THE PRECAMBRIAN IN OHIO: REASSESSING EXISTING MODELS AND THE NEED FOR NEW SEISMIC DATA

The Precambrian of Ohio is covered by a thickness of 750 to 4,500 meters of Phanerozoic sedimentary rocks and glacial deposits. Consequently, interpretations of Ohio’s Precambrian geology have been based on coarse geophysical data (seismic, gravity, and magnetic) and the 250 basement-penetrating drill holes in the state. While the COCORP OH-1 seismic reflection line was originally designed in 1987 to image the continental crust/mantle boundary, these data have been used to interpret gravity and magnetic anomalies along the length of the line. Using COCORP data, researchers interpreted Precambrian sedimentary basins, rifting, and thrust faults possibly related to orogenic activity 1.1–1.0 billion years ago. These interpretations are consistent with the lithologies observed in drill samples in the area, including Precambrian sandstones, mafic volcanic and intrusive rocks, and metamorphic rocks. In 2009, COCORP data were reprocessed and used to further refine age relationships and the evolution of the midcontinent. These seismic data were used in conjunction with depth-to-basement data from boreholes to create a structure map of Ohio’s Precambrian basement. Considering these reinterpretations, researchers may benefit from new seismic lines approximately parallel to COCORP, either to the north or to the south, to understand the structural tectonic history of Ohio.