Constraints on Transport Direction Along a Shallow Detachment in the Upper Precambrian of the Eastern Midcontinent
Abstract
Dipping reflections observed on seismic reflection profiles imaging the eastern midcontinent display no evidence of west dipping reflections that can be associated with the Coshocton Zone, but support northwest directed transport along a shallow late-Precambrian detachment. Multi-channel seismic reflection profiles were reprocessed and/or analyzed along 60 km east-west and north-south transects that cross at the midpoint. These profiles display south dipping reflectors on the north-south transect and east dipping reflectors on the east-west transect. These dipping reflectors appear to penetrate to 5 km depth and are buried beneath undisturbed, subhorizontal Paleozoic sediments of the Appalachian Basin in southern Ohio and northern Kentucky. These features dip approximately 30 degrees south on the north-south line and 40 degrees east on the east-west line. No reflections with conflicting dips were observed on either transect. Other industry profiles reported in this region display similar reflections with predominately east dipping orientations in the shallow Precambrian section. In no case do these profiles have cross lines that provide limited three-dimensional control. Farther north, west-dipping reflections of the Coshocton Zone are imaged on COCORP Ohio line 2. These reflections dip approximately 40 degrees west beginning directly beneath Paleozoic cover. The shallowest of these reflectors appear to be crosscut by east dipping reflections that merge into a much deeper detachment. However, reflections observed on the westernmost portion of Ohio line 2 do not appear to be consistent with reflections observed 20 km to the north on a shorter industry profile. This southwest-northeast transect displays northeast dipping reflections in the shallow Precambrian that extend to at least 5 km depth. The constraints imposed by these data are interpreted as evidence for northwest oriented transport direction along an approximately 5 km deep detachment. A late Grenville age of this detachment in the south is presumed to be consistent with that inferred from other regional profiles. The Coshocton zone is either not imaged in these profiles, has a markedly different reflective character than that displayed to the north or does not extend as far west as previously hypothesized. The northeast dipping reflections to the north of Ohio Line 2 are inferred to image a previously unidentified Grenvillian lateral ramp. Such an interpretation is consistent with other fold and thrust belts found throughout the world.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AGUFM.T51B0882S
- Keywords:
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- 8102 Continental contractional orogenic belts;
- 8110 Continental tectonics: general (0905);
- 8199 General or miscellaneous