COCORP finds thick Proterozoic (?) strata under midcontinent



Thick, laterally extensive stratified rocks lie hidden within the Precambrian basement of the central United States. The layers dwarf the overlying Phanerozoic sedimentary section and may exceed in volume the entire Phanerozoic cover of the continental interior.

The extent of the layered rocks became evident last summer as the Consortium for Continental Reflection Profiling (COCORP) completed a major deep seismic reflection traverse across Ohio, Indiana, Illinois, and part of Missouri. The survey was conducted partly because industrial seismic data and studies by the Illinois Geological Survey showed basement layering in southern Illinois, partly because earlier COCORP surveys also showed such layering in Oklahoma and Texas, and partly because COCORP's broad program calls for comprehensive exploration of the entire continental basement of the United States.