Marta Lúthien Gutiérrez Albarrán 2014 Venus Topography Radar mapping Magellan Venuss atmosphere in UV Pioneer12 and radar mapping Magellan Venus Surface features ID: 500458
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Slide1
The Global Resurfacing of Venus
Marta Lúthien Gutiérrez Albarrán, 2014Slide2
Venus:
Topography
Radar mapping (
Magellan
)
Venus’s atmosphere in UV (
Pioneer-12
) and radar mapping (
Magellan
)Slide3
Venus:
Surface features
Global topographic map of Venus (
Magellan
)Slide4
Pancake volcanoes, lava channels and shield plain
VolcanismSlide5
Arachnoid
Corona
Unique surface featuresSlide6
Highlands of
tesserae terrain and ridge belt
Tectonic activitySlide7
[Computer generated, based on
Magellan radar data]
Impact Craters
Sequence of surface unitsSlide8
Resurfacing models: Crater distribution
Turcotte et al. (1998)Slide9
Resurfacing models: Mean surface age
Crater frequencies on Venus are low compared with those on the surface of the Moon and Mars. This shows that the surface is young, perhaps no older than a mean of
500 Myr
(estimates of the crater production rate predict ages between
190-800 Myr
)Slide10
The
spatial and hypsometric distribution of craters cannot be distinguished from a random distribution
.
The random
crater distribution
is
independent of size.
The density of small craters declines with decreasing diameters due to atmospheric filtering
.
The
spectrum of crater modification
differs greatly from that of other planets: 62-84% are
pristine
, 2.5-4% are
embayed by lavas
, aprox. 8.5% are
slightly fractured
,
and only 3.5% (aprox.) are
highly fractured
.
The
lava embayed craters
are
concentrated in zones of recent volcanism
, and the
highly fractured craters
are associated with the
equatorial rift systems
.
Resurfacing models: Constraints
[Schaber et al. 1992;
Strom et al. 1994]Slide11
Resurfacing models: Global vs Regional
Global resurfacing
: Catastrophic burial associated with instantaneous overturn of the lithosphere and intense volcanic and tectonic activity about 300-500 Myr ago which ended abruptly.
Regional resurfacing
: Progressive burial of small areas at a time as new volcanic centers developed. Requires a constant rate and spatially random distribution of volcanism. Ultimately, the whole planet would be resurfaced, albeit over a longer time period.Slide12
Global vs Regional resurfacing: Simulations
Strom et al. 1994Slide13
Bullock&Grinspoon 1993
Global vs Regional resurfacing: Simulations
Equilibrium regional scenario.
30
%
partially
embayed
craters, substantially greater than observed. Equilibrium number significantly less than observed.
Catastrophic, global scenario.
950 surviving craters
5% partially
embayed
craters.
Competing
processes of constant rate impact cratering and volcanism
. Initially crater-free surface.
Resurfacing age uniquely determined by number of observed surviving and partially embayed craters.Slide14
Global vs Regional resurfacing: Conclusions
Objections to regional resurfacing models
:
Simulations result in about
17 times/15% more embayed craters than observed
.
Simulations result in
unobserved nonrandom crater distributions for resurfacing areas between 0.03% and 100% of the planet’s surface.
Models
not consistent with the number and nonrandom distribution of volcanoes and the nonrandom distribution of embayed and heavily fractured craters.
Global resurfacing models
are
consistent with
:
The
spatially random crater distribution
and its
diameter independence
.
The
random hypsometric crater distribution
.
The
very low abundance of embayed craters and fractured craters
.
The
concentration of embayed and highly fractured craters at zones of recent volcanism and tectonism
.
[Bullock&Grinspoon 1993; Strom et al. 1994]Slide15
References
Basilevsky, A. T
.
& McGill
, G. E
.
2013.
Surface Evolution of Venus, in Exploring Venus as a Terrestrial Planet (eds L. W. Esposito, E. R. Stofan and T. E. Cravens), American Geophysical Union, Washington, D.C.Bullock
, M. A., D. H. Grinspoon
,
&
J. W. Head III
1993.
Venus resurfacing rates: Constraints provided by 3-D Monte Carlo simulations, Geophys. Res. Lett., 20(19),
2147–2150.
Herrick,
Robert
R
. 1994.
Resurfacing history of Venus.
Geology
,
vol. 22, no 8, p.
703-706
.
Saunders, R. S., Arvidson, R. E., HEAD, J. W., Schaber, G. G., Stofan, E. R., & Solomon, S. C
.
1991.
An overview of Venus geology.
Science
,
252
(5003), 249-252.
Strom, R. G., G. G. Schaber
,
&
D. D. Dawson
1994.
The global resurfacing of Venus, J. Geophys. Res., 99(E5),
10899–10926.
http
://
en.wikipedia.org/wiki/Geology_of_Venus
http
://
csep10.phys.utk.edu/astr161/lect/venus/surface.html
http
://
ircamera.as.arizona.edu/NatSci102/NatSci102/text/venusgeol.htm
http
://
geology.about.com/od/venus/a/aa_venus.htm
http
://
www.harmonicamundi.org/HGS/atmos_proj/resurfacing.html
http
://
explanet.info/Chapter07.htm
http://www.geol.umd.edu
/~
jmerck/geol212/lectures/12.html
http
://
global.britannica.com/EBchecked/topic/625665/Venus/54191/Interior-structure-and-geologic-evolution
http://geology.about.com/gi/o.htm?zi=1/XJ&zTi=1&sdn=geology&cdn=education&tm=8923&f=10&tt=14&bt=8&bts=1&zu=http%3A
//
www.lpi.usra.edu/publications/slidesets/venus.htmlSlide16
Thank you!