Structural Geology; Surface Processes; Basin Analysis; Lithospheric Extension; Numerical Modelling
I am a tectonician/structural geologist and currently I am a Research Fellow at the University of Leeds.
My primary discipline of research is lithospheric deformation leading to the formation of rifted margins and its expression at the Earth’s surface. My research combine a variety of methods and tools at different scales, such as fieldwork, geophysics, geochronology, and numerical modelling.
I started working on rifted margins during my MSc at the University of Strasbourg when I did my research project with Gianreto Manatschal on the deformation processes related to mantle exhumation at the Ocean-Continent transition. Using direct field observations from ancient margins exposed in the Alps (Platta, Eastern Switzerland), petrological studies, and geophysical data from the present-day Iberia margin, I tried to understand the processes of deformation leading to the lithospheric rupture at magma-poor rifted margins.
I then did my PhD at the Vrije Universiteit of Amsterdam where I worked on the Central Atlantic margins, with a special focus on the NW African rifted margin and its NE American conjugate. My work consisted on combining structural geology, basin analysis, seismic data, low-temperature geochronology (Fission tracks and (U/Th)He analysis), and numerical modeling to (i) understand the kinematic evolution of the conjugate margins of Morocco and eastern North America, (ii) quantify horizontal and vertical movements taking place during and after rifting, and (iii) link surface deformation and topography formation to deep (mantle) processes at a regional scale.
I started my postdoctoral research at Memorial University of Newfoundland where I was part of a North Atlantic plate reconstruction project. I focused mainly on the Orphan basin located offshore Newfoundland (Eastern Canada). The aim was to quantify crustal extension in the basin related to the Mesozoic Atlantic rifting, reconstruct the brittle structures which guided deformation, explore the relationship between crustal and subcrustal thinning, and finally propose an evolutionary model for the basin and compare it with other basins along the Newfoundland margin and the conjugate on the European side.
Before coming to Leeds, I was a Research Associate in a large project (CMIC-Footprints) investigating the footprint of unconformity-type Uranium ore deposits. The project aims at integrating different approaches and datasets (geological, geochemical, mineralogical, petrophysical, and geophysical) to improve undercover exploration by better understanding the ore-system footprint and identifying its extent in three dimensions.
My primary research interest is to investigate the processes of lithospheric deformation and their expression at the Earth’s surface. The main focus of this research to date has been on processes governing lithospheric extension, which is expressed in the structural and tectonic style of continental rifts, the amount of horizontal and vertical motions occurring during and following rifting, and the relationship between deep mantle lithosphere processes and surface topography in the rift basins and adjacent domains. Examining lithospheric deformation requires a multi-skill approach that enables the integration of various geological and analytical techniques at different scales. Thereby, in my research I combine: fieldwork and geophysical data (e.g. seismic, gravity, and magnetic data) to illustrate the structural style and the tectonic of crustal deformation; geochronology and thermochronology to date deformation and quantify vertical movements; and numerical modelling to perform basin analysis and investigate tectonic processes at various scales (surficial, crustal, and mantle) and their interaction.
My previous and ongoing research can be divided into three interrelated topics: rifting of continental lithosphere; post-rift vertical movements along rifted continental margins; and continental heat flow variations in time and space.
Rifting of continental lithosphere
The processes that drive lithospheric extension and lead to continental breakup in rifted margins are still debated. Major questions remain to be answered regarding the role of inherited lithospheric heterogeneities in deformation, the processes controlling lithospheric thinning and stretching, and the role and timing of low-angle detachment faults in mantle exhumation and continental breakup. My work on lithospheric extension is focused on the eastern and western Atlantic margins where rift systems show a large variability in the style and the geometry of crustal deformation. However, they are all characterized by widely distributed upper crustal stretching, localized lithosphere thinning, exhumed mantle in the Ocean-Continent transition zone, and discrepancies between horizontal stretching and vertical thinning. Observations from the Moroccan margin in the Central Atlantic and the Newfoundland margin in the North Atlantic suggest that pre-rift lithospheric heterogeneities (e.g. inherited lateral variation in thickness and rheology, and inherited large-scale structures) play a key role during rifting, and should be considered when building quantitative models to describe the tectonic evolution during lithospheric deformation.
