Spatial chemistry, textural and chemical zoning of a mineral records significant information about the magma chamber process and pre-eruptive magmatic history. Moreover, estimation and evaluation of the pressure, temperature, and water content from mineral-melt and mineral-mineral pairs in the rocks ensure significant information and evidence about the magma chamber process, magma storage, and volcanic eruption processes.
In this contribution, the textural and element zoning of the plagioclases, which are a significant recorder of magma chamber processes, from some basaltic rocks from the Tepekent Volcanics (Northwest of Konya city-Central Anatolia), were examined and their textural and mineral stratigraphies were investigated. Along with that, the thermometers and the hygrometers of the investigated plagioclase minerals were calculated to enlight the magma chamber processes.
The composition of the plagioclase cores in the basalts are generally labradorite, rarely andesine and bytownite (core:An45-66). Moreover, plagioclases in the basalts scarcely have normal zoning, generally display reverse and oscillatory zoning with An, Fe, Mg, and along with that demonstrate fine-sieve, dusty sieve and scarce coarse- sieve texture with glass and microlitic inclusions. Combined with their An, Fe, Mg contents and textural and chemical zoning paterns from core to the rim it is suggested that some of the plagioclases from the basalts may be xenocrysts.
Plagioclase-liquid thermobarometer calculations yield 1026-1048 °C temperature and P 3.53-7.86 kbar pressure, as well as hygrometer calculations reveal that H2O contents of the magma they formed range between 0.42 and 12.2 %wt. The H2O contents of the plagioclases increase with the An contents.
Based on the spatial chemical data and the textural properties of the investigated plagioclases it could be reported that the decompression processes in addition to the open system processes (such as magma recharging and contamination) have a key role in the evolution of the basalts. Moreover it can be stated that plagioclases are derived from high temperature magmas with a relatively high water content. ORCID ID: 0000-0003-0185-2806
Anahtar Kelimeler: Decompression, Element zoning, Hygrometers, Plagioclase, Thermometer