Back-arc basin

Definition

A back-arc basin is a geologically active area located behind a volcanic island arc, typically formed due to the extension of the lithosphere in response to subduction processes. These basins can be characterized by sediment accumulation and tectonic activity, often leading to the development of new oceanic crust. They play a significant role in the dynamics of collisional and accretionary orogens by influencing the overall tectonic environment and the formation of mountain ranges.

5 Must Know Facts For Your Next Test

1. Back-arc basins are typically formed when the overriding plate in a subduction zone experiences extension due to the pull from the sinking slab.
2. These basins can be sites for significant sedimentation, which can lead to rich mineral deposits and influence local ecosystems.
3. Examples of back-arc basins include the Japan Sea and the Bering Sea, both of which have distinct geological features linked to their tectonic settings.
4. The formation of back-arc basins can also affect volcanic activity in the adjacent island arcs, often leading to changes in eruption patterns.
5. Back-arc basins are important for understanding tectonic processes as they help scientists study the interactions between oceanic and continental crusts.

Review Questions

• How do back-arc basins influence the geological processes associated with subduction zones?
  • Back-arc basins influence geological processes at subduction zones by providing areas for lithospheric extension and sediment accumulation. The pulling forces from a subducting slab can create tension in the overriding plate, leading to rifting and the formation of these basins. As these areas evolve, they can impact volcanic activity in nearby island arcs and contribute to mountain building through orogenic processes.
• Discuss the significance of sedimentation within back-arc basins in relation to regional geology and resources.
  • Sedimentation within back-arc basins is significant because it not only contributes to the local geological record but also plays a vital role in resource development. These basins often collect sediments eroded from surrounding landmasses and volcanic arcs, creating environments rich in minerals and hydrocarbons. This accumulation can enhance biodiversity by providing habitats, while also offering opportunities for resource extraction in economically viable deposits.
• Evaluate how back-arc basin formation impacts the overall dynamics of collisional and accretionary orogens.
  • The formation of back-arc basins significantly impacts the dynamics of collisional and accretionary orogens by influencing stress distribution, sedimentation patterns, and volcanic activity. As lithospheric extension occurs behind an island arc, it alters the tectonic regime, potentially leading to increased seismicity and changes in magmatic processes. This evolution can drive further orogenic growth as materials are uplifted and deformed, shaping regional landscapes and affecting tectonic interactions across broader areas.

Related terms

Subduction zone: An area where one tectonic plate moves under another plate, leading to geological activity such as earthquakes and volcanism.

Orogeny:

The process of mountain formation, especially through tectonic plate interactions, such as collision and subduction.

Island arc: A curved chain of volcanic islands that forms along the edge of a tectonic plate where subduction occurs.