GSA Connects 2022 meeting in Denver, Colorado

Paper No. 244-8
Presentation Time: 9:00 AM-1:00 PM

A REVIEW OF THE EVIDENCE PERTAINING TO NEOPROTEROZOIC EXHUMATION ASSOCIATED WITH THE GREAT UNCONFORMITY


KELLER, C. Brenhin and MCDANNELL, Kalin, Department of Earth Sciences, Dartmouth College, Hanover, NH 03755

While unconformities are common throughout the geologic record, the anomalous abundance of large unconformities and nonconformities shortly before the start of the Phanerozoic has long been noted. The origin of this pattern, sometimes known as the Great Unconformity, has recently become a topic of significant debate. Here we review the available evidence spanning from geochemistry to thermochronology to direct physical observations -- with a particular focus on the latter. This includes, for example, the relative survival through time of surficial phenomena such as impact craters and epigene ore deposits, as well as thermobarometric estimates of the depth of structures now exposed at the surface. The results suggest a remarkable level of consistency in timing and magnitude of late Neoproterozoic exhumation across disparate localities and tectonic settings, including in stable cratonic interiors where surface processes represent the only plausible known drivers of large-scale exhumation.