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EXHUMATION OF METAMORPHIC TERRANES UNIVERSITY OF RENNES 31 August - 2 September 1999 SECOND CIRCULAR This conference is sponsored by the Metamorphic Studies Group, a special interest group affiliated to both the Mineralogical Society of Great Britain (1) and the Geological Society of London (2). The aim of this meeting is to discuss the processes by which metamorphic terranes are unroofed, the relative importance of these processes in different types of metamorphic terrane, and the rates at which these processes operate. The meeting is designed to bring together petrologists, structural geologists, geochronologists, clastic sedimentologists, geophysicists, theoretical modellers and geomorphologists in a multi- disciplinary attack on the problem. The meeting is being convened by: Dr. Michel Ballevre, Geosciences Rennes, Universite de Rennes I, F-35042 Rennes Cedex, France. tel: (+33) 2 99 28 60 81 fax: (+33) 2 99 28 26 02 e-mail: [log in to unmask] Dr. Simon Cuthbert, Department of Civil, Structural & Environmental Engineering,University of Paisley, Paisley PA1 2BE, UK. tel: (+44) 141 848 3263 fax: (+44) 141 848 3275 e-mail: [log in to unmask] Dr. Giles T.R. Droop, Department of Earth Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK. tel: (+44) 161 275 3809 fax: (+44) 161 275 3947 e-mail: [log in to unmask] PLEASE FORWARD THIS CIRCULAR TO ANY OF YOUR COLLEAGUES WHO YOU THINK MAY NOT BE AWARE OF THE MEETING, AND WHO MAY WISH TO ATTEND 1 Registered charity 233706 2 Registered charity 210161 Scope of the meeting:- A number of key topics have been identified which will be addressed during the meeting, possibly forming the basis of discrete sessions. These include: Metamorphic records of exhumation: Decompressive P-T paths; Diffusion in minerals: the "geospeedometry" approach. Exhumation of ultra-high-pressure rocks. Kinematics of tectonic exhumation: the macro-, meso- and micro-structural record. Exhumation rates constrained by high-resolution geochronology. Sedimentological records of unroofing in foreland and intramontane basins. Present-day erosion rates in mountain belts. Thermal / mechanical models of exhumation. Exhumation of metamorphic terranes in contrasting geo-tectonic settings. Fluid movement during exhumation. These topics will be addressed in oral and poster sessions. The following keynote speakers have been approached and have agreed to talk at the meeting: J.P. Platt (UCL, London) V. Sautter (MNHN, Paris) C. Passchier (Mainz) J.R. Wijbrans (Amsterdam) B. Bluck (Glasgow) D.W. Burbank (Penn. State) A. Chemenda (Nice) A. Hynes (McGill) Language:- The official language of the meeting will be English. All talks and posters must be in English. Venue:- The meeting will be held at the University of Rennes campus, which is located ca. 8 km east of Rennes city centre. Lectures will be held in the Louis Antoine Lecture Theatre in No. 2 building. Poster sessions will be held in the same building. Two slide projectors, an overhead projector and two projection screens will be available for use in the lecture theatre. Posters:- One or two rooms will be devoted to poster sessions. The maximum size for posters is 1.2m high by 1.0m wide. Posters should be prepared in advance and erected by the participants. Registration:- The registration fee covers all conference materials, tea/coffee, invited speakers' costs, and costs of administration. There is a reduced registration fee for students and also for members of the following learned societies: the Mineralogical Society of Great Britain, the Geological Society of London, the Societe Geologique de France, and the Societe Francaise de Mineralogie et de Cristallographie. A registration form (MS.Word6 format) is being sent out with this circular. In the event of decoding problems, hard copies of the registration form may be obtained from Giles Droop (address above). The deadline for registration is 1 May 1999. There is an extra late- registration charge for registrations received after this date. All costs itemised on the registration form include an 11% institutional overhead levied by the University of Rennes. Accommodation:- Accommodation is available on campus in the form of rooms in student halls of residence. Hotel accommodation is also available close to the campus and in the city centre. Please contact Michel Ballevre if you need more detailed information about the hotels available. Meals:- For delegates in student accommodation, breakfast will be available at the University Restaurant, but for delegates in hotels, breakfast will be provided by the hotel. Lunch (specially prepared for the meeting) will be at the University