Thursday, July 24, 2014

Banded Slump in Berzelius W

A complex interplay of slumping and slides in the northwest wall of Berzelius W result in banding patterns; downslope is toward the bottom right in this 230 meter-wide field of view from LROC NAC observation M174921824R, LRO orbit 10912, November 3, 2011; 53.59° incidence angle, resolution 40 cm from 23.87 km over 38.06°N, 53.02°E [NASA/GSFC/Arizona State University].
J. Stopar
LROC News System

Berzelius W (7.17 km; 38.137°N, 53.103°E), on the northeast limb of the Moon (as seen from the Earth), exhibits abundant evidence for mass wasting.

Materials of varying albedo create intricate patterns on the walls of the crater, including the banding patterns featured in the opening image. 

This particular portion of the wall includes a block of slumped material, as indicated by the characteristic arcuate faults near the crater's rim crest (see image below). The slumped material is overprinted by finger-like flows of finer particles that moved as slides of dry debris.

Arrow indicates the arcuate faults at the head of the slumped material in the wall of Berzelius W. This slumping may have triggered the associated narrower and finger-like landslides of lower albedo (darker) boulders and debris; 600 meter field of view [NASA/GSFC/Arizona State University].
When did these mass-wasting events occur? Did they occur during the impact event, shortly after while the landscape was still ringing from the shock of impact, or millennia later? The lack of high albedo (bright) ejecta around the crater and the subdued appearance of the rim crest indicate that this crater did not form particularly recently; perhaps it is between 1 and 2 billion years old. 

Berzelius W (7.17 km; 38.137°N, 53.103°E) in 35.7 km-wide field of view from LROC WAC monochrome (604 nm) mosaic of M161965061C and M161971828C, LRO orbit 9003 and 9004, June 6, 2011; 73.5° incidence at 61.5 meters resolution from 44.9 km [NASA/GSFC/Arizona State University].
The crisp edges of the debris flows and arcuate scarps in the walls, however, suggest that they are much younger than the crater. So, while this landslide probably did not form yesterday, it is likely significantly younger than the crater itself, probably less than half its age. However, without more data, it is impossible to know precisely when these events occurred. Repeated imaging over many decades may provide more insight into how crater walls age with time. Alternatively, samples returned from crater walls may provide a method to age-date mass-wasting events. 

Try to find at least three other examples of mass-wasting features in the western half of this crater below. Pan and zoom to find examples of landslides, talus deposits, and boulder tracks:

Full 850 meter-wide field of view from remarkably high resolution LROC NAC observation M174921824R [NASA/GSFC/Arizona State University].
View full-window HERE.

Related Features:

No comments: