Numerical modelling of erosional landforms driven by offshore groundwater flow on siliciclastic continental margins: a conceptual approach
Offshore freshened groundwater (OFG) has long been hypothesised to be a key factor shaping continental margins worldwide. Field observations from siliciclastic margins suggest strong causal links between sub-seafloor OFG flow and seafloor depressions, canyons and landslide scars. These links have be...
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Frontiers Media S.A.
2025-01-01
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| Online Access: | https://www.frontiersin.org/articles/10.3389/feart.2025.1453255/full |
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| author | Shubhangi Gupta Shubhangi Gupta Aaron Micallef |
| author_facet | Shubhangi Gupta Shubhangi Gupta Aaron Micallef |
| author_sort | Shubhangi Gupta |
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| description | Offshore freshened groundwater (OFG) has long been hypothesised to be a key factor shaping continental margins worldwide. Field observations from siliciclastic margins suggest strong causal links between sub-seafloor OFG flow and seafloor depressions, canyons and landslide scars. These links have been hard to validate due to a paucity of appropriate field data and difficulty in simulating the subsurface flow and geomorphic processes in the laboratory. Here we present a numerical study that simulates the geomorphic action of sub-seafloor OFG seepage in an idealised 3D continental margin. Analysis of the coupling conditions highlights the multiplicative nature of the primary driving mechanisms (seepage-induced erosion and slope instability), suggesting a continuous transition between flow- and stress-controlled landforms. We find that OFG can create landforms in siliciclastic margins when buried flow pathways exist. Shelf-break depth determines landform type and timing. Shelf-breaks deeper than the sea-level lowstand lead to shallow circular depressions in the mid-shelf region, while those shallower than the lowstand yield V-shaped and theatre-headed valleys in the outer shelf to upper slope. Landforms emerge during falling sea-levels, starting as pockmark trains along the edges of the buried channels. Sensitivity studies show that: (1) channel width and depth affect only landform size, not type, and (2) OFG-related landforms are mainly erosion-driven and can evolve into slope failures in coarse-grained sediments with low cohesive strength. Our model aligns with field observations of pockmarks, canyons, and landslides in various continental margin settings. |
| format | Article |
| id | doaj-art-c62711647e4e4800841fc9b66b230de5 |
| institution | Kabale University |
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| language | English |
| publishDate | 2025-01-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Earth Science |
| spelling | doaj-art-c62711647e4e4800841fc9b66b230de52025-01-31T06:41:15ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632025-01-011310.3389/feart.2025.14532551453255Numerical modelling of erosional landforms driven by offshore groundwater flow on siliciclastic continental margins: a conceptual approachShubhangi Gupta0Shubhangi Gupta1Aaron Micallef2Deptartment of Geosciences, University of Malta, Msida, MaltaGEOMAR Helmholtz Center for Ocean Research, Kiel, GermanyMonterey Bay Aquarium Research Institute, Moss Landing, CA, United StatesOffshore freshened groundwater (OFG) has long been hypothesised to be a key factor shaping continental margins worldwide. Field observations from siliciclastic margins suggest strong causal links between sub-seafloor OFG flow and seafloor depressions, canyons and landslide scars. These links have been hard to validate due to a paucity of appropriate field data and difficulty in simulating the subsurface flow and geomorphic processes in the laboratory. Here we present a numerical study that simulates the geomorphic action of sub-seafloor OFG seepage in an idealised 3D continental margin. Analysis of the coupling conditions highlights the multiplicative nature of the primary driving mechanisms (seepage-induced erosion and slope instability), suggesting a continuous transition between flow- and stress-controlled landforms. We find that OFG can create landforms in siliciclastic margins when buried flow pathways exist. Shelf-break depth determines landform type and timing. Shelf-breaks deeper than the sea-level lowstand lead to shallow circular depressions in the mid-shelf region, while those shallower than the lowstand yield V-shaped and theatre-headed valleys in the outer shelf to upper slope. Landforms emerge during falling sea-levels, starting as pockmark trains along the edges of the buried channels. Sensitivity studies show that: (1) channel width and depth affect only landform size, not type, and (2) OFG-related landforms are mainly erosion-driven and can evolve into slope failures in coarse-grained sediments with low cohesive strength. Our model aligns with field observations of pockmarks, canyons, and landslides in various continental margin settings.https://www.frontiersin.org/articles/10.3389/feart.2025.1453255/fulloffshore freshened groundwatertopographically driven flowlandscape evolution modellingpockmarkcanyonlandslide |
| spellingShingle | Shubhangi Gupta Shubhangi Gupta Aaron Micallef Numerical modelling of erosional landforms driven by offshore groundwater flow on siliciclastic continental margins: a conceptual approach Frontiers in Earth Science offshore freshened groundwater topographically driven flow landscape evolution modelling pockmark canyon landslide |
| title | Numerical modelling of erosional landforms driven by offshore groundwater flow on siliciclastic continental margins: a conceptual approach |
| title_full | Numerical modelling of erosional landforms driven by offshore groundwater flow on siliciclastic continental margins: a conceptual approach |
| title_fullStr | Numerical modelling of erosional landforms driven by offshore groundwater flow on siliciclastic continental margins: a conceptual approach |
| title_full_unstemmed | Numerical modelling of erosional landforms driven by offshore groundwater flow on siliciclastic continental margins: a conceptual approach |
| title_short | Numerical modelling of erosional landforms driven by offshore groundwater flow on siliciclastic continental margins: a conceptual approach |
| title_sort | numerical modelling of erosional landforms driven by offshore groundwater flow on siliciclastic continental margins a conceptual approach |
| topic | offshore freshened groundwater topographically driven flow landscape evolution modelling pockmark canyon landslide |
| url | https://www.frontiersin.org/articles/10.3389/feart.2025.1453255/full |
| work_keys_str_mv | AT shubhangigupta numericalmodellingoferosionallandformsdrivenbyoffshoregroundwaterflowonsiliciclasticcontinentalmarginsaconceptualapproach AT shubhangigupta numericalmodellingoferosionallandformsdrivenbyoffshoregroundwaterflowonsiliciclasticcontinentalmarginsaconceptualapproach AT aaronmicallef numericalmodellingoferosionallandformsdrivenbyoffshoregroundwaterflowonsiliciclasticcontinentalmarginsaconceptualapproach |