FARKLI VOLKANİK PATLAMALAR SONUCU FRAGMANTE OLAN KÜLLERİN FİZİKSEL VE KİMYASAL ÖZELLİKLERİNİN İNCELENMESİ

Abstract

Volcanic ash is formed by magmatic and hydromagmatic eruptions. The formation and fragmentation mechanism of volcanic ash depends on many factors such as the chemistry and physical properties of magma and the presence of water during the eruption. Therefore, volcanic ash has different morphological and chemical properties which depend on the eruption dynamics and the fragmentation mechanism. In this study, the particle size distribution and statistical parameters, chemical and physical properties of volcanic ash were examined and eruption dynamics were determined. Basaltic and acidic phreatomagmatic eruption, the matrix of block-and-ash flow, the matrix of debris avalanche and lahar, Plinian fall deposits and Strombolian eruption deposits, blast deposits, matrix of indurated ignimbrite samples were investigated chemically and morphologically. The particle size distributions and related statistical parameters of the samples were calculated. The chemical composition of the volcanic glass was determined with the help of the major oxide values in the chemical analysis from the volcanic glasses. Subsequently, two-dimensional (2D) and three-dimensional (3D) morphological analysis were carried out on each volcanic ash particle. Particularly, samples of magmatic eruption (fall deposits, ignimbrite) are generally distinguished from other samples by their high roughness (Ra), surface area (SA) and fractal dimension (DSA) values. Moreover, two-dimensional parameters which are solidity and form factor values are low, while the product of the rectangularity parameter and the circularity parameter gets high values. Surges formed by phreatomagmatic eruptions and block-and-ash flow samples have been observed to have similar morphological parameter values. High solidity and form factor values of surge deposits in 2D morphological analysis; low fractal dimension, roughness and surface area related parameters values of surge deposits in 3D morphological analysis has been calculated. Debris avalanches and lahar samples were observed to contain volcanic ash with different morphological characteristics. Blast deposits has been determined in debris avalanches. Considering all the observations, volcanic ash particles can present various chemical and morphological properties that contain clues to the eruption dynamics that formed them.