dc.contributor.author |
Vázquez, M. |
dc.contributor.author |
Asebriy, L. |
dc.contributor.author |
Azdimousa, A. |
dc.contributor.author |
Jabaloy, A. |
dc.contributor.author |
Booth-Rea, G. |
dc.contributor.author |
Barbero, L. |
dc.contributor.author |
Mellini, Marcello |
dc.contributor.author |
González-Lodeiro, F. |
dc.contributor.author |
Consejo Superior de Investigaciones Científicas (Espanya). Instituto Andaluz de Ciencias de la Tierra |
dc.date |
2013 |
dc.identifier |
https://ddd.uab.cat/record/112543 |
dc.identifier |
urn:10.1344/105.000001843 |
dc.identifier |
urn:oai:ddd.uab.cat:112543 |
dc.identifier |
urn:articleid:16965728v11n3p277 |
dc.identifier |
urn:oai:raco.cat:article/269670 |
dc.identifier |
urn:scopus_id:84884553150 |
dc.identifier |
urn:wos_id:000325040200002 |
dc.format |
application/pdf |
dc.language |
eng |
dc.publisher |
|
dc.relation |
Geologica acta ; Vol. 11, Núm. 3 (September 2013), p. 277-293 |
dc.rights |
open access |
dc.rights |
Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan aquestes es distribueixin sota la mateixa llicència que regula l'obra original i es reconegui l'autoria de l'obra original. |
dc.rights |
https://creativecommons.org/licenses/by-sa/3.0/ |
dc.subject |
Low-grade extensional metamorphism |
dc.subject |
Illite crystallinity |
dc.subject |
Kübler index |
dc.subject |
Tanger-Ketama unit |
dc.subject |
External Rif |
dc.subject |
Northern Morocco |
dc.title |
Evidence of extensional metamorphism associated to Cretaceous rifting of the North-Maghrebian passive margin : the Tanger- Ketama Unit (External Rif, northern Morocco) |
dc.type |
Article |
dc.description.abstract |
The distribution pattern of diagenetic conditions to very low-grade metamorphism in the eastern Rif has been determined based on a study of clay-mineral assemblages and illite crystallinity of Mesozoic metapelites. Low-grade conditions were reached in marbles and also in the Beni-Malek serpentinites, as suggested by the mineral assemblages present in the marbles and antigorite growth in serpentinites. Previous thermochronological data are based on i) 40Ar/39Ar in amphiboles from greenschists, ii) K/Ar in white micas from metasandstones, and iii) fission tracks in apatites and zircons from metasandstones. These data indicate a Late Cretaceous age (∼80 Ma) for the very low- to low-grade metamorphism. We propose an evolutionary model for the Tanger-Ketama Unit consisting of a Lower Cretaceous sequence deposited in half-graben basins over an exhumed serpentinized mantle in a setting similar to the West Galician non-volcanic margin. The sediments underwent diagenesis to very low-grade metamorphism under relatively high heat flow in this extensional setting. Miocene contractional deformation of the Tanger-Ketama Unit resulted in a penetrative crenulation cleavage associated to asymmetric inclined folds. This crenulation developed, mostly by solution-transfer processes, without significant mineral growth. Miocene metamorphism reset the apatite fission-tracks, but metamorphic conditions were not high enough to reset either the K/Ar ages or the zircon fission tracks |