What is a Bouma sequence 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.
Why is Bouma sequence important?
Description. The Bouma sequence specifically describes the ideal vertical succession of structures deposited by low-density (i.e., low sand concentration, fine-grained) turbidity currents.
Where are turbidites found?
Turbidites are deposited in the deep ocean troughs below the continental shelf, or similar structures in deep lakes, by underwater avalanches which slide down the steep slopes of the continental shelf edge.
What is a turbidite sequence?
A turbidite is a sedimentary bed deposited by a turbidity current or turbidity flow. It is composed of layered particles that grade upward from coarser to finer sizes and ideally display a (complete or incomplete) Bouma sequence (Bouma, 1962).
What causes cross bedding?
Cross-bedding is formed by the downstream migration of bedforms such as ripples or dunes in a flowing fluid. Cross-bedding can form in any environment in which a fluid flows over a bed with mobile material. It is most common in stream deposits (consisting of sand and gravel), tidal areas, and in aeolian dunes.
What are common depositional environments?
Types of depositional environments Alluvial – type of Fluvial deposit. Fluvial – processes due to moving water, mainly streams. Common sediments are gravel, sand, and silt. Lacustrine – processes due to moving water, mainly lakes.
What type of rock is Diamictite?
Definition: Unsorted or poorly sorted, clastic sedimentary rock with a wide range of particle sizes including a muddy matrix. Biogenic materials that have such texture are excluded.
What causes a turbidite?
Rivers flowing into the ocean deposit sediments on the continenal shelf and slope. These slopes fail in response to excessive sedimentation load and sometimes earthquake shaking, sending the sediments sliding down to the ocean bottom to create a turbidite.
Why do turbidite beds fine upwards?
The rocks fine upward as the flow slows, resulting in the bouma sequence. The wavy line at the base of Bouma a in Figure 7 indicates an erosional surface, and flute casts or scour marks are sometimes present.
What does the presence of cross-beds indicate?
Significance. Cross-beds can tell geologists much about what an area was like in ancient times. The direction the beds are dipping indicates paleocurrent, the rough direction of sediment transport. The direction of motion of the cross-beds can show ancient flow or wind directions (called paleocurrents).
What is the difference between cross bedding and ripple marks?
RIPPLE MARKS are produced by flowing water or wave action, analogous to cross-bedding (see above), only on a smaller scale (individual layers are at most a few cm thick). The cross-beds or (more accurately) cross-laminae are inclined to the right, thus the water was flowing from left to right.
What are the 3 major types of depositional environments?
Definition of Depositional Environments There are 3 kinds of depositional environments, they are continental, marginal marine, and marine environments. Each environments have certain characteristic which make each of them different than others.