Quanternary Displacement Rates On A Meeman-Shelby Fault and The East-Bounding Fault Of The Joiner Ridge Horst, Eastern Arkansas

The Meeman-Shelby fault (~8 km from Memphis) and the Joiner Ridge horst (~54 km from Memphis) are two blind structures in the Mississippi River floodplain of northeastern Arkansas that have no modern seismicity but do have reported Quaternary displacement. Cores collected on the down-thrown sides of both a Meeman-Shelby fault and east-bounding fault of Joiner Ridge show upward fining alluvium and top-of-Eocene at depths of 36.5 m and 35.5 m, respectively. Seismic reflection profiles and radiometrically dates permitted the calculation of slip rates on two faults. A fault within the Meeman-Shelby fault zone has 4-m of displacement at a depth of 10-m on sediment dated at 11,250 ± 50 ka thus indicating a Holocene slip rate of 0.4 mm/yr. The Joiner Ridge east-bounding fault has 12-m of displacement at a depth of 40-m on sediment dated at 20,320 ± 63 ka thus indicating a Quaternary slip rate of 0.6 mm/yr