1. Hydrothermal activity beneath Namche Barwa-Gyala Peri massif
Dave Craw, Peter Koons, Bill Kidd, Peter Zeitler, Mandy Booth, Page Chamberlain

2. = hot springs
Indian crust

3. Quartz vein in garnet gneiss
Quartz vein cuts
augen gneiss

4. Gyala Peri massif
Marble, calc-silicate gneiss
Granite
gneiss
East-dipping
micaceous gneiss
shear zone
Gongto Glacier

5. Fluid inclusions in quartz vein, Gyala Peri massif 300°C >500°C
30 microns (approx)

6. Fluid inclusions in quartz vein, Tsangpo gorge

9. Solvus for two separate fluids
Observed T’s and compositions

10. Sample calculations from fluid inclusion observations
300 bars fluid pressure (hydrostatic)
Fluid T = Rock T
Average fluid density = 1.0 g/cc
=> Depth = 3 km
Temperature = 300°C
=> Thermal gradient = 100°C /km
Age: rock passed through 300°C
1 million years ago
=> Uplift rate = 3 mm/year

11. Hot spring system

14. Dry steam at °C