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Andréa Tommasi

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Marine geologist
Andréa Tommasi
Alma materUniversité de Montpellier
Scientific career
InstitutionsGeosciences Montpellier
French National Centre for Scientific Research (CNRS)
ThesisDéveloppement de systèmes de décrochements d'échelle continentale dans une lithosphère hétérogène : cas naturels et modélisation numérique (1995)

Andréa Tommasi is a geoscientist from Brazil known for her research on geodynamics and terrestrial deformation. She is a recipient of the CNRS silver medal and an elected fellow of the American Geophysical Union.

Education and career

Tommasi earned her Ph.D. from the University of Montpellier in 1995. Following her Ph.D., she was a postdoc at the University of Leeds from 1997 until 1998. In 1998 she joined the faculty of the French National Centre for Scientific Research (CNRS). As of 2020, Tommasi is the research director of the Geosciences Laboratory at the University of Montpellier.

In 2016, Tommasi was elected a fellow of the American Geophysical Union who cited her "for pioneering work on deformation mechanisms and microstructures within the Earth and their impact on plate tectonics".

Research

Tommasi's early research was on deformation of rocks in the Dom Feliciano Belt in Brazil. Her research includes the development of numerical models to study seismic anisotropy and continental rifting. Tommasi's research extends to locations around the globe including Siberia, the Avacha volcano in Kamchatka, Hawaii, and the Southwest Indian Ridge.

Tomassi’s research utilizes preferred lattice orientation and seismic property analysis of mineral grains, laboratory deformation experiments, and numerical modeling including viscoplastic self-consistent and equilibrium based models. She also utilizes x-ray fluorescence analysis, electron probe analysis, and field relationships of mantle rock to contribute to scientific understanding of mantle processes and deformation.

Notable publications

Tomassi has collaborated on over 150 articles since 1989, with publications cited more than 9,000 times overall. Her most cited paper is Tomassi et al. (2000), followed by le Roux et al. (2007) and Mainprice et al. (2005).

Tomassi et al. (2000) created models accurately capturing the development of mineral alignment (lattice preferred orientation) of olivine and seismic anisotropy in response to upper mantle plastic flow. The anisotropic viscoplastic self-consistent model had the best correlation to natural and experimental observations of how olivine alignment during deformation affects seismic properties, as S-wave and P-wave propagation prediction errors were less than 15º off. While equilibrium-based models are slightly less accurate, the authors note that they still save a significant amount of computation time. These models describing mineral alignment on the small scale have implications for analyzing geologic deformation on larger scales.

Le Roux et al. (2007) centers around the investigation of the Lherz Massif, a large body of mantle peridotite located in the French Pyrenees. This investigation concerned the history of lherzolite in the Lherz body, which was previously considered to be pristine, minimally altered mantle rock. Le Roux et al. (2007) suggests that much of this lherzolite is not pristine mantle, based on geochemical analysis and structural relationships between the lherzolite and adjacent harzburgite, which is produced by the partial melting of lherzolite. Le Roux et al. (2007) suggests that if the lherzolite is an example of pristine mantle, then it must be older than the adjacent harzburgite. However, based on the cross-cutting relationship of the lherzolite and the harzburgite and a trace element comparison, the lherzolite is revealed to be younger. Thus, this paper argues that lherzolite is not an example of pristine mantle rock. Any research that uses the Lherz massif as a basis for conclusions regarding the mantle are therefore unsupported, and must be called into question.

The findings in Mainprice et al. (2005) challenges previous theories that olivine deforms via dislocation creep at depths above 250 km in the upper mantle, and via diffusion creep at deeper depths. This was believed to explain the presence of seismic anisotropy above 250 km depth, and little anisotropy below this depth. However, experiments performed in this study found that high pressure dislocation creep dominates the upper mantle below 250 km depth, but in a different slip direction, which produces little seismic anisotropy and can explain the observed change in anisotropy with depth.

