Post-Cretaceous faulting at head of Mississippi embayment

Conference · Mon Mar 01 04:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:7206964

Nelson, W J ^[1]; Harrison, R W ^[2]

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1. Illinois State Geological Survey, Champaign, IL (United States)
2. 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--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:3
• Country of Publication: United States
• Language: English

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58 GEOSCIENCES
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DEVELOPED COUNTRIES
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
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ILLINOIS
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NORTH AMERICA
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