What is the Bouma sequence in geology?
1. n. [Geology] A characteristic sequence of sedimentary structures occurring in sedimentary rocks deposited in areas of deep water sedimentation by turbidity currents, which form deposits called turbidites.
What type of sediments are turbidites?
Turbidite is a fine-grained sediment (or sedimentary rock) that gradually changes from coarse- to fine-grained and that was deposited by turbidity currents.
What is the main erosion type for turbidites?
Turbidites all have the same flow characteristics consisting of a very strong erosive flow, deposition of a normally graded bed that is massive, followed by upper plane bedding, rippled finer sands, coarsely laminated silts, then shales. Keywords: bouma sequence.
Why is the Bouma sequence rarely complete?
Because of nonuniform grain size distribution and flow transformations (Fisher, 1983), the complete sequence is rare. Turbidite beds represent the typical deposit of low-concentration turbidity flows and related non-cohesive density flows.
What type of bedding is associated with turbidity currents which is originated by slope failure?
GRADED BEDDING
GRADED BEDDING means that the grain size within a bed decreases upwards. This type of bedding is commonly associated with so called turbidity currents. Turbidity currents originate on the the slope between continental shelves and deep sea basins.
What is the best definition of a turbidite?
Definition of turbidite : a sedimentary deposit consisting of material that has moved down the steep slope at the edge of a continental shelf also : a rock formed from this deposit.
Where do turbidites form?
Turbidites are deposited from slurries of sediment and water in any standing body of water (lakes, oceans). They can occur in any layer of a water body (near surface, benthic) as long as there is an oversteepened slope. The fluid involved is water, which mixes with sediment.
Where are turbidites formed?
How does Bouma describe the layers of turbidites?
Each layer described by Bouma has a specific set of sedimentary structures and a specific lithology (see below), with the layers overall getting finer-grained from bottom to top. Most turbidites found in nature have incomplete sequences – Bouma describes the ideal sequence where all layers are present.
What is Bouma sequence in geology?
The Bouma sequence specifically describes the ideal vertical succession of structures deposited by low-density (i.e., low sand concentration, fine-grained) turbidity currents.
What is the sequence of a turbidite?
Most turbidites found in nature have incomplete sequences – Bouma describes the ideal sequence where all layers are present. The layers are as follows. E: Massive, ungraded mudstone, sometimes with evidence of trace fossils (i.e., bioturbation ).
What is the Bouma sequence of Devonian sandstone?
Turbidite from the Devonian -age Becke-Oese Sandstone, Germany showing a complete Bouma sequence. The Bouma Sequence (after Arnold H. Bouma, 1932–2011) describes a classic set of sedimentary structures in turbidite beds deposited by turbidity currents at the bottoms of lakes, oceans and rivers.