Amphitheater-Headed Valley (Venus)

  • Goro KomatsuEmail author
  • Henrik Hargitai
Living reference work entry
DOI: https://doi.org/10.1007/978-1-4614-9213-9_332-1

Keywords

Fluid Flow Fracture System Descriptor Term Permeable Medium Rock Debris 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Definition

Amphitheater-headed elongate depressions (valleys and/or channels) cut into topography on Venus.

Synonyms

Note

They are commonly referred to as “sapping valleys” (e.g., Komatsu et al. 1992, 2001) from morphological resemblance to valleys produced by sapping (e.g., Baker et al. 1990).

Subtypes

  1. (1)

    Valley networks on Venus formed initially from fracture systems and became enlarged by inferred low-viscosity lava sapping processes (Komatsu et al. 2001; Oshigami et al. 2009) (Lava Channel) (Fig. 1).

     
  2. (2)

    Subsidiary channels associated with chaotic terrain at the source of outflow channels. Example: 5–10 km long valleys or channels at 40°S, 202°E (Kargel et al. 1994).

     
Fig. 1

Portion of a labyrinthic valley network on Venus, at 8°S, 87°E. Magellan right-look radar image (NASA/JPL)

Interpretation

Arcuate reentrants resulted from slumping, collapse, and sapping (e.g., Kargel et al. 1994).

Formation

Outflow of low-viscosity subsurface fluids (on Venus: lava) augmented by surface flow causes undermining and subsequent collapse of surface material, producing valley networks. This process was named lava sapping (Komatsu et al. 1992). The lavas probably moved through permeable media and fractures (Komatsu et al. 2001). Subsidiary channels were hypothesized to have formed also by sapping, involving subsurface “aquifers” of low-viscosity liquids that reached the surface at low discharge rates and could flow for tens of km without solidifying. The ground fluid then transports downstream the rock debris produced by fluid flow and mass wasting (Baker et al. 1992; Kargel et al. 1994).

Composition

Sapping agent may be silicate lavas of mafic to ultramafic or mafic alkaline varieties or sulfur or carbonatites (Komatsu et al. 1992, 2001), e.g., natrocarbonatite (Kargel et al. 1994).

IAU Descriptor Term

See Also

References

  1. Baker VR, Kochel RC, Laity JE, Howard AD (1990) Spring sapping and valley network development. Geol Soc Am Spec Pap 525:235–266CrossRefGoogle Scholar
  2. Baker VR, Komatsu G, Parker TJ, Gulick VC, Kargel JS, Lewis JS (1992) Channels and valleys on Venus: preliminary analysis of Magellan data. J Geophys Res 97(E8):13,421–13,444CrossRefGoogle Scholar
  3. Kargel JS, Kirk RL, Fegly B Jr, Treiman AH (1994) Carbonate-sulfate volcanism on Venus? Icarus 112:219–252CrossRefGoogle Scholar
  4. Komatsu G, Gulick VC, Baker VR (2001) Valley networks on Venus. Geomorphology 37(3–4):225–240CrossRefGoogle Scholar
  5. Komatsu G, Gluick VC, Kargel JS, Baker VR (1992) Venus lava sapping valleys. LPSC XXIII, pp 719–720Google Scholar
  6. Oshigami S, Namiki N, Komatsu G (2009) Depth and longitudinal profiles of Venusian sinuous rilles and valley networks. Icarus 199:250–263. doi:10.1016/j.icarus.2008.10.012CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  1. 1.International Research School of Planetary SciencesUniversità d’AnnunzioPescaraItaly
  2. 2.Planetary Science Research GroupEötvös Loránd University, Institute of Geography and Earth SciencesBudapestHungary