Analysis of geological features and seasonal processes in the Cavi Novi region of Mars

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Analysis of geological features and seasonal
processes in the Cavi Novi region of Mars
C. Córdoba-Jabonero, D. Fernández-Remolar, C.
González Kessler, F. Lesmes, S.C. Manrubia, F.
Selsis, and O. Prieto Ballesteros Centro de
Astrobiología, INTA-CSIC, Madrid, SPAIN Sz.
Bérczi (Eötvös University, Budapest), A.
Gesztesi, and A. Horváth (Planetarium Budapest,
HUNGARY)
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Location The area of study is located in Mars
southern hemisphere, between 330º - 315º W and
63º - 71ºS Pityusa patera has about 330 km of
diameter SE mountains raise to 1600 m, and the
minimum regional height is found at a small
crater inside Pityusa patera, -145 m.
330 km
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Local topography
32º34E 65º33S
40º46E 65º33S
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2
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41º31E 69º05S
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32º01E 69º04S
Shaded relief image of regional topography
obtained from MOLA data. Image is illuminated
from NE.
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Motivation and Scientific Objectives The area of
study undergoes seasonal frosting and defrosting
along the martian year Previous analysis have
shown the recurrent appearance of peculiar
defrosting structures on a low-albedo,
dune-forming material 1,2 Dark Dune
Spots With this study we aim at
understanding the role played by different
variables (topography, surface composition,
climatic and other seasonal changes, ...) on the
seasonal processes the dynamical mechanisms
through which DDS are formed any other on-going
processes relevant in shaping this heterogeneous
area 1 M.C. Malin and K.S. Edgett, LPSC XXXI
1056 XXXII 1966 2 A. Horváth, T. Gánti, Sz.
Bérczi, A. Gesztesi, and E. Szathmáry, LPSC XXXII
1543 XXXIII 1108, 1109, 1221 XXXIV 9999
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Methodology A simultaneous analysis of regional
and local features will be carried out. Our first
step consists in obtaining a description as good
as possible of the geological setting and
environmental variables. (Data are integrated
with ERDAS software.) DATA SOURCES Mars Orbiter
Camera of MGS. All narrow angle and wide angle
images with center within 320 and 326 W and 65
and 68 S have been analysed (56 images from AB
to E12 phases) 1 MOLA topography has been
compared with visual information Climatic and
meteorological data (estimated CO2 coverage, T,
atm. pressure, and winds) have been obtained
from simulations using the European Mars Climate
Database (http//www-mars.lmd.jussieu.fr
2) The energy flux reaching the surface has
been calculated with a radiative transfer model
(taking into account the optical depth measured
by MGS, the variation in Ls, and the location on
Mars) 1 http//www.msss.com 2 S.R. Lewis,
M. Collins, P.L. Read, F. Forget, F. Hourdin, R.
Fournier, C. Hourdin, O. Talagrand, and J.-P.
Huot, J. Geoph. Res. 104, 177 (1999).
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Seasonal changes
Seasonal mosaics have been made taking WA MOC
images from the same Ls range. Climatological
variables have been calculated for each group of
images. Winter is not well represented. Autum
is not represented.
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CO2 (Kg/m2)
T (K)
290 260 230 200 170 140
750 600 450 300 150 0
3 2 1 -1 -2
-2 -1 1 2 3
(m/s)
Wind
Av. atm. pressure 4,7 mb
SZA at noon 57.6 E flux
(UVVIS) 159.1 W/m2
Ls
0
270
M0400521 M0400904 M0705740
90
180
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CO2 (Kg/m2)
T (K)
290 260 230 200 170 140
750 600 450 300 150 0
3 2 1 -1 -2
-2 -1 1 2 3
(m/s)
Wind
Av. atm. pressure 5,3 mb
SZA at noon 50.1 E flux
(UVVIS) 197.3 W/m2
Ls
0
270
E0700999 E0701437 E0701582 E0702124
90
180
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CO2 (Kg/m2)
T (K)
290 260 230 200 170 140
750 600 450 300 150 0
3 2 1 -1 -2
-2 -1 1 2 3
(m/s)
Wind
Av. atm. pressure 5,2 mb
SZA at noon 43 E flux
(UVVIS) 237.7 W/m2
Ls
0
270
90
E1200802 E1201650 E1202669
180
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CO2 (Kg/m2)
T (K)
290 260 230 200 170 140
750 600 450 300 150 0
M1202466 M1202879 M1400699 M1500955
3 2 1 -1 -2
45 km
-2 -1 1 2 3
(m/s)
Wind
Av. atm. pressure 4,9 mb
SZA at noon 53 E flux
(UVVIS) 130.7 W/m2
Ls
0
270
90
180
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Seasonal features perennial CO2 layer
The flat ice feature inside the crater is present
in all images, from winter to summer perennial
ice layer The perennial CO2 layer does not
suffer any substantial areal change (as measured
with WA MOC images it is 14500km2) This effect
can be also seen using NA images from two
consecutive springs However, it is probably
thinner in summer due to sublimation this is
based on the observation of convection cells in
the surface
M0303083
E0700101 M0702775
M1202879
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Seasonal features Dark / Frosted bedforms
Summer
Early spring
Images of the martian summer show dark bedforms
on the northern hillside. Images of early spring
from a near area show the bedforms covered by ice.
M0702776
E1200802
M0702775
E1200801
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Seasonal features Dark Spots

