%0 Conference Proceedings %T SOURCE TO SINK STUDY OF THE CONGO SYSTEM SINCE 40 MYR :A MEASUREMENT OF THE RATIO BETWEN MECHANICALAND CHEMICAL EROSION. %+ Géosciences Rennes (GR) %A Guillocheau, François %A Galmier, Valentin %A Robin, Cécile %< avec comité de lecture %( Source to Sink: a long term perspective of sediment budgets and sources characterization, Abstracts %B Source to Sink: a long term perspective of sediment budgets and sources characterization %C Rennes, France %P 62 %8 2016-11-30 %D 2016 %Z Sciences of the Universe [physics]/Earth Sciences/StratigraphyConference papers %X The erosional processes are of two types; mechanical and chemical. If the first one are extensivelystudied, the chemical ones are less known whether it is for the coupling between geomorphologicalprocesses and chemical alteration or two the knowledge of the ratio betweenmechanical and chemical erosion. In 1995 Gaillardet and coauthors proposed based on globalgeochemical mass budget of the modern Congo River, a ratio between physical and chemicalweathering of 1.5.To test this ratio, we here performed a source to sink study of the Congo System (catchmentand depositional system up to the abyssal plain) since 40 Myr, time interval during which theCongo catchment did not experience major climate changes.The continental denudation was measured by subtracting the present-day topographyfrom the so-called African Surface, etchplain (weathering surface) shaped between 70 and 40Ma. This etchplain is today preserved as remnant planation surfaces from the eastern limb ofthe East-African Dome to the high plateaus of Cameroon and Angola. The deposited volumeswere measured from seismic line and petroleum wells. Dated time-lines were drawn based onthe principles of the seismic stratigraphy. The measured volumes from the coastal to the abyssalplains were compacted for a better comparison with the eroded volumes.From 40 Ma to today, 799 000 km3 of rocks were denudated over the Congo River catchmentand 488 000 km3 of (compacted) sediments were deposited along the delta and thedeep-sea-fan. The ratio between eroded and deposited volumes is around 1,64 (1,3 – 2,1 includinguncertainties).In the absence of any type of buffer effect with temporary sediments storage along theCongo Basin, we interpret this difference of volume between erosion and sedimentation asthe amount of chemical erosion. The value is quite similar to this measured by Gaillardet et al.(1995). %G English %L insu-01406482 %U https://insu.hal.science/insu-01406482 %~ INSU %~ UNIV-RENNES1 %~ UR2-HB %~ CNRS %~ GR %~ OSUR %~ GIP-BE %~ UR1-HAL %~ UR1-SDLM %~ GR-PPDB %~ UNIV-RENNES2 %~ TEST-UNIV-RENNES %~ TEST-UR-CSS %~ UNIV-RENNES %~ INRAE %~ UR1-ENV %~ GR-R