Date of Award
Master of Science (MS)
The Kula volcanics are a small Pleistocene to Recent volcanic field located on the north shoulder of the Gediz graben, approximately 120 km east of Izmir. The field consists of a mixture of flows, small cones and pyroclastic deposits erupted during three periods of volcanic activity beginning about one million years ago. The volcanics range in composition from basanites to trachybasalts, commonly porphyritic with abundant clinopyroxene, olivine and amphibole phenocrysts. The lavas also host a wide variety of megacrysts, crustal xenoliths and hydrous mantle-derived nodules. These volcanics unconformably overlie Neogene lacustrine sedimentary rocks and the metamorphic basement rocks of the late Proterozoic-Eocene Menderes Massif.
Results of analyses of up to 24 lava samples and 4 hydrous ultramafic nodules for whole rock major elements, selected trace elements and Rb/Sr isotopes are presented. Paragenetic models utilizing a least-squares subtraction program for major elements suggests that fractional crystallization processes can explain compositional variations between products erupted from the same cone during a single eruptive period , but not between different cones or different eruption periods. Trace element concentrations do not seem to support the major element fractionation models, which suggests a-more complex origin for the lavas. Variations in trace element and Rb/Sr isotopic values support the hypothesis that the Kula source region has undergone a recent enrichment in incompatible elements, similar to recently proposed models of paragenesis for ocean island basalts. This enrichment is thought to be related to a change from a compressional to extensional tectonic regime in western Turkey during Neogene time. Further isotopic analyses will be necessary to adequately test this hypothesis.
Dyer, Julie M., "Petrology of the Kula Volcanic Field, western Turkey" (1987). Geology Theses and Dissertations. 20.