SECCO - Chile: The coupled vegetation, weathering, erosion and sediment-export response to climate change unraveled from novel proxies in Chilean marine sediment

 

Investigator Names and Contact Info:

• Anne Bernhardt (Geology / Sedimentology). Department of Geosciences, Free University of Berlin, Germany
• Hella Wittmann-Oelze (Geochemistry). German Research Centre for GeoSciences (GFZ) Potsdam, Germany
• Dirk Sachse (Paleohydrology / Organic Geochemistry). German Research Centre for GeoSciences (GFZ) Potsdam, Germany
• Patrick Frings (Geochemistry). German Research Centre for GeoSciences (GFZ) Potsdam, Germany

 

Chilean Collaborators Involved:

• Antonio Maldonado (Paleoclimate). Universidad La Serena & Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Chile
• Daniel Melnick (Geodynamics). Universidad Austral, Valdivia, Chile

 

 

PhD 5a: mSecco

Quantifying modern links between vegetation, hydrology and Earth surface processes from inorganic and organic geochemical proxies in Chilean modern river sediment.

• Nestor E. Gaviria Lugo. GFZ Potsdam, Germany

supervisor: H. Wittmann-Oelze, co-supervisors: D. Sachse, P. Frings, A. Bernhardt

 

PhD 5b: pSecco

Reconstruction of changes in paleohydrology, vegetation and earths surface processes from inorganic and organic geochemical proxies in marine sediment from the Last Gracial Maximum to present.

• Charlotte Läuchli. Free University of Berlin, Germany

supervisor: A. Bernhardt, co-supervisors: D. Sachse, P. Frings, H. Wittmann-Oelze

 

BSc

Variance of 9Be in the rocks of the Maipo River catchment.

• Simon Hartig. Freie Universität Berlin, Germany

supervisor: A. Bernhardt, Co-supervisor: H. Wittmann-Oelze

 

 

 

Project summary:

Understanding landscape response to climate change is a central problem in the geosciences today, as substantial future changes in precipitation patterns and intensity are expected. Here we aim to investigate these responses by taking advantage of the unique vegetation and hydrological gradient along the Chilean continental margin and the climatic change over the last 20.000 years recorded in marine sedimentary archives off-shore.

Specifically, this project seeks to identify the cascade of changes in weathering, erosion, and sediment export following the large hydrologic and vegetation changes along the Chilean coast from the Last Glacial Maximum (LGM) to present. We will use state-of-the-art tools, e.g. compound distribution, and compound-specific carbon and hydrogen isotope composition of leaf wax n-alkanes as indicators for vegetation type and hydrology, Lithium stable isotopes to constrain weathering intensity, and meteoric cosmogenic 10Beryllium (10Be) to stable 9Be (10Be/9Be) ratios to quantify weathering and erosion rates. In detail, this project will:

a) Identify how present-day climate, vegetation, weathering, and erosion vary along the Chilean margin and how they are recorded in inorganic and organic geochemical proxies. This aim requires establishing how modern gradients in hydrology, vegetation, weathering, and erosion are recorded in the proxies and thus the analysis of suspended sediment material from modern rivers draining the Chilean ranges and the analysis of marine surface sediment. This will lead to a calibration of the proxies, as well as an assessment of their fidelity in marine surface sediments by a comparison of the core tops with the modern river data.

b) Reconstruct the temporal development of climate, vegetation, weathering, erosion, and sediment export since the LGM along the Chilean margin. To achieve this aim, we will analyze three marine sediment cores covering the time period from the LGM (ca. 20.000 years ago) to today with inorganic and organic proxies.

3) Identify the temporal leads and lags between climate, vegetation, weathering, erosion and sediment export, and analyze and mechanistically understand spatio- temporal patterns and their differences in the studied regions (i.e. arid, semi-arid, humid). We will compare lead and lag-time patterns between the key proxies along three study sites of the Chilean climate gradient to understand drivers of these lags and the feedbacks between climate, vegetation, weathering, erosion, and sediment export to the ocean.

This proposal is a first-time proposal and newly established within EarthShape phase 2.