The Petrography and Geochemistry of the Kadinhani Area, Central Turkey

Geology, Geochemistry

Kurt, Huseyin

University:University of Glasgow

关键词: Geology, Geochemistry;   

Others  :  http://theses.gla.ac.uk/75482/1/13832068.pdf

来源: University of Glasgow

【 摘 要 】

The petrographic and geochemical investigations of the Kadinhani metamorphic, igneous and sedimentary rocks indicate a great range in petrography and geochemistry. The stratigraphy in the area starts with the metasedimentary Esiragili Formation which is followed upwards in the Devonian by the Bagrikurt Formation which is characterized by metavolcanic rocks, cherts, metasedimentary rocks, pelite, carbonate, calc-silicate and block limestone. The formation is overlain by the upper Devonian-lower Carboniferous Kursunlu formation limestone, which reflects a shelf environment and is cut by intrusive dykes. The Lorasdagi Formation carbonate was deposited in the an open shelf environment in the Jurassic to Cretaceous, overlies the older rocks unconformably and continues up to the unconformably overlying upper Miocene-Pliocene Osmankayasi Tepe Formation limestone which is overlain by dacite which itself is overlain by the Plio-Quaternary Toprakli Formation. Three phases of deformation (D1-D3) have been recognized in the present area.The microstructural and petrographic investigations show distinct phases of deformation and different metamorphic events. The apparent absence of any mineral growth during D2 and the post tectonic mineral overgrowth, indicates a metamorphic relaxation followed the Mi metamorphism. The second metamorphic event involves retrogression with pseudomorphic replacement of chloritoid, biotite, amphibole and feldspar. The area was metamorphosed first under the conditions of the greenschist facies (the most important minerals, muscovite, chlorite, chloritoid, actinolite and stilpnomelane) and then later under the blueschist facies metamorphism which gave rise to magnesio riebeckite, crossite, glaucophane, phengite and albite minerals. The psammite and quartzites have a passive or active continental margin setting. The cherts haye been deposited in a relatively shallow-water environment similar to recent continental shelf slope environment. The pelitic rocks were originally shales in which the main control in composition was the sheet silicates. The metabasic schists were possibly tuffs in the pelites. The calc silicate rocks were originally impure siliceous limestones with variable amounts of clay material. The carbonate rocks contains variable amounts of terrigenous material and dolomite is possibly of late diagenetic origin. The meta-igneous and igneous rocks are of a subalkaline character. The metahornblende gabbros were derived from a subalkaline basaltic melt with oceanic affinity. The metadolerites reveal a parental magma source similar to subduction- related lavas in a continental margin environment. The parental magma of the metadolerite involved a mix of subcontinental lithosphere and subduction components. The possiblity of derivation of the metatrachyandesite from basaltic magma via crystal fractionation of mafic minerals conflicts with the degree of REE fractionation of the metabasaltic andesite. The dacites were evolved mainly by amphibole fractionation under hydrous conditions at shallow levels in the continental crust and probably formed by fractional crystallization from an andesitic parental magma. The thesis contain 18 REE analyses, 153 XRF analyses of metamorphic, igneous and sedimentary rocks, microprobe analyses of feldspars, sheet silicates, amphiboles, pyroxenes, carbonate minerals, stilpnomelane, chloritoids, tourmalines, rutiles, epidotes, pumpellyites and magnetites. There is a new geological map of the area.