Surficial Deposits and Access to Materials with Known ... · Domain 3 – Surficial deposits •...
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Surficial Deposits Surficial Deposits and Access to Materials with and Access to Materials with Known Geological Context Known Geological Context
on Venus on Venus Mikhail KreslavskyMikhail Kreslavsky
University of California – Santa Cruz
In collaboration with: Nataliya Bondarenko Nataliya Bondarenko James HeadJames Head
GEOLOGICAL / GEOCHEMICAL DOMAINS OF VENUSafter Basilevsky and Head [today]
1. Whole Planet Emphasis on planet interior
2. Planetary Crust: Geologic bodies units seen in the radar images 100s m – 10s km thick
3. Planetary Surface layer: eolian and “impact” sediments seen in the panoramas and implied from microwave properties 10s mm – 10s m thick
4. Surface: Dust, Condensates, Weathering products millimeters to microns thick
This is what we wantto probe
And th
is is
what
we can
reac
h
Domain 4 - Surface
• Venus is a dusty planet ⇐ thick dry atmosphereFine dust:– is lifted by impacts– is suspended in the atmosphere– is distributed by high-latitude winds– slowly settles at the surface– sticks to rocks– is sintered and become a part of rocks
⇓spectroscopy does not probe local material
Domain 3 – Surficial deposits
• Surficial deposits seen in the radar images:impact-related diffuse features = meters-thick mantles
• splotches• dark crater halos• dark parabolas• etc
– Wind streaks• a great variety
– Dune fields • resolved dunes• microdunes
Domain 3 – Surficial deposits
• Surficial deposits NOT seen in the radar images:– from Magellan radiometry:
• parabolas in emissivity are wider than in radar images
• emissivity-only parabolas
– from Magellan SAR –E-W backscatering anisotropy
– from Magellan radar altimeter N-S backscatering anisotropy
• ubiquity of eolian deposits
Bondarenko and Head, 2004
Domain 3 – Surficial deposits
• Surficial deposits NOT seen in the radar images:– from Magellan radiometry– from Magellan SAR – E-W backscattering anisotropy– from Magellan altimeter - N-S backscattering anisotropy
Weitz et al. 1994
Domain 3 – Surficial deposits
• Surficial deposits NOT seen in the radar images:– from Magellan radiometry– from Magellan SAR – E-W backscattering anisotropy– from Magellan altimeter - N-S backscattering anisotropy
ubiquity of eolian deposits
Kreslavsky & Vdovichenko, 1999
Domain 3 – Surficial deposits
Bondarenko et al., 2006
• Surficial deposits NOT seen in the radar images:– from Magellan radiometry– from Magellan SAR – E-W backscattering anisotropy– from Magellan altimeter - N-S backscattering anisotropy
ubiquity of eolian deposits
Domain 3 – Surficial deposits
• Surficial deposits NOT seen in the radar images:– from Magellan radiometry– from Magellan SAR – E-W backscattering anisotropy– from Magellan altimeter - N-S backscattering anisotropy
ubiquity of eolian deposits
Bondarenko et al., 2006
Domain 3 – Surficial deposits
• Surficial deposits NOT seen in the radar images:– from Magellan radiometry– from Magellan SAR – E-W backscattering anisotropy– from Magellan altimeter - N-S backscattering anisotropy
⇓Surface is covered with decimeters or meters of non-local material almost everywhere.
Direct inference from SAR images Reality
Domain 3 – Surficial deposits
• Surficial deposits NOT seen in the radar images:– from Magellan radiometry– from Magellan SAR – E-W backscattering anisotropy– from Magellan altimeter - N-S backscattering anisotropy
⇓Surface is covered with decimeters or meters of non-local material almost everywhere.
Drilling is needed to access local materialor
Radar-dark parabolas give easy access to non-local material from known source
or
Search for gaps in the surficial deposits
Radiometry Radar
Conclusions• Mixed (indurated) dust from ambiguous remote sources
cover local materials everywherespectroscopy does not probe local material
• Surficial deposits are almost everywhere reliable access to igneous material requires ~10 m drilling capabilityCrater-related parabolas give reliable easy access to material from a known source
• There are limited areas with local igneous material within ~ 1 cm from the surface
they can be found by analysis of Magellan data