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TitleInteractions between continent-like 'drift', rifting and mantle flow on Venus: gravity interpretations and Earth analogues
AuthorHarris, L B; Bédard, J H
SourceVolcanism and tectonism across the solar system; by Platz, T (ed.); Massironi, M (ed.); Byrne, P (ed.); Hiesinger, H (ed.); Geological Society, Special Publication vol. 401, 2014 p. 1-30, https://doi.org/10.1144/SP401.9 Open Access logo Open Access
Image
Year2014
Alt SeriesEarth Sciences Sector, Contribution Series 20130152
PublisherGeological Society of London
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
AreaVenus
Subjectstectonics; extraterrestrial geology; shear zones; shearing; gravity interpretations; gravity surveys; bouguer gravity; plate tectonics; tectonic interpretations
Illustrationslocation maps; images; block diagrams
ProgramTargeted Geoscience Initiative (TGI-3), 2005-2010
Released2014 05 19
AbstractRegional shear zones are interpreted from Bouguer gravity over northern polar to low southern latitudes of Venus. Horizontal gravity gradient edges ('worms') portray hitherto unrecognised crustal structures whose geometry resembles faults and fractures in oceanic crust on Earth. High anomalies and thinned crust comparable to the Mid-Continent Rift in North America suggest underplating of denser, mantle-derived mafic material beneath extended crust in Sedna and Guinevere planitia. These rifts are partitioned by transfer faults and flank a zone of mantle upwelling (Eistla Regio) between colinear hot, upwelling mantle plumes. Data support the northward drift and indentation of Lakshmi Planum in western Ishtar Terra and 1000 km+ transcurrent displacement between Ovda and Thetis regiones. Large displacements of areas of continent-like crust are interpreted to result from mantle tractions and pressure acting against their deep lithospheric mantle 'keels' commensurate with extension in adjacent rifts. Displacements of Lakshmi Planum and Ovda and Thetis regiones on Venus, a planet without plate tectonics, cannot be attributed to plate boundary forces (ridge push, slab pull). Continent like 'drift' on Venus resembles the westward translation of the Americas and northward displacement of India which are driven by mantle flow tractions on the keels of their Precambrian cratons.
Summary(Plain Language Summary, not published)
Magellan (NASA) gravity data for Venus has been reinterpreted to reveal large horizontal displacements of ¿continent¿-like blocs on Venus; the movement of which has created mountain ranges similar to the Himalayas. Since there is no evidence for seafloor spreading or subduction on Venus, movement is attributed to mantle flow pressure on the deep mantle keels that underlie these continent-like blocs. Similar processes are inferred to be responsible for the westward drift of the Americas and northward drift of India. The space vacated by the drifting venusian continents is occupied by large lava-flooded rifts, and reflects vigorous ascent of mantle plumes.
GEOSCAN ID292798

 
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