32-5 Characterization of fault propagated folds along the Eastern Reelfoot Rift margin

Session: Latest Research Advances in Structural Geology and Tectonics (Posters)

Poster Booth No.: 223

Presenting Author:

IPSITA MITRA

Authors:

MITRA, IPSITA¹, COX, RANDEL TOM ², SARKER, KAUSHIK³, ISLAM, SAHIDUL⁴, KARKI, KAPIL⁵, BRACKMAN, THOMAS⁶, CRAMER, CHRIS⁷

Abstract:

A corridor of northeast trending topographic ridges along the eastern Reelfoot rift margin (ERRM) has been identified as probable sites of neotectonic deformation associated with reactivation of basement faults within the Reelfoot rift region. Combined earthquake epicenters and paleoseismological studies reveal that the ERRM was active during late Quaternary south of a restraining bend in the New Madrid fault complex, but the ERRM north of the restraining bend and underlying the corridor of linear ridges is seismically quiescent. We collected 2D electric resistivity (ER) profiles to image subsurface structure of a prominent linear topographic ridge along the northern segment of the ERRM.

The study site is in close proximity to Union City, TN airport. In a crop field, 5 survey lines were run perpendicular to the fault with 2m electrode spacing, and 4 perpendicular lines with 2 m electrode spacing were surveyed at a golf course, 1.3 km from the crop field site. Another quarry site was chosen to examine similar splay fault structure in Tipton County with 4 perpendicular lines and 2m electrode spacings. These ER surveys were performed using Advanced Geoscience Inc.(AGI) Supersting R8 to image subsurface faulting. Using a dipole-dipole array, each electrode served alternatively as a current and potential electrode making it useful for identifying lateral resistivity changes in subsurface associated with vertical structures such as faults. Data were processed and interpreted using EarthImager 3D inversion software.  Surveys lines were combined into 2.5D models in EarthImager and then subjected to further inversion. The 2.5D models were updated by solving linearized inversion problems to minimize data misfit. 

The maximum vertical depth of the crop field 2.5D model is 25.2 m. It images eastward verging drag folds from a depth of 10m to 20m, suggesting a transpressional flower structure controls the linear ridge at the Union City site.  These results will improve our understanding of the history of linked components of the New Madrid complex transferring the activity between different fault segments, thus giving insights into the seismotectonic model of the ERRM. These results will also give valuable understanding regarding the evolution of strike-slip restraining bends in general. 

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8817

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