Document Type

Article

Publication Date

5-2025

Publication Title

Southeastern Geology

Volume

55

Issue

1

Pages

47-67

Abstract

Beds interpreted as Eocene bolide-generated impact and tsunami deposits occur at Paint Hill in the Upper Atlantic Coastal Plain of Moore County, North Carolina, USA. These strata, herein named the Mount Helicon Formation, consist of four distinct beds comprising about one meter of total section. Bed 1 (the basal bed) is approximately 43 cm thick and consists of sandy carbonaceous clay with carbon glass and rock fragments and contains 14-18 parts per billion (ppb) iridium (interpreted as bolide impact ejecta). Bed 2 is approximately 9 cm thick and consists of non-cohesive silt-size particles and loosely bound sand-size accretionary lapilli-like masses composed of quartz and carbon glass particles imbedded in a gray-green, flakey clay matrix and contains 2-6 ppb iridium (interpreted as atmospheric fallout deposits). Bed 3, is a sandy-matrix breccia approximately 6 cm thick (although thickness is greater in some places because of large clasts). This bed has terrestrially-derived clasts such as paleosol rip-ups (gravel to boulder-size) and petrified wood logs, along with marine-derived clasts, such as fossiliferous chert fragments and (up to) meter-size clasts of rolled strata contains 1-2 ppb iridium (interpreted as tsunami-surge deposits). Bed 4 is approximately 15 cm thick and consists of medium to coarse quartz sand with occasional pea size quartz gravel (interpreted as a possible later tsunami deposit). The beds of the Mount Helicon Formation fill a channel cut into the upper part of newly described upper middle Eocene (Bartonian) siliciclastic strata, herein named the Paint Hill Formation. The Paint Hill Formation consists of approximately 11 m of clay, sandstone (some glauconitic), and conglomerate (interpreted as nearshore marine strata) that are divided into five intervals of fining-upward or coarsening-upward sediments comprising 2.5 high-resolution transgressive regressive cycles. The age of the Paint Hill Formation as determined from fossil shark teeth, specifically Pseudabdounia claibornensis, is Bartonian, 41.2-37.7 Ma, late middle Eocene. The uppermost unit in the Paint Hill Member has weathered to plinthic paleosol, indicating that the land area hosting these marine strata became subaerially emergent , probably during the late Eocene. This emergent land provided a source for rip-up paleosol clasts found in Bed 3 of the Mount Helicon Formation. This discovery indicates that a catastrophic event (most likely the ~35 Ma Chesapeake Bay Impact that occurred about 380 km to the northeast of Paint Hill) generated bolide impact and tsunami deposits in a shallow marine and adjacent terrestrial setting in the southwestern part of the North Carolina Coastal Plain.

Rights

Included with kind permission from the author(s).

Copyright © 2025 Southeastern Geology. All rights reserved.

Original Publication Citation

Ganis, G., Willoughby, R., Cicimurri, D., Whittecar, G., & Hageman, S. (2025). Evidence for distal bolide impact and tsunami deposits in the upper Atlantic coastal plain of Moore County (North Carolina, USA) generated by the eocene Chesapeake Bay bolide impact. Southeastern Geology, 55(1), 47-67.

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