SUPERHEATED ICE IN PURE WATER FLUID INCLUSIONS FROM MOOSE RIVER, NY

Several pure water fluid inclusions in hydrothermal quartz from the west-central Adirondack highlands (near Moose River, NY) retain ice even after heating beyond the H₂O triple point temperature (0.01°C). This superheated ice was observed at temperatures between +3.6 and +6.1°C. Similar temperatures for superheated ice (up to +6.5°C) are reported by Roedder (1967; Science, v. 155, p 1413).

Superheated ice can form only in fluid inclusions with a bulk density greater than the density of ice Ih (~0.9165 g/cm³). This includes pure water fluid inclusions with homogenization temperatures (Th) of ~150°C or less. Pure water fluid inclusions with a Th greater than ~150°C show typical triple point behavior upon warming (i.e. vapor + ice → vapor + liquid). All fluid inclusions from Moose River with Th > 150°C show triple point behavior at 0.0 ± 0.1°C, thus confirming a pure water composition.

Upon warming, fluid inclusions from Moose River with Th < 150°C preserve ice Ih metastably along a low pressure extrapolation of the negatively sloping ice–water univariant curve (to pressures lower than the triple point). The metastable preservation of ice is caused by the mechanical difficulty of nucleating an H₂O vapor bubble from liquid inside the inclusions at the H₂O triple point (T= 0.01°C, P = 0.006 bars) and at lower pressures.

Because both homogenization and final (metastable) ice Ih melting temperatures are recorded, fluid inclusions from Moose River quartz provide pressure–volume–temperature data for this unusual region of pressure–temperature space.