SMARTIES

Type Oceanographic cruise
Ship Pourquoi pas ?
Ship owner Ifremer
Dates 13/07/2019 - 23/08/2019
Chief scientist(s) MAIA Marcia , BRUNELLI Daniele , LIGI Marco

GEO-OCEAN - UMR 6538

Univ. Brest, CNRS, Ifremer, Univ. Bretagne Sud

Place Nicolas Copernic

29280 Plouzané

https://www.geo-ocean.fr/
DOI 10.17600/18001107
Objective

Large-offset transforms, or mega-transforms, induce extreme cooling at the edge of axial ridge segments due to the associated enhanced age contrast and peculiar tectonics. The Equatorial Atlantic hosts several mega transforms, where the interactions between low mantle potential temperatures and large lithospheric age contrast with melt production are poorly understood. This proposal focuses on one of the largest transform faults in the oceans: the Romanche transform in the Equatorial Atlantic. The 950  km left stepping offset of the Mid Atlantic Ridge (MAR) axis results in an age contrast of about 55 My. As a consequence, a rather old, thick and cold lithosphere faces the warm axial segment tips on both sides of the transform. In particular, the eastern Ridge- Transform Intersection (RTI) shows the dramatic effects of the lateral cooling of the ridge segment. The style of spreading changes from normal to oblique when approaching the transform fault. Magmatism is reduced, or even absent, which is accompanied by a change of the accretionary style along the axial domain with the appearance of smoothseafloor (SSF)-like structures at the RTI.

In this proposal we intend first to complete the mapping of the region in order to recognize the boundaries of the SSF domain and its persistence through time. We will then explore in detail the change in deformation patterns on selected targets already identified from available bathymetric data. The detailed study will consist on the acquisition of a surface bathymetry with the largest possible resolution (about 30 m with low velocity - 5 knots - and high overlap) over the main targets and dives with the Nautile to acquire high-resolution images (video/photographs) of the structures as well as magnetic profiles and samples. The images will allow a detailed mapping of the fault and of the deformation patterns of different parts of the RTI, where we observed different, or contrasting, tetonic styles. Sampling is the second goal and a most important part of this proposal, as we intend to study rock compositions and rheological properties, with particular attention to the serpentinization process. The integrated study of rock characteristics and of geophysical surveys allows tackling the interactions between magmatism and tectonics. Direct observations and sampling will also help to understand the nature of the peculiar alkaline, water-rich, magmatism observed in the region.

One of the outcomes of this proposal is the understanding of the thermal regime at complex transform domains. Of particular interest is the existence of hydrothermal activity associated to the large mantle serpentinite exposures and its impact on the chemical and heat transfers from the seafloor to the hydrosphere in a poorly-known region.

 

Published data

Maia Marcia, Brunelli Daniele, Grenet Lea, Briais Anne, Hamelin Cedric (2023). SMARTIES cruise - Nautile videos of the axial domain of the Mid-Atlantic Ridge south of the Romanche transform fault. https://doi.org/10.17882/95946


Gregory Emma, Wang Zhikai, Singh Satish, Yu Zhiteng, Maia Marcia, Brunelli Daniele (2023). SMARTIES cruise - Ocean Bottom Seismometer (OBS) data - Datasets from OBS #1 to #9. https://doi.org/10.17882/96103


Data managed by SISMER

Dives

Bibliography

Publications

Yu Zhiteng, Singh Satish C., Maia Marcia (2023). Evidence for low Vp/Vs ratios along the eastern Romanche ridge-transform intersection in the equatorial Atlantic Ocean. Earth And Planetary Science Letters, 621, 118380 (11p.). https://doi.org/10.1016/j.epsl.2023.118380


Yu Zhiteng, Singh Satish, Grenet Lea, Maia Marcia, Hamelin Cédric, Briais Anne, Petracchini Lorenzo, Brunelli Daniele (2022). CO2 degassing in the mantle triggers deep earthquakes at the Mid-Atlantic Ridge. Preprint, (Version 1). Publisher's official version : https://doi.org/10.21203/rs.3.rs-1945608/v1 , Open Access version : https://archimer.ifremer.fr/doc/00795/90650/


