Coarse Clastic Rocks of North-Eastern Kamchatka: Morphology, Material Composition, Formation Settings

The results of studying the conditions of occurrence, morphological features and material composition of coarse-grained rocks of the Cenozoic molasse of the Olyutorsky terrane of North-Eastern Kamchatka are considered. Consideration of the obtained data allows us to draw conclusions about the paleogeological conditions of their formation. Morphological studies have shown that conglomerates are usually medium-sized, fairly well sorted and rounded, however, during the transition from marine to continental deposits, their dimension increases slightly, and the sorting and roughness deteriorate. Gravelites range from medium gravel in marine deposits to large gravel in continental ones. Sorting and rounding of fragments is good. Analysis of the obtained data shows that the accumulation of rocks of the Alugin and Pakhacha formations occurred in narrow intermountain troughs covered by a shallow sea, and the Korf formation in continental environments. The area of demolition was the mining structures that bordered the basins and supplied them with a huge amount of coarse grained material transported by temporary and permanent watercourses. The material composition of the psephite fragments indicates that mainly local sources of demolition were eroded, composed of a complex of volcanogenic-siliceous and terrigenous formations underlying the molasse. A secondary sources that supplied the basin with fragments of feldspar-quartz sandstones, ancient siliceous and granite-metamorphic rocks were the Cretaceous-Paleocene turbidites of the Ukclayat terrane and the Late Paleozoic-Early Mesozoic formations of the Koryak folded region located to the north.