<p> Granitic and associated metamorphic rocks of Precambrian age in southeastern Ontario, Canada have been studied in order to determine the relationship of K, Rb and Tl and their behaviour during the process of partial melting and magmatic differentiation and metasomatism. </p> <p> Analytical results for major elements and rubidium and thallium abundances for 52 samples are given. </p> <p> From the present data, it appears possible that the series of migmatite and granodiorite gneiss originated by partial melting of paragneiss, together with pink granite which developed by late magmatic processes from a granodiorite melt, as was proposed by Chesworth (1967). </p> <p> Consideration of the geochemical data shows that the principal aspects of the distribution of Rb and Tl during partial melting are controlled by the mineralogical composition of the residuum which remains after partial melting. If mica is present in the residuum a newly-formed melt could have higher or the same K/Rb, K/Tl and Rb/Tl ratios as the parent rock and thus the "classical rule" of lower K/Rb and K/Tl in the anatectic melt is not valid. </p> <p> Enrichment of Tl in rocks affected by metasomatic processes is demonstrated. The marked decrease of K/Tl and Rb/Tl in the contact rocks (calc-silicate marbles) is caused by stronger migration of Tl, relative to K and Rb, from the intruded pink granite. </p> <p> The high mobility of thallium compounds is an important factor in the distribution of Tl during metasomatic and magmatogenic processes. </p> / Thesis / Master of Science (MSc)

The Menderes Massif forms a large metamorphic culmination in western Turkey &amp / #8211 / an extensional province where continental lithosphere has been stretching following Palaeogene crustal thickening. Northern sector of the Massif on the horst between G&ouml / rdes and Demirci Basins was chosen for structural analysis aimed to study the tectono-metamorphic evolution of the northern Menderes Massif. Within the study area, four groups of rocks are recognized: (1) the metamorphic rocks &amp / #8211 / orthogneisses and metasediments / (2) pegmatoids / (3) Neogene sedimentary rocks / and (4) Quaternary alluvial sediments. The tectono-metamorphic history of the region involves a regional metamorphism (M1) at upper-amphibolite-facies conditions, coeval with a top-tothe-NNE contractional D1 deformation during the northward backthrusting of Lycian Nappes (Eocene main Menderes metamorphism). Partial anatexis during the latest stages of the M1 was speculated to be the main mechanism for the formation of the migmatites and the granitic magma. Pegmatoid domes and dikes/sills formed during late increments of this phase. A second metamorphism (M2) and coeval top-to-the-NNE deformation (D2) took place during the Early Miocene exhumation of the metamorphic rocks along a presently low-angle normal fault in an extensional shear zone at presumably greenschist facies conditions during declining P-T conditions. The latest deformation phase (D3) is high-angle normal faulting due to N&amp / #8211 / S extension affecting western Anatolia. The E&amp / #8211 / W grabens dissecting the Massif into northern, central and southern submassifs are the result of this phase, commenced during Pliocene-Pleistocene and gave the western Anatolia much of its present-day shape. The evidence presented supports the idea of episodic two-stage extension in western Turkey.