19 Depositional systems and resource distribution in eastern and southern North America: from orogens to coastal plains
We welcome studies related to the sourcing, dispersal, and deposition of clastic sediments from the hinterlands to the coast, including the provenance, paleogeography, sedimentology, and economic significance of these deposits.
Tuesday, 10 March 2026
8:30 AM - 11:30 AM
RCC, 105
Seasonal organic and inorganic accretion in the Balize delta marshes
Paper number: 19-9
Program: Technical Sessions
Time: 10:35 AM – 10:50 AM
Authors
Abstract
Wetland sustainability in deltaic marshes relies on the elevation maintenance of intertidal platforms, which is regulated by seasonal flood pulses that deliver inorganic sediment and organic material trapping and preservation above and belowground. The lower Mississippi river mouth, called the Balize delta, experiences some of the largest relative sea-level rise (RSLR) rates in the entire Mississippi delta. Cycles of growth and deterioration have plagued its 500 year history, with the most notable wetland loss documented post-1950. Today, multiple mitigation strategies such as man-made crevasses and beneficial use of dredge spoil are being employed to maintain wetland surfaces/area. This study documents the natural delivery of sediment to marshes on the distributary channels of the Balize delta during the flood pulse of 2025. We used sediment tiles deployed on the vegetated marsh surface in February 2025 along transects from the main channel (5m, 10m, 20m distance) and near distributary openings and terminus (N = 52). Tiles were collected in June 2025 when water levels returned to lower discharge conditions. Average sediment tile vertical accretion over the 3-month period was 6.6 ± 8.5 mm, indicating sediment delivery to wetland surfaces during flood pulses remains substantial, however may be inadequate to offset local RSLR of 10-25 mm/yr. Sediment was further processed in the lab for organic content, bulk density, grain size, and 7Be concentration, and a repeat of the analyses is planned spring 2026 to capture the yearly rates. This information will contribute to a larger mass-balance budget of sediment delivery from the Mississippi River to the coastal ocean, and is vital when considering restoration projects along the channels and interdistributary wetlands.
Geological Society of America Abstracts with Programs. Vol. 58, No. 1
doi: 10.1130/abs/2026SE-411804
© Copyright 2026 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.