Reconstructing cold climate paleoenvironments from micromorphological analysis of relict slope deposits (Serra da Estrela, Central Portugal)

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 macro- scopic techniques. Results show that different processes are involved in the develop- ment of the slope deposits, reflecting different environmental conditions. The main processes responsible for the emplacement of the relict slope deposits are solifluc- tion, debris-flow and runoff, but postdepositional changes are also present. Solifluc- tion 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 altitu- dinal range of the relict rock glaciers, indicating the elevation limit of permafrost. Below this altitude platy microstructures are less frequent. Slope deposits in north- facing 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 micro- structures 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.