The primary motivation for planning future scientific drilling on the eastern Campeche Bank in the southeastern Gulf of Mexico is to sample Cenozoic sediment drifts which record the inception and history of the Loop Current, which feeds the Gulf Stream and influences the surface hydrography of the Gulf of Mexico. We invite workshop participants who are interested in Cretaceous-Cenozoic paleoceanography, and we also strongly encourage participation from scientists with specialties outside paleoceanography, whose fields may benefit from new samples or measurements from the eastern Campeche Bank. Modern scientific ocean drilling is heavily interdisciplinary and including scientists from other disciplines at this stage will ensure a proposal that can be of broadest possible use to the community. USSSP will fund the participation of a limited number of US-affiliated scientists. We are committed to supporting the participation of scientists from under-represented groups, early career scientists, and scientists from disciplines outside paleoceanography.

The Loop Current is a critically important component of the global thermohaline circulation and an important driver of North American climate. As one of the main feeder currents of the Gulf Steam, it is an important pathway for the movement of warm, salty water from the Caribbean northward. The Loop Current also controls the average oceanographic characteristics of surface waters in the Gulf of Mexico by periodically spinning off warm-core eddies which drift west. Individual eddies can disrupt fisheries, strain offshore infrastructure, and provide a potent warm-water fuel source for hurricanes.

The Loop Current is broadly recognized as important, but it is still poorly understood. We do not know when the Loop Current first formed, nor do we have a clear understanding of whether it was stronger or weaker during the last ice age, let alone at other points in the Cenozoic. Answering these questions will have direct implications for predictions of whether the Loop Current will weaken or strengthen as the climate warms in the coming decades, and allow us to define possible tipping points in the Loop Current system as future warming approaches past analog climate states, which may or may not have had a Loop Current.

Most studies of Loop Current history focus on the Florida Bank, where the current forms its namesake loop and bends back south to exit the Gulf through the Florida Straits. Existing results from this area suggesting that the Loop Current was stronger during Last Glacial Maximum are complicated by the fact that this area is also strongly affected by Mississippi River (fresh-water) discharge. This makes it difficult to know whether proxy records indicate increased salinity because there was an increased flow of warm salty water north via the Loop Current or because there was a reduced flow of fresh water south from the Mississippi. Records from the Florida Straits themselves have the same issue. To get around this problem, we propose to study the Loop Current where it first enters the Gulf, north of the Yucatan Strait along the Campeche Bank.

The Campeche Bank is an area of gently sloping sediment drifts on a bench below the bathymetric high of the Yucatán carbonate platform and above the Campeche Escarpment, a cliff which drops into the deep Gulf of Mexico Basin. Active sediment drifts attributable to the Loop Current were discovered on the Campeche Bank by a cruise of the German ship Meteor in 2008. A subsequent reflection seismic survey funded by NSF and carried out by a team of American and Mexican scientists (the workshop committee) on the Mexican research ship B/O Justo Sierra in summer 2022, identified identical features buried in the subsurface, indicating that these drifts contain a record of current flow into the Gulf of Mexico back to the onset of the Loop Current. These seismic profiles show a clear evolution of contourite deposits, with pre-drift early Cenozoic strata overlain by a package of large mounded sediment drifts with moats of impressive scale (100s of m deep and several km wide). The moats of these mounded drifts gradually reduce in size and abundance as the deposit transitions to younger plastered sediment drifts. With only a single Deep Sea Drilling Project site (Site 95) on the far eastern edge of this area, there are no cores of these deposits with which to study the evolution of the current. However, with our new high resolution seismic data, it is now possible to plan a coring campaign to target specific seismic units to: 1) constrain the ages of key reflectors to develop an improved understanding of the timing of different stages of current development and 2) develop high-resolution proxy records to reconstruct the development of the proto-Loop Current and Loop Current through time.

IODP drilling in this area was originally proposed in 917-PRE. The IODP Science Evaluation Panel was supportive of this effort, but emphasized the need for new seismic data before the submission of a Full Proposal. After several pandemic-induced delays, we have finally collected that new seismic data. However, the future of scientific ocean drilling has evolved significantly in the meantime, and the future of drilling beyond 2024 is now uncertain. In order to determine how best to leverage this new seismic data in the evolving world of scientific ocean drilling, we are proposing a workshop to bring together interested members of the scientific ocean drilling community to prioritize the science questions that can be addressed by studying the sediment drifts in this key gateway and develop a strategy to sample these sediment drifts through drilling. 

This workshop will be hosted by Ligia Perez Cruz and Jaime Urrutia Fucugauchi from the National Autonomous University of Mexico (UNAM), in Mexico City at the UNAM Botanical Gardens August 16-18, 2023.

Our goals for this workshop are:

1.     Prioritize key scientific questions that can be addressed by studying the newly mapped sediment drifts east of Campeche Bank in the Yucatán Channel.

2.     Develop a list of sites at which sediments can be recovered to accomplish those priorities.

3.     Develop a plan (or a series of options) to core those sites in light of the changing landscape of scientific ocean drilling.

The potential science questions that could be addressed by coring on the Campeche Bank and in the Yucatán Channel are strongly aligned with the 2050 Science Framework (Koppers and Coggon et al., 2021). In particular, this work falls under the Flagship Initiative “Ground Truthing Future Climate Change.” Studying these drift deposits will “provide information about the ocean’s [i.e., Loop Current’s] response to past natural climate variability to help improve models that predict future change” and provide a new paleoclimate record to identify whether the Loop Current system is “susceptible to abrupt and irreversible change” (Koppers and Coggon et al., 2021). In so doing, this work will address several Strategic Objectives:

• • Earth’s Climate System: What is the role of the Loop Current in the northward transport of heat throughout the Cenozoic?
  • Feedbacks in the Earth’s System: Is changing Loop Current strength associated with changes in Atlantic Meridional Overturning Circulation?
  • Tipping Points in Earth History Was the development of the Loop Current driven by climate, and thus might be reversed? Or was it driven gateway changes, and is thus likely to continue regardless of climate change?
  • Natural Hazards Impacting Society Was the Loop Current stronger or weaker during warm climate states, and thus more or less likely to shed warm core eddies as the Earth warms?