Other
Scientific paper
Dec 2001
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2001agufm.p22a0535p&link_type=abstract
American Geophysical Union, Fall Meeting 2001, abstract #P22A-0535
Other
5462 Polar Regions
Scientific paper
The relative paucity of small impact craters with diameter D < 5 km upon the Martian polar layered deposits (PLD) indicates crater retention surface ages of well under 1 Myr for the north PLD [1] and up to tens of millions of years for the south PLD [1,2]. However, larger impact craters approximately 20 km in diameter have also been observed at the margins of both the North and South PLD [3,4], suggesting PLD surface ages on the order of hundreds of millions of years. Although the recent removal of smaller PLD craters is widely attributed [1] to either deposition (of ice and/or dust) or ablation (via sublimation or eolian erosion), there are two main problems with such depth-dependent resurfacing mechanisms: (A) the vertical resurfacing rates required to eradicate the (missing) smallest craters should have long ago obliterated the (still observed) largest craters; and (B) vertical resurfacing should produce craters spanning a range of depths (relative to the base of the initial crater cavity), yet most PLD craters with D > 1 km are notably shallow relative to other Martian craters [2,3]. Therefore, instead of deposition or ablation, we propose that PLD crater resurfacing predominantly occurs via viscous creep relaxation of the dusty water ice comprising the PLD itself, which we will extensively model using the finite-element code Tekton [5]. Our preliminary results (for a PLD thickness of 2 km, ice grain size of 1 mm, dust fraction of 0.25, annual average surface temperature of 185 K, and subsurface thermal gradient of 10 K/km) indicate that a D = 2 km crater within the PLD undergoes extremely rapid deformation, relaxing to less than half of its initial depth in just 250 kyr, and less than 10% of its initial depth in 1 Myr. We will simulate the relaxation of craters ranging from 200 m < D < 20 km within PLD deposits ranging in thickness from 500 m to 3 km in order to calculate PLD crater retention surface age as a function of crater diameter and underlying PLD thickness. This will allow us to explicitly test our relaxation hypothesis by comparing our model predictions to the observed distribution of PLD craters, which we expect to be preferentially retained in thinner PLD terrains. References: [1] Herkenhoff and Plaut (2000), Icarus, 144, 253. [2] Koutnik et al. (2001), in preparation. [3] Garvin et al. (2000), Icarus, 144, 329. [4] Howard et al. (1982), Icarus, 50, 161. [5] Melosh and Raefsky (1980), Geophys. J.R. Astr. Soc., 60, 333.
Paige David A.
Pathare Asmin V.
Turtle Elizabeth Pope
No associations
LandOfFree
Viscous Creep Relaxation of Impact Craters Within the Martian Polar Layered Deposits does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Viscous Creep Relaxation of Impact Craters Within the Martian Polar Layered Deposits, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Viscous Creep Relaxation of Impact Craters Within the Martian Polar Layered Deposits will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1238956