Open AccessPaleocryogenic processes in the Volyn` Upland
Author(s) -
Оleksandr Bonchkovskyi
Publication year - 2018
Publication title -
vìsnik dnìpropetrovsʹkogo unìversitetu. serìâ geologìâ, geografìâ/vìsnik dnìpropetrovsʹkogo unìversitetu. geologìâ, geografìâ
Language(s) - English
Resource type - Journals
eISSN - 2409-9864
pISSN - 2313-2159
DOI - 10.15421/111801
Subject(s) - solifluction , pleistocene , tundra , geology , quaternary , loess , glacial period , geomorphology , paleontology , physical geography , geography , arctic , oceanography
On the basis of the study of 13 Quaternary loess-soil sections in the Volyn’ Upland, cryogenic horizons of different ranges have been recorded and positioned within the Quaternaty stratigrpahical framework of Ukraine. A short-period cyclicity in development of cryogenic processes has been revealed. Time units of formation of cryostuctures − ‘cryostages’ – have been ranged into four categories in correspondence with landscape-climate conditions of their formation and their relations with the units of paleogeogrpahic framework of Ukraine. The differences in cryostructures and cryodeformations for each category of cryostages are shown. A variety of cryostructures and their sizes became larger from the beginning to the end of the Pleistocene that reflects an increase in the climate harshness. Six cryogenic stages were revealed for Early Pleistocene: mr2, sl, lb1b1-b2, lb2, lb3b1-b2, tl. At these times, small ice wedges, ground wedges, solifluction and different types of postcryogenic textures were formed. The cryogenic processes during the Middle Pleistocene developed more intensely. Six Middle Pleistocene cryostages were established: zv2, zv3b1-b2, or, pt2, pt3b-c, dn. The complex of cryostructures of the majority of these stages include large ice wedges, different types of ground wedges, diverse solifluction forms, and tundra spots-medallions. The largest cryogenic structures and deformations are revealed for the cold time spans during the Late Pleistocene: ice wedges (reach up to 5 m in depth), tundra spots-medallions, sand wedges, solifluction and congelifluction forms, different types of ground wedges and postcryogenic textures. Sixteen Last Pleistocene cryostages are revealed: kd1a-b, kd1b1-b2, kd2, kd3b1-b2, ts, pl1a-b, pl1b1-b2, pl1b-c, pl2, pl3b1-b2, ud, vt1b1-b2, vt2, bg, pc1, pc3. The specific features and sizes of cryostructures and cryodeformation of each cold stage, substage and phase have been used as a base for reconstruction of their geocryological conditions.