Pockmarks

Investigations of seafloor pockmarks intensified during the last two decades. The origin of these features is related to the periodical leakage of fluids (mainly methane) from deeper sited reservoirs. The rapidly increasing search for hydrocarbons, led oil industry and academia to broad investigations in the North Sea and the Norwegian Sea revealing the presence of large pockmark fields. In 1998 I started to study pockmarks with multibeam, sidescan-sonar and seismic records as well as targeted seafloor sampling. Our results showed the ubiquitous presence of methanogenic carbonates at most pockmark sites. In 2004 I documented the first evidence of authigenic carbonates from the Norwegian margin and more recently (TTR16 cruise) for the first time we managed to sample gas hydrates from the Nyegga region. Our results provided crucial information to understand the present day dynamics of these pockmarks and gave insights to distinguish the mechanisms that initiated the gas seepage. Our approach combined acoustic records interpretations with petrography, geochemistry, and fluid inclusions studies. I also analysed large collection of authigenic carbonates from numerous palaeo-seepage sites from Barbados, Colorado, Italy, North Sea combining comparative diagenetic and geochemical studies. Publications: (Kenyon et al., 1999; Kenyon et al., 2001; Mazzini et al., 2002; Parnell et al., 2002; Mazzini et al., 2005; Mazzini et al., 2006; Ivanov et al., 2007; Akhmetzhanov et al., 2008).

Selected reading:

Ivanov, M., Mazzini, A., Blinova, V., Kozlova, E., Laberg, J.-S., Matveeva, T., Taviani, M. and Kaskov, N., 2010. Seep mounds on the Southern Vøring Plateau (offshore Norway). Marine and Petroleum Geology, 27(6): 1235-1261.

Ivanov, M., Blinova, V., Kozlova, E., Westbrook, G., Mazzini, A., Minshull, T. and Nouzé, H., 2007. First sampling of gas hydrate from the Vøring Plateau. EOS, 88(19): 209-210.

Mazzini, A., Svensen, H., Hovland, M. and Planke, S., 2006. Comparison and implications from strikingly different authigenic carbonates in a Nyegga complex pockmark, G11, Norwegian Sea. Marine Geology, 231: 89-102.

Mazzini, A., Aloisi, G., Akhmanov, G.G., Parnell, J., Cronin, B. and Murphy, P., 2005. Integrated petrographic and geochemical record of hydrocarbon seepage on the Vøring Plateau. Geological Society, 162: 815-827.

Parnell, J., Mazzini, A. and Honghan, C., 2002. Fluid inclusion studies of chemosynthetic carbonates: strategy for seeking life on Mars. Astrobiology, 2 (1): 43-57.