EGU21-4669
https://doi.org/10.5194/egusphere-egu21-4669
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Continental Hotspots Tracks from Analysis of GOCE Gravity Gradients Data

Marianne Greff-Lefftz1, Isabelle Panet2, and Jean Besse1
Marianne Greff-Lefftz et al.
  • 1Université de Paris, Institut de physique du globe de Paris, CNRS, F-75005 Paris, France (greff@ipgp.fr)
  • 2Université de Paris, Institut de physique du globe de Paris, CNRS, IGN, F-75005 Paris, France

Hotspots are thermal instabilities that originate in the mantle and manifest themselves on the surface by volcanism, continental breaks or "traces" observed in the oceans. Theirs effects under the continents are still debated: in addition to a phase of activity associated with surface volcanism, a residual thermal anomaly could persist durably under the lithosphere along the trajectory of the hotspot.
For a simple model of thermal anomaly (parallelogram aligned in a fixed direction), we compute the perturbations of the geoid, of the gravity vector and of the associated gravity gradients. We show that in a coordinate system aligned with the parallelogram, gravity gradients have a characteristic signal with an order of magnitude of a few hundred mEotvos, well above the current data detection level. Thus for four real cases: in North Africa (with the Hoggar, Tibesti, Darfur and Cameroon hotspots), in Greenland (Iceland and Jan Mayen), in Australia (Cosgrove) and in Europe (Eifel), we calculate the paleo-positions of the hotspots during the last 100 Ma in a reference frame linked to the lithospheric plates, and we build maps of gravity gradients at different altitudes filtered at the spatial scale of a few hundred kilometers (scale of the hotspot) and oriented along the direction of the trajectory.
We clearly find signals aligned in the direction of the movement of the plates on spatial scales of a few hundred kilometers.
This signal is sometimes correlated with the topography and it is difficult to separate the sources resulting from volcanic edifices and their associated isostatic crustal roots from that induced by residual thermal anomaly. These results show that gradiometric data are able to detect and follow the tracks of hotspots in the continental lithosphere, during at least a few tens of millions of years, providing new clues to constrain their trajectory and improve reference frame tied to the mantle.

How to cite: Greff-Lefftz, M., Panet, I., and Besse, J.: Continental Hotspots Tracks from Analysis of GOCE Gravity Gradients Data, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4669, https://doi.org/10.5194/egusphere-egu21-4669, 2021.

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