CRYOGENIC RAPIDCREEKITE OF THE MALAYA NIZHNEUDINSKAYA CAVE (EASTERN SIBERIA)
E.P. Bazarova1, O.I. Kadebskaya2, M.N. Rubtsova1, O.V. Korotchenkova2, A.M. Kononov1,3
1Institute of the Earth Crust, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
2Mining Institute, Ural Branch of the Russian Academy of Sciences, Perm, Russia
3Irkutsk National Research Technical University, Irkutsk, Russia
Keywords: cave, cryogenesis, isotope composition, rapidcreekite
Abstract
The morphology and mineral composition of cryogenic formations of the Malaya Nizhneudinskaya Cave have been studied by electron microscopy and X-ray powder diffraction. This cave is confined to permafrost. The temperature in the cave is near zero all year round, as a result of which ice formations are widely developed in the cave. When solution freezes, and the subsequent partial evaporation of ice occurs, a cryogenic residue composed of gypsum, calcite, and a rare mineral rapidcreekite Ca2(SO4)(CO3)·4H2O is formed. Rapidcreekite forms radial-radiant aggregates of acicular crystals of up to 200 μm in length. In our opinion, the source of sulfur is represented by the locally developed interlayers of gypsum in the non-karsting rocks overlaying the limestones. This is the second finding of rapidcreekite in the speleo-cryomineralogenesis environment in the world and the first discovery of this mineral in the caves in Russia.
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