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 ~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 R. J, ZUBER M. T, SMREKAR S. E, MELLON M. T, HEAD J. W, TANAKA K. L, et al. (2008). Mars North Polar Deposits: Stratigraphy, Age, and Geodynamical Response. SCIENCE, 320, 1182-1185 [10.1126/science.1157546].

Mars North Polar Deposits: Stratigraphy, Age, and Geodynamical Response

PETTINELLI, Elena;
2008

Abstract

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 ~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 R. J, ZUBER M. T, SMREKAR S. E, MELLON M. T, HEAD J. W, TANAKA K. L, et al. (2008). Mars North Polar Deposits: Stratigraphy, Age, and Geodynamical Response. SCIENCE, 320, 1182-1185 [10.1126/science.1157546].
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11590/139842
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