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FIELD TRIP OBJECTIVES
The juvenile 1.89 Ga oceanic arc volcanic rocks of the Paleoproterozoic Flin Flon volcanic belt are host to several world-class volcanogenic massive sulphide (VMS) deposits, including the recently discovered Au-rich Lalor Lake VMS deposit at Snow Lake (Fig. 1). This trip uses spectacular roadside out-crops (Figs. 2-5) to highlight current understanding of the nature and setting of the regionally metamorphosed VMS mineralization and alteration at the eastern end of the belt at Snow Lake. An underground tour of the just-opened Lalor Lake mine and a sur face tour of outcrops at the Snow Lake gold mine round out this trip.
Figure 1
Figure 1. Aerial view of headframe and hoisthouse at Lalor Lake mine, November 2012.
Figure 2
Figure 2. ‘Silicified’ pillowed flow, Welch formation, lower Anderson sequence.
Figure 3
Figure 3. Epidosite alteration domain with amphibole and quartz-feldspar rims overprinting a fragment with an albite-quartz altered rim in a heterolithic breccia bed of the Edwards formation, lower Chisel sequence
Figure 4
Figure 4. A mafic synvolcanic dyke (upper left) with adjacent zones of pervasive and mottled albite and silica enrichment developed in bedded Edwards mafic wacke, lower Chisel sequence.
Figure 5
Figure 5. Symmetrical ripples, trough cross bedding in tidal-reworked mafic tuff of the Threehouse formation, upper Chisel sequence.
The excellent outcrop exposure, large domains of hydrothermally altered rocks and abundant VMS deposits at Snow Lake make this area an important natural laboratory for applying modern volcanic massive sulphide theories to ancient deposits. The trip will be useful to researchers and explorationists interested in the volcanic architecture, hydrothermal evolution and metamorphism of a prolifically mineralized VMS terrane. The trip presents outcomes of projects conducted over the past two decades by the Manitoba Geological Survey and Natural Resources Canada (under MITEC, CAMIRO, Shield Margin NATMAP and TGI programs), Laurentian University (NSERC-supported research) and HudBay Minerals Inc.
OTHER INFORMATION
This excursion will visit readily accessible roadside exposures, with some short (<500 m) hikes on trails. Participants will meet at 12:00 noon, May 18 th , 2013, at Winnipeg International Airport and travel to Snow Lake by van. Participants return to Winnipeg, arriving between 10 PM and 11 PM on Tuesday May 21 st . Participants going underground at the Lalor Lake mine require fit testing for a respirator. They must be clean shaven to pass the respirator fit test, and without this test they will not be allowed underground.
List of figures
Figure 1
Figure 1. Aerial view of headframe and hoisthouse at Lalor Lake mine, November 2012.
Figure 2
Figure 2. ‘Silicified’ pillowed flow, Welch formation, lower Anderson sequence.
Figure 3
Figure 3. Epidosite alteration domain with amphibole and quartz-feldspar rims overprinting a fragment with an albite-quartz altered rim in a heterolithic breccia bed of the Edwards formation, lower Chisel sequence
Figure 4
Figure 4. A mafic synvolcanic dyke (upper left) with adjacent zones of pervasive and mottled albite and silica enrichment developed in bedded Edwards mafic wacke, lower Chisel sequence.
Figure 5
Figure 5. Symmetrical ripples, trough cross bedding in tidal-reworked mafic tuff of the Threehouse formation, upper Chisel sequence.