An example of neotectonism in a continental interior — Thebes Gap, Midcontinent, United States

Harrison, Richard W.; Hoffman, David J.; Vaughn, James D.; Palmer, James; Wiscombe, Christine L.; McGeehin, John P.; Stephenson, William J.; Odum, Jack K.; Williams, Robert A.; Forman, Steven L.

doi:10.1016/s0040-1951(99)00010-4

Cited by 35 publications

(8 citation statements)

References 29 publications

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“…The Mounds Gravel has been rotated to dips of 54~ ~ into the fault ( Figure 15B). The graben-filling Quaternary gravel is post-Mounds Gravel and is similar to a pre-Late Illinoian gravel (informal Happy Hollow Formation of Harrison et al, 1999) recognized elsewhere in southeast Missouri . It is roughly equivalent to the informal Metropolis Formation found in southern Illinois and northwestern Kentucky (Nelson et al, 1997).…”

Section: Neotectonism and Seismicity In The Central Tectonic Domainsupporting

confidence: 53%

“…Surface exposures document deformation in Ordovician through Quaternary deposits at places along the CGL (Stewart, 1942;Stewart and McManamy, 1944;Harrison and Schultz, 1994b;Harrison et al, , 1999Nelson et al, 1997;Clendenin and Diehl, 1999;Harrison, 1999; in press). Several seismic-reflection profiles acquired across the CGL show that this deformation extends vertically to several kilometers of depth (Palmer et al, 1997b, b;Stephenson et al, 1999;Odum et al, 2002).…”

Section: Commerce Geophysical Lineamentmentioning

confidence: 99%

“…Deformation from this episode is widespread in the Thebes Gap area, where it is constrained as post-Roxana Silt and pre-Peoria Loess Harrison et al, 1999;Harrison et al, in press). This episode appears to be regional in extent, as many Neogene faults in southern Illinois exhibit extension in an east-west to northeast-southwest direction (Nelson et al, 1997), which is consistent with our anomalous orientation and opposite that of the present-day stress field.…”

Section: Neotectonism Along the Commerce Geophysical Lineamentmentioning

confidence: 99%

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Tectonic Framework of the Southwestern Margin of the Illinois Basin and Its Influence on Neotectonism and Seismicity

Harrison

Schultz

2002

Seismological Research Letters

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Section: Neotectonism and Seismicity In The Central Tectonic Domainsupporting

confidence: 53%

Section: Commerce Geophysical Lineamentmentioning

confidence: 99%

Section: Neotectonism Along the Commerce Geophysical Lineamentmentioning

confidence: 99%

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Tectonic Framework of the Southwestern Margin of the Illinois Basin and Its Influence on Neotectonism and Seismicity

Harrison

Schultz

2002

Seismological Research Letters

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“…However, crustal deformation also occurs in the interior of the plates as evident by intraplate seismicity and geodetic measurements of vertical and horizontal crustal movements caused by crustal loading and epeirogeny processes (Brown and Reilinger 1986;Harrison et al 1999;Nelson et al 1999;Talwani 1999). Two endogenic forces, (1) crustal rebound (glacial unloading of the Weichselian ice cap) and (2) plate-tectonic processes caused by [a] convergence of Africa-Eurasia, [b] North Atlantic sea-floor spreading (ridge-push), have the most potential to cause active crustal movements inside the NW-German Basin.…”

Section: Discussionmentioning

confidence: 99%

Evidence for active tilting of the NW-German Basin from correlations between fluvial landscape and geological subground

Szeder

Sirocko

2005

Int J Earth Sci (Geol Rundsch)

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The catchment basin of the River Hunte (Lower Saxony, NW-German Basin) was studied on a mesoscale (length of $90 km) to investigate the influence of the geological subground on modern morphology. A Geo Information System (GIS) was used to calculate linear correlation coefficients between the depth of geological strata (Base Zechstein to Base Quaternary) and the height of the modern landscape (Holocene Alluvial Plain, Lower Weichselian Terrace, catchment basin and watershed). High linear correlation coefficients between the Base of Tertiary and the height of the modern topography (catchment basin [r 2 =0.87], Lower Weichselian Terrace [r 2 =0.95] and Holocene Alluvial Plain [r 2 =0.95]) indicate control of the modern topography by the depth of the geological subsurface via tilting of the entire basin. Most likely northward tilting of the NW-German Basin forces the River Hunte to flow in a northerly direction by relative uplift of the hinterland (Wiehengebirge, Rhenish Massif) and subsidence of the North Sea area.

