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| Titel |
Revised Sediment Budget of the North-Alpine Foreland Basin and the Role of Erosional Recycling: Did Erosion Rates Change at 5 Million Years? |
| VerfasserIn |
Ramona Baran, Anke M. Friedrich, Fritz Schlunegger |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250082897
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| Zusammenfassung |
| The fundamental discussion of whether or not climate change triggered a global acceleration of erosion at 5 Ma is widely based on volumetric estimates of eroded material in sedimentary basins. The sediment budget of the Alps is one of the most striking data sets in the world apparently recording a substantial increase in sediment discharge over the past ~ 5 Ma. Recently, however, this increase has been challenged by the argument that it may reflect an artefact due to observation and measurement biases. We therefore re-assessed the sediment-budget dataset by considering the effects of erosional recycling of previously deposited Alpine detritus. We found that from ~ 34 – 5 Ma eroded Alpine material was deposited in proximal basins such as the north-Alpine foreland basin, whereas from ~ 5 – 0 Ma most of the sediments were mainly deposited in distal basins such as the North Sea and the Black Sea. During the last 5 – 10 Ma, the north-Alpine foreland basin was uplifted by several hundred meters as indicated by subsidence curves, and stratigraphic as well as apatite fission-track data document its erosion implying a significant increase of the potential erosion area. The original erosion area of 20 000 km² calculated by Kuhlemann et al. (2000) for the Western Alps increases to ca. 28 000 km² when the area of the adjacent eroded foreland basin, the Swiss portion, is included. Similarly, the erosion area of the Eastern Alps increases to c. 71 500 km² by including the German-Austrian portion of the foreland basin. However, for the Po and Pannonian basins adjacent to the southern and eastern borders of the Alps, such a late phase of uplift and erosion has not been documented. Accordingly, we re-calculated the Alpine erosional history based on the adjusted erosional areas, which resulted in a nearly constant Alpine sediment yield since before 5 Ma. The recycling of Alpine deposits from the north-Alpine foreland basin since 5 Ma contributed significantly to the overall distal increase in sediment discharge. Our findings require tectonically-driven uplift of the Alps and its foreland basin since 5 Ma. We thus challenge recently published views that climate change accelerated the erosion of high mountainous areas since 5 Ma. We propose that models invoking climatically-triggered isostatic rebound of the Alps since 5 Ma need to be revised in light of the effects of erosional recycling of previously deposited material explained above. |
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