Second Call to Participate: Expedition 501: New England Shelf Hydrogeology

Second Call to Participate in IODP³-NSF Expedition 501: New England Shelf Hydrogeology now open!

Offshore freshened groundwater (OFG) systems, defined as subseafloor environments with porewater that has salinity less than seawater salinity, have been documented worldwide, yet the hydrogeological, geochemical, and microbiological evolution and dynamics of these systems have not been directly evaluated. Prior ocean drilling data have documented OFG beneath the Atlantic continental shelf off New England, with further investigation of extent and emplacement mechanisms using marine electromagnetic surveys, and hydrogeological models.

IODP³-NSF Expedition 501 was developed and implemented to collect sediment, fluid, and microbiological samples that will help us evaluate the dynamics of the OFG system south of Martha’s Vineyard and Nantucket, Massachusetts, USA. Expedition 501 specifically aimed to understand the geological evolution of the aquifer and aquitard system within the continental shelf, the timing and driving mechanism(s) of OFG system emplacement, the abundance and activity of the microbiological ecosystem in the OFG system, and the role of groundwater in biogeochemical cycling within shelf sediments (Dugan et al., 2025). This dedicated hydrogeological expedition provided data and samples to better constrain the local OFG system within the US Atlantic continental shelf and will also improve our understanding of OFG systems around the world.

During offshore and onshore operations, and continuing during post-expedition research the Expedition 501 is actively working on the following scientific measurements and assessments of the OFG system using lithostratigraphy, geochemistry, noble gases of pumped groundwater, hydrogeology, biostratigraphy, petrophysics and physical properties, and microbiology.

Based on the completed offshore and onshore operations and initial analyses of samples and data collected during Expedition 501, the Science Team identified potential research opportunities that will help expand the knowledge base of OFG systems and expand the impact of the geological evolution of the active OFG system within the US Atlantic continental shelf. These include, but are not limited to:

• Glacial sedimentology and geomorphology
• Onshore-offshore stratigraphic correlation
• Terrestrial basin analysis
• Terrestrial paleoclimate proxy analysis
• Novel geochronological tools

Applications are welcomed from scientists scientists based in IODP³ Core and Associate Member nations, and the US proposing to either: (a) adopt these or any other approaches to address the original objectives of the expedition without duplicating the plans of the original Science Team; or (b) use core samples recovered during the expedition to address new objectives and deliver new science not envisaged by the original expedition proposal

For more information please read the full call on the PDF below.

Applications must be submitted by 23:59 BST on Friday 13 November 2026 using the IODP³ Gateway system, accessed via Apply to Participate on the IODP³ webpage.