Thermodynamic model of chemical re-magnetization on the example of Girvas paleovolcano of the Onega structure of Karelian craton

Abstract

Volcano Girvas is a complexly constructed volcano complex of the Yatuli age. Apparently, it is a shield lava volcano, which was probably one of the supply channels of the vast lava field of the western Prionezhie region within the Girvas volcanic zone. Despite the fact that the Girvassky volcano is bare only fragmentary, the structure of the current is perfectly preserved in the rocks, allowing to reconstruct the direction of flow. Among these rocks, there is a zone of postvolcanic hydrothermal changes in the rocks, consisting mainly of nesting and veined tourmalization and silicification, as well as subsequent epidotization, sulfidization, chloritization and albitization. The zones of secondary changes are confined to faults, while their spatial-temporal correlation remains unclear. Reconstruction of the geological structure showed that there were two main processes at the Girvasa volcano: 1) pneumatolysis of type due to magmatic gases separated from gabbro-dolerite sills, 2) heating and circulation of exogenous waters with formation of near propylites. Based on the proposed scheme, thermodynamic modeling was performed.