NARG Project: Mesozoic km-scale vertical movements in the rims of the Central Atlantic Ocean
Low-Temperature Thermochronology (LTT) potentially allows for the investigation of the cooling history of the upper part of Earth’s crust. In the Central Atlantic margins, the vast majority of LTT data was obtained in the domain adjacent to the rifted margins and a large portion of the ages correspond to the early post-rift phase.
To explain this, some authors have argued that the rift thermal signature outreached its rift zone, and affected the geothermal gradient of the unstreched continental crust, resulting in a reset of the LTT ages rapidly followed by cooling after continental break-up. Others have submitted tectono-climatic processes such as: i) far-field stresses, ii) enhanced erosion by climatic/landmass position change(s), and/or iii) dynamic topography.
To test the above-mentioned hypotheses, we compiled over 6000 LTT ages from the rim of the Central Atlantic Ocean. We discuss LTT spatial and temporal patterns in regards to the pre-, syn- (Triassic to Early Triassic), and post-rift phases. Further, we run a tailored geodynamic model in order to monitor the evolution of the Partial Annealing Zone through time in the unstretched continental crust.
2 manuscripts in preparation
NARG Project: Exhumation and landscape evolution modelling in NW Africa
Part 1: Exhumation data
Low-temperature thermochronology studies revealed major exhumation events affecting domains in the hinterland of the Central Atlantic margins, where Palaeozoic and/or Precambrian basement is exposed. Thus, domains traditionally assumed to be stable since at least the Variscan and juxtaposed to subsiding Meso-Cenozoic basins, appear to be affected by km-scale vertical movements during the Atlantic rifting and after the Early Jurassic breakup in the Central Atlantic. In this project, we investigate the extent and the magnitude of these motions along the NW African margin (Morocco-Mauritania-Senegal).
Part 2: Landscape Evolution Modelling
Paleo-altimetry, stratigraphy, and sediment budgets may be evaluated with numerical models commonly refered to as ‘Landscape Evolution Models’ (LEMs). Source-to-sink studies have limitations: the spatial and temporal resolution of each component for instance or the quality of the sedimentary record. This renders the examination of past source-to-sink systems a challenging task, however the range of possible outcomes can be partially addressed by building multiple models using process-based modelling tools such as LEMs. In NW Africa, the distribution of eroded sediments in the rifted margin is controlled by the drainage systems connected to the hinterland. However, most of paleo-river systems were not fossilised or are not exposed, resulting in a lack of data for their size, sediment flux, and entry-point position. In order to better understand Moroccan Mesozoic source-to-sink systems, we use the LEM ‘pyBADLANDS’ code (Salles et al., 2018). We input the timing, location and amplitude of exhumation events, as documented by low-temperature thermochronology data.
Mohamed Gouiza, Giovanni Bertotti, Rémi Charton, K. Haimoudane, I. Dunklan, and A. Anczkiewicz
in Journal of Geophysical Research Solid Earth, Volume 124 of November 2019
+ 2 manuscripts in preparation
NARG Project: GIS Database
The ‘NARG GIS Database’, is a long term geoscientific project conducted by the North Africa Research Group (NARG; http://www.narg.org.uk/). It aims at gathering geological features and knowledge generated by former, current, and future NARG members and displaying them on a ‘map’. The NARG GIS Database extends from 30°W to 50°E, and from 0°N to 40°N. It currently contains over 50 layers pertaining to geological research and petroleum exploration. It is designed and kept up-to-date by NARG members for the NARG sponsors and partners.
2 manuscripts in preparation
Ph.D Project: Phanerozoic Vertical Movements in Morocco
The project, supervised by Prof. G. Bertotti, Prof. J. Redfern, and Dr. J. Storms, focuses on the exhumation, erosion and sedimentation system, which developed during Jurassic to Cretaceous times in the passive continental margin of North West Africa. A large portion of Morocco experienced km-scale exhumation producing sediments that were transported by fluvial systems to the west and deposited onshore and offshore.
Our aim is to constrain the exhumation, erosion, distributary and depositional (onshore and offshore) patterns. Analysis of transitional successions outcropping in Morocco and of deep-water deposits seismically imaged offshore will provide a reconstruction of the depositional system.
This project is funded by ISES (The Netherlands Research Centre for Integrated Solid Earth Science) and supported by the NARG (North Africa Research Group) as part of the Early Cretaceous Morocco Project.
Rémi Charton, Giovanni Bertotti, Angel Arantegui, and Luc Bulot
in Journal of African Earth Sciences, Volume 141 of April 2018
Mohamed Gouiza, Rémi Charton, Giovanni Bertotti, Paul Andriessen, and Joep Storms
in International Journal of Earth Sciences, Volume 106 of March 2017
+ 2 manuscripts in preparation
M.Sc. Project: Diagenetic history of Middle Jurassic formations from the Paris Basin
The project was supervised by Dr. P.Y. Collin of the UMR 6282 at the University of Burgundy (Dijon) and funded by the Bureau de Recherches Géologiques et Minières (BRGM).
For the BRGM, the Paris Basin (France) is a potential location for deep geological storage of CO2. The “Oolithe Blanche” Formation (Bathonian, Middle Jurassic) and its lateral equivalent formations are currently studied for this purpose. The site suitability as a storage zone depends on its petrophysical properties (porosity/permeability), which are influenced by compaction and cementation.
Several sets of fluids (meteoric, marine or mixed) have circulated within these mainly oolitic formations at different times during their diagenetic history. To constrain the composition and the origin of these fluids, analyses of cement phases were conducted across the Paris Basin. From the northwestern Bathonian fringe in Normandy down to Poitou and Centre, nine sedimentological sections were selected in order to provide the base of this work. Forty thin sections were made out of these outcrops and analysed by microscopy, staining and cathodoluminescence.
Bathonian sediments have undergone the three diagenetic stages: eogenesis, mesogenesis and telogenesis. Parent fluids of mesogenetic cements are widely compared on the eastern side of the basin (geochemistry, ferrous content, luminescence) but not on the opposite side. This work shows that mesogenetic phases are clearly different across the Paris Basin. However, parent fluids origins, ages and paths were not well constrained.
Sophie Violette, Pierre-Yves Collin, Vincent Lagneau, Fabien Aubertin, Yasin Makhloufi, Rémi Charton, and Françoise Bergerat
in Comptes Rendus Geoscience, Volume 348 of September-October 2016