Are dates on carbonate cements in Pasco Basin regionally relevant?
Uranium-thorium is a radiometric technique for dating carbonates. Paces (2014) estimated the ages of secondary carbonate cements in the southern Pasco Basin using U-series methods as part of a probabilistic seismic hazard assessment of the U.S. Department of Energy's Hanford Site. Ages on calcic paleosols (marker beds) help geologists constrain Quaternary deformation rates in the Yakima Fold Thrust Belt. The material sampled for analysis was carbonate-silica rinds on cobbles
Syngenetic Ice Wedge Growth
Syngenetic ice wedges form in polar regions in places where new sediment is periodically added to the ground surface (Layers A, B, C). Cracks that fill with ice and eventually sediment descend through the new layer into the older ice wedge below (Mackay, 1990). Repeat sedimentation, cracking, and sediment infilling produces sheeted ice wedges that appear to "grow" upward with the aggrading surface. The figure above shows syngenetic growth at 4 time steps. At Time 1, the width