Mineralogical and petrographic characteristics of Eocene Çaltı and Bizmişen Plutons, NW Kemaliye (Erzincan, Turkey)

Abstract

In this study, the mineralogical and petrographic characteristics of the Çaltı and Bizmişen Plutons located to the east of the Tauride-Anatolide Platform were investigated. The geological units are Mesozoic carbonate rocks, Cretaceous ophiolitic rocks and ophiolitic melange, Eocene plutonic rocks, Miocene volcanic rocks and Oligocene-Pliocene sedimentary rocks in the study area. The Eocene Çaltı and Bizmişen Plutons intruded the Upper Cretaceous ophiolite melange are unconformably overlain by sedimentary rocks of the Early Miocene Kemah Formation. The Çaltı Plutonic rocks are petrographically in the composition of granite, granodiorite, quartz diorite and tonalite in sizes ranging from fine- to coarse-grained and contain mafic microgranular enclaves of different sizes and shapes. The unit is partially cut by dark-coloured diabase dykes of different sizes. The unit is partially cut by dark-colored diabase dykes of different sizes. The Bizmişen Plutonic rocks are represented by medium-grained granite, granodiorite and quartz diorites. Mafic microgranular enclaves of different shapes and sizes are seen mainly in rocks with granite and granodiorite composition. Mineral paragenesis of the Çaltı and Bizmişen plutonic rocks consists of plagioclase, K-feldspar, quartz, amphibole, biotite and opaque minerals. Plagioclases commonly observed as prismatic subhedral or euhedral crystals are characteristic with albite, albite+carlsbad and polysynthetic twinning. Although zoning is observed in some plagioclase crystals, twin lamellae cannot be clearly observed in samples with alteration. In some plagioclase crystals, embayed and sieve textures expressing disequilibrium crystallization are observed. K-feldspars are generally in the form of anhedral crystals, and hornblende, plagioclase and quartz minerals are found in the K-feldspars as mineral inclusions. Quartz minerals, which is seen as anhedral crystal, shows wavy extinction. Hornblend minerals occur in euhedral or subhedral, prismatic or hexagonal shapes. Plagioclase mineral inclusions are present in some hornblende crystals. Biotites are observed as micaceousprismatic euhedral/subhedral crystals. The investigated rocks texturally display holocrystalline, porphyric holocrystalline, poikilitic and graphic textures. The presence of mafic microgranular enclaves in the rocks and the texturally poikilitic and graphic textures indicate the presence of magma mixing processes in the formation of these rocks.