Valley networks on Venus are classified as rectangular, labyrinthic and pitted, or irregular. The venusian valley networks are structurally controlled, as indicated by the morphological patterns of valley branches, consistency between valley and fracture orientations, and associations with the deformed terrains. The morphologies resemble those of terrestrial and martian sapping valleys. Valley networks on Venus probably formed initially from fracture systems and became enlarged by low viscosity lava sapping processes. Subsurface flow of lava may locally have been assisted by surface flows. The lavas probably moved through permeable media and fractures. Venusian valley networks have a higher degree of network integration than do lunar sinuous rilles, but they are less integrated than martian and terrestrial sapping valleys. The viscosity of valley-forming lavas must have been very low, but was not low enough to exploit the permeable media so extensively as to attain a high degree of network integration. The compositions of these lavas may have been mafic to ultramafic or mafic alkaline. Alternatively, the lavas could have had more exotic compositions, such as carbonatite and sulfur. Valley networks are often associated with corona and corona-like features, which are hypothesized to be the surface expressions of mantle plumes. A plume association could mean that the lavas came from the mantle. q 2001 Elsevier Science B.V. All rights reserved.

Valley networks on Venus

KOMATSU, Goro;
2001-01-01

Abstract

Valley networks on Venus are classified as rectangular, labyrinthic and pitted, or irregular. The venusian valley networks are structurally controlled, as indicated by the morphological patterns of valley branches, consistency between valley and fracture orientations, and associations with the deformed terrains. The morphologies resemble those of terrestrial and martian sapping valleys. Valley networks on Venus probably formed initially from fracture systems and became enlarged by low viscosity lava sapping processes. Subsurface flow of lava may locally have been assisted by surface flows. The lavas probably moved through permeable media and fractures. Venusian valley networks have a higher degree of network integration than do lunar sinuous rilles, but they are less integrated than martian and terrestrial sapping valleys. The viscosity of valley-forming lavas must have been very low, but was not low enough to exploit the permeable media so extensively as to attain a high degree of network integration. The compositions of these lavas may have been mafic to ultramafic or mafic alkaline. Alternatively, the lavas could have had more exotic compositions, such as carbonatite and sulfur. Valley networks are often associated with corona and corona-like features, which are hypothesized to be the surface expressions of mantle plumes. A plume association could mean that the lavas came from the mantle. q 2001 Elsevier Science B.V. All rights reserved.
File in questo prodotto:
File Dimensione Formato  
Venus_valleys.pdf

Solo gestori archivio

Tipologia: PDF editoriale
Dimensione 7.2 MB
Formato Adobe PDF
7.2 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11564/231872
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 17
  • ???jsp.display-item.citation.isi??? 17
social impact