| Abstract: | The Cottage Grove fault system in southern Illinois has long been interpreted as an intracratonic dextral strike-slip fault system. We investigated its structural geometry and kinematics in detail using (1) outcrop data, (2) extensive exposures in underground coal mines, (3) abundant borehole data, and (4) a network of industry seismic reflection profiles, including data reprocessed by us. Structural contour mapping delineates distinct monoclines, broad anticlines, and synclines that express Paleozoic-age deformation associated with strike slip along the fault system. As shown on seismic reflection profiles, prominent near-vertical faults that cut the entire Paleozoic section and basement-cover contact branch upward into outward-splaying, high-angle reverse faults. The master fault, sinuous along strike, is characterized along its length by an elongate anticline, ???3 km wide, that parallels the southern side of the master fault. These features signify that the overall kinematic regime was transpressional. Due to the absence of suitable piercing points, the amount of slip cannot be measured, but is constrained at less than 300 m near the ground surface. The Cottage Grove fault system apparently follows a Precambrian terrane boundary, as suggested by magnetic intensity data, the distribution of ultramafic igneous intrusions, and patterns of earthquake activity. The fault system was primarily active during the Alleghanian orogeny of Late Pennsylvanian and Early Permian time, when ultramatic igneous magma intruded along en echelon tensional fractures. ?? 2004 Geological Society of America. |
| Genre: | Article |
| ProdID: | 70026362 |
| Citation Author: | Duchek, A. B.; McBride, J. H.; Nelson, W. J.; Leetaru, H. E. |
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| Citation End Page: | 1484 |
| Citation Issue: | 11-12 |
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| Citation Language: | English |
| Citation Larger Work Title: | Bulletin of the Geological Society of America |
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| Citation Number Of Pages: | 20 |
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| Citation Search Results Text: | The Cottage Grove fault system (Illinois Basin): Late Paleozoic transpression along a Precambrian crustal boundary; 2004; Article; Journal; Bulletin of the Geological Society of America; Duchek, A. B.; McBride, J. H.; Nelson, W. J.; Leetaru, H. E. |
| Citation Start Page: | 1465 |
| Citation Volume: | 116 |
| Citation Year: | 2004 |
| Type: | citation/reference |
| Text: | The Cottage Grove fault system (Illinois Basin): Late Paleozoic transpression along a Precambrian crustal boundary; 2004; Article; Journal; Bulletin of the Geological Society of America; Duchek, A. B.; McBride, J. H.; Nelson, W. J.; Leetaru, H. E. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DIGITAL OBJECT IDENTIFIER): | http://dx.doi.org/10.1130/B25413.1 |
| Date Other: | Thu, 1 Jan 2004 00:00 -0600 |
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