Bouma sequence
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The Bouma Sequence (after Arnold H. Bouma, 1962) describes a classic set of sedimentary beds (turbidites) deposited by a sediment-water turbidity current. The Bouma Sequence specifically describes the medium grained variety, which are usually found in the continental slope or rise setting.
The Bouma Sequence is divided into 5 distinct beds labelled A through to E, with A being at the bottom and E being at the top and each bed is described by Bouma as having a specific lithology (see below). In a real Bouma Sequence, some beds may be missing - Bouma describes the ideal sequence.
The beds are:
- E: Muds, ungraded, often bioturbated.
- D: Parallel laminated silts.
- C: Cross laminated sands.
- B: Parallel laminated sands.
- A: Sands and any larger grains the turbidity current was carrying at the time of deposition.
[edit] References
- Bouma, Arnold H., 1962, Sedimentology of some Flysch deposits;: A graphic approach to facies interpretation, Elsevier, 168 pp.
- Schlumberger Oilfield Glossary
- http://www.geologyrocks.co.uk/word.php?word=Bouma%20Sequence
