Complutense University Library

40Ar/39Ar laserprobe dating of mylonitic fabrics in a polyorogenic terrane of NW Iberia

Gómez Barreiro, Juan and Wijbrans, Jan R. and Castiñeiras García, Pedro and Martínez Catalán, José R. and Arenas Martín, Ricardo and Díaz García, Florentino and Abati Gómez, Jacobo (2006) 40Ar/39Ar laserprobe dating of mylonitic fabrics in a polyorogenic terrane of NW Iberia. Journal of the Geological Society, 163 . pp. 61-73. ISSN 0016-7649

[img] PDF
850kB

Official URL: http://www.geolsoc.org.uk/index.html

View download statistics for this eprint

==>>> Export to other formats

Abstract

The tectonothermal evolution of a polyorogenic terrane in the Variscan belt of NW Spain has been
constrained by 40Ar/39Ar laserprobe incremental heating experiments on mylonitic fabrics developed in major
structures. Transitional levels between HP–HT and IP upper units in the O´ rdenes Complex where
metamorphic and structural records demonstrate two cycles of burial and exhumation were selected for dating.
Two groups of ages have been defined: (1) Silurian–Early Devonian, obtained from mylonites of the Forna´s
extensional detachment, here considered as the minimum age for the start of tectonic exhumation of the HP–
HT units and an upper age-limit for the HP–HT event itself; (2) Early to Mid-Devonian, from structures
related to the Variscan convergence in the area, which include top-to-the-east thrusts and extensional
detachments. A single, younger Carboniferous age obtained from the uppermost allochthonous sequences
possibly reflects the final stages of emplacement of the allochthonous complexes. Our data indicate a
polyorogenic character for a part of the Iberian allochthonous complexes, including Variscan (sensu stricto)
and Early Variscan convergence, as well as an older, Early Palaeozoic cycle.


Item Type:Article
Uncontrolled Keywords:Polyorogenic terrane; Variscan belt; NW Iberian
Subjects:Sciences > Geology > Petrology
ID Code:14028
Deposited On:07 Dec 2011 10:35
Last Modified:07 Dec 2011 10:35

Repository Staff Only: item control page