HR: 1340h
AN: P13A-0979    [Abstracts]
TI: Northern Polar Layered Deposits on Mars: Identification and Characterization of Signals of Possible Climatic Origin
AU: * Milkovich, S M
EM: sarah_milkovich@brown.edu
AF: Brown University Dept of Geological Sciences, Box 1846, Providence, RI 02912
AU: Head, J W
EM: james_head_iii@brown.edu
AF: Brown University Dept of Geological Sciences, Box 1846, Providence, RI 02912
AB: The record of recent climate change on Mars is encoded in the polar layered deposits (PLD). Individual MOC images of exposed layer sequences in troughs provide the equivalent of cores through the PLD. Techniques employed in the study of terrestrial sediment cores to search for patterns in layer sequences (Fourier analysis) and to determine correlations between sequences (curve-shape matching algorithms) were applied to the north PLD in an attempt to decode this record by 1) characterizing quantitatively the layers in individual locations and 2) assessing possible correlations between locations. Several properties of north polar cap stratigraphy were revealed: 1) A characteristic wavelength of ~30 m thickness exists throughout the upper part of the cap. 2) We have thus far been able to correlate layers across at least three quarters of the cap. We tentatively interpret these results as follows: 1) the ~30 m signal is a climate signal that may correspond to a 51 kyr insolation cycle. 2) Net layer accumulation processes occur across the cap, not confined within a single trough. Analysis of a composite stratigraphic column reveals that the ~300 m thick upper unit (Zone 1) has a dominant wavelength of ~30 m, and overlies Zone 2, a ~100 m thick unit with no dominant signal. We interpret Zone 2 as a lag deposit formed during a recent high-obliquity phase, at which time polar volatiles underwent mobilization and transport equatorward. Below these units lies Zone 3 (~200m) containing a dominant wavelength of ~35 m, and Zone 4 (~200m), characterized by multiple signals but no dominant signal.
DE: 5450 Orbital and rotational dynamics
DE: 5462 Polar regions
DE: 6225 Mars
DE: 4267 Paleoceanography
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting