HR: 09:30h
AN: H41H-07    [Abstracts]
TI: Tectonic and Climatic Controls on Silicate Weathering
AU: * West, J
EM: jw257@esc.cam.ac.uk
AF: Dept. Earth Sciences, Downing Street, Cambridge, CB2 3EQ United Kingdom
AU: Galy, A
EM: Albert00@esc.cam.ac.uk
AF: Dept. Earth Sciences, Downing Street, Cambridge, CB2 3EQ United Kingdom
AU: Bickle, M
EM: mb72@esc.cam.ac.uk
AF: Dept. Earth Sciences, Downing Street, Cambridge, CB2 3EQ United Kingdom
AB: Chemical weathering of silicate minerals is thought to provide the temperature-sensitive feedback that regulates global climate on geological timescales. However it has proved hard to distinguish the temperature sensitivity of weathering rates from other factors such as physical erosion rates, rainfall and vegetation. Even the premise that weathering rates depend on temperature has been contested. Previous interpretations of weathering in small catchments have produced conflicting results and do not explain the scatter that emerges at larger basin scales. Here we present a new compilation of chemical and physical erosion rates in small catchments and show that the overall variation in chemical weathering rates with physical erosion rates, rainfall, and temperature is predictable from consideration of the limiting relationships. The data fit with an activation energy between 50 and 100 kJ/mol, a linear dependence on rainfall and a square-root dependence on erosion rate. The analysis confirms the concepts of "transport" and "weathering" limited regimes. Chemical weathering rates are ultimately controlled by a combination of climatic and tectonic processes with the more rapidly eroding terrains providing the temperature-sensitive feedback which regulates long-term climate change.
DE: 4885 Weathering
DE: 1886 Weathering (1625)
DE: 1045 Low-temperature geochemistry
DE: 1625 Geomorphology and weathering (1824, 1886)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting