The metamorphic events (full details below) consist of: Special session: Metamorphism in the ore environment One of W-Th-F May , 2013

Transcription

1 This is an announcement for a paired special session and field trip concerned with metamorphosed ore deposits, to be held at the GAC- MAC Joint Annual Meeting in Winnipeg, May 22-28, The metamorphic events (full details below) consist of: Special session: Metamorphism in the ore environment One of W-Th-F May , 2013 Invited speakers: Dr. Andy Tomkins (Monash University): The critical role of deformation in metamorphic sulfide melting. Dr. Paul Spry (Iowa State University): The use of trace element chemistry of gahnite and garnet as exploration guides to Broken Hilltype mineralization. Field trip: Metamorphosed alteration zones and regional metamorphism, Trans-Hudson Orogen, Manitoba F-Sa-Su-M-T May 24-28, 2013 Abstracts are currently being accepted up until the deadline of January 21, 2013 at the meeting website: Registration for all events (special session, field trip) opens on March 1, Details of metamorphic events: 1. SS-12 Metamorphism in the ore environment Session description: This session is concerned with all aspects of metamorphism and ore deposits, including: metamorphism of ore bodies; regional and contact metamorphism in mining districts; metamorphism of mineralization-related alteration zones; metamorphic minerals as vectors to metamorphosed ore deposits; metamorphically-related remobilization; sulphide anatexis during metamorphism; and the role of metamorphic fluids in generating or

2 modifying ore bodies. Invited guest speakers: Dr. Andy Tomkins (Monash University): The critical role of deformation in metamorphic sulfide melting. Dr. Paul Spry (Iowa State University): The use of trace element chemistry of gahnite and garnet as exploration guides to Broken Hilltype mineralization. Convenors: Chris Couëslan (Manitoba Geological Survey; Doug Tinkham (Laurentian University; David Pattison (University of Calgary; Simon Gagné (Manitoba Geological Survey; Session details Date: One day out of Wednesday-Thursday-Friday, May , 2013 (exact dates TBA) Supported by: GAC Mineral Deposits Division and the Society of Economic Geologists Location: Winnipeg convention centre in downtown Winnipeg. Presentation options: oral presentations (20 minutes) and posters (balance to be dictated by Meeting organizers) Cost: included in meeting registration (meeting costs TBA) Abstract deadline: January 21, Abstract submission: through the GAC-MAC Winnipeg 2013 website ( Special Session and Meeting registration: through the GAC-MAC Winnipeg 2013 website ( Registration opens March 1, Social activities associated with Special Session: We plan to have an informal (pay as you go) group dinner on the evening following the Special Session at a nearby restaurant. Details TBA. 2. Post-meeting field trip: Metamorphosed alteration zones and regional metamorphism:

3 Examples from the Trans-Hudson Orogen Dates: Friday Tuesday, May 24-28, 2013 Leaders: Chris Couëslan (Manitoba Geological Survey; Doug Tinkham (Laurentian University; Al Bailes (Bailes Geoscience; Simon Gagné (Manitoba Geological Survey; Field trip description: Regional metamorphism in the Paleoproterozoic Trans-Hudson Orogen has resulted in greenschist to granulite facies assemblages. This field trip will focus on the effects of regional metamorphism in a variety of ore environments and will summarize previous work and present the results of recent work on defining and mapping isograds and delineation of metamorphosed hydrothermal alteration zones. Localities to be visited will include: Thompson Nickel Belt: Paleoproterozoic Ospwagan Group rocks, which are host to the Nibearing ultramafic intrusions of the belt, were subjected to low pressure metamorphism during the Trans-Hudson metamorphism. A series of nested metamorphic domains elongate parallel to the regional strike of the belt progress from staurolite+andalusite to sillimanite to sillimanite+k-feldspar to K-feldspar+garnet+cordierite assemblages. Recognizing the Ospwagan Group rocks at various metamorphic grades is an added challenge to Ni-exploration in the belt. Snow Lake area: Metamorphosed VMS alteration systems were recognized in bimodal volcanic and volcaniclastic rocks of the Snow Lake arc assemblage (1.89 Ga). The primitive Anderson sequence is host to the Anderson, Stall and Linda deposits whereas the mature Chisel sequence is host to the Chisel, Ghost and the newly discovered Lalor deposits. The mineralization is spatially associated with rhyolite complexes and synvolcanic intrusive rocks. The mineralized volcanic sequences contain prominent zones of alteration formed by

4 synvolcanic hydrothermal activity which were subsequently recrystallized during 1.81 Ga regional mid-amphibolite facies metamorphism. The alteration zones are easily recognized with their distinctive metamorphic mineral assemblages. Centimetre-scale, euhedral crystals of chlorite, phlogopitic biotite, amphibole, muscovite, garnet and staurolite are common within metamorphically recrystallized semi-conformable alteration zones. Recrystallized discordant alteration zones also contain coarse-grained kyanite and andalusite. Three major periods of hydrothermal activity are identified within the Snow Lake arc assemblage. Sherridon area: Paleoproterozoic Sherridon gneisses are dominantly derived from felsic volcanic rocks that host several VMS deposits within the Sherridon structure. Paleoproterozoic deformation, upper amphibolite facies metamorphism and partial melting of felsic gneiss complicates the identification of VMS hydrothermal alteration systems associated with the Cu-Zn deposits. Controversial garnet-sillimanite-biotite assemblages containing cordierite and/or gedrite are derived from hydrothermally altered felsic volcanics, some of which themselves experienced partial melting, but locally could represent partially melted sediments. Garnet-cordierite-gedrite assemblages developed in altered mafic rocks are widespread throughout the structure but are volumetrically insignificant compared to the altered felsic rocks. Cost and registration: Cost: $730 CDN, on top of the meeting registration fee What s included: transportation, accommodation in hotels (double room occupancy), packed lunches, dinners, breakfasts, juice/water during the field days, and a field guide. Enrollment limit: 16. Registration: through the GAC-MAC Winnipeg 2013 website. Registration opens March 1, Logistical details: Departure time and place: 12 noon on Friday, May 24 th at the Winnipeg Convention Center. Return time and place: 7 pm on Tuesday, May 28 th at the Winnipeg

5 Airport and/or Winnipeg Convention Center. Towns where we will be staying the night: Thompson, Snow Lake, Bakers Narrows, Flin Flon. Mode of transport: Rental vehicles. Rather than drive back to Winnipeg, participants can choose to fly from Flin Flon to Winnipeg at the end of the trip (May 28 th ) at their cost. Style of field trip: a mixture of roadside outcrops and traverses. Weather in May in central/northern MB: unpredictable, 0 C and snow to 25 C and sun. Hammers and sampling: sampling is allowed at many of the stops. Out-of-pocket expenses: all alcoholic beverages, supper on the evenings of May 24 th and 27 th, breakfast and lunch on May 28th. We look forward to seeing you in Winnipeg! Best wishes, Chris Couëslan, Doug Tinkham, Dave Pattison, Simon Gagné, Al Bailes