SEQUENCE STRATIGRAPHY OF MARINE HOST ROCKS WITH PREFERENTIAL ZONES OF GOLD MINERALIZATION: CARLIN TREND, NORTHEASTERN NEVADA

Gold deposits can occur in many different environments and along with the differences in environments comes the variability in other rocks and minerals associated with that particular setting. Each deposit has its own characteristics to signify it belongs to a particular deposit. The Carlin Trend gold deposit in Northeastern Nevada possesses its own individuality. The gold was deposited here by means of an acidic geothermal system in a disseminated manner. The host rock is an accumulation of limestone that formed on the margins of a prehistoric continental shelf. The gold dispersion among the host rock is controlled by structure, permeability, and composition. Variances within the controls dictate the gold accumulation. The purpose of this study is to identify a key bed that the gold is more preferential to than others supported by geochemistry, biostratigraphy, and paleoecology. The findings of such a bed will improve the resolution of the stratigraphic column for correlation within the Leeville Underground and possibly with other mine-sites.

The Leeville underground mine in the North area is composed of the main Leeville deposit with satellite deposits on the peripherals (Turf, Four Corners). Long-hole exploration drill hole analysis from Leeville suggests that the constraints for gold mineralization include structure and differences in stratal composition. The concern here is being able to find a particular bed or facies where the gold mineralization is partial to deposition more than surrounding beds in the host rock. The discovery of a specific package of strata will lead to a faster more efficient ore control program. Visual identification of a correlative stratigraphic layer or layers will aid in field work.

Correlative layer identification will be determined from the described lithologies, biostratigraphy and geochemistry of three exploratory holes drilled from the same drill program at the West Leeville mine-site. Conodont distribution patterns will be analyzed to determine the spatial similarities of correlative strata and the affects they have on gold deposition.