Gold mineralization at Poplar Mountain, Western New Brunswick, Canada ¨C Potential relation to granitic intrusions

CIM Edmonton 2004
Guoxiang Chi, Sheila Watters, William J Davis, Sebastien Castonguay,
Abstract The Poplar Mountain gold deposit is hosted in the Poplar Mountain Volcanic Complex located along the Woodstock fault zone in western New Brunswick. Gold is associated with arsenopyrite which mostly occurs disseminated in the host rocks and to a lesser extent in quartz-carbonate-sericite veins and quartz-cemented breccias. The mineralization is associated with sericite-ankerite alteration which is superimposed on chlorite-calcite alteration. Potential origins for the deposit include relation to the host rock (subvolcanic intrusion), to the Woodstock Fault, and to unexposed granitic intrusions. A genetic link with granitic intrusions is suggested by geochronology, trace elements, and C and O isotopes. U-Pb dating of zircon and Ar/Ar dating of mineralization-associated sericite indicates that the age of the host rocks is ¡Ü 459¡À3 Ma, and the age of mineralization is 411¡À3.7 Ma, which is similar to the ages of the Pokiok granite batholith (402-415 Ma) adjacent to Poplar Mountain. Mineralization-associated alteration is accompanied by enrichment of Rb, Cs, As, Sb, and W. The d18O and d13C values of the fluids associated with mineralization are estimated at 6.4 to 8.3¡ë (SMOW) and -6.8 to -8.3¡ë (PDB), respectively, which are well within the range for magmatic fluids.
Keywords: Gold deposits, Poplar Mountain, New Brunswick, intrusion-related
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