Publication details
Význam valounových analýz ledovcových sedimentů pro paleogeografické rekonstrukce pleistocenního kontinentálního zalednění Jesenicka
| Title in English | Importance of clast petrological analyses of glacial sediments for palaeogeographical reconstruction of Pleistocene continental glaciation in the Jeseníky area |
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| Authors | |
| Year of publication | 2015 |
| Type | Article in Periodical |
| Magazine / Source | Geologické výzkumy na Moravě a ve Slezsku |
| MU Faculty or unit | |
| Citation | |
| Field | Geology and mineralogy |
| Keywords | Clast petrology and provenance; continental glaciation sediments; advance directions of continental glacier; Pleistocene; Rychleby Mts. foothill; Zlaté Hory Highlands. |
| Description | Sediments of Middle Pleistocene continental glaciation at the northern foothill of Rychleby Mts. and Zlaté Hory Highland contain clasts of local to Nordic provenance. Local clasts have palaeogeographical importance for a local reconstruction of ice sheet advance directions. General advance direction from NW to SE has been reconstructed basing on local clasts in earlier studies (mainly Gába 1981a, b, Gába – Pek 1999). This interpretation has been based on the fact that the shares of clasts of rocks cropping primarily in NW part of the Rychleby Mts. decrease towards the SE. New, in this contribution presented, interpretation reconstructs the ice sheet advance generally from the North to the South, with variations conditioned by local landscape. The new interpretation presumes the colluvial, alluvial and fluvial transport of the debris towards the northern and north-eastern mountain forefield before the ice sheet advance. Ice sheet advancing from the North eroded and transported this debris towards the South. Monotonous and distant provenance poor sediments originated at places, where the source preglacial deposits must have been petrologically monotonous considering the lithology of source areas. Concurrently, morphologically conditioned preglacial accumulation of vast lithologically monotonous deposits took place at some places (proximal parts of mountain ridges and saddles foothill). Rather polymict and distant provenance clast rich sediments originated during the later phase of ice sheet decay. Debris from the whole ice sheet body, not only from the glacier base or its front, released to the depositional system at that time. Sites with these sediments are located beyond the mountain foothill, where mixing of debris originating from alluvial fans or rivers flowing form the mountain range took place. |