Deep-marine facies association

Definition

A deep-marine facies association refers to a collection of sedimentary deposits and features that are characteristic of deep ocean environments, typically found at depths greater than 200 meters. This term encompasses a variety of sediment types, such as turbidites and pelagic sediments, and reflects the processes of sedimentation that occur in low-energy, deep-water settings. Understanding these associations is crucial for interpreting past marine environments and the geological history of ocean basins.

5 Must Know Facts For Your Next Test

1. Deep-marine facies associations typically include characteristics such as graded bedding, which indicates changes in energy conditions during deposition.
2. These associations are often found in areas where sediment is transported from the continental shelf to deeper ocean floors through processes like turbidity currents.
3. The study of deep-marine facies can provide insights into ancient oceanographic conditions, including water depth, circulation patterns, and biological productivity.
4. Common components of deep-marine facies associations include fine-grained sediments like clay and silt, which accumulate slowly in low-energy environments.
5. Deep-marine environments are critical for understanding Earth's history, as they hold significant records of past climatic changes and oceanic events.

Review Questions

• How do turbidity currents contribute to the formation of deep-marine facies associations?
  • Turbidity currents play a key role in the formation of deep-marine facies associations by transporting sediment from shallower areas to deeper ocean floors. These fast-moving currents carry large amounts of sediment down continental slopes and deposit it in deep-sea environments, creating features like graded beds that reflect varying energy levels during deposition. The characteristics of these deposits help geologists understand the sedimentary processes and conditions present in ancient marine settings.
• Discuss the significance of pelagic sediments within deep-marine facies associations and their role in interpreting past marine environments.
  • Pelagic sediments are a major component of deep-marine facies associations and consist primarily of microscopic organisms like foraminifera and diatoms. These sediments accumulate very slowly over time, providing valuable records of past biological productivity and environmental conditions. By analyzing pelagic sediment layers within deep-marine deposits, scientists can infer historical climate changes, nutrient availability, and ocean circulation patterns, allowing for a better understanding of Earth's geological history.
• Evaluate how studying submarine fans can enhance our understanding of deep-marine facies associations and their implications for geological research.
  • Studying submarine fans provides critical insights into the dynamics of sediment deposition within deep-marine facies associations. Submarine fans are formed from turbidity currents that deposit sediments at the base of continental slopes, creating complex sedimentary structures. By examining these fans, researchers can uncover information about ancient sediment transport mechanisms, the energy levels of past marine environments, and the interplay between geological processes and sea-level changes. This knowledge is vital for reconstructing past marine ecosystems and understanding their evolution over time.

Related terms

turbidite: A type of sedimentary deposit formed by the rapid flow of sediment-laden water, usually resulting from underwater landslides or currents.

pelagic sediment: Sediments that accumulate in the open ocean, primarily consisting of tiny organisms like foraminifera and diatoms, along with volcanic ash and dust.

submarine fan: A large, fan-shaped deposit of sediment that forms on the ocean floor at the base of a continental slope, created by turbidity currents.