A variety of techniques have been used in attempts to date the mineralization in Carlin-type deposits in the Great Basin, with highly variable results. These techniques and results are reviewed in this paper, along with presentation of two new dates, for the Rodeo deposit on the Carlin trend and for the Barneys Canyon deposit in Utah. Complete resetting of sericite by hydrothermal fluids of the temperature and duration of hydrother-mal activity that form Carlin-type deposits is considered highly unlikely. Therefore, dates from sericite are generally of questionable value unless that sericite can be shown to have formed during the same hydrothermal event during which Au was deposited. For the deposits that have been investigated to date, sericite dates rarely, if ever, record the age of Au mineralization. However, sericite ages do appear to record pre-Au events in some districts. Such events may have contributed to ground preparation and, to a much lesser extent, to the tenor of the ore. Fission-track and U/Th-He techniques provide important age constraints on mineralization in some districts but also suffer from a less than clear association with Au. Rb-Sr dating of galkhaite, an Hg sulfosalt, provides the only direct age of mineralization, but galkhaite has been recognized in only a few locations (and dated in only two deposits). In a similar manner, adularia is contemporaneous with Au at Twin Creeks, but Twin Creeks is the only Carlin-type deposit where adularia has been reported. Several other techniques (U-Pb, Re-Os, Sm-Nd) have been used in attempts to date the deposits but with limited success.