• From late winter to spring dark spots appear over
  the seasonal ice, until complete defrosting of
  dark surface material in summer.
• DS characteristics
• Related to bedforms influenced by local
  topography and soil
• Circular to ellipsoidal, sometimes with more
  than one lobule, following main slopes
• Occasionally, liquid material flows downhill
• Concentric halos (black center, first whitish
  corona, second grey halo) present from winter
  to early spring
• Diameter from dozens to hundreds of meters
• Seasonal recurrence

E0700101
E0701581
E0701581
E0700101
M0702775
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Dust activity wind transport
During summer, an extense deposit of dark
dust-like material covers the northern part of
Pityusa Patera This dark area has an estimated
surface between 23000 and 34000 km2 Dark dust
moves from the bottom of the crater up to the
highlands probably due to dominant summer winds
These dark deposits are similar to others
analysed on Mars 1. They probably have a
basaltic composition
N
M1202879
1 P.R. Christensen, J. L. Bandfield, M.D.
Smith, V.E. Hamilton, and R.N. Clark, J. Geoph.
Res. 105, 9609 (2000) J.L. Bandfield, V.E.
Hamilton, and P. R. Christensen, Science 287,
1626 (2000).
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Dust activity wind streaks / dust devils
The movement of the dust during summer leaves
wind streaks signals over the surface Over the
perennial ice layer some dust devil traces can be
observed
1300 m
E1200801
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Dark layer /residual dark sheet
A dark layer inside or at the bottom of the
seasonal ice can be recognized in many
images. When the ice layer disapears a residual
dark sheet is observed covering the surface.
Time
E0701581
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Substrate Cracks
In late spring the substrate presents cracks
which result from volume changes in the uppermost
layer.
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Summary Several permanent and seasonal features
have been observed and described in the eastern
area of Cavi Novi. The interaction of
geological and climatological variables have
created a very heterogeneous environment in and
around the Pityusa patera crater. Features
originating at the large time-scale (an old
impact bed, high mountains, a permanent CO2
layer, the storage of dust enhanced by the
topography, bedforms) influence seasonal
processes and the associated observed features
(dust devils, wind streaks, ice frosting and
defrosting, formation of DS, substrate cracks).
Eventually, we aim at getting a dynamical
picture of the area as complete as possible. To
this end, also data from TES and THEMIS and
experimental studies will be considered together
with the ones here shown in order to assess the
influence of different surface materials on
seasonal processes. A similar methodology can be
also applied to other areas in order to obtain an
integrated description of global and local
processes and features.