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The spatial and temporal distribution of pipe and pockmark formation

Moss, Jennifer Leigh 2010. The spatial and temporal distribution of pipe and pockmark formation. PhD Thesis, Cardiff University.

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Abstract

This research concentrates on two study areas.  A family of blowout pipes from North Namibia imaged in 3D seismic data; and a group of large buried pockmarks and a field of small seabed pockmarks from the Western Nile Deep Sea Fan (NDSF) imaged in ultra high resolution 2D data.  The general themes of this research are pipe and pockmark morphology and formation process, their spatial and temporal distribution and the magnitude and frequency of fluid flux through the conduit. A family of blowout pipes from Namibia exhibit a variety of seismic characteristics, with the largest pipes containing a blowout crater and evidence of possible stacked palaeo-pockmarks. Pipe formation is shown to be intermittent and persistent throughout the Neogene. The spatial position of pipes adheres to both basinal and local controls. A group of large buried pockmarks on the NDSF are interpreted to have formed between 15,000 yrs BP and 125,000 yrs BP, the majority of which are believed to have formed at the same time c. 60,000-80,000 yrs BP.  These buried pockmarks show evidence for highly focused, episodic fluid flow following burial of the pockmark.  The longevity of post formation fluid migration is estimated to be ~50,000-100,000 yrs. A field of > 13,800 small seabed pockmarks (Nile Deep Sea Fan) are interpreted to have formed within the last 1,000 yrs.  Spatial statistics identified an exclusion zone or drainage cell surrounding each pockmark which is not penetrated by the formation of any other pockmark.  A conceptual model for a drainage cell is proposed whereby pockmark formation dissipates, a radius/area of fluid and overpressure, thereby preventing the formation of another pockmark within that cell.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Earth and Ocean Sciences
Subjects: Q Science > QE Geology
Date of First Compliant Deposit: 30 March 2016
Last Modified: 19 Mar 2016 23:29
URI: http://orca-mwe.cf.ac.uk/id/eprint/54111

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