HT-fabrics in a garnet-bearing quartzite from Western Portugal: geodynamic implications for the Iberian Variscan Belt
✍ Scribed by Francisco J. Fernández; Helder I. Chaminé; Paulo E. Fonseca; José M. Munhá; António Ribeiro; Jesus Aller; Mercedes Fuertes-Fuentes; Frederico S. Borges
- Publisher
- John Wiley and Sons
- Year
- 2003
- Tongue
- English
- Weight
- 591 KB
- Volume
- 15
- Category
- Article
- ISSN
- 0954-4879
No coin nor oath required. For personal study only.
✦ Synopsis
ABSTRACT The study of a garnet‐bearing quartzite from a major suture zone in Iberia reports an unusual high‐T fabric. Quartz c‐axis patterns were plotted using shaped garnet as reference axis for the finite stretch (X‐axis). The pole figures are characterized by a dominant single maximum around X together with other point maxima along the XY plane (mylonitic foliation). These patterns suggest that dominant <c> prism slip and subordinated <a> prism slip operated during quartz plastic deformation in agreement with P–T conditions for syntectonic garnet growth (4–5 kbar and 700 ± 50 °C) and, pre‐dating the well‐known (late) Variscan D1 event (<6 kb and 600 ± 30 °C). The geotectonic framework suggests that the fabrics were formed along the western shear margin of the Ossa‐Morena Zone during the early stages of the Variscan orogeny.