In the complex history of Mesozoic magmatism and ore formation in the Eastern Transbaikalia, the latest stages of the history, associated with the formation of numerous linearly elongated depressions of northeastern strike, are the least studied. They are bordered by large faults and are filled with Late Mesozoic sedimentary and volcanogenic rocks. It is to the depressions that the areas of the strongest manifestation of young tectonic movements and manifestation of the latest magmatic formations gravitate. Accordingly, the latest manifestations of hydrothermal mineralization in the Eastern Transbaikalia are closely related to depressions themselves or to the systems of discontinuities surrounding them (gold deposits of the Baley type, deposits of fluorspar, ferberite-antimony-nite ores of the Barun-Shivey type, ore occurrences of antimonite, cinnabar, barite, etc.). The overwhelming majority, if not all these ore occurrences, belong to the type of low-temperature hydrothermal formations of shallow depths. Both the source of this mineralization and its age are still disputable. However, in recent years the opinion has been expressed that this mineralization is related to the Lower Cretaceous volcanogenic complexes. Therefore, it is very important to study the history of Lower Cretaceous volcanism of the Eastern Transbaikalia, in particular, to investigate various subvolcanic, vent, etc. formations, since in a number of geologically similar areas their location largely determines the peculiarities of mineralization placement ...

Over the last few years, many works on metallogeny of the Eastern Transbaikalia have raised the question of the relationship between volcanism and hydrothermal formations. In some cases, volcanic structures are considered to be the most favorable sites for localization of mineralization, while in other cases, a closer (genetic and paragenetic) connection between volcanic and hydrothermal processes is assumed. Proponents of the latter point of view in support of their ideas refer to the age proximity of Late Mesozoic volcanogenic complexes and Late Mesozoic mineralization, to the confinement of volcanic formations and ore fields to the same regional structures, to the characteristic surface appearance of ores of a number of deposits, to analogies with other ore areas, in particular, with the classical areas of development of “subvolcanic” deposits. While these arguments are convincing, they lack more direct, geochemical data on the links between volcanic and hydrothermal formations. The identification of such relationships is an important but very laborious task, involving the need to perform and compare a large number of diverse analyses. However, some characteristic petrographic features of the effusive formations of Priargunya can already be used in solving the question about the potential ore-bearing capacity of those magmatic centers with which the effusives are associated ...