menderes Massif. Detailed petrographic analyses were made to identify which had suitable mineral assemblage for thermobarometric calculations. Using the OSU Electron Microprobe, three major possible zoning types are identified in Menderes Massif garnets: retrograde zoning (compositions affected by diffusion), prograde zoning (preserves compositions during growth), and polymetamorphic zoning (compositional changes during multiple stages of garnet growth) This thesis presents 60 new X-ray element garnet maps and 6 new P-T conditions from garnet-bearing assemblages from the Menderes Massif. Thermobarometric results are often used to develop models for the evolution of the Menderes Massif. The results presented in this thesis show that rocks from this area have a potential to have experienced different metamorphic events, thus recording a polymetamorphic history. X-ray element garnets maps and transects across garnets from samples collected from the same unit, even the same outcrop, in the central Menderes Massif show very different zoning profiles. P-T conditions estimated for garnet-bearing assemblages collected from the same unit, even the same outcrop, in the central Menderes Massif show yield very different thermal conditions. The P-T conditions generated from Menderes Massif rocks in this thesis are consistent with their mineral assemblages, and range from ~8 to 12 kbar and ~500�C-750�C. This is the first study that reports more than one thermobarometric constant from a single outcrop in the Menderes Massif and has implications for previous P-T work in the region.