Restaurant. Tickets will be issued for meals ordered via the registration form. Evening meals will also be obtainable at the University Restaurant, but there are also many good restaurants in the city centre for those who wish to forage further afield. The Conference Dinner will be on the evening of 1st September. Tea/coffee is included in the registration fee. Breakfast and lunch will be included in the costs of the meeting (see registration form), but, with the exception of the Conference Dinner, evening meals will not. Publication:- The proceedings of the meeting will be published as a book by the Mineralogical Society of Great Britain, and will be edited by Michel Ballevre, Simon Cuthbert and Giles Droop. Both keynote and contributed papers will be published. Papers should contain a substantial review component. Papers should be prepared in Mineralogical Magazine format, and should be submitted as hard copy (three copies please). The deadline for submission of papers will be 1 November 1999, although we would encourage submission at the time of the meeting. Travelling to Rennes:- Flying to Rennes is possible via Paris, though may involve changing airports from Charles de Gaulle to Orly. Travelling to Rennes by train from Paris is very easy and convenient; the high-speed train (TGV) takes only two hours from Paris (Gare de Montparnasse) and leaves almost every hour. There are also a few TGV from CdG airport. The conference organisers are exploring the possibility of hiring a bus to take participants from Paris (Gare Montparnasse) to Rennes on the afternoon of 30 August, provisionally departing at 2pm. The cost would probably be about 100 FRF. A return bus on the evening of 2 September is also a possibility. Viability in either case would depend on the number of people interested. If you are interested in travelling by this method, please indicate on the registration form. By car, Rennes is an easy 350km from Paris, mostly along motorway. Delegates travelling from the UK by car can cross the English Channel by ferry from Portsmouth to St Malo. From St Malo to Rennes is only 70km by road. Field Trip:- The meeting will be followed by a 4-day field trip to review the metamorphic evolution of the Variscan Belt of southern Brittany. Attention will be focussed mainly on the high-pressure rocks, including the blueschist-facies rocks of the Ile de Groix, and the eclogite-facies rocks of the Champtoceux Nappe and the Vendee. Some key structures for constraining exhumation mechanisms of high-P rocks (e.g. synkinematic leucogranites with C-S structures in extensional detachments) will be shown. As a counterpart to the high-pressure rocks, the classic migmatites of the Morbihan area will also be visited. The field trip will be led by Michel Ballevre, Denis Gapais and Gaston Godard. The field trip will be limited to a maximum of thirty participants. Participation is open to any bona-fide geologists, but priority will be given to people who are also registering for the meeting. Places on the trip will be filled on a first-come-first-served basis. If you wish to book a place on the trip, please indicate on the registration form. Financially, this trip is completely separate from the meeting in Rennes. The cost of the trip is likely to be about 3000 FRF; detailed information about costs will be circulated to interested people at a later date. Provisional Itinerary:- 2 Sept. Depart ca. 5 pm. Drive to Lorient. Overnight in Lorient. 3 Sept. Ferry to Ile de Groix. Blueschists and associated rocks. (Many of the best sites are now protected, but we shall visit some localities where it is still possible to collect beautiful samples.) Overnight on Ile de Groix. 4 Sept. Blueschists (cont'd). Back to Lorient. Quiberon Shear Zone (a detachment zone with a syn-kinematic leucogranite, contributing to the exhumation of the blueschists). Migmatites of the Morbihan area (just below the detachment). Overnight in Vannes. 5 Sept. South Armorican Shear Zone (S-C fabrics). Champtoceaux Nappe: garnet-kyanite-mica-schists and eclogites; cross-section of the nappe along the Loire: inverted metamorphism associated with thrusting of the upper migmatitic unit over the lower unit rich in kyanite- and glaucophane- eclogites. Overnight at Nantes. 6 Sept. Eclogite-facies metamorphism in the Vendee: different types of eclogite, and overprinting of cordierite-bearing assemblages in the country- rock gneisses by high-P garnet-kyanite parageneses. End of the trip. Return to Rennes via Nantes airport and railway station (2 hours to Paris by TGV). ------------------------------------------------------------------------------ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%