Physical Volcanology, Hydrothermal Alteration and Massive ...

STURGEON LAKEN/o POST -CALDERA VOLCANICS00 MASSIVE SULPHIDE DEPOSITS~ CALDERA RElA1ED VOLCANICS~ PRECALDERA VOLCANICSo lRONDHJEMITIC IN1RUSIVES1Zl FAULTSB CON1ACTSFigure 2. Generalized geological map illustrating the regionalextent of the sturgeon Lake Caldera Complex.The combination of well preserved volcanic textures, a variable 55 0 to 90 0 dip ofa north-facing, essentially homoclinal volcanic sequence and more than 600,000 m ofdiamond drilling over an apparent 4,500 m stratigraphic interval presents the opportunityto examine successive stages of caldera evolution. This includes initial subaerial-shallowsubaqueous collapse, subaqueous silicic explosive volcanism and ore formation, andterminal dome building with sedimentary and lava flow fill and burial.The main purpose of this field trip is to illustrate the physical volcanology of anancient, ore-hosting caldera and to stress the importance of volcanism and synvolcanicstructures in controlling the occurrence and location of hydrothermal alterationassemblages and volcanogenic massive sulphide deposits.REGIONAL GEOLOGYThe south Sturgeon Lake area is located within the Archean Wabigoon volcanosedimentarygreenstone belt within the Superior Province. The Wabigoon subprovince is3