Climate Forcing of the Growth and Destruction of the European Alps
Abstract
At the scale of an orogen, climatic and tectonic processes operate together to produce and form topography and to modulate the proxy signals that reflect that topography, including cooling ages and sediment yield. However, in terrestrial settings, there are few unambiguous climate proxies and disentangling climatic and tectonic forcing of geologic data is difficult. Small convergent orogens such as the Alps are particularly interesting as products of tectonic and climatic forcing as they are frequently in a state of near-balance between accretionary and erosional fluxes, so that perturbations can have a large effect. Models of the coupling between tectonic crustal deformation and climate-modulated surface erosion provide insight into how we might best differentiate between tectonic and erosional forcing, predicting a relationship between mountain belt height, width, sediment yield and exhumation rate. In particular, positively or negatively correlated changes between sediment yield and orogen width can be used to identify climate forcing. Two major events stand out in late Alpine history as potential climatically-forced events. The period from 30 to 20 Ma, characterized by little outward growth of the Alps, but high rates of exhumation and sediment yield, was terminated at the Aquitanian, Burdigalian boundary. At this time, the Alps expanded southward into their foreland, accompanied by a decrease in sediment yield both north and south of the Alps. This can be interpreted as a climatically-driven change from a steady to a constructive state. The second major event occurred at 5 Ma, when southward expansion of the Alps ceased, and the northern foreland inverted and began to erode, both characteristics of the transition to a destructive state. This transition was accompanied by a large increase in sediment yield, supporting the hypothesis that this was also a climatically-driven change.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.T41C..08W
- Keywords:
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- 8499 General or miscellaneous