Minerageny of Jurassic deposits of the northeastern side of the Ulyanovsk-Saratov depression

Abstract

The Jurassic terrigenous-clayey complex on the territory of the northeastern side of the Ulyanovsk-Saratov depression contains numerous groups of solid minerals. Some of them are at the stages of industrial development, some have not found application due to local distribution. Analysis of the composition and conditions of formation of solid mineral raw materials showed that the main factor influencing the formation of minerals was the marginal position of the territory in the Middle-Upper Jurassic time. The relatively high bioproductivity of the epicontinental Central Russian paleosea contributed to the accumulation of layers of calcareous marls, oil shale and phosphate raw materials. All these rocks were formed in the Mesozoic basin of sedimentation with the active participation of organic matter, the producers of which were zoo- and phytoplankton. The accumulation of coccolithophora in clayey silts led to the formation of calcareous marls, the accumulation of dying algae in bottom sediments led to the formation of oil shale. Nodular phosphorites are also biochemogenic raw materials. During periods of regressive development of the Central Russian paleosea along the coast, conditions were created for the accumulation of oolitic siderites together with leguminous goethite-hydrogethite aggregates of iron ores. Periodically, regional faults were activated on the northeastern edge of the Ulnovsko-Saratov depression. At this time, there was an upward migration of deep mineralized fluids through weakened zones. Unloading in the bottom part of the Central Russian paleosea, they contributed to the formation of fields of pyrite and barite mineralization in sedimentary rocks.