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UDC 551.222:552.322(235.222) BASALTIC TUFFISITES OF GORNY ALTAI: GEOLOGICAL POSITION, PETROGRAPHIC FEATURES, EXAMINATION PROBLEMS
The paper provides information on geological position, petrographic and some other features of basaltic tuffisites – fluidogenic rocks (fluidoliths) that are widespread in the northern part of the Mountain Altai, although they have not been registered by most researchers. The paper discusses field and petrophysical examination of tuffisites in the context of a number of indicators convergence of these formations and rocks of other genesis, e. g. pyroclastic and volcanoclastic rocks. At the same time, specific structure-texture features and heterogeneous composition of basaltic tuffisites in the Charysh River basin are pointed out, which prove intrusive origin of the rocks as the results of explosive injections and abrupt decrystallization (at a sharp change in thermodynamic conditions) of fluidized magmatic melt in the upper tectonized horizons of the Earth’s crust. The tuffisites examined by the author are characterized by combined fluidization and brecciform structure as well as occurrence of a complex matrix of authoclastic fragments and xenoliths of the hosting rocks. It was found to be necessary to conduct further more detailed field, petrogeochemical, and mineralogical study of fluidoliths as well as critical approach to a number of geological models generated in the past.
Key words: basaltic tuffisites, fluidization, sills, dykes, Gorny Altai.
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