How do you identify turbidites?

Classic, low-density turbidites are characterized by graded bedding, current ripple marks, climbing ripple laminations, alternating sequences with pelagic sediments, distinct fauna changes between the turbidite and native pelagic sediments, sole markings, thick sediment sequences, regular bedding, and an absence of …

What are turbidites in geology?

Turbidites are sea-bottom deposits formed by massive slope failures. 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.

What type of sedimentary structure do turbidites show?

Characteristics of Deposited Sediment The most common sedimentary structures associated with turbidites are current ripple cross laminations, flame structures, sole marks, planar laminations, and contorted ripple laminae. The below pictures should give you a better idea of what these structures look like in the field.

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 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 does graded bedding indicate?

Graded bedding simply identifies strata that grade upward from coarse-textured clastic sediment at their base to finer-textured materials at the top (Figure 3). The stratification may be sharply marked so that one layer is set off visibly from those above and beneath it.

What are turbidite sequences useful for?

The turbidite sequences are highly sought by petroleum geologists because they can constitute good reservoirs for hydrocarbons (oil and natural gas).

What does cross bedding indicate?

Cross-beds are the groups of inclined layers, and the sloping layers are known as cross strata. Cross bedding forms on a sloping surface such as ripple marks and dunes, and allows us to interpret that the depositional environment was water or wind.

What part of the turbidity current is responsible for depositing the TA of a Bouma sequence?

Processes. The Bouma sequence is deposited during waning flow as turbidity currents move downslope.

What is the cause of graded bedding?

Graded beds form when a steep pile of sediment on the sea floor (or lake floor) suddenly slumps into a canyon or off a steep edge. As the sediment falls, water mixes in with it, creating a slurry of sediment and water that flows quickly down a sloping bottom. When the bottom levels out, the flow begins to slow.

What is the difference between cross bedding and graded bedding?

Cross-beds form as sediments are deposited on the leading edge of an advancing ripple or dune. Each ripple advances forward (right to left in this view) as more sediment is deposited on its leading face. Graded bedding is characterized by a gradation in grain size from bottom to top within a single bed.

How do you tell the direction of cross bedding?

The cross-beds reflect the steep faces of ripples and dunes. These steep faces tilt down-current and thus indicate current flow direction. Cross-beds are commonly curved at the base; this gives a handy way of determining right-side up in complexly deformed rocks.

Where are turbidites deposited in a standing body of water?

Turbidites provide a good summary of the ideas we have been talking about, e.g. facies and sedimentary structures related to flows. Turbidites are deposited from slurries of sediment and water in any standing body of water (lakes, oceans). (photos of turbidites) Turbidity flows start with slope failure in soft sediment.

Where was the discovery of the turbidite facies?

A nice, hour long lecture on turbidites in the Monterrey Bay Canyon, CA, is worth listening to for more information. The actual lecture starts about 5 minutes into the video. Turbidite facies analysis and the resulting facies model led to the discovery of a new process. Sedimentologists had characterized turbidites all over the world.

How are turbidites and stratigraphy related to each other?

Turbidites and Stratigraphy Turbidites provide a good summary of the ideas we have been talking about, e.g. facies and sedimentary structures related to flows. Turbidites are deposited from slurries of sediment and water in any standing body of water (lakes, oceans). ( photos of turbidites) Turbidity flows start with slope failure in soft sediment.

How are turbidites different from the Bouma sequence?

This different set of structures is known as the Lowe sequence, which is a descriptive classification that complements, but does not replace, the Bouma sequence. Turbidites are sediments which are transported and deposited by density flow, not by tractional or frictional flow.