Catchment-wide denudation rates (CWDRs) obtained from cosmogenic nuclides are an effi cient way to determine geomorphic processes quantitatively in alpine mountain ranges over Holocene time scales. These rate estimations assume steady geomorphic processes. Here we use a time series (3 yr) in the Aare catchment (central Swiss Alps) to test the impact of spatially heterogeneous stochastic sediment supply on CWDRs. Our results show that low-frequency, high-magnitude debris-fl ow events signifi cantly perturb cosmogenic nuclide ( 10 Be, 14 C) concentrations and thus CWDRs. The 10 Be concentrations decrease by a factor of two following debris-fl ow events, resulting in a doubling of inferred CWDRs. The variability indicates a clear time and source dependency on sediment supply, with restricted area-weighted mixing of sediment. Accordingly, in transient environments, it is critical to have an understanding of the history of geomorphic processes to derive meaningful CWDRs. We hypothesize that the size of debris fl ows, their connectivity with the trunk stream, and the ability of the system to suffi ciently mix sediment from low-and highorder catchments control the magnitude of CWDR perturbations. We also determined in situ 14 C in a few samples. In conjunction with 10 Be, these data suggest partial storage for colluvium of a few thousand years within the catchment prior to debris-fl ow initiation.

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In this study, we focus on the postglacial Chironico landslide in Valle Leventina, the valley of the Ticino river immediately south of the Gotthard pass (southern Swiss Alps). At Chironico, 530 million m 3 of granite gneiss detached from the eastern wall of Valle Leventina and slid along valley-ward dipping foliation joints and fractures. The slide mass was deposited into the valley bottom and blocked the Ticino river, as well as a tributary, the Ticinetto stream, on the opposite side of the valley. Wood fragments found in lacustrine sediments in the slide-dammed upstream lake were previously dated, yielding a minimum age for the landslide of approximately 13,500 cal years BP. Based on the deposit morphology, the landslide was in the past interpreted as being composed of two events. In order to directly date the landslide, ten boulders were dated using the cosmogenic nuclides 10 Be and 36 Cl. Mean exposure ages indicate that the landslide occurred at 13.38 ± 1.03 ka BP, during the Bølling-Allerød interstadial. This implies that the Chironico landslide, one of the few pre-Holocene slides known in Alps, is also the oldest in crystalline rock. With runout modelling using DAN3D we could reproduce the hypothesized singleevent failure scenario, as well as the character and extent of motion of the landslide mass. Both the ages and the modelling suggest that the landslide was released in one event around 3,000 years following deglaciation.

The Vienna Basin at the transition between the Alpine and Carpathian belt hosts a number of large Pleistocene sub‐basins forming along an active continental scale strike‐slip fault (Vienna Basin strike‐slip fault). We utilize first‐order derivatives from industrial Bouguer gravity data to unravel the impacts of Pleistocene kinematics on the Vienna Basin and to compensate for the lack of near‐surface fault data. Anomalies have been evaluated by independent geophysical and geological data and were integrated to build up a tectonic model. Factors influencing the wavelength and the amplitude of anomalies were additionally investigated by 2‐D models to better interpret field data. Subsidence and related accumulation of Quaternary sediments in the Vienna Basin produce significant gravity signals related to the activity of the strike‐slip fault. The constrained fault patterns and structures highlight tight and elongated transtensional pull‐apart basins with typically associated features like separated depocenters and Riedel fractured sidewalls in an en‐echelon alignment. Further Pleistocene basins are highlighted as tectonic grabens developing along branches of the master fault. The Vienna Basin is additionally affected by minor deformation represented by both subsidence along major Miocene sidewalls and NW‐SE faulting resulting in distinct topographic features, which manifests kinematics on a regional scale. The clear density contrasts between Miocene marine and Quaternary terrestrial sediments, as well as the exceptional database, provide a unique framework to demonstrate advantages of incorporating gravity derivatives for near‐surface fault analysis.

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