FN Archimer Export Format
PT J
TI Crustal structure of the eastern Algerian continental margin and adjacent deep basin: implications for late Cenozoic geodynamic evolution of the western Mediterranean
BT 
AF BOUYAHIAOUI, B.
   SAGE, F.
   ABTOUT, A.
   KLINGELHOEFER, Frauke
   YELLES-CHAOUCHE, K.
   SCHNUERLE, P.
   MAROK, A.
   DEVERCHERE, Jacques
   ARAB, M.
   GALVE, A.
   COLLOT, J.Y.
AS 1:1;2:2;3:1;4:3;5:1;6:3;7:4;8:5;9:6;10:2;11:2;
FF 1:;2:;3:;4:PDG-REM-GM-LGG;5:;6:;7:;8:;9:;10:;11:;
C1 CRAAG, Algiers 16340, Algeria.
   UMPC, UNSA, CNRS, Geoazur,IRD, F-06560 Valbonne, France.
   Inst Francais Rech Exploitat Mer IFREMER, F-29280 Plouzane, France.
   Univ Tlemcen, Dept Earth & Universe Sci, Tilimsen 13000, Algeria.
   Univ Brest UBO, CNRS Domaines Ocean UMR6538, Inst Univ Europeen Mer, F-29280 Plouzane, France.
   Algerian Natl Oil Co, Sonatrach Explorat, Algiers, Algeria.
C2 CRAAG, ALGERIA
   UNIV PARIS 06, FRANCE
   IFREMER, FRANCE
   UNIV TLEMCEN, ALGERIA
   UBO, FRANCE
   SONATRACH, ALGERIA
SI BREST
SE PDG-REM-GM-LGG
UM LGO
IN WOS Ifremer jusqu'en 2018
   copubli-france
   copubli-univ-france
   copubli-int-hors-europe
   copubli-sud
IF 2.484
TC 39
UR https://archimer.ifremer.fr/doc/00269/38016/36103.pdf
LA English
DT Article
CR MARADJA/2
   SAMRA
   SPIRAL
BO Le Suroît
   L'Atalante
DE ;Tomography;Composition of the oceanic crust;Continental margins;divergent;Africa
AB We determine the deep structure of the eastern Algerian basin and its southern margin in the Annaba region (easternmost Algeria), to better constrain the plate kinematic reconstruction in this region. This study is based on new geophysical data collected during the SPIRAL cruise in 2009, which included a wide-angle, 240-km-long, onshore–offshore seismic profile, multichannel seismic reflection lines and gravity and magnetic data, complemented by the available geophysical data for the study area. The analysis and modelling of the wide-angle seismic data including refracted and reflected arrival travel times, and integrated with the multichannel seismic reflection lines, reveal the detailed structure of an ocean-to-continent transition. In the deep basin, there is an ∼5.5-km-thick oceanic crust that is composed of two layers. The upper layer of the crust is defined by a high velocity gradient and P-wave velocities between 4.8 and 6.0 km s−1, from the top to the bottom. The lower crust is defined by a lower velocity gradient and P-wave velocity between 6.0 and 7.1 km s−1. The Poisson ratio in the lower crust deduced from S-wave modelling is 0.28, which indicates that the lower crust is composed mainly of gabbros. Below the continental edge, a typical continental crust with P-wave velocities between 5.2 and 7.0 km s−1, from the top to the bottom, shows a gradual seaward thinning of ∼15 km over an ∼35-km distance. This thinning is regularly distributed between the upper and lower crusts, and it characterizes a rifted margin, which has resulted from backarc extension at the rear of the Kabylian block, here represented by the Edough Massif at the shoreline. Above the continental basement, an ∼2-km-thick, pre-Messinian sediment layer with a complex internal structure is interpreted as allochthonous nappes of flysch backthrusted on the margin during the collision of Kabylia with the African margin. The crustal structure, moreover, provides evidence for Miocene emplacement of magmatic intrusions in both the deep basin and the continental margin. Based on the crustal structure, we propose that the eastern Algerian basin opened during the southeastward migration of the European forearc before the collision, along a NW–SE elongated spreading centre that ran perpendicular to the subduction trend. Such an atypical geometry is explained by the diverging directions of the subduction rollback during the backarc opening: eastward for the Corsica–Sardinia block, and southward for the Kabylian blocks. This geometry of the forearc can be interpreted as the surface expression of a slab tear at depth, which is responsible for atypical magmatism in the overlying backarc oceanic basin.
PY 2015
PD JUL
SO Geophysical Journal International
SN 0956-540X
PU Oxford Univ Press
VL 201
IS 3
UT 000355321800048
BP 1912
EP 1938
DI 10.1093/gji/ggv102
ID 38016
ER

EF