Sulfur and strontium isotope analyses have been used to test the possibility that barite veins in the Galeana district of northeastern Mexico formed where barium-bearing solutions intersected an overlying gypsum-bearing unit. Sulfur isotope analyses confirm that the sulfur in the barite has the same range as Olvido gypsum. The mean isotopic composition of the barite is about 1.2 per mil heavier than the mean gypsum composition, suggesting that fractionation took place during barite deposition. Strontium isotope compositions of Huizachal Group rocks fall on an isochron with an age of 227.5 ± 3 m.y. and an initial 87Sr/86Sr ratio of 0.70816 ± 0.00004, and the age-corrected, average Huizachal isotopic composition agreed with that of the Galeana barites about 30 m.y. ago, consistent with the geologic estimates of the age of mineralization. Compositions of whole rocks and dilute acid leachates from the Huizachal Group indicate that the strontium, and presumably also the barium, were derived from the bulk rock rather than the easily leachable carbonate cement and veinlets. Additional study results are discussed.
|Original language||English (US)|
|Number of pages||11|
|Publication status||Published - Dec 1988|
ASJC Scopus subject areas
- Geochemistry and Petrology