TY  - JOUR
A1  - Loprieno, Andrea
A1  - Bousquet, Romain
A1  - Bucher, Stefan
A1  - Ceriani, Stefano
A1  - Dalla Torre, Florian H.
A1  - Fügenschuh, Bernhard
A1  - Schmid, Stefan M.
T1  - The valais units in Savoy (France) a key area for understanding the palaeogeography and the tectonic evolution of the Western Alps
JF  - International journal of earth sciences
N2  - The Valais units in Savoy (Zone des BrSches de Tarentaise) have been re-mapped in great detail and are subject of combined stratigraphic, structural and petrological investigations summarized in this contribution. The sediments and rare relics of basement, together with Cretaceous age mafic and ultramafic rocks of the Valais palaeogeographical domain, represent the heavily deformed relics of the former distal European margin (External Valais units) and an ocean-continent transition (Internal Valais unit or Versoyen unit) that formed during rifting. This rifting led to the opening of the Valais ocean, a northern branch of the Alpine Tethys. Post-rift sediments referred to as "Valais trilogy" stratigraphically overlie both External and Internal Valais successions above an angular unconformity formed in Barremian to Aptian times, providing robust evidence for the timing of the opening of the Valais ocean. The Valais units in Savoy are part of a second and more external mid-Eocene high-pressure belt in the Alps that sutured the Brian double dagger onnais microcontinent to Europe. Top-N D1-deformation led to the formation of a nappe stack that emplaced the largely eclogite-facies Internal Valais unit (Versoyen) onto blueschist-facies External Valais units. The latter originally consisted of, from internal to external, the Petit St. Bernard unit, the Roc de l'Enfer unit, the MoA >> tiers unit and the Quermoz unit. Ongoing top-N D2-thrusting and folding substantially modified this nappe stack. Post 35 Ma D3 folding led to relatively minor modifications of the nappe stack within the Valais units but was associated with substantial top-WNW thrusting of the Valais units over the Dauphinois units along the Roselend thrust during W-directed indentation of the Adria block contributing to the formation of the arc of the Western Alps.
KW  - Alpine geology
KW  - Valais ocean
KW  - Palaeogeography
KW  - Structural geology
KW  - Tectonics
KW  - Metamorphism
Y1  - 2011
U6  - https://doi.org/10.1007/s00531-010-0595-1
SN  - 1437-3254
VL  - 100
IS  - 5
SP  - 963
EP  - 992
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Schmid, Florian
A1  - Petersen, Gesa M.
A1  - Hooft, Emilie E. E.
A1  - Paulatto, Michele
A1  - Chrapkiewicz, Kajetan
A1  - Hensch, Martin
A1  - Dahm, Torsten
T1  - Heralds of future volcanism: Swarms of microseismicity beneath the submarine Kolumbo volcano indicate opening of near-vertical fractures exploited by ascending melts
JF  - Geochemistry, geophysics, geosystems
N2  - The Kolumbo submarine volcano in the southern Aegean (Greece) is associated with repeated seismic unrest since at least two decades and the causes of this unrest are poorly understood. We present a ten-month long microseismicity data set for the period 2006-2007. The majority of earthquakes cluster in a cone-shaped portion of the crust below Kolumbo. The tip of this cone coincides with a low Vp-anomaly at 2-4 km depth, which is interpreted as a crustal melt reservoir. Our data set includes several earthquake swarms, of which we analyze the four with the highest events numbers in detail. Together the swarms form a zone of fracturing elongated in the SW-NE direction, parallel to major regional faults. All four swarms show a general upward migration of hypocenters and the cracking front propagates unusually fast, compared to swarms in other volcanic areas. We conclude that the swarm seismicity is most likely triggered by a combination of pore-pressure perturbations and the re-distribution of elastic stresses. Fluid pressure perturbations are induced likely by obstructions in the melt conduits in a rheologically strong layer between 6 and 9 km depth. We conclude that the zone of fractures below Kolumbo is exploited by melts ascending from the mantle and filling the crustal melt reservoir. Together with the recurring seismic unrest, our study suggests that a future eruption is probable and monitoring of the Kolumbo volcanic system is highly advisable.
KW  - aegean
KW  - hellenic volcanic arc
KW  - santorini
KW  - submarine volcanism
KW  - earthquake swarms
Y1  - 2022
U6  - https://doi.org/10.1029/2022GC010420
SN  - 1525-2027
VL  - 23
IS  - 7
PB  - American Geophysical Union
CY  - Washington
ER  -