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“…The best documented case is the northeast-striking Commerce Fault zone (regionally, the CGL, Figure 2), which displaces Wisconsinan loess and Holocene sediments in southeastern Missouri (Harrison and Schultz, 1994;Harrison et al, 1999;Stephenson et al, 1999;Odum et al, 2002). The CGL, expressed as a northeast trend of gravity and magnetic anomalies, seems to correlate spatially with moderate-magnitude earthquake epicenters between northeastern Arkansas and southeastern Illinois (Harrison and Schultz, 1994;Langenheim and Hildenbrand, 1997).…”

mentioning

confidence: 98%

Integrated Geological and Geophysical Study of Neogene and Quaternary-age Deformation in the Northern Mississippi Embayment

McBride

Nelson

Stephenson

2002

Seismological Research Letters

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A program of shallow drilling, trenching, outcrop mapping, and seismic-reflection acquisition in southern Illinois, just north of the New Madrid seismic zone, has produced the most comprehensive documentation to date of Quaternaryage faulting in the northern Mississippi embayment. Detailed structural cross-sections over five northeast-trending faults that continue from the Fluorspar Area fault complex southward into the embayment (Massac County, Illinois) indicate narrow grabens into which latest Cretaceous, Paleocene, and Eocene sediments were dropped and protected from erosion. The bounding faults were active during Neogene through middle Pleistocene time; in the deepest graben, the Late Miocene-Pleistocene-age Mounds Gravel is downthrown 150 m. Notably, definitive faulting of Wisconsinan loess or Holocene alluvium is not observed at any site, which would indicate that the faults have been inactive for at least 55 ka (basal loess ages) to 128 ka (youngest Illinoian age). Seismic profiles reveal that faults in Quaternary sediments penetrate Paleozoic bedrock, thus indicating that these are tectonic faults and not products of landsliding, solution collapse, or other merely near-surface processes. The faults exhibit vertical to steeply dipping normal and occasional reverse displacements that outline a variety of structures, including a series of narrow grabens. Tilting or folding of strata associated with faulting is also locally observed. At one site, observed faulting is superimposed over a prominent bedrock anticline, which may itself be a result of the Quaternary deformation that created the steep normal and reverse faults. Our results indicate that shallow sediment and bedrock faulting extends beyond the localized fault zones, implying that Quaternary deformation of the northern Mississippi embayment is more pervasive than formerly believed. The trend of Quaternary-age structures in southern Illinois is in line with the northeasttrending New Madrid seismic zone and is parallel to other geologically active features in the region, such as the Commerce geophysical lineament; the lack of observed Holocene movement, however, suggests that the faults in our study area are not currently active and thus may not contribute to seismic hazard. We propose a dynamic structural model that suggests a mechanism by which seismicity and active (Holocene) faulting have shifted within the central Mississippi Valley (away from the Fluorspar Area fault complex) over the last several 10,000's of years.

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An example of neotectonism in a continental interior — Thebes Gap, Midcontinent, United States

Cited by 35 publications

References 29 publications

Tectonic Framework of the Southwestern Margin of the Illinois Basin and Its Influence on Neotectonism and Seismicity

Tectonic Framework of the Southwestern Margin of the Illinois Basin and Its Influence on Neotectonism and Seismicity

Evidence for active tilting of the NW-German Basin from correlations between fluvial landscape and geological subground

Integrated Geological and Geophysical Study of Neogene and Quaternary-age Deformation in the Northern Mississippi Embayment

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