Laser-based, in situ measurements of fine-scale variations in the delta (super 18) O values of hydrothermal quartz
Laser-based, in situ measurements of fine-scale variations in the delta (super 18) O values of hydrothermal quartz
Geology (Boulder) (September 1992) 20 (9): 812-816
- analysis
- fluid inclusions
- framework silicates
- geochemical indicators
- geochemistry
- gold ores
- Guanajuato Mexico
- hydrothermal alteration
- hydrothermal conditions
- hydrothermal processes
- in situ
- inclusions
- isotopes
- laser methods
- mass spectroscopy
- metal ores
- metasomatism
- Mexico
- mineral deposits, genesis
- minerals
- O-18/O-16
- ore-forming fluids
- oxygen
- quartz
- quartz veins
- silica minerals
- silicates
- silver ores
- spectroscopy
- stable isotopes
- techniques
- veins
- Tayoltita
Recently developed laser-based techniques have been used to make in situ measurements of the delta (super 18) O values of hydrothermal vein quartz from the Tayoltita and Guanajuato mining districts of Mexico. The delta (super 18) O (sub qtz) values within a single 2 x 5 cm sample of banded quartz from Guanajuato varied from 12.6&permil: to 17.3ppm. Similarly, delta (super 18) O (sub qtz) values measured in a 2 x 3 cm sample from Tayoltita ranged from 5.7ppm to 9.5ppm. In both cases, the spread of delta (super 18) O values measured within individual samples is comparable to the total ranges of delta (super 18) O values previously reported for vein samples from the respective districts. Fluid-inclusion homogenization temperatures measured for these samples rule out the possibility that the changes in the delta (super 18) O values observed could have been caused by temperature fluctuations; therefore, they must be the result of large shifts in the isotopic composition of the vein fluids.
