Cleopatra (crater)

Coordinates: 65°48′N 7°06′E / 65.8°N 7.1°E / 65.8; 7.1
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Cleopatra crater
Radar image of Cleopatra by Magellan
Feature typedouble ring impact crater[1]
Coordinates65°48′N 7°06′E / 65.8°N 7.1°E / 65.8; 7.1
Diameter105 km
EponymCleopatra VII

Cleopatra,[2] initially called Cleopatra Patera, is an impact crater on Venus, in Maxwell Montes.

Cleopatra is a double-ring impact basin about 100 kilometers (62 mi) in diameter and 2.5 kilometers (1.6 mi) deep. A steep-walled, winding channel a few kilometers wide (Anuket Vallis) breaks through the rough terrain surrounding the crater rim. A large amount of lava originating in Cleopatra flowed through this channel and filled valleys in Fortuna Tessera. Cleopatra is superimposed on the structures of

Cleopatra VII.[4]

Patera geologic description

Zoomed in view extrapolated from Magellan spacecraft imagery of Cleopatra patera, eastern flank of Maxwell Montes on Ishtar Terra, Venus, Feb 5, 1994.

Cleopatra is a nearly circular

Venera 15/16 spacecraft, the structures seen in the crater has cleared the scientific controversy and has been since identified as an impact crater.[1][7][10][12][13]

lava flows which have spilled from the bowl shape of the crater due to the impact hitting the steep side of Maxwell Montes, occurring at impact.[7] When the magma chamber at the floor of Cleopatra erupted, subsidence occurred explaining the large depth of the crater.[7][14]

Crater impact model

viscous relaxation".[14] This was found in Venusian craters larger than 70 km in diameter by using altimetry data which shows surfaces with different elevations from the Magellan mission.[14]

Original volcanic model

Prior to improved satellite imagery from the

orogenic belts either through obduction or isostatic subsidence as the mountain grows in height.[6] Based on the model and the information pertinent to understanding the tectonic environment surrounding the patera, crustal anatexis is a viable model for the origin of magmatism at Cleopatra Patera.[6] This process could be associated with other high mountain belts on Venus and with melting of pre-existing rock in the Himalayan granites.[6] This results in the melting of the lower levels of the thickened crust and potential magmatic activity, volcanism, and caldera formation at the surface.[6]

Volcanic evidence

The following evidence from Scraber et al.[11] was the leading explanation for a volcanic origin for twelve years until Magellan imagery was returned in the early 1990s.[1][8][9][10]

  1. a volcanic origin of Cleopatra patera included its association with plains forming deposit sloping away from the crater in a lava flow[7][11]
  2. the depth and steepness of the walls of the crater interpreted as multiple calderas[7][11]
  3. the elongation of the outer rim deposits following along the same path as the
    tectonic features of the area[6][7][11]
  4. the absence of a raised highly backscattered rim deposit seen in impact craters[6][7][11]
  5. the large depth to diameter ratio[1][7][11]
  6. and its situation in a regional tectonic environment[5][7][11]
Volcanotectonic interpretation of ring structures of Cleopatra Patera as interpreted from Peterfreund et al.

The best comparison to Cleopatra is the

Alba Patera on Mars and Cleopatra's ring structure was intensely interpreted to link it to a volcanic origin.[5][11]
Peterfreund et al. and Scraber et al. described their interpretation of the rings as follows:

  1. Alba patera has a caldera of similar size to Ring B, interpreted image of rings to the right, and is surrounded by structural patterns produced by tectonic deformation (refer to previous image).[5][11]
  2. Cleopatra shares commonalities with impact craters on Venus because of it radially smooth interior and rough exterior.[5][11] However, the asymmetry of ring A challenges an impact hypothesis.[5][11]
  3. Ring C and D represents structural areas associated with the initial crater[5]
  4. The area within C is related to material ejected from a volcano or has been heavily fractured and deformed very differently from the surrounding terrain.[5]
  5. Ring D has a tectonic fracture that was involved in deformation.[5]

See also

References

  1. ^ a b c d e Hamilton, Calvin (1993). "Venusian Impact Craters". Soler Views. Retrieved 3 April 2014.
  2. ^ "Cleopatra Patera". Gazetteer of Planetary Nomenclature. International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN). 2014-08-27. Retrieved 2014-10-16.
  3. ^ Catalog Page for PIA00149
  4. ^ "Cleopatra". Gazetteer of Planetary Nomenclature. International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN). 2014-08-27. Retrieved 2014-10-16.
  5. ^ a b c d e f g h i j k l m Peterfreud, A.R. (1984). Head, J.W. (ed.). Cleopatra Patera, A Circular Structure in Maxwell Montes, Venus; Volcanic or Impact?. Lunar and Planetary Science. Brown University. pp. 641–642.
  6. ^ a b c d e f g h i Nikishin, A.M. (1988). "Tectonic and Magmatic Models for the Origin of Cleopatra Patera". Lunar and Planetary Science Conference: 860–861.
  7. ^ a b c d e f g h i j k l m n o p Basilevsky, A.T.; et al. (1991). "Cleopatra Crater on Venus: Happy Solution of the Volcanic vs Impact Controversy". Lunar and Planetary Science Conference. XXII (22): 59–60.
  8. ^ a b Athena Publications (2001). "Impact craters on Venus, Earth, and other planets". Athena Review. Retrieved 3 April 2014.
  9. ^ a b c d e f Alexopoulos, Jim & William McKinnon (1993). "RINGED IMPACT CRATERS ON VENUS: AN ANALYSIS FROM MAGELLAN IMAGES". International Colloquium on Venus. pp. 2–4. Retrieved 3 April 2014.
  10. ^ a b c Christiansen, Eric (1995). "Exploring the Planets". Prentice Hall. Retrieved 3 April 2014.
  11. ^ .
  12. ^ a b Kempler, Steven (2009). "HIGH-RESOLUTION RADAR IMAGES OF VENUS". NASA. Archived from the original on 7 April 2014. Retrieved 3 April 2014.
  13. ^ a b Vita-Finzi, C; et al. (2004). "Venusian Craters and the Origin of Coronae". Lunar and Planetary Science. Retrieved 4 April 2014.
  14. ^ a b c Basilevsky, A.T.; et al. (1994). "Geology and Morphometry of Large Impact Craters of Venus". Lunar and Planetary Science Conference. XXV: 67–68.

External links