Scientists from the U.S. Geological Survey (USGS), St. Petersburg Coastal and Marine Science Center (SPCMSC) conducted a time-series collection of shallow sediment cores from the back-barrier environments along the Chandeleur Islands, Louisiana from March 2012 through July 2013. The sampling efforts were part of a larger USGS study to evaluate the effects on the geomorphology of the Chandeleur Islands following the construction of an artificial sand berm in response to the Deep Water Horizon oil spill. The objective of this study was to evaluate the response of the back-barrier tidal and wetland environments to the berm. This report serves as an archive for sedimentological, radiochemical, and microbiological data derived from the sediment cores. Data is available for a time-series of four sampling periods: March 2012; July 2013; September 2012; and July 2013. Data is available in downloadable spreadsheet, Joint Photographic Experts Group and Portable Document File formats. Additional files included: ArcGIS shape files of the study sites, detailed results of sediment grain size analyses, and formal Federal Geographic Data Committee (FDGC) metadata.