Northeastern Section–41st Annual Meeting (20–22 March 2006)

Paper No. 3
Presentation Time: 1:00 PM-4:00 PM


KING, Marylynn, COLIACOMO, Erika, GOLDSTEIN, Art, PECK, William and SELLECK, Bruce, Department of Geology, Colgate University, 13 Oak Drive, Hamilton, NY 13346,

Stable isotope and fluid inclusion analyses were conducted on cm-scale quartz and calcite fibrous strain fringes from the Hatch Hill Formation in the Taconic Slate Belt of Western Vermont. The goal of this study is to assess the geochemical and thermal histories of fluids that moved through the rocks during strain fringe formation (cf. Goldstein et al., 2005 Geology). The fluids precipitated calcite and quartz in the form of fibrous strain fringes around rigid sub-spherical pyrite framboids. Three strain events are recorded in the strain fringes by three different growth directions of mineral fibers. Primary aqueous fluid inclusions in quartz have Th ranging from 110°C to 160°C; Tm range from 0°C to -2.4°C. Values of δ13C in calcite from two strain fringes vary from -3.4 to -3.2‰ (n=22), with lower values found in the youngest (last formed) calcite. Values of δ18OSMOW of calcite range from 16.0 to 17.1‰, from oldest to youngest parts of the strain fringe, while δ18OSMOW of quartz varies from 19.0 to 20.3‰. Stable isotope thermometry of the strain fringe growth ranges from 190 to 300ºC, and demonstrates a prograde thermal history for this slate unit during strain fringe development. The δ18OSMOW of water calculated from equilibrium considerations is in the range of 6.0 to 8.0‰, similar to metamorphic fluids in other low-grade terranes