Cape Cod: Onshore-Offshore Drilling and Sampling along the New England Continental Shelf

to Understand Freshwater Resources

We hypothesize that the rapid incursion of freshwater on the New England continental shelf could have been caused by: (1) meteoric recharge during Pleistocene sea-level lowstands including vertical infiltration of freshwater associated with local flow cells on the shelf; (2) sub-ice-sheet recharge during the last glacial maximum; and/or (3) recharge from pro-glacial lakes. We further hypothesize that the overpressures could be due to: (1) Pleistocene sediment loading; and/or (2) fluid density differences associated with emplacement of a thick freshwater lens over saltwater (analogous to excess pressures in the gas legs of petroleum reservoirs). We argue these different freshwater recharge mechanisms and overpressure models can be distinguished through drilling, coring, logging, and fluid sampling. Noble gas and environmental isotope data are necessary to completely evaluate recharge models.

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