Project Details
Projekt
SECCO- Chile: The coupled vegetation, weathering, erosion, and sediment-export response to climate change unravelled from novel proxies in Chilean marine sediment
Subject Area
Palaeontology
Term
from 2018 to 2023
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 408246516
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. Earth's surface is vulnerable to complex feedbacks between climate, hydrology, vegetation, weathering, erosion, and sediment deposition that affect the evolution of landscapes that we live on. However, precisely how vegetation, weathering and erosion, and associated sediment dynamics, respond to climate change is currently unknown. This gap in knowledge severely obstructs the interpretation of marine sedimentary records as archives of changes in climate and/or surface processes. In Chile, there is published evidence for a direct response between an onshore climatic forcing and the offshore sedimentary archive: following onshore aridification in the last deglacial, turbidite-deposit thickness and frequency strongly decreased offshore.This project seeks to identify the cascade of changes in weathering, erosion, and sediment export to the ocean following hydrologic and vegetation changes from the Last Glacial Maximum (LGM) to the present along the Chilean coast. To achieve this goal, we link the disciplines of sedimentary systems research, geochemistry, and biology to jointly explore the feedbacks between changes in hydrology and vegetation and Earth-surface processes over a large spatial (the Chilean coast) and temporal (LGM to Holocene) scale. We hypothesize that the impact of deglacial climate change on Chilean landscapes is strongly modulated through the presence of vegetation. Hence, we suggest that temporal lags occurred between changes in climate/ hydrology and vegetation, and changes in weathering, erosion, and sediment export.We propose to test this hypothesis by applying a unique combination of novel state-of-the-art proxies that allow the detection of changes in vegetation and hydrology (by lipid biomarker analysis and their delta 13C and delta D isotope composition), weathering (by using Li stable isotopes, delta 7Li), and erosion (by using novel cosmogenic meteoric 10Be/9Be ratios) that followed deglacial aridification. In a first work package (WP1), we will identify present-day spatial differences in the evolution of these proxies along the Chilean climatic gradient, by sampling modern erosion products from riverine and offshore surface sediment from core tops. In WP2, we use the same methods on independently dated marine sedimentary archives that provide the depositional legacy necessary to reconstruct the temporal dynamics of these proxies from the LGM to the present day, as spatially representative archives are mostly absent onshore. This modern calibration (WP1) in combination with the paleo-record (WP2) will allow us to identify and mechanistically understand the sources of variability in and the temporal leads and lags between changes in vegetation, weathering, erosion, and sediment export to the ocean following a major hydrological change.
DFG Programme
Priority Programmes
Subproject of
SPP 1803:
EarthShape: Earth Surface Shaping by Biota
Co-Investigator
Dr. Patrick Frings
