Numerical Texture Analysis on NW Iran Dacite, Basalt, and Tephraphonolite: Implications to Constrain their Petrogenesis

Abstract

ABSTRACT In this research, our focus has been on the quantitative calculations of the texture of volcanic rocks. For this purpose, the rocks with acidic to basic and ultrabasic combinations were selected, and the shape, size, and spatial distribution (CSD and SDP) of their phenocrysts were investigated. The results showed that in volcanic rocks, the ratio of nucleation to crystal growth (J/G) was several times higher, and crystal growth per time unit (Gt) was higher in rocks with fewer nuclei. It also turns out that to evaluate the magma mixing, CSD pattern analysis can be instrumental. The spatial distribution of grains in the extrusive rocks is clustered to random, probably due to the high degree of overstepping and under-cooling conditions. The mineral clusters may form before the emplacement of the flow, at depth during the residence time before the eruption flow, or throughout the rise and flow. The importance of these results displays that due to the progress of imaging methods and statistical-numerical work on crystals and textures; it is time that all petrologists from all over the world, along with geochemical work, pay attention to these types of studies to provide a complete petrological work.