Elastic thickness of the Venus lithosphere estimated from topography and gravity

The very close correlation observed on Venus between topography and gravity on a regional scale is clearly related to the isostatic compensation of the topographic loads. Observed gravity anomalies over topographic features of moderate lateral extent, located in the equatorial region (0° to 40° N latitude and 10° W to 60° E longitude) are somewhat larger than those computed with a model of local isostatic compensation (of Airy type). They may rather be explained by a model of compensation including elastic forces within the lithosphere which contribute to support topographic loads through elastic stresses. We have applied the theory of lithospheric flexure : to explain in wavelength and in amplitude the observed gravity anomalies, a flexural rigidity of ∼ 4 × 1028 dyne cm has been estimated for the Venus lithosphere in the rolling plains province. This value is very low compared to the oceanic terrestrial lithosphere (ranging from ∼ 1028 dyne cm near ridge crests to ∼ 2 × 1031 dyne cm near subduction zones). The corresponding thickness of the elastic upper layer able to maintain elastic stresses for long time duration is ∼ 7.5 km. This value may not be representative of the entire Venus lithosphere.

[1]  I. Shapiro,et al.  Venus gravity: A high-resolution map , 1981 .

[2]  W. M. Kaula,et al.  Tectonics and evolution of venus. , 1981, Science.

[3]  M. Steckler,et al.  Observations of flexure and the rheology of the oceanic lithosphere , 1981 .

[4]  G. Pettengill,et al.  Pioneer Venus Radar results: Geology from images and altimetry , 1980 .

[5]  W. Sjogren,et al.  Gravity anomalies on Venus , 1980 .

[6]  Eric M. Eliason,et al.  Pioneer Venus Radar results altimetry and surface properties , 1980 .

[7]  A low-order global gravity field of Venus and dynamical implications , 1980 .

[8]  A. Cazenave,et al.  On the response of the ocean lithosphere to sea‐mount loads from Geos 3 satellite radar altimeter observations , 1980 .

[9]  J. Head,et al.  Lunar mascon basins - Lava filling, tectonics, and evolution of the lithosphere , 1980 .

[10]  W. Sjogren,et al.  Gravity Field of Venus: A Preliminary Analysis , 1979, Science.

[11]  A. Watts.  An analysis of Isostasy in the World''s Oceans 1 , 1978 .

[12]  C. Thurber,et al.  Martian lithospheric thickness from elastic flexure theory , 1978 .

[13]  M. Toksöz,et al.  Thermal evolutions of the terrestrial planets , 1975 .

[14]  J. R. Cochran,et al.  Gravity anomalies and flexure of the lithosphere: A three-dimensional study of the Great Meteor Seamount, northeast Atlantic , 1975 .

[15]  R. Reynolds,et al.  On the thermal evolution of the terrestrial planets , 1974 .

[16]  R. Walcott.  Flexure of the lithosphere at Hawaii , 1970 .

[17]  G. Woollard.  Evaluation of the isostatic mechanism and role of mineralogic transformations from seismic and gravity data , 1970 .

[18]  J. F. Brotchie,et al.  On crustal flexure , 1969 .

[19]  J. Gillis,et al.  Methods in Computational Physics , 1964 .