The origin of foid minerals in alkalen rocks of the eastern pontides

The origin of foid minerals in Eocene aged alkaline volcanic rocks in Trabzon and Bayburt regions was studied. Differences from previous studies, it was investigated whether euhedral analcime crystals in potassium-rich volcanics could form from leucite crystals by creating experimental environments. On the SiO2 – NaAlSiO4 – KalSiO4 diagrams used to examine the phase transitions, it was concluded that analcime samples formed in natural environments were leucite transformation products at a temperature of less than 1 kbar and at a temperature of around 1000°C. As a result of the experimental studies carried out in the hydrothermal environment, it was determined that the leucite transformation product analcimes were formed by diffusion means as a result of SEM – EDS examinations. Especially the presence of analcime on the leucite crystals synthesized in the laboratory environment and the absence of a single analcime crystal indicate mineral transformation by diffusion method. The success of leucite analcime syntheses and transformation reactions carried out in the laboratory environment shows that the transformations in natural environments also occur in basic conditions, but the transformation process can take place in a very short time and the paleogeographic data point to the presence of a marine environment during the rock formation process shows that it recrystallize to analcime in the marine environment.