Selected publications

Awards and honors

References

  1. ^ "Une bourse pour révolutionner la géodynamique". Université de Montpellier (in French). April 15, 2020. Archived from the original on 2020-05-24. Retrieved 2021-09-16.
  2. ^ "Andréa Tommasi | CNRS". www.cnrs.fr (in French). 13 February 2020. Retrieved 2021-09-16.
  3. ^ "Tommasi". Honors Program. Retrieved 2021-09-16.
  4. Tommasi, Andréa; Vauchez, Alain; Femandes, Luis A. D.; Porcher, Carla C. (1994). "Magma-assisted strain localization in an orogen-parallel transcurrent shear zone of southern Brazil". Tectonics. 13 (2): 421–437. Bibcode:1994Tecto..13..421T. doi:10.1029/93TC03319. ISSN 1944-9194.
  5. Fernandes, L.A.D.; Tommasi, A.; Porcher, C.C. (1992-01-01). "Deformation patterns in the southern Brazilian branch of the Dom Feliciano Belt: A reappraisal". Journal of South American Earth Sciences. 5 (1): 77–96. Bibcode:1992JSAES...5...77F. doi:10.1016/0895-9811(92)90061-3. ISSN 0895-9811.
  6. Tommasi, Andréa (1998). "Forward modeling of the development of seismic anisotropy in the upper mantle". Earth and Planetary Science Letters. 160 (1–2): 1–13. Bibcode:1998E&PSL.160....1T. doi:10.1016/S0012-821X(98)00081-8.
  7. Tommasi, Andréa; Tikoff, Basil; Vauchez, Alain (1999). "Upper mantle tectonics: three-dimensional deformation, olivine crystallographic fabrics and seismic properties". Earth and Planetary Science Letters. 168 (1–2): 173–186. Bibcode:1999E&PSL.168..173T. doi:10.1016/S0012-821X(99)00046-1.
  8. Tommasi, Andréa; Vauchez, Alain (2001-02-15). "Continental rifting parallel to ancient collisional belts: an effect of the mechanical anisotropy of the lithospheric mantle" (PDF). Earth and Planetary Science Letters. 185 (1–2): 199–210. Bibcode:2001E&PSL.185..199T. doi:10.1016/S0012-821X(00)00350-2. S2CID 54618989.
  9. Tommasi, Andréa; Vauchez, Alain; Ionov, Dmitri A. (2008). "Deformation, static recrystallization, and reactive melt transport in shallow subcontinental mantle xenoliths (Tok Cenozoic volcanic field, SE Siberia)". Earth and Planetary Science Letters. 272 (1–2): 65–77. Bibcode:2008E&PSL.272...65T. doi:10.1016/j.epsl.2008.04.020.
  10. Soustelle, V.; Tommasi, A.; Demouchy, S.; Ionov, D. A. (2010-01-01). "Deformation and Fluid-Rock Interaction in the Supra-subduction Mantle: Microstructures and Water Contents in Peridotite Xenoliths from the Avacha Volcano, Kamchatka". Journal of Petrology. 51 (1–2): 363–394. doi:10.1093/petrology/egp085. ISSN 0022-3530.
  11. Tommasi, Andréa; Mameri, Lucan; Godard, Marguerite (2020). "Textural and Compositional Changes in the Lithospheric Mantle Atop the Hawaiian Plume: Consequences for Seismic Properties" (PDF). Geochemistry, Geophysics, Geosystems. 21 (8): e2020GC009138. Bibcode:2020GGG....2109138T. doi:10.1029/2020GC009138. ISSN 1525-2027. S2CID 219658482.
  12. Bickert, M.; Cannat, M.; Tommasi, A.; Jammes, S.; Lavier, L. (2021). "Strain Localization in the Root of Detachment Faults at a Melt-Starved Mid-Ocean Ridge: A Microstructural Study of Abyssal Peridotites From the Southwest Indian Ridge" (PDF). Geochemistry, Geophysics, Geosystems. 22 (5). Bibcode:2021GGG....2209434B. doi:10.1029/2020GC009434. ISSN 1525-2027. S2CID 234807912.

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