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.
Mars north polar deposits: Stratigraphy, age, and geodynamical response / Roger J., Phillips; Maria T., Zuber; Suzanne E., Smrekar; Michael T., Mellon; W., Head James; Kenneth L., Tanaka; E., Putzig Nathaniel; Sarah M., Milkovich; A., Campbell Bruce; Jeffrey J., Plaut; Safaeinili, Ali; Seu, Roberto; Daniela, Biccari; M., Carter Lynn; Giovanni, Picardi; Roberto, Orosei; P., Surdas Mohit; Essam, Heggy; Richard W., Zurek; F., Egan Anthony; Emanuele, Giacomoni; Federica, Russo; Marco, Cutigni; Elena, Pettinelli; John W., Holt; J., Leuschen Carl; Lucia, Marinangeli. - In: SCIENCE. - ISSN 0036-8075. - 320:5880(2008), pp. 1182-1185. [10.1126/science.1157546]
Mars north polar deposits: Stratigraphy, age, and geodynamical response
SEU, Roberto;
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
