Istituto di Scienze Marine     
Garcia-Garcia A., Orange D. L., Miserocchi S., Correggiari A., Langone L., Lorenson T. D., Trincardi F., Nittrouer C. A. What controls the distribution of shallow gas in the Western Adriatic Sea?. In: Continental Shelf Research, vol. 27 (40271) pp. 359 - 374. Pergamon-elsevier Science Ltd, 2007.
In this paper, we discuss what controls the occurrences of shallow gas off the Western Adriatic coast. This region of the Western Adriatic, including the Po delta and the late-Holocene mud wedge, was sampled with the R/V Seward Johnson II within the framework of the EuroSTRATAFORM project. As a part of the program, we were evaluating the causes of anomalous sub-surface and seafloor features, and specifically, quantifying shallow gas and identifying its impact on geophysical properties. The highest gas concentration off the Po delta region yielded 4.1 x 10(4) ppm, where as offshore Tronto River, the highest methane value was 7.9 x 10(4) ppm. Headspace gas analyses match well with acoustic anomalies along the Western Adriatic coast. Shallow biogenic gas off the Po delta (NW Adriatic) is spatially correlated with organic matter deposition driven by rapid and thick flood deposition. In contrast to the Po Delta, where sub-surface gas is associated with the flood deposition of organic matter, shallow gas along the Central Adriatic occurs deeper in cores, and appears to be related to methanogenesis of organic matter present in deeper deposits. (c) 2006 Elsevier Ltd. All rights reserved.
DOI: 10.1016/j.csr.2006.11.003
Subject Adriatic Sea
acoustic anomalies
shallow gas seeps

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