Long-lived deformation in the southern Mississippi Embayment revealed by high-resolution seismic reflection and sub-bottom profiler data

Abstract

Three high-resolution seismic reflection profiles and two sub-bottom profiler sections acquired along the Mississippi River in southern-Central U.S. image deformation in post-Paleozoic sediments. The northernmost profile images two faults offsetting Cretaceous through at least Eocene Cane River reflectors, interpreted to strike northwest and to be part of the Arkansas River fault zone. The central profile shows a down-to-the-north fault, displacing Cretaceous and Paleocene Midway Group reflectors by~210 m and~160 m, respectively. The fault is interpreted as the northern edge fault of the Monroe Uplift, a Late Cretaceous uplift associated with igneous intrusions. The southernmost profile displays a down-to-the-south fault, offsetting Cretaceous and Paleocene-Eocene Wilcox Group reflectors by~125 m and~32 m, respectively. Tilted reflectors in the first 80 m indicate Eocene-Oligocene activity of the fault, although Quaternary activity cannot be ruled out. Quaternary tectonic activity is proposed for a series of faults that offset shallow (<40 m depth) Eocene sequences and the base of the Quaternary alluvium as imaged on two sub-bottom profiler sections. These shallow faults are imaged in the vicinity of Holocene earthquake-induced liquefaction fields, corroborating the evidence for recent tectonic activity in the area. The spatial coincidence of the imaged faults with the inferred location of the Alabama-Oklahoma transform strongly argues toward a long-lived influence of this Precambrian continental margin in focusing tectonic activity in the southern U.S. by controlling the reactivation of Triassic-Jurassic syn-rift basement structures and guiding the emplacement of Late Cretaceous igneous intrusions and the location of Cenozoic deformation.

Dense lower crust elevates long‐term earthquake rates in the New Madrid seismic zone

“…By contrast, despite liquefaction evidence of strong Holocene shaking [e.g., Obermeier et al, 1993;Munson et al, 1997] the Wabash Valley seismic zone may not be subject to anomalously high long-term stress. Seismicity there may instead reflect optimally oriented faults in the regional stress field, transient perturbations due to glacial isostatic adjustment [Grollimund and Zoback, 2001] Additionally, the vertical throw on individual faults imaged in seismic data is generally~100 m or less [Schweig and Ellis, 1994;Van Arsdale, 2000;Odum et al, 2010;Hao et al, 2013Hao et al, , 2015]. Yet we argue that deviatoric stress in the NMSZ is elevated and, implicitly, that the source of this stress is likely Middle/Late Cretaceous in age.…”

“…In addition to the NMSZ, our model predicts elevated stress along the multiply reactivated [ Cox et al ., ; Hao et al ., ] Alabama‐Oklahoma Transform (Figure d). The Guy‐Greenbrier, Arkansas, earthquake swarms coincide with another locus of elevated stress (Figure d), suggesting that body forces influence both natural and induced seismicities.…”

“…The large earthquakes in the NMSZ have puzzled geodesists in recent decades because the rate of strain accumulation is low (~10 −9 /yr) if even detectable [ Newman et al ., ; Calais et al ., ; Frankel et al ., ; Craig and Calais , ; Boyd et al ., ], issues of postseismic deformation notwithstanding. Additionally, the vertical throw on individual faults imaged in seismic data is generally ~100 m or less [ Schweig and Ellis , ; Van Arsdale , ; Odum et al ., ; Hao et al ., , ]. Yet we argue that deviatoric stress in the NMSZ is elevated and, implicitly, that the source of this stress is likely Middle/Late Cretaceous in age.…”

“…subsidence created accommodation space for the sedimentary fill of the Mississippi Embayment [Cox and Van Arsdale, 2002]. Dated, Late Cretaceous intrusions and Neogene-Quaternary normal faults [Hao et al, 2015] abound southwest of the NMSZ, likely manifestations of multiple reactivations of the Proterozoic southern margin of Laurentia [Cox et al, 2013]. Irregularly periodic but recurrent Cenozoic slip (generally dextral to reverse-oblique) has migrated among numerous subparallel faults in the Mississippi Embayment [Pratt, 1994;Johnston and Schweig, 1996;Cox et al, 2006].…”

A joint local and teleseismic tomography study of the Mississippi Embayment and New Madrid Seismic Zone

“…The Mississippi Embayment (ME) is a large SSW plunging sedimentary basin in the South‐Central United States filled with unconsolidated Upper Cretaceous and younger sediments [ Cox and Van Arsdale , ]. Extensional features developed during the breakup of supercontinent Rodinia in Early Cambrian time lie below the ME [e.g., Thomas , ; Hao et al ., ]. The Reelfoot Rift is the most recognizable feature, but the entire embayment is underlain by rifted crust [ Johnson et al ., ; Cox and Van Arsdale , ; Cox et al ., ].…”