Occurrence of pockmarks on the Ortegal Spur continental margin, Northwestern Iberian Peninsula

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• 作者：G. Jané ; A. Maestro ; G. Ercilla ; J. Ló ; pez-Martí ; nez ; J.R. De André ; s ; D. Casas ; D. Gonzá ; lez-Aller ; M. Catalá ; n-Morolló ; n
• 关键词：Pockmarks ; Fluid flow ; Basement faults ; Ortegal Spur ; Galician margin
• 刊名：Marine and Petroleum Geology
• 出版年：2010
• 出版时间：August 2010
• 年：2010
• 卷：27
• 期：7
• 页码：1551-1564
• 全文大小：3573 K

文摘

A total of 445 pockmarks were observed on the upper continental slope of the northwest corner of the Iberian Peninsula (the Ortegal Spur area) by swath bathymetric and ultrahigh resolution seismic data. The pockmarks are U-, V- and W-shaped and have terraces or indentations in cross-section, and are dish-shaped (circular to oval) in plan view. They occur on the surface of the seabed and buried within the Plio-Quaternary and Neogene sediments. Four types of pockmarks were identified and mapped on the basis of their plan-view and cross-section morphology: regular, irregular, asymmetric and composite. The concentration of pockmarks is attributed to seepage of fluids migrating up-dip from deeper parts of the sedimentary basin. A linear high-density concentration with a NNW to N, NE and ESE trend of pockmarks is observed above inferred basement faults that do not affect the Quaternary succession. These pockmarks are thus caused by seepage of thermogenic gas and/or other pore fluids from deeper Late Cretaceous units, and their distribution may help to improve our understanding of the fluid system and migration regime in this part of the Galicia continental margin.