1 QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Tolstoj Quadrangle Mark Robinson and Brett Denevi Arizona State University Scott Murchie, APL MESSENGER GDG Telecon 11/20/2007
Jan 23, 2016
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QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Tolstoj Quadrangle
Mark Robinson and Brett Denevi
Arizona State University
Scott Murchie, APL
MESSENGER GDG Telecon 11/20/2007
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Quick Reminder
System Major Unit Base Age LunarKuiperian crater materials 1.0 Gyr CopernicanMansurian crater materials 3.0-3.5 Gyr Eratosthenian
Calorian
Caloris Group; plains, craters, small basin materials 3.9 Gyr Imbrian
Tolstojan
Goya formation; craters, small basins, plains material 3.9 - 4.0 Gyr Nectarian
pre-Tolstojan
Intercrater plains, multiring basins, crater materials PRE-4.0 Gyr pre-Nectarian
From Spudis and Guest in Mercury (1988)
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Main features
• Intercrater plains (light orange color)
• Tolstoj Basin (350 km, 3.97 Gyr)• Southern portion of Caloris
(1300 km, 3.77 Gyr)– Odin formation (medium blue)
similar to Alpes of Imbrium
• Tolstoj, Tir, Budh (peach color) and Caloris smooth plains occupy much of the region
• Mozart - fresh, large (285 km) crater on terminator
• Complex structural features
BudhBudh
Tir Plan
itia
Tir Plan
itia
TolstojTolstoj
MozartMozart
CalorisCaloris
Hummocky plainsHummocky plains
Intercrater plainsIntercrater plainsTolstoj rim materialTolstoj rim material
Smooth plains
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Significant Features
• Smooth Plains (Tolstoj, Tir, Budh)• Low albedo, blue material around Tolstoj• High albedo enigmatic crater floor deposits
(Tyagaraja, Zeami, Balzac)• Structural features (wrinkle ridges, lobate
scarps)
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Smooth plains
• Tir, Tolstoj, and Budh planitia all radar bright compared to surrounding intercrater plains (Harmon et al., 2004) – Opposite of lunar mare, which are
radar dark due to Fe, Ti
– Compositional differences between smooth plains and surroundings?
– Rougher small-scale surface texture than surroundings?
• Lots of small bright craters in Budh planitia (0.2-0.3)
Budh Planitia
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Low albedo region around Tolstoj
• Tolstoj smooth plains overlie dark material (below one std deviation of average Mercury albedo)
• High UV/Orange ratio (among bluest material on planet), enriched in opaques (Robinson and Taylor, 2001)
• Ancient crustal material or secondary process such as pyroclastic?
Arrows and X indicate low reflectancematerial, image 675 km wide.
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Enigmatic crater floor materials
• Good examples of these materials in Tolstoj quad
• Albedos up to ~0.3• Dark halo? Mentioned in
literature…• Dzurisin (1977) - local
physio-chemical alteration along impact-induced fractures
• Schultz (1977) - compositional or endogenic modification possible causes of color differences
Tyagaraja
Zeami
Balzac
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Structural Features
• Chock full of wrinkle ridges in smooth plains
• A few lobate scarps
• Local compression, plains contained in broad depressions
• Global compression result in lobate scarps?
Smooth plains, wrinkle ridges in Tostoj Quadrangle (Tir), 800 km wide
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Tectonics, Geology,
Image
White worms indicateWrinkle ridges
Black with triangle showLobate scarps
Thanks to T. Watters!