Post-Cretaceous faulting at head of Mississippi embayment
- Illinois State Geological Survey, Champaign, IL (United States)
- Geological Survey, Reston, VA (United States)
Recent mapping in southernmost Illinois and southeastern Missouri has revealed numerous faults that displace Cretaceous and Tertiary strata. Units as young as the Pliocene-Pleistocene( ) Mounds Gravel are deformed; some faults possibly displace Quaternary sediments. The faults strike northeast, dip nearly vertically, and exhibit characteristics of dextral strike-slip. Pull-apart grabens occur along right-stepping fault strands, they contain chaotically jumbled blocks of Paleozoic, Cretaceous and Tertiary rocks downdropped as much as 800 m relative to wall rocks. Faults at the head of the Mississippi embayment probably originated during Cambrian rifting (Reelfoot rift) and have a long, complex history of reactivation under different stress fields. Some faults are on strike with faults in the New Madrid seismic zone. Kinematics of post-Cretaceous displacements fit the contemporary stress regime of ENE-WSW compression. Similar fault orientations and kinematics, as well as close proximity, suggest a close link between faulting at the head of the embayment and ongoing tectonism in the New Madrid seismic zone.
- OSTI ID:
- 7206964
- Report Number(s):
- CONF-9303210-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 25:3; Conference: 27. annual Geological Society of America (GSA) North-Central Section meeting, Rolla, MO (United States), 29-30 Mar 1993; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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