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Palaeomagnetic and AMS study of the Tarfaya coastal basin, Morocco: an early Turonian palaeopole for the African plate

By
Vicente Carlos Ruiz-Martínez
Vicente Carlos Ruiz-Martínez
Departamento de Geofísica y Meteorología, Facultad de Física, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040, Madrid
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Alicia Palencia-Ortas
Alicia Palencia-Ortas
Departamento de Geofísica y Meteorología, Facultad de Física, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040, Madrid
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Juan José Villalaín
Juan José Villalaín
Departamento de Física, Escuela Técnica Superior, Universidad de Burgos, Avda. Cantabria s/n, 09006, Burgos
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Gregg Mclntosh
Gregg Mclntosh
Departamento de Geofísica y Meteorología, Facultad de Física, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040, Madrid
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Fátima Martín-Hernández
Fátima Martín-Hernández
Departamento de Geofísica y Meteorología, Facultad de Física, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040, Madrid
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Published:
January 01, 2011

Abstract

An early Turonian (c. 93 Ma) anoxic, cyclic marine deposition is registered in the unfolded outcrops from the Tarfaya coastal basin, where very high sedimentation rates enable the investigation of past geomagnetic field record at high temporal resolution. One hundred and fourteen samples have been sampled along a 10.5 m vertical profile (c. 200–500 ka) of orbital-scale forced sedimentation. Rock magnetic investigations reveal mineralogy principally controlled by diamagnetic and paramagnetic behaviour, along with very low concentrations of low-coercivity ferromagnetic material which is probably magnetite. A well-defined magnetic fabric can be seen with the minimum susceptibility axis perpendicular to the foliation plane, and magnetic lineation compatible with NW African palaeostress since sedimentation times and/or the palaeocurrent associated with upwelling system deposition. Magnetic signature has the potential for performing reliability checks of reversed tiny wiggles, which were found in four samples not considered for the tectonic analysis. Alternating field demagnetization shows a single, stable, low-coercivity directional component. The new palaeopole (N=88; PLat=64.3°, PLon=256.3°, A95=2.5°; K=38.7), obtained after moderate (f=0.8) inclination flattening correction, is the first early Turonian palaeopole for the NW African Craton. It can contribute to the 90 Ma-centred sliding window of the different proposed synthetic Apparent Polar Wander Paths.

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Geological Society, London, Special Publications

The Formation and Evolution of Africa: A Synopsis of 3.8 Ga of Earth History

D. J. J. Van Hinsbergen
D. J. J. Van Hinsbergen
University of Oslo, Norway
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S. J. H. Buiter
S. J. H. Buiter
Geological Survey of Norway
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T. H. Torsvik
T. H. Torsvik
University of Oslo
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C. Gaina
C. Gaina
Geological Survey of Norway
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S. J. Webb
S. J. Webb
University of the Witwatersrand, South Africa
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Geological Society of London
Volume
357
ISBN electronic:
9781862396050
Publication date:
January 01, 2011

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