Fingerprint of magma mixture in the leucogranites: Spectroscopic and petrochemical approach, Kalebalta-Central Anatolia, Türkiye

Abstract

Leucogranites of Kalebalta in Central Anatolia are composed of plagioclase, quartz, orthoclase, and biotite and contains mafic microgranular enclaves (MME) in sizes ranging from few cm to 70 cm. In the total alkali-silica diagram, they fall typically in the granite field and show a calc-alkaline nature in the alkalis-iron-magnesium diagram whereas enclaves are Medium K series calc-alkaline, which represents the transition from tholeiitic to calc-alkaline. Leucogranites which have A/CNK(mol%) > 1 are strong peraluminous and seen as the products of magma derived from a metasedimentary source. Signs of magma mixing expressing the mantle inputs are also observed in many bivariation diagrams. Zircon and apatite saturation temperatures calculated on the basis of whole rock chemistry are 744–829°C for leucogranites and 761–832°C for their enclaves. According to the Raman spectra, biotite and plagioclase minerals in leucogranites and their enclaves show similar Raman spectrums. The biotite minerals have Mg–O and/or Fe–O translational (transformation) bonds between 182 and 552 cm−1, Si–O–Si bending between 552 and 1,100 cm−1 and Si–O–Si vibrational bonds between 1,100 and 1,200 cm−1. The results of this study suggest that the leucogranites and enclaves are most probably derived from different magmas. In addition, according to geochemical and spectroscopic data, they may also have fractional crystallization, which is effective after the mixing process.

Keywords

• leucogranites
• mafic microgranular enclave
• mantle inputs