Yu Zhiteng, Singh Satish C., Gregory Emma P. M., Maia Marcia, Wang Zhikai, Brunelli Daniele (2021). Semibrittle seismic deformation in high-temperature mantle mylonite shear zone along the Romanche transform fault. Science Advances, 7(15), eabf3388 (10p.). Publisher's official version : https://doi.org/10.1126/sciadv.abf3388 , Open Access version : https://archimer.ifremer.fr/doc/00689/80070/


Di Giuseppe Dario, Perchiazzi Natale, Brunelli Daniele, Giovanardi Tommaso, Nodari Luca, Della Ventura Giancarlo, Malferrari Daniele, Maia Marcia, Gualtieri Alessandro F. (2021). Occurrence and characterization of tremolite asbestos from the Mid Atlantic Ridge. Scientific Reports, 11(1), 6285 (12p.). Publisher's official version : https://doi.org/10.1038/s41598-021-85576-w , Open Access version : https://archimer.ifremer.fr/doc/00685/79703/


References of Technical Reports

Maia Marcia, Brunelli Daniele, Barre Ghislain, Bonnet Fiona, Briais Anne, Ceuleneer Georges, Cipriani Anna, Cuffaro Marco, Gregory Emma, Hamelin Cédric, Jbara Rim, Kaczmarek Mary-Alix, Lombardi Fabio, Martinez Roman Juan José, Mougel Bérengère, Soltanmohammadi Azam, Petracchini Lorenzo, Pina Figuls David, Puzenat-Vassor Valentine, Revillon Sidonie, Seyler Monique, Verhoest Léna, Wang Zhikai (2021). Campagne SMARTIES / SMARTIES Cruise (Smooth regions at the Mid-Atlantic Ridge Transform-Intersections under Extreme thermal gradientS). NO “Pourquoi Pas?” 13/07/2019 – 23/08/2019 – Mindelo-Mindelo, Cape Verde. https://archimer.ifremer.fr/doc/00838/95018/


SMARTIES Cruise report (2020)

References of International Seminar Communications

Justine Marie Charlotte Flahaut, Ewan Pelleter, Marcia Maia, Olivier Rouxel, Jessica Langlade, Sandrine Cheron, Audrey Boissier and Daniele Brunelli (2023). Geological, mineralogical, and geochemical characterization of an inactive ultramafic-hosted seafloor massive sulfide (SMS) deposit: Example of the RTI Romanche (MAR). Goldschmidt

Léa Grenet, Marcia Maia, Cédric Hamelin, Anne Briais, and Daniele Brunelli (2023). Construction of the neo-volcanic area of a slow-spreading ridge in a cold mantle context: Mid-Atlantic Ridge Eastern Intersection with Romanche Transform Fault. EGU general assembly, Vienna.

M. Maia, A. Briais, L. Petracchini, M. Cuffaro, M. Ligi, D. Brunelli, L. Grenet and C. Hamelin (2023). Temporal variation in spreading processes at the Eastern Romanche-Mid-Atlantic Ridge intersection. EGU general assembly, Vienna.

Léna Verhoest, Christophe Hemond, Philippe Nonnotte, Anna Cipriani, Federico Lugli, Marcia Maia and Daniele Brunelli. (2021) Cold Spots as a Tool to Reveal Short-Scale Mantle Heterogeneities. AGU Fall meeting

Zhiteng Yu, Satish Chandra Singh, Marcia Maia and Daniele Brunelli. (2021) Seismic observations in the eastern Romanche ridge-transform intersection (Equatorial Atlantic) from microseismicity data and seismic tomography. AGU Fall meeting

Maia M., Brunelli, D. and the SMARTIES Cruise Scientific Party. (2020). The Eastern Romanche ridge-transform intersection (Equatorial Atlantic): slow spreading under extreme low mantle temperatures. Preliminary results of the SMARTIES cruise. EGU 2020

