The generation of prograde P–T–t points and paths; a textural, compositional, and chronological study of metamorphic monazite G. Foster a, * , R.R. Parrish b,c , M.S.A. Horstwood c , S. Chenery d , J. Pyle e , H.D. Gibson f a Department of Earth Sciences, Wills Memorial Building, University of Bristol, Queens Road, Bristol, BS8 1RJ, UK b Department of Geology, University of Leicester, University Road, Leicester, LE1 7RH, UK c NERC Isotope Geosciences Laboratory, British Geological Survey, Nottingham, NG12 5GG, UK d British Geological Survey, Nottingham, NG12 5GG, UK e Department of Earth and Environmental Sciences, Rensselearer Polytechnic Institute, Troy, NY 12180-3502, USA f Department of Geosciences, University of Massachusetts, Amherst, MA 01003, USA Received 9 June 2004; received in revised form 18 August 2004; accepted 9 September 2004 Available online 27 October 2004 Editor: B. Wood Abstract Analogue and computational models principally provide our present understanding of the mechanisms of prograde metamorphism and orogenesis, yet, due to the difficulty of linking prograde age information with the pressure–temperature (P–T) evolution of a rock, these models for the most part remain untested. Here, we describe an approach that allows multiple prograde pressure–temperature–time (P–T–t) points to be generated on single samples providing a means to construct detailed P–T–t loops, enabling the duration of metamorphic events, the timing of burial and the rate of heating experienced by individual samples to be determined. We use this combination approach to generate multiple prograde P–T– t points for three samples from the Himalayan and Canadian Cordillera and show for the first time that the duration of the metamorphic events are similar in each area and prograde heating rates vary from 2.4F1.2 8C/Ma to 5.0F2.0 8C/Ma. The P–T–t paths generated this way agree well with the established geological history of the studied areas and allow additional constraints to be placed on the mechanisms of orogenesis. D 2004 Elsevier B.V. All rights reserved. Keywords: monazite; geochronology; U–Pb; laser ablation; geothermobarometry; P–T–t paths 1. Introduction Central to our understanding of orogenic processes is an appreciation of the timescales over which these processes operate. Knowledge of such time informa- tion has increasingly been one of the goals of 0012-821X/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.epsl.2004.09.024 * Corresponding author. Tel.: +44 117 954 5235; fax: +44 117 925 3385. E-mail addresses: G.L.Foster@Bristol.ac.uk (G. Foster)8 rrp@nigl.nerc.ac.uk (R.R. Parrish)8 mash@bgs.ac.uk (M.S.A. Horstwood)8 srch@bgs.ac.uk (S. Chenery)8 pylej@rpi.edu (J. Pyle)8 gibson@geo.umass.edu (H.D. Gibson). Earth and Planetary Science Letters 228 (2004) 125 – 142 www.elsevier.com/locate/epsl