%0 Conference Proceedings %T A «SOURCE TO SINK» APPROACH OF THE LAKE ALBERT RIFT(UGANDA, EAST AFRICAN RIFT SYSTEM):RELATIONSHIPS BETWEEN SEDIMENTARY BASINAND UPSTREAM LANDFORMS %+ Géosciences Rennes (GR) %+ TOTAL S.A. %A Simon, Brendan %A Guillocheau, François %A Robin, Cécile %A Dauteuil, Olivier %A Dall’asta, Massimo %< 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 95-96 %8 2016-11-30 %D 2016 %Z Sciences of the Universe [physics]/Earth Sciences/Stratigraphy %Z Sciences of the Universe [physics]/Earth Sciences/GeomorphologyConference papers %X This study is based on a coupled basin infilling study and a landforms analysis of the LakeAlbert Rift located at the northern part of the western branch of the East African Rift.The basin infilling study is based on both subsurface data and outcrops analysis. Theobjective was to (1) actualize age model, (2) to reconstruct the 3D architecture of the rift usingsequence stratigraphy correlations and seismic data interpretation, (3) to characterize the deformationand its changes through times and (4) to quantify the accommodation for severaltime intervals. The infilling essentially consists of isopach fault-bounded units composed oflacustrine deposits wherein were characterized two major unconformities dated at 6.2 Ma (UppermostMiocene) and 2.7 Ma (Pliocene-Pleistocene boundary), coeval with major subsidenceand climatic changes.The landforms analysis is based on the characterization and relative dating of Ugandanlandforms which consist of stepped planation surfaces and incised valleys.We here proposed a seven-steps reconstruction of the deformation-erosion-sedimentationrelationships of the Lake Albert Basin and its catchments:- 55-45 Ma: formation of laterites corresponding to the African Surface during the veryhumid period of the Lower-Middle Eocene;- 45-22: stripping of the African Surface in response of the beginning of the East-AfricanDome uplift and formation of a pediplain which associated base level is the AtlanticOcean;- 17-2.5 Ma: Initiation of the Lake Albert Basin around 17 Ma and creation of local baselevels (Lake Albert, Edward and George) on which three pediplains tend to adapt;- 18—16 Ma to 6.2 Ma: «Flexural» stage (subsidence rate: 150-200 m/Ma; sedimentationrate 1.3 km3/Ma between 17 and 12 Ma and 0.6 km3/Ma from 12 to 6 Ma) – depocenterslocation (southern part of Lake Albert Basin) poorly controlled by fault;- 6.2 Ma to 2.5 Ma: Rift stage 1 (subsidence rate: > 500m/Ma up to 600-800 m/Ma; sedimentationrate: 2.4 km3/Ma) – Rifting climax;- 2.5-0.4 Ma: uplift of the Ruwenzori Mountains and shifting from an alluvial system to anetwork of bedrock river incision – Rift Stage 2 (subsidence rate: 450 to 250 m/Ma; sedimentationrate: 1.5 km3/Ma);- 0.4-0 Ma: long wavelength downwarping of the Tanzanian Craton, initiation of the LakeVictoria trough, drainage network inversion and uplift of the present-day Ugandan escarpment(normal faulting motion of the border faults) with formation of perched valleysassociated to the Lower Pleistocene (2.5-0.4 Ma) rivers network.The sediment budget is successful with, between 17 and 2.5 Ma, an excess of 16 % ofupstream eroded material compared to the sediment volume deposited that can be explainedby the chemical erosion prevailing at this period in Central Africa. The significant (60%)opposite difference between 2.7 and 0 Ma may be the consequence of a high sediment supplyresulting from the erosion of the uplifted Ruwenzori Mountains. %G English %L insu-01406577 %U https://insu.hal.science/insu-01406577 %~ 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-SE %~ GR-R %~ TEST3-HALCNRS