Mars north polar deposits: stratigraphy, age, and geodynamical response.
The Shallow Radar (SHARAD) on the Mars Reconnaissance Orbiter has imaged the internal stratigraphy of the north polar layered deposits of Mars. Radar reflections within the deposits reveal a laterally continuous deposition of layers, which typically consist of four packets of finely spaced reflectors separated by homogeneous interpacket regions of nearly pure ice. The packet/interpacket structure can be explained by approximately million-year periodicities in Mars' obliquity or orbital eccentricity. The observed approximately 100-meter maximum deflection of the underlying substrate in response to the ice load implies that the present-day thickness of an equilibrium elastic lithosphere is greater than 300 kilometers. Alternatively, the response to the load may be in a transient state controlled by mantle viscosity. Both scenarios probably require that Mars has a subchondritic abundance of heat-producing elements.
Phillips
Roger J
RJ
Southwest Research Institute, Boulder, CO 80302, USA. roger@boulder.swri.edu
Zuber
Maria T
MT
Smrekar
Suzanne E
SE
Mellon
Michael T
MT
Head
James W
JW
Tanaka
Kenneth L
KL
Putzig
Nathaniel E
NE
Milkovich
Sarah M
SM
Campbell
Bruce A
BA
Plaut
Jeffrey J
JJ
Safaeinili
Ali
A
Seu
Roberto
R
Biccari
Daniela
D
Carter
Lynn M
LM
Picardi
Giovanni
G
Orosei
Roberto
R
Mohit
P Surdas
PS
Heggy
Essam
E
Zurek
Richard W
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Egan
Anthony F
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Giacomoni
Emanuele
E
Russo
Federica
F
Cutigni
Marco
M
Pettinelli
Elena
E
Holt
John W
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Leuschen
Carl J
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Marinangeli
Lucia
L