^(18)O/^(16)O homogenization of the middle crust during anatexis: The Thor-Odin metamorphic core complex, British Columbia: Comment and Reply

Abstract

Space constraints prevented us (Holk and H. P. Taylor, 1997) from addressing the issues raised by Beaudoin and B. E. Taylor in the Comment above. Our objective was just to record the evidence for pervasive ^(18)O/^(16)O homogenization in the Thor-Odin complex. However, we welcome this opportunity to preview our data from the Valhalla metamorphic core complex, which bears more directly upon these issues. Our results (Fig. 1) indeed support their proposal that ascending metal-bearing aqueous fluids derived from crystallizing leucogranite magma mixed with deeply circulating meteoric ground waters, producing numerous Ag-Pb-Zn-Au vein deposits in the Kokanee Range (on the east side of the cross section in Fig. 1). The history before 15 Ma (Beaudoin et al., 1992a) of Eocene extension-related mineralization in this area produced three main ore groupings (Sandon, Ainsworth, and Bluebell; Beaudoin et al., 1992c), and Beaudoin et al. (1992b) showed that the component of magmatic and/or metamorphic H_2O in these ore fluids tapped different Pb sources: lower crust (Ainsworth), mantle (Bluebell), and Valhalla complex gneisses and leucogranites (Sandon). Our new data (Fig. 1) apply mainly to the Sandon deposits, commonly hosted in the overlying Slocan Group sediments, and the closest (<25 km) of the three groups to the Slocan Lake detachment fault.