Post-rift vertical movements along rifted margins
The evolution of Atlantic-type rifted margins following continental breakup is often described as mainly controlled by the thermal cooling of the rifted lithosphere, which is expressed by subsidence and deposition of thick post-rift sedimentary sequences. However, low-temperature geochronology data from many domains on both sides of the Atlantic reveal the existence of major km-scale upward (subsidence) and downward (uplift and denudation) motions in the upper crust. The timing, vertical magnitude, and lateral extent of these vertical movements is intriguing as they occur shortly after the initiation of ocean floor spreading and affect large domains that extend few hundred kilometers away from the (preserved) rift systems. My research concentrates on investigating the role of mantle lithosphere processes (e.g. small-scale convection cells in the mantle lithosphere; phase change at the base of the crust), intra-plate stresses, and lithospheric heterogeneities (e.g. inherited structures and rheological weaknesses) in generating crustal uplift and surface topography. Coupled thermo-mechanical modelling that integrates field and subsurface observations indicate that mantle lithosphere processes needs to be enhanced/coupled with intra-plate compressional deformation (far field stresses transmitted through the lithosphere) to explain km-scale uplift of the upper crust. This is coherent with post-rift shortening reactivations documented in many Atlantic rifted margins.
Continental heat flow variations in time and space
My interest in continental heat flow started recently with the necessity to accurately convert the temperature history obtained from low-temperature geochronology data to vertical motions. Most of the studies that investigate vertical movements of the Earth’s surface using thermochronology data (e.g. Fission tracks and (U-Th)/He on apatites or zircons) rely on constant geothermal gradients, which are usually derived from present-day measurements of surface heat flow. However, it is known that the thermal state of continental lithosphere evolves with time and is greatly influenced by the thermal state of the mantle and the active crustal tectonic processes (erosion, sedimentation, magmatism, etc.). Understanding the interaction between these processes and their impact on surface heat flow is crucial for the quantification of vertical motions in the crust and the resulting surface topography.
In the future I would like to build on my current research topics with projects aimed at investigating:
Seismic methods in Petroleum geology.
Gouiza, M., J. Hall, and G. Bertotti (2014), Rifting and pre-rift lithosphere variability in the Orphan Basin, Newfoundland margin, eastern Canada, Basin Research, doi:10.1111/bre.12078.
Bertotti, G., and M. Gouiza (2012), Post-rift vertical movements and horizontal deformations in the eastern margin of the Central Atlantic: Middle Jurassic to Early Cretaceous evolution of Morocco, International Journal of Earth Sciences,doi:10.1007/s00531-012-0773-4.
Gouiza, M.(2011), Mesozoic Source-to-Sink Systems in NW Africa: Geology of vertical movements during the birth and growth of the Moroccan rifted margin, PhD Thesis, ISBN: 978-90-8570-428-7, VU University Amsterdam, Netherlands. (Link to download a complete copy of the thesis: http://dare.ubvu.vu.nl/bitstream/1871/24498/1/dissertation.pdf).
Gouiza, M., G. Bertotti, M. Hafid, and S. Cloetingh (2010), Kinematic and thermal evolution of the Moroccan rifted continental margin: Doukkala-High Atlas transect, Tectonics, 29, 22 PP., doi:201010.1029/2009TC002464.
Manatschal, G., Y. Lagabrielle, O. Munterer, A.M. Karpoff, J.B. Edel, G. Péron-Pinvidic, G. Mohn, and M. Gouiza (2006). La Transition Océan-Continent (TOC) préservée dans les Alpes : un cas unique pour comprendre l’amincissement des marges continentales et le début de l’océanisation. Abstract volume Colloque du GDR-Marges, Paris, 28 to 30/3/06; p. 37