The morphology of pockmarks on the north-east Antarctic Peninsula continental shelf

• Published in: Antarctic Science
• Main Authors: Batchelor, Christine L., Frinault, Bétina A.V., Christie, Frazer D.W., Montelli, Aleksandr, Dowdeswell, Julian A.
• Other Authors: Natural Environment Research Council, Prince Albert II of Monaco Foundation
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2022
• Subjects: Antarc*; Antarctic; Antarctic Peninsula; Antarctic Science
• Online Access: http://dx.doi.org/10.1017/s0954102022000177; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102022000177

Abstract Pockmarks are sea-floor depressions that form when gas or liquid escapes from underlying sediments. Although they are a common feature of both glaciated and lower-latitude continental shelves, pockmarks have not been reported previously from the north-east Antarctic Peninsula margin. Here we use high-resolution geophysical data acquired using autonomous underwater vehicles to map > 240 pockmarks in three locations along the north-east Antarctic Peninsula shelf. The pockmarks are 0.4–45 m wide and 0.1–2.5 m deep, encompassing both smaller unit-pockmarks and larger normal-pockmarks. The high resolution of our data enables the identification of subdued features associated with the pockmarks, including acoustic flares within the water column, ejecta rims, intra-pockmark blocks and possibly even biological structures. The overprinting of subglacial and ice-marginal landforms by the pockmarks constrains their timing of formation to the last ~11 ka. The high density of pockmarks within the surveyed areas, together with geophysical evidence for the active seepage of gas to the sea floor, suggests that the expulsion of subsurface fluids is a widespread process on the north-east Antarctic Peninsula shelf that could have important implications for benthic biodiversity and the global carbon cycle.