Structural style, regional distribution, and seismic implications of midcontinent fault-anti-dold zones, United States

Stephen Marshak, Timothy Paulsen

Research output: Contribution to journalArticlepeer-review

Abstract

Paleozoic/Mesozoic strata of the United States continental interior contain arrays of steeply dipping faults and associated monoclinal forced folds. Though these Midcontinent fault-and-fold zones clearly were active in pulses during the Phanerozoic, we suggest that they initiated during episodes of Proterozoic extensional tectonism. Based on fault-trace orientation, we divide Midcontinent fault-and-fold zones into two sets - one trending N to NE and the other trending W to NW These sets effectively break the upper crust into blocks that jostle with respect to each other in response to changes in stress state. Notably, many W- to NW-trending fault-and-fold zones link along strike to define semi-continuous NW-trending deformation corridors. One of these, the 200 km-wide Transamerican tectonic zone (TTZ), traces over 2,500 km from Idaho to South Carolina. Seismic events occur in association with fault-and-fold zones, presumably because the zones persist as crustal weaknesses and/or stress risers. Significantly, seismicity most frequently occurs where N- to NE-trending fault-and-fold zones cross the TTZ, suggesting that intracratonic strain in the United States currently concentrates at or near intersecting fault zones within this corridor.

Original languageEnglish (US)
Pages (from-to)511-520
Number of pages10
JournalSeismological Research Letters
Volume68
Issue number4
StatePublished - Jul 1997

ASJC Scopus subject areas

  • Geophysics

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