A SOURCE TO SINK MEASUREMENT METHOD IN ANOROGENIC SETTINGS.

Cécile Robin (1) , François Guillocheau (1) , Jean Braun (2) , Delphine Rouby (3) , Brendan Simon (1) , Paul Bessin (4, 5) , Guillaume Baby (1)

1 GR - Géosciences Rennes
2 GFZ - German Research Centre for Geosciences - Helmholtz-Centre Potsdam
3 GET - Géosciences Environnement Toulouse
4 LPG - Laboratoire de Planétologie et Géodynamique [UMR 6112]
5 LPG - Le Mans - Laboratoire de Planétologie et Géodynamique - Géosciences Le Mans

We developed a double method for measuring both deposited sediment volumes (sink) based on basins stratigraphy and eroded rock volumes in upstream catchments (source) based on geomorphology. This method was drafted in Africa - characterized by large plateaus and plains surrounded by passive margins and interior basins (sags and rifts) - in the frame of the TopoAfrica project funded by the French Research Agency ANR. Measurement of deposited sediment volumes: This measurement is based on subsurface data (seismic lines and wells) in passive margin or rifts/sags. • Biostratigraphic dating of reference wells and definition of a regional sequence stratigraphic framework based on key seismic lines, • Isochore maps from the regional propagation of key time-lines, • Depth conversion of the isochore to isopach maps, • Compaction of the sediments (knowledge of the lithology and the porosity), • Measurement of the compacted volumes and quantification of the uncertainties based on the software Volume Estimator developed by J. Braun. Measurement of the eroded volumes: This study is based on the mapping of the characteristic landforms of the anorogenic reliefs: the planation surfaces. • Analysis and relative chronology of the different stepped planation surfaces: etchplains and pediments/pediplains, and their associated incised valleys, • Dating of the planation surfaces based on the dating (when they exist) of (1) the thin sediment covers, (2) the contemporaneous magmatism and/or (3) the weathering profiles (magnetostratigraphy, geochronology, chemostratigraphy..), • Mapping of the relevant planation surfaces, • Reconstruction of the successive topographies by restoring the initial shape of the eroded planation surfaces by younger landforms, • Measurement of the eroded volumes.

Domaines: Stratigraphie

Cécile Robin, François Guillocheau, Jean Braun, Delphine Rouby, Brendan Simon, et al.. A SOURCE TO SINK MEASUREMENT METHOD IN ANOROGENIC SETTINGS.. Source to Sink: a long term perspective of sediment budgets and sources characterization, Géosciences-Rennes, Nov 2016, Rennes, France. pp.89. ⟨insu-01406567⟩