『Abstract
There is growing evidence that Quaternary rock uplift in parts
of the European Alps is a consequence of climate- and erosion-driven
isostatic rebound. Contemporary rates of rock uplift U in the
Swiss Alps show two distinctive dome-like peak regions that attain
〜1.6 mm yr-1. We focus on the Alpenrhein catchment
and its surroundings, where one of these peak regions spatially
coincides with widely exposed Cretaceous Bunder（uの頭に¨）
schist and lower Tertiary flysch. Field assessments and analyses
of hillslope gradient distributions quantitatively demonstrate
the low rock-mass strength and high erodibility of these rocks.
This is reflected in mean postglacial catchment erosion rates
D 〜4 mm yr-1, as opposed to 0.7 mm yr-1
in more resistant crystalline rocks. Though largely inferred from
landslide- and debris-flow prone tributary catchments ＜20 km2,
the localised erosion rates in Bunder（uの頭に¨）
schist and flysch are among the highest documented for the Alps,
and corroborated by historic suspended sediment yields, and thus
export, from the region. We further find that the steepness of
bedrock rivers, the density of large landslides, and D correlate
with the highest values of U. Our observations highlight the possibility
that erosion of mechanically weak Bunder（uの頭に¨）
schist and flysch enhanced by large landslides may have contributed
to regional crustal unloading, and concomitant rock uplift. Irrespective
of whether this is betraying a coupling between long-term uplift
and erosion modulated by rock type, our findings indicate that
long-term (103 to 104 yr) geomorphic signals
contained in bedrock-river steepness, spatial density of large
landslides, and postglacial erosion rates strikingly correlate
with regional gradients of historic (101 yr) rock uplift
rates.
Keywords: Swiss alps; uplift; erosion; flysch; isostasy; bedrock
incision; landslide』
1. Introduction
2. Study area
3. Methods
4. Erosion, uplift, and rock-mass strength
4.1. Rates of rock uplift and rock type
4.2. Steepness of bedrock rivers
4.3. Spatial density of large landslides
4.4. Hillslope gradients
4.5. Drainage basin erosion and rock type
5. Discussion
5.1. Uplift, erosion, and rock type: process controls
5.2. Erosion-induced uplift: model constraints
5.3. Regional context
6. Conclusions
Acknowledgements
References