- Tytuł:
- Reconsidering the glaciogenic origin of Gondwana diamictites of the Dwyka Group, South Africa
- Autorzy:
-
Molén, Mats O.
Smit, J. Johan - Powiązania:
- https://bibliotekanauki.pl/articles/2204360.pdf
- Data publikacji:
- 2022
- Wydawca:
- Uniwersytet im. Adama Mickiewicza w Poznaniu
- Tematy:
-
surface microtexture
sediment gravity flows
Late Palaeozoic Ice Age
pavement
Nooitgedacht
mikrotekstura powierzchni
osad
epoka lodowcowa
nawierzchnie - Opis:
- The Gondwana Late Palaeozoic Ice Age is probably best represented by the Dwyka Group in South Africa. Striated and grooved surfaces or pavements are commonly considered to have formed subglacially, as are diamictites which have been interpreted as in-situ or reworked tillites. These interpretations were tested by investigation of outcrops in formerly well-studied areas, throughout South Africa. Detailed analyses have focused on striated surfaces/pavements and surface microtextures on quartz sand grains in diamictites. The sedimentological context of four pavements, interpreter to be glaciogenic, display features commonly associated with sediment gravity flows, rather than glaciation. A total of 4,271 quartz sand grains were subsampled from outcrops that are considered mainly to be tillites formed by Continental glaciation. These grains, analysed by SEM, do not demonstrate the characteristic surface microtexture combinations of fracturing and irregular abrasion associated with Quaternary glacial deposits, but mainly a mix of surface microtextures associated with multicyclical grains. The Dwyka Group diamictites warrant reinterpretation as non-glacial sediment gravity flow deposits.
- Źródło:
-
Geologos; 2022, 28, 2; 83--113
1426-8981
2080-6574 - Pojawia się w:
- Geologos
- Dostawca treści:
- Biblioteka Nauki
Artykuł