Last Glacial to Holocene vegetation succession recorded in polyphase slope-failure deposits on the Malenik Ridge, Outer Western Carpathians

摘要

Structural settings and palaeoenvironmental reconstruction of a polyphase Late Pleistocene deep-seated landslide at the Malenik Ridge in the Eastern part of the Czech Republic are presented. The deep-seated rotational landslide is about 480 m long and 1540 m wide and it is a part of much larger landslide complex. The depositional record of two generations of former near-scarp depressions revealed a multiple deep-seated landslide activity during the last Quaternary climatic cycle. With the minimum age of 47704 +/- 2346 cal b2k, the landslide belongs among the oldest dated landslides in the outer Western Carpathians and Carpathian Foredeep in the Czech Republic. The younger reactivation started at 12662 +/- 73 cal b2k during Younger Dryas. The palaeobotanical and depositional record from the landslide brought unique palaeoenvironmental data for two time intervals of the last Quaternary climatic cycle. The reconstructed MIS 3 forest vegetation with the predominance of stone pine-larch (Pinus cembra - Larix) taiga with Pinus sylvestris and Betula pendula/pubescens are the first evidences of the forest vegetation for the GS13 to GI12 transition in Outer Western Carpathians. Similarly, documented events of MIS 3 landslide activity from Outer Western Carpathians are rather rare. The Late Glacial to Holocene record from the younger near-scarp depression revealed vegetation and landscape changes during the Pleistocene/Holocene transition. The evidenced oldest parts of the landslide at the Malenik Ridge had to originate during more humid interpleniglacial conditions. The geomorphological evidence for landslide activity from this period has almost completely disappeared from the ground surface topography due to intensive periglacial processes operating later during the Last Glacial Maximum and subsequent fluvial and anthropogenic processes of the Holocene. The cold and relatively dry period of the pleniglacial is considered as a time when deep-seated mass movements use to be halted and overprinted by shallow solifluction of the active layer masking former deep-seated landslide features. (C) 2017 Elsevier Ltd and INQUA. All rights reserved.