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Low-pressure regional metamorphism in the Pyrenees and its implications for the thermal evolution of rifted continental crust

Wickham, S. M. and Oxburgh, E. R. and Reading, H. G. and Vissers, R. L. M. (1987) Low-pressure regional metamorphism in the Pyrenees and its implications for the thermal evolution of rifted continental crust. Philosophical Transactions A: Mathematical, Physical and Engineering Sciences, 321 (1557). pp. 219-242. ISSN 1364-503X . http://resolver.caltech.edu/CaltechAUTHORS:20141113-131610048

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Abstract

During late Palaeozoic (Hercynian) low-pressure regional metamorphism in the Pyrenees, exceptionally high thermal gradients existed within the upper crust, and temperatures as high as 700 degrees C were attained at depths as shallow as 10 km, resulting in large-scale crustal anatexis. Stable isotope studies indicate that the crust was flushed by circulating ground waters to depths of 12 km, but the amount of fluid involved below 8 km was probably not much greater than 50% of the rock mass, and this fluid apparently did not penetrate the pre-Palaeozoic basement below 12 km. There is no evidence for continental collision in the region at that time, and these data, together with other geological and geophysical constraints, suggest that the most plausible tectonic setting for the metamorphism is a zone of continental rifting, possibly associated with strike-slip movement. Thermal modelling suggests that a transient, high-temperature heat source in the lower crust is required to account for the observed metamorphic P-T arrays. Among a range of possible solutions, a basaltic sill, 6-8 km thick and emplaced at 14 km could generate a maximum temperature array similar to those observed in the Pyrenees.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1098/rsta.1987.0012 DOIArticle
http://rsta.royalsocietypublishing.org/content/321/1557/219PublisherArticle
http://www.jstor.org/stable/37730JSTORArticle
Additional Information:© 1987 The Royal Society. S.M.W. acknowledges a research fellowship at Trinity Hall, Cambridge, an N.E.R.C. post-doctoral research fellowship and a visiting associateship at the California Institute of Technology. E. R. 0. acknowledges a Sherman Fairchild Distinguished Visiting Scholarship at the California Institute of Technology. Discussions with Hugh Taylor, Scott Baldridge, Mike Bickle and Tim Holland have been very helpful. We are indebted to Steve Sparks, Colin Graham, M. R. St-Onge and J. E. King for detailed critical reviews which substantially improved this paper. We thank Jane Shears and Sandra Last for typing the manuscript and Sheila Ripper for drafting the diagrams.
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Natural Environment Research Council (NERC)UNSPECIFIED
Sherman Fairchild FoundationUNSPECIFIED
Record Number:CaltechAUTHORS:20141113-131610048
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20141113-131610048
Official Citation:Wickham, S. M., Oxburgh, E. R., Reading, H. G., & Vissers, R. L. M. (1987). Low-Pressure Regional Metamorphism in the Pyrenees and its Implications for the Thermal Evolution of Rifted Continental Crust [and Discussion]. Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences, 321(1557), 219-242. doi: 10.1098/rsta.1987.0012
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ID Code:51718
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:14 Nov 2014 17:01
Last Modified:20 Nov 2014 23:42

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