Chemical and physical weathering and subsequent erosion from hillslopes provide the raw materials for river transport and deposition. As such, active channel sediments and sedimentary archives such as alluvial terraces contain within them a record of catchment-wide weathering and erosion processes. Cosmogenic nuclides are regularly called on to measure denudation rates, which represent the sum these processes. However, in rapidly evolving landscapes cosmogenic nuclides provide insights into catchment-averaged weathering and erosion processes only over relatively short timescales. For example, in the Southern Alps of New Zealand, denudation rates can exceed 10mm/yr, implying cosmogenic nuclide averaging timescales of less than a century. Similarly, sediment yields also provide a geologically near-instantaneous picture of catchment-wide denudation. An interesting problem then arises in which it becomes challenging to separate the effects of long-term geologic drivers of weathering and erosion such as ongoing rapid uplift from those of recent low frequency/high magnitude geologic events or anthropogenic activity. In these rapidly evolving settings, soil profiles, sedimentary deposits and geomorphic form can be useful archives to disentangle these confounding factors. We combine cosmogenic nuclides with; elemental mass balance, grain size, U/Pb, and landscape morphology to interrogate the drivers (e.g., uplift) and constrain the rates of weathering and erosion across Aotearoa, New Zealand.

The distribution of grain size in sedimentary fans is commonly used as a record of past climate fluctuations. The fidelity of this record can, however, be affected by several processes such as highly condensed stratigraphy or strong autogenic geomorphic processes that tend to ‘shred’ the climate signal. In this study, we use a coupled FastScape erosional–depositional landscape evolution model with a gravel grain-size model to identify the environmental and geomorphic conditions that optimize the generation and preservation of climate-driven grain-size signals. Our results indicate that such signals are most reliably recorded in low-bypass, transient, and topographically constrained alluvial fans.

To illustrate this, we apply an optimization approach to a gravel fining dataset, catchment wide erosion rates, and topographic profiles from two alluvial fans in Death Valley described in D’Arcy et al. (2017). These fans were interpreted as preserving climate signals tied to Milankovitch-scale rainfall variability despite some channel incision on a neighbouring fan surface (D’Arcy et al, 2017). Our analysis suggests that these systems are near-optimally configured for archiving climatic fluctuations. The methodological framework we present can be used to inform the design of future grain-size data collection strategies and offers a tool for assessing the potential of other fan systems to preserve paleoclimate signals in their depositional stratigraphy.

D’Arcy, M. et al. (2017). Sedimentology, 64(2), 388–424

Changes in continental precipitation patterns may drastically reshape landscapes and living-environments of humans in terms of geomorphological settings and sedimentological regimes. Dust based quaternary sediment archives like widespread loess-palaeosol-sequences (LPS) record climatic changes and provide key geomorphological and sedimentological information. These records are also essential for comprehending precipitation changes across continents and associated terrestrial system responses. Currently, precipitation quantities strongly vary along a W-E gradients across Europe, but this pattern is likely to have changed dramatically in the past – especially when the Nordic ice-sheets started to grow upon their massive extend during their glacial maxima. Here we present first precipitation estimates considering a suite of established chemical (δ¹³C of the total organic carbon) and magnetic measures for the Nantois section (northern Brittany, France) covering the Saalian (penultimate glaciation) with its cold and harsh conditions and the Eemian (last interglacial), when the climate was globally warmer than today. We discuss our sedimentological results considering the special geomorphological setting of the Nantois section and its role regarding the reaction to dry-moister cycles. Based on this, we demonstrate the advantage of combining sedimentological and geomorphological perspectives when aiming at a more holistic landscape understanding.

Lake sediments are valuable natural archives of environmental change, providing insights into sediment transport, deposition, and landscape evolution. To better understand the landscape evolution and past environmental change in the northern Andes, a region known for its high biodiversity and vulnerability to climate change, we analyzed lake sediment archives from three areas near Ecuador's capital, Quito. Our pilot study combined sub-bottom profiling (SBP) with a multi-proxy analysis of short sediment cores from lakes Muertepungo, San Pablo, as well as Caricocha and Chiriyacu in the Mojanda Lake Region. These lakes are situated at high elevations (2500-4000 m a.s.l.) and are of different volcanic origin.

In this contribution, we focus on SBP data to understand the bathymetry, morphology, and sediment infill characteristics of the studied lakes, providing a first interpretation of the sedimentary evolution. We used an Innomar "compact" parametric sediment profiler to record sub-bottom profiles in lakes with water depths ranging from a few meters to over 100 m. Stratigraphic correlation was supported by five short sediment cores collected from different water depths. Radiocarbon and tephra analysis were used to establish a chronological framework.

Preliminary results indicate differences in sediment properties and thicknesses, as well as distinct layering patterns, which may be linked to past environmental conditions such as shifts in water levels, temperature, trophic state, and other factors. These findings have important implications for understanding the complex interactions between climate, geology, ecosystems, and natural hazards, such as volcanic eruptions and landslides, in this region.

Quantitative Provenance Analysis (QPA) and Geomorphology provide complementary yet traditionally decoupled insights into sediment generation. QPA reconstructs lithological sources from detrital compositions, while geomorphology quantifies sediment erosion, transport pathways and morphometric controls. Their integration defines Sediment Generation as an emerging process-based discipline that seeks to quantify how sediments with specific compositional and textural properties are produced from source rocks under variable tectonic, climatic and morphodynamic conditions.

Studies of tectonically active catchments in Colombia and southern Italy reveal that sediment production and flux is nonlineraly controlled by both lithological properties, such as erodibility and textural inheritance, and morphometric parameters like slope, structural connectivity and sediment routing potential. Weathering rates and both steady-state and episodic erosional processes like landsliding and rock falls, controlled by hillslope morphology, directly affect sediment compositions including bulk geochemistry, clay mineralogy and geochemistry, sand petrography and detrital geochronology.

Numerical integration of morphometric parameters and derived indices, such as the index of connectivity and global erodibility index, with basic sediment generation models based on endmember mixing enables the quantification of lithological and morphometric controls. The relative contributions of heterogeneous parent rocks to sand, silt and clay grain sizes are primarily governed by lithological characteristics. However, these controls may be overridden by morphometric features and local drainage configuration.

The interdisciplinary QPA-geomorphology approach permits high-resolution sediment budgets, advances predictive sediment modeling, and redefines our understanding of anthropogenic disruptions such as deforestation and hydroelectric damming. It further offers a critical advancement for unraveling source-to-sink dynamics in both recent and ancient sedimentary systems.