Millennial-scale sea-level control on avulsion events on the Amazon Fan

Mark Maslin, Paul C. Knutz, Tony Ramsay

Research output: Contribution to journalArticleResearchpeer-review

30 Citations (Scopus)

Abstract

The Late Quaternary Amazon deep-sea fan provides a modern analogue to ancient fan systems containing coarse-grained hydrocarbon reservoirs. Sand lenses deposited within the Amazon Fan, due to abrupt shifts in channel pathways called avulsion events, were drilled as part of ODP Leg 155. The hemipelagic sediment directly on top of the avulsion sands was dated using primarily AMS radio carbon dating. This dating shows that these large sand lobes (∼1 km3) are triggered by relatively small, millennial scale changes in marine transgression and regression (±5-10 m). Relative sea level also controls the architecture of the Channel-levee distributive systems within the Amazon Fan. For example prior to 22 k calendar years BP there is a tripartite channel system. After 22 ka there is only one active Channel-levee system. Transitions between the multi-channel and single channel configurations are related to variations in the volume of sediment supply resulting in aggradation or erosion of channel floor and levee growth in the canyon-channel transition area. The sensitivity of the Amazon deep-sea Fan sedimentation to relatively small changes in sea level supports one of the central assumptions of the theory of Sequence Stratigraphy. In addition this study demonstrates how traps for hydrocarbons may have been formed in ancient fan systems.

Original languageEnglish
Pages (from-to)3338-3345
Number of pages8
JournalQuaternary Science Reviews
Volume25
Issue number23-24
DOIs
Publication statusPublished - Dec 2006
Externally publishedYes

Programme Area

  • Programme Area 5: Nature and Climate

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