Publication Date:
2017-05-19
Description:
Cold seeps on the Hikurangi Margin off New Zealand exhibit various seabed morphologies producing different intensity patterns in backscatter images. Acoustic backscatter characteristics of 25 investigated seep sites do not show a continuous range of patterns between two end members, but fall into four distinct types characterised by variations in backscatter intensity, distribution and inferred structural heights. The types reflect different carbonate morphologies including up to 20 m high structures (type 1), low-relief crusts (type 2), scattered blocks (type 3) and carbonate free sites (type 4). Each seep corresponds to a single type; ntermediates were not observed. Although the observed morphologies and backscatter patterns may have been caused by variations in sediment burial of seep carbonates or differential exhumation by erosion, they probably epresent varying onsets of authigenic carbonate precipitation. Precipitation of carbonate is episodic, which is likely the result of internal forcing. Blocking and subsequent reorganisation of the seep plumbing system lead to abandonment of old seeps and formation of new sites.
Type:
Article
,
PeerReviewed
Format:
text
DOI:
10.1007/s00367-014-0361-7
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