Monday, April 1, 2013

Unassuming volcanic vent north of Aristarchus Plateau

This unassuming textured surface surrounding a smooth tongue of material is likely a volcanic vent. Field of view 1500 meters, from LROC Narrow Angle Camera (NAC) observation M181495512L, spacecraft orbit 11859, January 18, 2011; angle of incidence 66.53° and 1.46 meters resolution from 147.24 km altitude [NASA/GSFC/Arizona State University].
Drew Enns
LROC News System

Igneous rocks are common on the Moon, basalt makes up the darker mare, and anorthosite makes up the lighter highlands. Less common are the volcanic structures that might have produced the mare. But in today's Featured Image we might have one such structure!

The area highlighted looks similar to vents (the source point of lava) on terrestrial volcanoes. How strong a case can we make for this being volcanic in origin? Maybe a larger view will help give context.

UPDATE: The "unassuming extrusive dome" from the east, in an oblique LROC NAC observation (camera and spacecraft slew -67° from nadir), M177927436LR mosaic, orbit 11357, December 7, 2011; roughly 3.2 meters per pixel resolution from 41.93 km over 30.98°N, 314.73°E (more than 140 km from target) [NASA/GSFC/Arizona State University].
LROC Wide Angle Camera mosaic providing context for the area highlighted within the LROC NAC Featured Image released April 1, 2013 (red asterisk). South lay the volcanic shield Aristarchus Plateau complex Field of view 58 v 80 kilometers [NASA/GSFC/Arizona State University].
The small channel in the Featured Image does not have much depth, so it is difficult to make out. But in the high incidence angle (nearly 80°) context mosaic we see that a shallow channel superposes the center of a low relief pancake-like mound. This pancake feature is very similar to shallow shield volcanoes on Earth. These types of volcanoes have very low slopes and additionally, Aristarchus Plateau is just to the south with a number of volcanic features (rilles, flat floored craters, and massifs). Taken together these observations present a strong case that the smooth area in today's Featured Image is the vent for a shield volcano!

Explore more of the area in the full LROC NAC, HERE.

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