Please use this identifier to cite or link to this item: https://www.um.edu.mt/library/oar/handle/123456789/93122
Title: Offshore freshened groundwater in continental margins
Authors: Micallef, Aaron
Person, Mark
Berndt, Christian
Bertoni, Claudia
Cohen, Denis
Dugan, Brandon
Evans, Rob
Haroon, Amir
Hensen, Christian
Jegen, Marion
Key, Kerry
Kooi, Henk
Liebetrau, Volker
Lofi, Johanna
Mailloux, Brian J.
Martin‐Nagle, Renée
Michael, Holly A.
Müller, Thomas
Schwalenberg, Katrin
Trembath‐Reichert, Elizabeth
Weymer, Bradley
Zhang, Yipeng
Thomas, Ariel T.
Keywords: Environmental management
Hydrogeology
Hydrology
Geotechnical engineering
Groundwater
Remote sensing
Continental margins
Issue Date: 2021
Publisher: Wiley-Blackwell Publishing Ltd.
Citation: Micallef, A., Person, M., Berndt, C., Bertoni, C., Cohen, D., Dugan, B., ... & Thomas, A. T. (2021). Offshore freshened groundwater in continental margins. Reviews of Geophysics, 59(1).
Abstract: First reported in the 1960s, offshore freshened groundwater (OFG) has now been documented in most continental margins around the world. In this review we compile a database documenting OFG occurrences and analyze it to establish the general characteristics and controlling factors. We also assess methods used to map and characterize OFG, identify major knowledge gaps, and propose strategies to address them. OFG has a global volume of 1 × 106 km3 ; it predominantly occurs within 55 km of the coast and down to a water depth of 100 m. OFG is mainly hosted within siliciclastic aquifers on passive margins and recharged by meteoric water during Pleistocene sea level lowstands. Key factors influencing OFG distribution are topography‐driven flow, salinization via haline convection, permeability contrasts, and the continuity/connectivity of permeable and confining strata. Geochemical and stable isotope measurements of pore waters from boreholes have provided insights into OFG emplacement mechanisms, while recent advances in seismic reflection profiling, electromagnetic surveying, and numerical models have improved our understanding of OFG geometry and controls. Key knowledge gaps, such as the extent and function of OFG, and the timing of their emplacement, can be addressed by the application of isotopic age tracers, joint inversion of electromagnetic and seismic reflection data, and development of three‐dimensional hydrological models. We show that such advances, combined with site‐specific modeling, are necessary to assess the potential use of OFG as an unconventional source of water and its role in sub‐seafloor geomicrobiology.
URI: https://www.um.edu.mt/library/oar/handle/123456789/93122
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