Geo-Marine Letters

, Volume 29, Issue 6, pp 379–394

Late Holocene chronology, origin, and evolution of the St. Bernard Shoals, Northern Gulf of Mexico, USA

  • Bryan E. Rogers
  • Mark A. Kulp
  • Michael D. Miner
Original

DOI: 10.1007/s00367-009-0162-6

Cite this article as:
Rogers, B.E., Kulp, M.A. & Miner, M.D. Geo-Mar Lett (2009) 29: 379. doi:10.1007/s00367-009-0162-6

Abstract

Several shore-parallel marine sand bodies lie on the Louisiana continental shelf. They are Trinity Shoal, Ship Shoal, Outer Shoal, and the St. Bernard Shoals. These shoals mark the submerged positions of ancient shorelines associated with abandoned deltas. Three of these shoals are single elongate deposits. The fourth shoal, the St. Bernard Shoals, consists of a group of discrete sand bodies ranging in size from 44 to 0.05 km2, 25 km southeast of the Chandeleur Islands in 15–18 m of water. The St. Bernard Shoals are stratigraphically above the St. Bernard delta complex, which was active 2,500–1,800 years b.p. Understanding the evolution of the St. Bernard Shoals is necessary to reconstruct the Holocene chronology of the St. Bernard delta complex and the eastern Louisiana continental shelf. For this study, 47 vibracores and 400 km of shallow seismic reflection data collected in 1987 across the Louisiana shelf were analyzed. In June 2008, 384 km of higher-resolution seismic reflection data were acquired across the study area and appended to the preexisting datasets. Vibracores were integrated with seismic profiles to identify facies and their regional distribution. Our results demonstrate that the deltaic package stratigraphically below the St. Bernard Shoals is chronologically younger than the northern distributaries, but derived from the same trunk distributary channel (Bayou la Loutre). The river eventually bypassed the northern distributaries, and began to deposit sediment further onto the continental shelf. After abandonment, the overextended delta lobe was rapidly transgressed, creating a transgressive shoreline that eventually coalesced with earlier shorelines in the region to form the Chandeleur Islands. The St. Bernard Shoals formed by the reworking of the relict distributary deposits exposed on the inner to mid shelf during and subsequent to shoreface ravinement.

Supplementary material

367_2009_162_MOESM1_ESM.pdf (1.9 mb)
Supplementary material, approximately 1.91 MB.

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Bryan E. Rogers
    • 1
  • Mark A. Kulp
    • 1
    • 2
  • Michael D. Miner
    • 2
  1. 1.Department of Earth and Environmental SciencesUniversity of New OrleansNew OrleansUSA
  2. 2.Pontchartrain Institute for Environmental SciencesUniversity of New OrleansNew OrleansUSA

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