%0 Conference Proceedings %T THE LAKE ALBERT RIFT (UGANDA, EAST AFRICAN RIFT SYSTEM):SEDIMENT BUDGET, DEFORMATION, BASIN AND RELIEF EVOLUTIONSINCE 17 MA %+ 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 %B International Meeting of Sedimentology 2017 %C Toulouse, France %3 Abstract book %P 833 %8 2017-10-10 %D 2017 %Z Sciences of the Universe [physics]/Earth Sciences/Stratigraphy %Z Sciences of the Universe [physics]/Earth Sciences/GeomorphologyConference papers %X The purpose of this study was to quantify the sediment budget, from the catchment to the basin, of anintra-continental rift: the Albertine Rift system located at the northern part of the western branch of the EastAfrican Rift. The measurement of deposited volumes of sediments is based on the basin infilling study whichconsists on both subsurface data and outcrops analysis. The main objectives were (1) to obtain an age modelbased on onshore mammals biozones and (2) to reconstruct the 3D architecture of the rift using sequencestratigraphy correlations and seismic data interpretation. Deformation evolution of the rift through times ischaracterized according to seismic interpretation and to the distribution and quantification of theaccommodation for several time intervals. Two major unconformities were identified and dated at 6.2 Ma(Uppermost Miocene) and 2.7 Ma (Pliocene-Pleistocene boundary), coeval with major subsidence and climaticchanges.The landforms analysis is based on the characterization, relative dating (geometrical re- lationships withvolcanism) and 3D mapping of Ugandan landforms which consist of stepped planation surfaces (etchplainsand pediplains) and incised valleys.We here proposed a seven-steps reconstruction of the deformation-erosion-sedimentation re- lationshipsof the Lake Albert Basin and its catchments.- <45 Ma (Lower-Middle Eocene): formation of laterites corresponding to the African Surface duringthe very humid period of the Lower-Middle Eocene;- 45-22 Ma (Upper Eocene to Lowermost Miocene): stripping of the African Surface in response of thebeginning of the East-African Dome uplift and formation of a pediplain as- sociated to the Atlantic Ocean baselevel;- 17-2.7 Ma (Uppermost Lower Miocene to Pliocene): initiation of the Lake Albert Basinaround 17 Ma and creation of local base levels (Lake Albert, Edward and George) on which threepediplains tend to adapt;° 17 Ma-6.2 Ma: ”low and diffuse deformation” stage (subsidence rate: 150-200 m/Ma;sedimentation rate 1.3 km3/Ma between 17 and 12 Ma and 0.6 km3/Ma from 12 to 6 Ma) – depocenterslocation is poorly controlled by fault;° 6.2 Ma-2.7 Ma: rift stage 1 (subsidence rate: > 500m/Ma up to 600-800 m/Ma; sedimentationrate: 2.4 km3/Ma) – rifting climax;- 2.7-0.4 Ma (Lower to Middle Pleistocene): rift stage 2; uplift of the Ruwenzori Mountains andshifting from an alluvial system to a network of bedrock river incisions (subsidence rate: 450 to 250 m/Ma;sedimentation rate: 1.5 km3/Ma);- 0.4-0 Ma (Middle to Upper Pleistocene): long wavelength downwarping of the Tanzanian Craton,initiation of the Lake Victoria trough, drainage network inversion and uplift of the present-day Ugandanescarpment.The sediment budget is successful with, between 17 and 2.7 Ma, an excess of 16 % of up-streameroded material compared to the sediment volume deposited that can be explained by the chemical erosionprevailing at this period in Central Africa. The significant (60%) opposite difference between 2.7 and 0 Mamay be the consequence of a high sediment supply resulting from the erosion of the uplifted RuwenzoriMountains. %G English %L insu-01718209 %U https://insu.hal.science/insu-01718209 %~ INSU %~ UNIV-RENNES1 %~ UR2-HB %~ CNRS %~ GR %~ OSUR %~ GIP-BE %~ UR1-HAL %~ UR1-SDLM %~ GR-PPDB %~ UNIV-RENNES2 %~ TEST-UR-CSS %~ UNIV-RENNES %~ INRAE %~ UR1-ENV %~ GR-SE %~ GR-R %~ TEST3-HALCNRS %~ TEST4-HALCNRS %~ TEST5-HALCNRS