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ISTeP - UMR 7193
Institut des Sciences de la Terre de Paris

Bourgois Jacques

Equipe : Lithosphère, structure et déformation

Directeur de recherche émérite

UPMC - Campus Jussieu, Tour 46-00, 3e étage - Case courrier 109

Tél : 01 44 27 59 98 - jacques.bourgois@upmc.fr

Thèmes de recherche

Since about 10 years, part of my studies focused at the interface of tectonics, oceanography, and climatology. The main objective is to understand the feedback processes between climate and tectonic deformation at the time scale of the glacial-interglacial cycle. Abrupt changes in the climate system induce tectonic responses including at the millennium time scale. To document these changes, to date them precisely and to understand the mechanisms require to use technique of analytical chemistry including 10Be cosmogenic isotopes.

Over the past ten years, my main contributions are related to the following topics :
(1) At the Chile triple junction area (Bourgois et al., 2000), the climate-induced variation of the sediment supply to the trench axis is the main factor controlling the continental margin tectonic regime. During the warm period of the interglacial episode at 117-130,000 years, rapid increase of the trench sediment accumulation caused the margin to switch from subduction-erosion or nonaccretion to subduction-accretion.
(2) Along the northwestern Peru forearc area (Bourgois et al., 2007), we infer that eustacy exerts important feedback coupling to seismic behavior of the Northern Peru subduction zone. We speculate that during sea level fall, pore-fluid pressure diminishes along the subduction channel inducing a possible seaward migration of the locked zone reaching a maximum by the end of the eustatic low stand at 19-23,000 years.
(3) At the Chile triple junction area (Bourgois et al., in progress), the major retreat of the northern Patagonia ice cap at 11-14,000 years controls the tectonic rebound of this segment of the Andes, and the funneling of the Andean runoff to the Pacific.

Selected references
Bourgois J., Bigot-Cormier F., Bourles D., Braucher R., Dauteuil O., Witt C., Michaud F., northwestern Peru coastal plain, and continental slope during the past 200 kyr. Journal of Geophysical Research, 112, B04104, doi:10.1029/2006JB004491.
Bourgois, J., Guivel C., Lagabrielle Y., Calmus T., Boulègue J., Daux, V., 2000 Glacial-interglacial trench supply variation, spreading-ridge subduction, and feedback controls on the Andean margin development at the Chile triple junction area (45-48° S), Journal of Geophysical Research, 105, 8355-8386.

Recherches actuelles

- Relations tectonique climat : Evolution tectonique de la marge nord péruvienne à partir de l’enregistrement morphologique de l’évolution du niveau marin. 
- Relations tectonique climat : Réponse isostatique à la fonte de la calotte glaciaire patagonienne. 
- La subduction andine, faits et théories à partir de l’évolution de la marge continentale Nord péruvienne depuis 450 kyr.

Bibliographie récente

Articles

Bourgois, J., D. Bourles, and R. Braucher (2011), Reply to comment by K. Pedoja et al. on “Tectonic record of strain buildup and abrupt coseismic stress release across the northwestern Peru coastal plain, shelf, and continental slope during the past 200 kyr”, Journal of Geophysical Research, 116, 6 pages, B09402, doi:10.1029/2011JB008582.
- Bandy, W.L., Michaud, F., Mortera-Gutiérez, C.A., Dyment, J., Bourgois, J., Royer, J.-Y, Calmus, T., Sosson, M., and Ortega-Ramirez, J. (2010), The Mid-Rivera transform discordance: morphology and tectonic development, Pure and Applied Geophysics, DOI 10.1007/s00024-010-0208-8.
Bourgois, J., (2010), A comment on “Non-steady long-term uplift rates and Pleistocene marine terrace development along the Andean margin of Chile (31 °S) inferred from 10Be dating”, Earth and Planetary Science Letters, doi:10.1016/j.epsl.2010.05.018
- Witt, C., Bourgois, J. (2010), Forearc basin formation in the tectonic wake of a collision-driven, coastwise migrating crustal block : the example of the North Andean block and the extensional Gulf of Guayaquil-Tumbes basin (Ecuador-Peru Border area). Geological Society of America Bulletin, 122, p. 89-108, doi: 10.1130/B26386.1.
- Witt C., Bourgois J. 2009, Forearc basin formation in the tectonic wake of a collision-driven, coastwise migrating crustal block : the example of the North Andean block and the extensional Gulf of Guayaquil-Tumbes basin (Ecuador-Peru Border area). Geological Society of America Bulletin, in press.

Vulgarisation

- VIDEO : « Des cailloux et des hommes » (campagnes de plongées du Nautile, Chef de mission JB) durée 53 mn diffusée a la BBC, en Belgique et au Danemark.
- Article au "NOUVEL OBSERVATEUR", 1991, « VOYAGE AU CENTRE DE LA MER » N°1384, p. 108-113.
- Le courrier du CNRS Bourgois, J., 1990, LA TERRE DE L’OBSERVATION A LA MODELISATION. Le Courrier du CNRS, Dossiers Scientifiques n°76, Coordinateur du dossier, 120 pages.

Enseignement

Professeur à la Escuela Politecnica Nacional (EPN) de Quito (Equateur) de 2001 à 2006.

24/02/16

Traductions :

    Chiffres clés

    L'ISTeP comprend 155 membres dont :

    • 16 professeurs (dont 2 associés)
    • 28 maîtres de conférences
    • 2 directeurs de recherche
    • 4 chargés de recherche
    • 13 ATER et post-docs
    • 50 doctorants
    • 24 ITA-IATOS
    • 18 collaborateurs bénévoles (dont 9 émérites)