Mathematics – Logic
Scientific paper
Sep 1995
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995gecoa..59.3469g&link_type=abstract
Geochimica et Cosmochimica Acta, vol. 59, Issue 17, pp.3469-3485
Mathematics
Logic
21
Scientific paper
Rivers carry the products of continental denudation either in a dissolved form (chemical erosion) or in a solid form (physical erosion). We focus in this paper on the relationship between physical erosion and chemical erosion. We establish the mass budget of the Congo Basin Rivers using chemical complementarities between river suspended sediments, sandy bedload, and dissolved load of the Congo Basin rivers reported in a previous paper (Dupré et al., 1995). A series of equations are presented, assuming that the physical and chemical erosion processes are in a steady state during one year. The total mass of river-borne material (dissolved and particulate) transported in the river over a given period of time should balance the mass of upper continental crust eroded during this time. We show that the local continental crust on each drainage basin can be estimated and solve our steady-state weathering model using an inversion procedure. The very good agreement between modelled and measured values of the river-suspended sediment concentrations validates the steady-state hypothesis in this wet tropical area. Consequently, in this area, the sediment yield provide a good estimate of the rates of mechanical denudation. This result also validates the calculation of the chemical and isotopic composition of the local continental upper crust using the bulk river load. Erosion rates for the silicate upper crust and thus independent of the lithological variability (silicates, evaporites, and carbonates) of the drainage basins are calculated. Mechanical erosion rates and chemical erosion rates for the Congo Basin at Brazzaville are 8 t /km 2 /y and 5 t/km 2 /y. The corresponding consumption of atmospheric CO 2 by weathering process is estimated to 51 × 10 3 mol/km 2 /an. These weathering and consumption rates are low in spite of the severity of the weathering conditions, of the high soil temperature, and of the intensity of precipitations. These conclusions indicate the limiting influence the dynamic equilibrium of soils for silicate weathering. Finally, by estimating the local continental crust chemical composition before the onset of erosion processes, especially for the most soluble elements, we can test the model of Taylor and McLennan.
Allègre Claude J.
Dupré Bernard
Gaillardet Jérôme
No associations
LandOfFree
A global geochemical mass budget applied to the Congo basin rivers: Erosion rates and continental crust composition does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with A global geochemical mass budget applied to the Congo basin rivers: Erosion rates and continental crust composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A global geochemical mass budget applied to the Congo basin rivers: Erosion rates and continental crust composition will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-827114