GRANULITE-FACIES METAMORPHISM IN THE ANATECTIC COMPLEX OF TOLEDO, SPAIN - LATE-HERCYNIAN TECTONIC EVOLUTION BY CRUSTAL EXTENSION

Authors
Citation
L. Barbero, GRANULITE-FACIES METAMORPHISM IN THE ANATECTIC COMPLEX OF TOLEDO, SPAIN - LATE-HERCYNIAN TECTONIC EVOLUTION BY CRUSTAL EXTENSION, Journal of the Geological Society, 152, 1995, pp. 365-382
Citations number
82
Categorie Soggetti
Geosciences, Interdisciplinary
ISSN journal
00167649
Volume
152
Year of publication
1995
Part
2
Pages
365 - 382
Database
ISI
SICI code
0016-7649(1995)152:<365:GMITAC>2.0.ZU;2-4
Abstract
The Anatectic Complex of Toledo consists of a heterogeneous suite of h igh-grade metamorphic rocks, mainly granulitic migmatites of pelitic c omposition and orthogneisses, and different types of syn-orogenic gran itoids with minor associated basic rocks. None of the metamorphic rock types records evidence of the early prograde history, and only the pe ak and retrograde P-T conditions can be estimated. The intrusion of th e syn-orogenic granitoids is either slightly before or synchronous wit h the metamorphic climax. These rock types thus can be used to make P- T estimates of the peak and retrograde conditions. Microtextural analy sis of reaction textures in conjunction with a petrogenetic grid, has enabled construction of an incomplete ''clockwise'' P-T path that is c haracterized by an isothermal decompression after or during the metamo rphic peak temperatures. The peak estimates from different geothermoba rometers are 800 degrees +/- 50 degrees C and 4-6 Kbar, the highest te mperatures recorded in this part of the Iberian Hercynian Belt. It is proposed that this high-T/low-P metamorphism is at least partially rel ated to an extensional process, possibly due to gravitational collapse of previously thickened crust.