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Western Ishtar Terra and Lakshmi Planum, Venus: Models of formation and evolotion
Author(s) -
Roberts Kari M.,
Head James W.
Publication year - 1990
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl017i009p01341
Subject(s) - venus , geology , astrobiology , physics
Regional geologic mapping and gravity data reveal a variety of characteristics that must be accounted for in models for the formation and evolution of Western Ishtar Terra and Lakshmi Planum, including: 1) high elevation, 2) plateau‐shaped profile, 3) abnormally steep bounding slopes, 4) foredeeps, 5) polygonal outline, 6) adjacent orogenic belts, 7) volcanic plains, 8) plains emplaced synchronously with orogenic belts, 9) paterae, 10) variable topography of Lakshmi, 11) tessera‐like material underlying Lakshmi, and 12) a large apparent depth of compensation. A tessera/peripheral deformation model, in which a preexisting block of tessera is the locus of convergence of adjacent thinner crust and lithosphere, underthrusting, mountain building, subsurface melting, and plateau uplift, is interpreted to account for most of the characteristics. The apparent depth of compensation is not simply explained by this model and appears to require a second, deeper mantle anomaly component, such as broad mantle upwelling or a hot spot.