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Title: | Multiple drivers and controls of pockmark formation across the Canterbury Margin, New Zealand |
Authors: | Micallef, Aaron Averes, Tanita Hoffmann, Jasper Crutchley, Gareth Mountjoy, Joshu J. Person, Mark Cohen, Denis Woelz, Susanne Bury, Sarah J. Ahaneku, Chibuzo Valeria Spatola, Daniele Luebben, Neeske Miserocchi, Stefano Krastel, Sebastian Torelli, Martina Omosanya, Kamaldeen. O. L. |
Keywords: | Groundwater flow -- New Zealand Sediments (Geology) -- New Zealand Hydrogeology -- New Zealand Hydrology -- New Zealand Geotechnical engineering -- New Zealand Seepage -- New Zealand Gas seepage -- New Zealand |
Issue Date: | 2022 |
Publisher: | Wiley-Blackwell Publishing Ltd. |
Citation: | Micallef, A., Averes, T., Hoffmann, J., Crutchley, G., Mountjoy, J. J., Person, M., ... & Omosanya, K. O. (2022). Multiple drivers and controls of pockmark formation across the Canterbury Margin, New Zealand. Basin Research, 1-26. |
Abstract: | Shallow seabed depressions attributed to focused fluid seepage, known as pock-marks, have been documented in all continental margins. In this study, we dem-onstrate how pockmark formation can be the result of a combination of multiple factors— fluid type, overpressures, seafloor sediment type, stratigraphy and bot-tom currents. We integrate multibeam echosounder and seismic reflection data, sediment cores and pore water samples, with numerical models of groundwa-ter and gas hydrates, from the Canterbury Margin (off New Zealand). More than 6800 surface pockmarks, reaching densities of 100 per km2, and an undefined number of buried pockmarks, are identified in the middle to outer shelf and lower continental slope. Fluid conduits across the shelf and slope include shal-low to deep chimneys/pipes. Methane with a biogenic and/or thermogenic origin is the main fluid forming flow and escape features, although saline and fresh-ened groundwaters may also be seeping across the slope. The main drivers of fluid flow and seepage are overpressure across the slope generated by sediment loading and thin sediment overburden above the overpressured interval in the outer shelf. Other processes (e.g. methane generation and flow, a reduction in hydrostatic pressure due to sea- level lowering) may also account for fluid flow and seepage features, particularly across the shelf. Pockmark occurrence coin-cides with muddy sediments at the seafloor, whereas their planform is elongated by bottom currents. |
URI: | https://www.um.edu.mt/library/oar/handle/123456789/93114 |
Appears in Collections: | Scholarly Works - FacSciGeo |
Files in This Item:
File | Description | Size | Format | |
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Multiple_drivers_and_controls_of_pockmark_formation_across_the_Canterbury_Margin_New_Zealand(2022).pdf Restricted Access | 4.33 MB | Adobe PDF | View/Open Request a copy |
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