Combined use of relative and absolute dating techniques for detecting signals of Alpine landscape evolution during the late Pleistocene and early Holocene

Abstract

Combined use of relative and absolute dating techniques for detecting signals of Alpine landscape evolution during the late Pleistocene and early Holocene Abstract A combination of three relative and two absolute(numerical) dating techniques, applied on nine soil profiles in an Alpine environment located in Val di Rabbi (Trentino, Northern Italy), was used to improve the investigation methodology of Alpine sites in response to climate change and to reconstruct the chronology of late Pleistocene and early Holocene landscape evolution. The degree of podzolisation, clay mineral evolution and the element mass balances of each site were investigated. Furthermore, the stable fraction of the soil organic matter (SOM) was extracted with 10% H2O2 and 14C-dated. The age of the organic residues was compared with the age of charcoal fragments found in one of the studied soils and with the age of rock boulders obtained by surface exposure dating (SED) with cosmogenic 10Be. Numerical dating and weathering characteristics of the soils showed a fairly good agreement and enabled a relative and absolute differentiation of landscape elements. The combination of 14C-dating of SOM and SED indicated that deglaciation processes in Val di Rabbi were already far advanced by around 14000 cal BP and that glacier oscillations affected the highest part of the region until about 9000 cal BP. The development of clay minerals is time-dependent and reflects weathering intensity. We found a close link between secondary clay minerals like smectite or vermiculite and soil age as obtained by the dating of the organic residues after the H2O2 treatment. Calculated element mass balances strongly correlated with the ages derived from 14C measurements. Old soils have lost a major part of base cations (up to 75% compared to the parent material), Fe and Al, which indicates a continuous high weathering intensity. Results of the chemical and mineralogical analyses were in good agreement with numerical dating techniques, showing the dynamics of an Alpine landscape within a relatively small area. The combination of relative and absolute dating techniques is a promising tool for the reconstruction of landscape history in high-elevation Alpine areas on siliceous substrates.

A Combination of Relative-Numerical Dating Methods Indicates Two High Alpine Rock Glacier Activity Phases After the Glacier Advance of the Younger Dryas

“…Although some uncertainties still exist about the timing of rock glacier activities, two distinct phases of rock glacier activity could be discerned. This finding was only made possible using a multi-parameter approach that consequently clearly shows its advantages [66,67].…”

Lateglacial and early Holocene dynamics of adjacent valley glaciers in the Western Swiss Alps

“…This Boreal advance (VI) with its more restricted extent may be related to the Schams cold phase ($8.7-9.5k cal a BP, Oberhalbstein/Schams after Maisch et al, 1999), and might mark the end of early Holocene advances of the Unnerbaech glacier. In the Val di Rabbi (Trentino, northern Italy), evidence for an advance at $9.4 ka, similar to that at the Belalp, is reported (Favilli et al, 2009): clearly older than the moraine from the Kromer stage ($8.4 ka, Kerschner et al, 2006) but younger than those from the Kartell stage ($10.8 ka, Ivy-Ochs et al, 2009;Maisch, 1995). This provides evidence for a cold reversal and climatic variability during Boreal times in the Alps, as the last advance was shortly before the Holocene climatic optimum (9-5.5k cal a BP) indicated by the innermost moraine VI at Belalp (9.6 AE 0.7 ka).…”

“…The YD and other Lateglacial stages have been firmly established at several sites in the European Alps, including Julier Pass (Ivy-Ochs, 1996;Ivy-Ochs et al, 1996, 2008, Great Aletsch (Kelly et al, 2004), Kartell (Ivy-Ochs et al, 2007), Kromer , Alpe Dosdé (Hormes et al, 2008), Piano del Praiet (Federici et al, 2008) and Val di Rabbi (Favilli et al, 2009). However, due to the relatively large geographical distance between these sites it has hitherto not been possible to account for local effects on glacier response.…”

Long-term base cation weathering rates in forested catchments of the Canadian Shield

“…Although the soil profiles that did not met the assumptions for mass balance calculations were rejected, our results nonetheless showed apparent accumulation in 7% of all calculations done for the four cations and the 21 catchments (Table 4). Some authors attributed soil enrichment in base cations to long-term exogenous material inputs such as mass wasting or aeolian deposition (Chadwick et al, 1999;Favilli et al, 2009;Bern et al, 2010). Based on geomorphologic and stratigraphic data, such addition is unlikely for our study area.…”