Comments on '(U-Th)/He dating of fluorite: application to the La Azul fluorspar deposit in the Taxco mining district, Mexico' by Pi et al. (Mineralium Deposita 39:976-982)

摘要

The age calculated for the La Azul fluorite deposit by the (U-Th)/He method can only be interpreted as a resetting age. The rhyolite dyke intrusion postdates the fluorite formation, as seen by the presence of fluorite xenoliths within the magmatic rock, in a way similar to a piecemeal stoping. Also, this intrusion produced the decrepitation and/or reequilibration of the fluid inclusions in fluorite. The genetic (epithermal) interpretation of Pi et al. (2005) is based upon a resetting age caused by the intrusion of the rhyolite dyke crosscutting the La Azul fluorite deposit. The geological setting, textures, and interrelations with the host limestone, along with characteristics of pristine fluid inclusions, make this deposit comparable to MVT-like deposits and similar to other fluorite deposits hosted in Cretaceous carbonates in Mexico.