Please use this identifier to cite or link to this item:
Title: Syn-deformational melt percolation through a high-pressure orthogneiss and the exhumation of a subducted continental wedge (Orlica-Śnieżnik Dome, NE Bohemian Massif)
Author: Aguilar Gil, Carmen María
Stípská, Pavla
Chopin, Francis
Schulmann, Karel
Pitra, Pavel
Závada, Prokop
Hasalová Pavlína
Martelat, Jean-Emmanuel
Keywords: Geologia estructural
Structural geology
Issue Date: 27-Apr-2021
Publisher: European Geosciences Union (EGU)
Abstract: High-pressure granitic orthogneiss of the south-eastern Orlica-Śnieżnik Dome (NE Bohemian Massif) shows relics of a shallow-dipping S1 foliation, reworked by upright F2 folds and a mostly pervasive N-S trending subvertical axial planar S2 foliation. Based on macroscopic observations, a gradual transition perpendicular to the subvertical S2 foliation from banded to schlieren and nebulitic orthogneiss was distinguished. All rock types comprise plagioclase, K-feldspar, quartz, white mica, biotite and garnet. The transition is characterized by increasing presence of interstitial phases along like-like grain boundaries and by progressive replacement of recrystallized K-feldspar grains by fine-grained myrmekite. These textural changes are characteristic for syn-deformational grain-scale melt percolation, which is in line with the observed enrichment of the rocks in incompatible elements such as REEs, Ba, Sr, and K, suggesting open-system behaviour with melt passing through the rocks. The P-T path deduced from the thermodynamic modelling indicates decompression from ~15−16 kbar and ~650-740 ºC to ~6 kbar and ~640 ºC. Melt was already present at the P-T peak conditions as indicated by the albitic composition of plagioclase in films, interstitial grains and in myrmekite. The variably re-equilibrated garnet suggests that melt content may have varied along the decompression path, involving successively both melt gain and loss. The 6-8 km wide zone of vertical foliation and migmatite textural gradients is interpreted as vertical crustal-scale channel where the grain-scale melt percolation was associated with horizontal shortening and vertical flow of partially molten crustal wedge en masse.
Note: Reproducció del document publicat a:
It is part of: Geophysical Research Abstracts, 2021, vol. 22, num. EGU21-2251
Related resource:
ISSN: 1029-7006
Appears in Collections:Articles publicats en revistes (Mineralogia, Petrologia i Geologia Aplicada)

Files in This Item:
File Description SizeFormat 
719720.pdf277.29 kBAdobe PDFView/Open

This item is licensed under a Creative Commons License Creative Commons