Marcia Maia, Daniele Brunelli, Anne Briais, Lorenzo Petracchini and the SMARTIES scientific team. (2020). Axial instability and time evolution at an ultra-cold slow-spreading ridge: the Mid-Atlantic Ridge-Romanche transform intersection. First results from the SMARTIES cruise. AGU 2020 Fall Meeting

Marcia Maia, Daniele Brunelli, Cédric Hamelin, Anne Briais, Ghislain Barré, Léa Grenet and the SMARTIES scientific team. (2020). Interplay Between Volcanic and Tectonic Axial Processes in a Cold Slow-spreading Ridge: the Mid-Atlantic Ridge South of the Romanche Transform Fault. AGU 2020 Fall Meeting. INVITED

Yu, Z., Singh, S., Gregory, E., Crawford, W., Maia, M. and Brunelli, D. (2020). Microseismicity constrains on the lithospheric structure at the ridge-transform intersection at the Romanche Transform Fault and Mid-Atlantic Ridge. EGU 2020

References of National Seminar Communications

M. Maia, A. Briais, L. Petracchini, M. Cuffaro, M. Ligi, D. Brunelli, L. Grenet, C. Hamelin (2022). Tectonic deformation and variable magma supply along the Mid-Atlantic Ridge axis south of the Romanche transform fault. Annual meeting of the Italian Geological Society, Torino, Italy.

Maia, Marcia. 52 PGGM, On-line. (2021) Influence of large offset transform faults on spreading processes: the Romanche-MAR Eastern ridge-transform intersection. INVITED

Verhoest L., Nonnotte P., Cipriani A., Hémond C., Maia M., Lombardi F., Ballabio G., Brunelli D., Alkali-rich MORB from the Romanche Eastern Ridge-Transform Intersection, equatorial Atlantic. Invited talk presented at: Working Group on Mediterranean Ophiolites - Winter Meeting, Ofioliti, 45, Abstract volume, (2020).

Verhoest L., Brunelli D., Bonatti E., Ligi M., Cipriani A., 2019, Melting of an overcooled heterogeneous mantle, equatorial Mid-Atlantic Ridge. Poster presentation at: Pavia PhD School, Structure and composition of the Lower Continental Crust, Ofioliti, 45, Abstract volume, (2020).

Verhoest L., Brunelli D., Bonatti E., Ligi M., Cipriani A., Mantle source heterogeneity in the equatorial Mid-Atlantic Ridge: a multi-isotopic approach. Invited talk presented at: joint SIMP-SGI-SOGEI Congresso Nazionale Parma, Il tempo del pianeta Terra e il tempo dell'uomo: le geoscienze tra passato e futuro, (2019).

DEA or MASTER 2 using campaign data

Justine Flahaut (2022). Caracte?risation ge?ologique, mine?ralogique et ge?ochimique d'un de?po?t sulfure? fossile sur substrat ultramafique : exemple de la RTI Romanche. mémoire de Master 2. Université de Bretagne Occidentale

Barré, G. (2020). « Étude de l'architecture magmato-tectonique de la dorsale Médio-Atlantique, au Sud-Est de la fosse de la Romanche », Mémoire de M2, Mention « Sciences de la Terre, des planètes et de l'environnement », Géosciences Océan, Université de Bretagne Occidentale

Thesis using campaign data

Panetier Aurélie (2023). Shipborne Global Navigation Satellite Systems for Offshore Atmospheric Water Vapor Monitoring. PhD Thesis, ENSTA Bretagne.


Verhoest Léna (2022). Fusion d'un manteau terrestre hétérogène sous un gradient thermique extrême / Melting a heterogeneous Earth's mantle under an extreme thermal gradient. PhD Thesis, Université de Bretagne Occidentale, Universita Degli Studi di Modena.


Léna Verhoest (2022). Melting a heterogeneous Earth mantle under an extreme thermal gradient . Thèse en co-tutelle U. Modena, Italie et UBO, France. Soutenue en Novembre 2022.