Quaternary displacement rates on the Meeman‐Shelby fault and Joiner ridge horst, eastern Arkansas: Results from coring Mississippi River alluvium

Seismological Research Letters
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Abstract

This research used coring and optically stimulated luminescence (OSL) dating of displaced, deeply buried Quaternary alluvium to determine vertical displacement rates for the Meeman‐Shelby fault and the Joiner ridge horst, two structures in northeastern Arkansas that have no modern seismicity associated with them. We drilled continuous cores of the entire alluvial section in the hanging wall of each structure, performed detailed core descriptions and analyses, and obtained three OSL ages from each core. The Meeman‐Shelby fault core consists of 36 m of 4.3–5.2‐ka Holocene alluvium overlying 4 m of 14.3‐ka Kennett alluvium that in turn overlies the upper part of Eocene Claiborne Group sediments at a depth of 41 m. Seismic reflection indicates that the basal (Kennett) alluvium at the Meeman‐Shelby fault is displaced ∼28  m across the Meeman‐Shelby fault, which equates to a time‐averaged vertical displacement rate of 2  mm/yr within the last 14.3 ka. The Joiner ridge horst core consists, in descending order, of 11 m of 6.3‐ka Holocene alluvium, 14 m of 11.5‐ka Morehouse alluvium, a paleosol, 6 m of Kennett alluvium, and 4 m of 20.3‐ka Sikeston alluvium that in turn overlies the upper part of Eocene Claiborne Group sediments at a depth of 36 m. Lignite exploration drilling conducted in the 1970s indicates that basal (Sikeston) alluvium is displaced ∼20  m across the eastern bounding fault of the Joiner ridge horst, resulting in a time‐averaged vertical displacement rate of ∼1  mm/yr within the last 20.3 ka. These late Quaternary displacement rates are comparable to time‐averaged displacement rates of faults within the active New Madrid seismic zone.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Quaternary displacement rates on the Meeman‐Shelby fault and Joiner ridge horst, eastern Arkansas: Results from coring Mississippi River alluvium
Series title Seismological Research Letters
DOI 10.1785/0220160171
Volume 88
Issue 2A
Year Published 2017
Language English
Publisher Seismological Society of America
Contributing office(s) Eastern Geology and Paleoclimate Science Center
Description 14 p.
First page 442
Last page 455
Country United States
State Arkansas
Other Geospatial Mississippi River