TY  - JOUR
A1  - Nishihara, Yu
A1  - Ohuchi, Tomohiro
A1  - Kawazoe, Takaaki
A1  - Spengler, Dirk
A1  - Tasaka, Miki
A1  - Kikegawa, Takumi
A1  - Suzuki, Akio
A1  - Ohtani, Eiji
T1  - Rheology of fine-grained forsterite aggregate at deep upper mantle conditions
JF  - Journal of geophysical research : Solid earth
KW  - high-pressure
KW  - olivine
KW  - rheology
KW  - upper mantle
Y1  - 2014
U6  - https://doi.org/10.1002/2013JB010473
SN  - 2169-9313
SN  - 2169-9356
VL  - 119
IS  - 1
SP  - 253
EP  - 273
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Vinnik, Lev
A1  - Silveira, Graca
A1  - Kiselev, Sergei
A1  - Farra, Veronique
A1  - Weber, Michael H.
A1  - Stutzmann, Eleonore
T1  - Cape verde hotspot from the upper crust to the top of the lower mantle
JF  - Earth & planetary science letters
N2  - We investigate the crust, upper mantle and mantle transition zone of the Cape Verde hotspot by using seismic P and S receiver functions from several tens of local seismograph stations. We find a strong discontinuity at a depth of similar to 10 km underlain by a similar to 15-km thick layer with a high (similar to 1.9) Vp/Vs velocity ratio. We interpret this discontinuity and the underlying layer as the fossil Moho, inherited from the pre-hotspot era, and the plume-related magmatic underplate. Our uppermost-mantle models are very different from those previously obtained for this region: our S velocity is much lower and there are no indications of low densities. Contrary to previously published arguments for the standard transition zone thickness our data indicate that this thickness under the Cape Verde islands is up to similar to 30 km less than in the ambient mantle. This reduction is a combined effect of a depression of the 410-km discontinuity and an uplift of the 660-km discontinuity. The uplift is in contrast to laboratory data and some seismic data on a negligible dependence of depth of the 660-km discontinuity on temperature in hotspots. A large negative pressure-temperature slope which is suggested by our data implies that the 660-km discontinuity may resist passage of the plume.
 Our data reveal beneath the islands a reduction of S velocity of a few percent between 470-km and 510-km depths. The low velocity layer in the upper transition zone under the Cape Verde archipelago is very similar to that previously found under the Azores and a few other hotspots. In the literature there are reports on a regional 520-km discontinuity, the impedance of which is too large to be explained by the known phase transitions. Our observations suggest that the 520-km discontinuity may present the base of the low-velocity layer in the transition zone.
KW  - hotspot
KW  - plume
KW  - crust
KW  - upper mantle
KW  - mantle transition zone
KW  - receiver function
Y1  - 2012
U6  - https://doi.org/10.1016/j.epsl.2011.12.017
SN  - 0012-821X
VL  - 319
IS  - 4
SP  - 259
EP  - 268
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Zobir, Soraya Hadj
A1  - Oberhänsli, Roland
T1  - The sidi Mohamed peridotites (Edough Massif, NE Algeria) - evidence for an upper mantle origin
JF  - Journal of earth system science
N2  - The Hercynian Edough massif is the easternmost crystalline massif of the Algerian coast. It consists of two tectonically superposed units composed of micaschists, gneisses, and peridotite. This study concentrates on the small and isolated Sidi Mohamed peridotite outcrop area (0.03 km(2)). The Sidi Mohamed peridotite is composed mainly of harzburgites (Mg-rich olivine and orthopyroxene as major minerals). The Ni (2051-2920 ppm), Cr (2368-5514 ppm) and MgO (similar to 28-35 wt.%) whole-rock composition and the relative depletion in Nb make these harzburgites comparable to depleted peridotites related to a subduction zone. We suggest that the Sidi Mohamed ultramafic body was derived directly from the upper mantle and tectonically incorporated into the gneiss units of the Edough metamorphic core complex in a subduction environment.
KW  - Peridotites
KW  - upper mantle
KW  - Edough
KW  - Algeria
Y1  - 2013
U6  - https://doi.org/10.1007/s12040-013-0358-z
SN  - 0253-4126
SN  - 0973-774X
VL  - 122
IS  - 6
SP  - 1455
EP  - 1465
PB  - Indian Academy of Science
CY  - Bangalore
ER  -