Pre-Cretaceous Geology Beneath Georgia Coastal Plain: ABSTRACT

Chowns, Timothy M.

doi:10.1306/c1ea497d-16c9-11d7-8645000102c1865d

Cited by 1 publication

(6 citation statements)

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“… Close up of the aeromagnetic data within the rift‐basin. Dashed black line marks the rift basin boundary defined by Chowns and Williams (1983). Gants fault (arrows) is aligned with a NE‐trending lineament that terminates ESE‐trending lineaments to the southeast.…”

Section: Resultsmentioning

confidence: 99%

“…Circles represent basement‐penetrating drill holes (Horton et al., 2022), colored by generalized rock type (see key); smaller circles represent cores with poor quality lithology (rank 4 or 5). Thin black line shows the onshore section of the South Georgia rift basin boundary (Chowns & Williams, 1983), thin white line shows the Fall Zone (Horton & Dicken, 2001). (b) Overlay of the gravity Bouguer anomaly derived from station data draped over a black‐and‐white rendering of the RTP magnetic field.…”

Section: Resultsmentioning

confidence: 99%

“…(b) Match‐filtered RTP magnetic anomaly, highlighting shallower sources. Thin white line shows the Fall Zone; thin black line shows the South Georgia rift basin boundary defined by Chowns and Williams (1983). Cyan dashed lines show geologic zones mapped within exposed Piedmont bedrock (Horton & Dicken, 2001) and their interpreted continuation beneath Atlantic Coastal Plain sediments (the southern edge of the Kiokee belt is not well‐constrained).…”

Section: Resultsmentioning

confidence: 99%

“…(b) Legacy aeromagnetic data compilation (Ravat et al., 2009). Black polygon delineates the onshore part of the South Georgia rift basin (Chowns & Williams, 1983). Dashed line represents the Fall Zone.…”

Section: Introductionmentioning

confidence: 99%

“… (a) U.S. Geological Survey 2018 National Seismic Hazard Model map showing peak horizontal ground acceleration (2% probability of exceedance in 50 years), highlighting intraplate seismic zones (Petersen et al., 2020) and rift basins in the central and eastern U.S. (Chowns & Williams, 1983; Coleman & Cahan, 2012). Mesozoic rift basins are shown in black; older rift basins in blue.…”

Section: Introductionmentioning

confidence: 99%

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Rift Basins and Intraplate Earthquakes: New High‐Resolution Aeromagnetic Data Provide Insights Into Buried Structures of the Charleston, South Carolina Seismic Zone

Shah

Pratt

Horton

2023

Geochem Geophys Geosyst

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The delineation of faults that pose seismic risk in intraplate seismic zones and the mapping of features associated with failed rift basins can help our understanding of links between the two. We use new high‐resolution aeromagnetic data, previous borehole sample information, and reprocessed seismic reflection profiles to image subsurface structures and evaluate recent fault activity within the Charleston seismic zone, the associated Mesozoic South Georgia rift basin, and surrounds. The new aeromagnetic data provide an unprecedented view of buried basement structures. NE‐ and NW‐trending lineaments of various lengths throughout the survey area are interpreted as Paleozoic orogenic structures and Mesozoic dikes, respectively. Within the rift basin, 15‐ to 20‐km long ESE‐trending lineaments are associated with faults in pre‐Cretaceous strata of the reflection data and are interpreted as Mesozoic rift structures. Various intersections and terminations of interpreted faults suggest rift‐related reactivation of Paleozoic faults and corresponding inheritance for Mesozoic structures. The reflection data show that several Paleozoic and Mesozoic faults are associated with deformation in Cretaceous and younger sediments, suggesting reactivation in the more recent passive margin setting. Two of these faults, one NE‐striking and one ESE‐striking, are coincident with surficial landforms, suggesting Quaternary slip; the ESE‐striking fault is also well‐aligned with a plan‐view offset in modern seismicity. A favorable orientation for reverse motion on ESE‐striking Mesozoic faults, a possible sub‐basin, and potentially weakened lithosphere are failed rift basin features that may influence intraplate seismicity within the Charleston seismic zone.

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Section: Resultsmentioning

confidence: 99%