Carbonate deposition, Pyramid Lake subbasin, Nevada: 2. Lake levels and polar jet stream positions reconstructed from radiocarbon ages and elevations of carbonates (tufas) deposited in the Lahontan basin

Most of the tufas in the Pyramid Lake subbasin were deposited within the last 35 000 yr, including most of the mound tufas that border the existing lake. Many of the older tufas (>21 000 yr BP) contained in the mounds were formed in association with groundwater discharge. Lake Lahontan experienced large and abrupt rises in level that are believed to indicate the passage of the polar jet stream over the Lahontan basin. During expansion of the Laurentide Ice Sheet, the jet stream moved south across the basin, and during the contraction of the Ice Sheet, the jet stream moved north across the basin. The bulk of the carbonate contained in the mound tufas was deposited during the last major lake cycle (~23 500-12 000 yr BP), indicating that ground- and surface-water discharges increased at ~23 500 and decreased at ~ 12 000 yr BP. -from Authors