A carregar...
Publicação
Reconstructing cold climate paleoenvironments from micromorphological analysis of relict slope deposits (Serra da Estrela, Central Portugal)
| Nome: | Descrição: | Tamanho: | Formato: | |
|---|---|---|---|---|
| 29.08 MB | Adobe PDF |
Orientador(es)
Resumo(s)
The paper focuses on analysis of macro- and micromorphological characteristics of
relict slope deposits in Serra da Estrela (Portugal) to understand the significance of
different slope processes and paleoenvironmental settings. Micromorphology is a
useful sedimentology technique allowing significant advances compared to macroscopic
techniques. Results show that different processes are involved in the development
of the slope deposits, reflecting different environmental conditions. The main
processes responsible for the emplacement of the relict slope deposits are solifluction,
debris-flow and runoff, but postdepositional changes are also present. Solifluction
was identified in slope deposits between 650 and 1500 m a.s.l. The common
microfeatures identified are circular arrangement of grains with a core grain, rounded
vesicles, vertical grains, matrix deformations and fine-grained deposits. Slope
deposits above 1300 m a.s.l have a platy microstructure and coincide with the altitudinal
range of the relict rock glaciers, indicating the elevation limit of permafrost.
Below this altitude platy microstructures are less frequent. Slope deposits in northfacing
slopes were affected by frost-induced processes in a seasonal frost regime,
followed by a postdeposition illuvial phase. Debris-flow and runoff were identified in
slope deposits between 680 and 1260 m a.s.l. The common microfeatures are
oblique grains, grain dumps, and coarse and fine grain lineations, and banded microstructures
were identified in runoff processes. Debris-flow deposits have a circular
arrangement of grains without a core grain, identified in sediments in paraglacial and
periglacial environments. The slope deposits show evidence of past periods of
enhanced periglacial activity since the last glaciation until the Younger Dryas.
Descrição
Palavras-chave
Micromorphology Paleoenvironments Periglacial processes Sedimentology Slope deposits Slope processes
Contexto Educativo
Citação
Nieuwendam, A., Vieira, G., Schaefer, C., Woronko, B., & Johansson, M. (2020). Reconstructing cold climate paleoenvironments from micromorphological analysis of relict slope deposits (Serra da Estrela, Central Portugal). Permafrost and Periglac Process, 31(4), 567–586. https://doi.org/10.1002/ppp.2054
Editora
Wiley