Search for: All records

This data set consists of raw multi-channel seismic reflection (MCS) data in SEG-Y format, collected in July 2022 along the continental slope of the Campeche Bank aboard R/V Justo Sierra. The research objective was to map the detailed stratigraphy of sediment drift deposits to explore the history of the Loop Current and its climatic implications. We used the portable high-resolution seismic acquisition system operated by Scripps Institution of Oceanography, which comprised a source array of two 45 cubic inches G.I. air-guns and a GeoEel streamer with 120 channels at a spacing of 6.25 m. The air-gun array was fired every 12.5 m and was towed at a depth of 3 m. Data was recorded using the Geometrics seismic recording system with sample rate of 0.5 ms and recording length of 4 ms. A 50-ms delay was created during each shot as a buffer between the timing pulse that starts the recording and the trigger pulse that fires the air-guns. A total of 11 seismic lines were acquired including two long strike lines, five dip lines, two tilted dip lines and two short transition lines. The shot spacing was not exactly 12.5 m during the first three lines (1001-1003) due to system glitches, therefore, it is necessary to merge navigation with SEG-Y headers to ensure accurate processing of these lines. Detailed acquisition parameters and cruise incidents are described in the associated documents. Funding for this work was provided through NSF awards OCE-1928888 and OCE-1450528, and CONTEX award 2018-38A. 

Abstract The Loop Current is a key component of global circulation via the northward transport of warm, salty water, and an important influence on Gulf of Mexico hydrography. Understanding how the Loop Current will respond to ongoing anthropogenic warming is critically important, but the history of the Loop Current is poorly known. Here, we present the results of a high resolution (3–8 m) multichannel seismic survey of pelagic carbonate sediment drifts on the eastern Campeche Bank associated with the Loop Current. We identify three seismic megasequences: Megasequence A is a Lower Cretaceous carbonate platform, Megasequence B comprises Cretaceous to lower Cenozoic pelagic carbonates with weak/no contour current flow, and Megasequence C comprises a series of large (100s of m thick) contourite drifts representing the inception and history of the Loop Current. The base of the contourites is marked by a regionally mappable unconformity eroding underling strata, sometimes incising hundreds of meters. The drifts contain a succession of sequence sets separated from each other by regional unconformities and comprising plastered drifts and massive mounded drifts, which characterize modern deposition with active moats on the seafloor. A lack of sediment cores in the study area precludes age determination of these drifts, except for the youngest (Late Pleistocene). Comparison to legacy seismic lines across Deep Sea Drilling Project Site 95, outside our study area, implies that the base of Megasequence C is Oligocene in age, and that the Loop Current developed during the global reorganization of ocean circulation around the Eocene‐Oligocene Transition.