Santorini is a volcanic island located in the south of the Aegean Sea. It has a varied history behind it, during which it turned into a large caldera. A rich collection of various volcanic rocks can be seen on the island.
With macroscopic observation and microscopic analysis using a scanning optical microscope, we performed an examination of the samples taken from the island of Nea Kameni and the locations of Kokkari and Vlychada. Some samples were subsequently examined with the help of a line electron microscope and, based on the obtained results, the chemical composition of the selected mineral grains in the sample was determined. X-ray powder diffraction analysis was used to determine the mineral composition and amorphous phase of individual samples. Based on the geochemical analysis, the rocks were divided into groups based on the ratio between the quartz content and the Zr/TiO2 ratio. Optical microscopy was used to determine the hypohyaline, aphanitic and oligophyric structure in all samples. All samples contain plagioclase and pyroxenes, some also contain olivine and non-replaceable minerals. In the samples from Nea Kameni and Kokkari, labradorite and bytownite occur among plagioclase, and augite and less commonly enstatite among pyroxenes. There are some olivines that are richer in magnesium. Among the plagioclases in the Vlychada sample, andesine dominates, while only enstatite is present among the pyroxenes. The results of the geochemical analysis showed that the island of Nea Kameni is dominated by rhyolites with a minor presence of andesites. The samples from the Kokkari location are predominantly red-brown in color and belong to andesite and trachy-andesite. The white and light rocks taken from the white beach of Vlychada were classified as trachytes. Volcanic rocks from the Nea Kameni location were attributed to the youngest volcanic activity, during which the island was formed. The rocks from the white beach of Vlychada were formed during the main Plinian eruptions, at the end of the first volcanic cycle. The andesite rocks of Kokkari Red Beach are of Quaternary age and were formed as a result of the onset of volcanic activity on Santorini. These are cinder cones that were formed during the explosive eruption of large volcanic bombs.
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