 |
| Titel |
Exploring the geochemistry of landscape dynamics using cosmogenic radionuclides |
| VerfasserIn |
J. W. Kirchner, K. L. Ferrier, C. S. Riebe |
| Konferenz |
EGU General Assembly 2009
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250024629
|
|
|
|
|
|
| Zusammenfassung |
| Physical erosion and chemical weathering regulate the topography of Earth's surface, the fertility of soils, the chemistry of natural waters, and, over long time scales, the composition of the atmosphere and thus Earth's climate. Cosmogenic nuclide methods have proven particularly useful for studying rates and patterns of surface denudation over thousands of years, at spatial scales ranging from individual outcrops to small catchments. When coupled with the bulk composition and mineralogy of parent materials and the soils that are formed from them, cosmogenic nuclide measurements can also be used to infer rates of chemical weathering over millennial time scales.
These methods are applicable to a wide range of field situations, thus facilitating comparative studies of weathering rates and processes. We have used these methods to measure rates of physical erosion and chemical weathering across three elevation transects, spanning up to 1500m in altitude, and across a network of over 40 field sites spanning large gradients in climate and tectonic forcing. Comparisons among these sites show that chemical weathering rates respond to variations in temperature and precipitation, and that they are also strongly coupled to rates of physical erosion. Rates of physical erosion, in turn, respond to variations in hillslope gradients, tectonic forcing, and lithology. Physical erosion rates are also highly episodic, as demonstrated by comparing cosmogenic nuclide measurements with direct measurements of erosion rates over decadal timescales. The view that emerges is of a highly dynamic system in which chemical weathering and physical erosion are coupled to one another, and are jointly driven by climatic and tectonic forcing. |
|
|
|
|
|
|