Geological Magazine



Original Article

PT conditions of Grenville-age eclogite facies metamorphism and amphibolite facies retrogression of the Glenelg–Attadale Inlier, NW Scotland


C. D. STOREY a1c1, T. S. BREWER a1 and S. TEMPERLEY a1
a1 Department of Geology, University of Leicester, University Road, Leicester LE1 7RH, UK

Article author query
storey cd   [Google Scholar] 
brewer ts   [Google Scholar] 
temperley s   [Google Scholar] 
 

Abstract

Peak and retrograde PT conditions of Grenville-age eclogites from the Glenelg–Attadale Inlier of the northwest Highlands of Scotland are presented. Peak conditions are estimated as c. 20 kbar and 750–780°C, in broad agreement with previous work. The eclogites subsequently followed a steep decompression path to c. 13 kbar and 650–700°C during amphibolite facies retrogression. Peak eclogite facies metamorphism occurred > 1080 Ma and retrogression at c. 995 Ma, suggesting fairly sluggish uplift rates of < 0.3 km/Ma and cooling rates of < 1.25°C/Ma, when compared with other parts of the Grenville orogeny and/or modern orogens. However, current poor constraints on the timing of peak metamorphism mean that these rates cannot be used to interpret the geodynamic evolution of this part of the orogen. The PTt data, together with petrology and the field relationships between the basement rocks of the Glenelg–Attadale Inlier and the overlying Moine Supergroup, mean that it is difficult to support the currently held view that an unconformable relationship exists between the two. It is suggested that more data are required in order to re-interpret the Neoproterozic tectonic evolution of the northwest Highlands of Scotland.

(Published Online September 16 2005)
(Received July 1 2004)
(Accepted April 28 2005)


Key Words: PT conditions; eclogite; retrograde; Moinian; Scotland.

Correspondence:
c1 Author for correspondence. Current address: Department of Earth Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK; e-mail: c.storey@open.ac.uk


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