8 New Insights from Paleontology, Stratigraphy, and Sedimentology on Accreted Terranes of Western North America I
Tuesday, 1 April 2003
8:30 AM - 12:10 PM
MOJAVE-SONORA MEGASHEAR: EVIDENCE FROM NEOPROTEROZOIC TO LOWER JURASSIC STRATA
Paper number: 8-1
Program: THEME SESSIONS
Time: 8:30 AM – 8:50 AM
Authors
Abstract
In the western United States, the distribution of facies in Neoproterozoic and Paleozoic strata indicates that the Cordilleran miogeocline trends about north-south . A north-south trend is also suggested in Sonora, and if so is compatible with offset of the miogeocline but not with the ideas that the miogeocline wrapped around the continental margin and trends east-west or east-southeast in Sonora. An imperfect stratigraphic match of supposed offset segments of the megashear is apparent. Some units are almost perfectly matched, but others show considerable differences. The mismatch is attributed to uncertainties concerning the original relative positions of the strata and/or to the possibility that indigenous succession of the western United States and offset segments in Mexico were not precisely side by side before offset but were separated by an area, now buried, eroded, or destroyed by igneous intrusion that contained strata of intermediate facies.