Extension of the southeastern terminus of the Midcontinent Rift System southward from Michigan to the Ohio-Kentucky border
- Univ. of Wisconsin, Superior, WI (United States). Dept. of Geology
The Midcontinent Rift System (MRS), a 2,700 km long, horseshoe shaped, intra-continental, thermo-tectonic structure of Middle Proterozoic age, extends from central Kansas to at least southern Ohio by way of the Lake Superior basin. Its western arm, geophysically identified as the Midcontinent Gravity High, has recently been clarified structurally and lithologically as a result of extensive seismic reflection surveying and the drilling of four state record-depth hydrocarbon exploration boreholes. The 1989 discovery, in southwestern Ohio, of the Middle Run Formation, a pre-Upper Cambrian red-bed clastic sequence, together with reflection seismology identification of extension structure in western Ohio, provides for the first time compelling evidence that the eastern arm of the MRS extends at least as far south as the Ohio-Kentucky border. Representative cuts of the Middle Run (type-section) core compare petrographically with QFL analyses of the Middle Proterozoic Oronto Group, the initial synrift sedimentary sequence exposed within the classic MRS Keweenawan outcrop belt of the south shore of Lake Superior in Wisconsin and Michigan. In addition, interpretation of a short reflection profile conducted over the Middle Run basin displays half-graben structure and seismic stratigraphy similar to that mapped in recent years by MRS seismic studies both onshore and offshore Lake Superior, and by onshore Lake Superior isopach mapping of MRS units. On the basis of similarities in petrography, seismic stratigraphy, structure, and proximity to regional gravity anomalies, the Middle Run Formation and its half-graben basin is proposed as evidence for the extension of the MRS from southeastern Michigan to southwestern Ohio. Minor adjustments in the MRS axis in southwest Ohio will be possible upon separation of the regional MRS from the Grenville Front Tectonic Zone gravity and magnetic field.
- OSTI ID:
- 5639174
- Report Number(s):
- CONF-921058-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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02 PETROLEUM
RIFT ZONES
GEOLOGY
USA
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
GEOPHYSICAL SURVEYS
KENTUCKY
LAKE SUPERIOR
LITHOLOGY
MICHIGAN
OHIO
SEISMIC SURVEYS
STRATIGRAPHY
DEVELOPED COUNTRIES
GREAT LAKES
LAKES
NORTH AMERICA
PETROLOGY
SURFACE WATERS
SURVEYS
580000* - Geosciences
020200 - Petroleum- Reserves
Geology
& Exploration