Laser-based, in situ measurements of fine-scale variations in the δ¹⁸O values of hydrothermal quartz Available to Purchase

Recently developed laser-based techniques have been used to make in situ measurements of the δ¹⁸O values of hydrothermal vein quartz from the Tayoltita and Guanajuato mining districts of Mexico. The δ¹⁸O_qtz values within a single 2 x 5 cm sample of banded quartz from Guanajuato varied from 12.6‰ to 17.3‰. Similarly, δ¹⁸O_qtz values measured in a 2 x 3 cm sample from Tayoltita ranged from 5.7‰ to 9.5‰. In both cases, the spread of δ¹⁸O values measured within individual samples is comparable to the total ranges of δ¹⁸O 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 δ¹⁸O 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.