IMPACT OF HINTERLAND EVOLUTION IN MINERALOGY OF CLASTICS SEDIMENTS: PRESENTATION OF A NEW PROJECT FOCUS ON THE MOZAMBIQUE MARGIN DURING MESO-CENOZOIC TIMES
Résumé
The early stage of oil exploration in sedimentary basins is based both on large scale tectonostratigraphic
approach from previous works and conventional imaging data mostly well-logs and 2D seismic. In particular
geologists face to the lack of model to be able to better predict the reservoir presence and quality of undrilled
basins. The source-to-Sink studies (“S2S”) on modern or recent systems are of particular interest because they
aim to understand and quantify the link from the source/hinterland area (drainage area, nature of the bedrock,
climate and topography) to the sink/basin (slope gradient, shelf size, eustasy and sedimentary process). The
application of this S2S approach on ancient sedimentary systems is challenging because of the lack of
constraints of some controlling factors like the climate, the composition of the source material, the location
and altitude of paleo-reliefs or the extent of the drainage area. Our aim is to explore if there is a way to
anticipate the impact of the tectonic /geodynamic and climatic evolution of a hinterland on clastic
accumulations in the basin and their related mineralogical composition in the basin using the same data-set
that can be obtained during an early exploration phase.
The Mozambique margin during Meso-and Cenozoic times is a well-documented S2S system. The ongoing
studies by G. Baby, J-P. Ponte PHD’s respectively on the South African Plateau and Mozambique
Margin provide through times: 1) in the source area, valuable mapping of weathering paleosurfaces that allow
to constraint the drainage areas and volume of eroded sediments and synthesis of thermochronology data and
2) in the basin, regional seismic interpretations, paleogeographic maps, quantification of deposited sediments
based on news biostratigraphical data. Knowledge of climate evolution during the Cretaceous is improved by
palynologic studies from wells done by TOTAL.
Here, we present a new project which will focus on the lithological and mineralogical records on cuttings
from two old exploration wells. In order to recognize the impact of provenance, climate, diagenesis and
transport processes on sediments mineralogy, we focus on the signature of the sandstones including
petrographical analysis (E. Garzanti; Milan University), heavy mineral quantification (S. Ando; Milan
University) and U/Pb datation on zircon. We will also quantify along the two wells the clay mineralogical
association of lutites by XRD analysis.