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A large (180-km diameter) crater occupies the scene, but it has been almost completely buried by the volcanic plains that make up the northern smooth plains. The rim of the buried crater, especially in the southeast, has helped to localize compressional deformation, leading to a wrinkle-ridge ring. The center is criss-crossed by extensional graben.
These images were acquired as part of MDIS's high-incidence-angle base map. The high-incidence-angle base map complements the surface morphology base map of MESSENGER's primary mission that was acquired under generally more moderate incidence angles. High incidence angles, achieved when the Sun is near the horizon, result in long shadows that accentuate the small-scale topography of geologic features. The high-incidence-angle base map was acquired with an average resolution of 200 meters/pixel.
Date acquired: March 09, 2014
Image Mission Elapsed Time (MET): 36713179, 36713230
Image ID: 5903920, 5903921
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filter: 7 (748 nanometers)
Center Latitude: 64.4°
Center Longitude: 23.8° E
Resolution: 258 meters/pixel
Scale: The buried basin is approximately 180 km (112 miles) across
Incidence Angle: 86.2°
Emission Angle: 51.1°
Phase Angle: 137.3°
Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
A series of troughs extends diagonally (southwest-northeast) across this high-resolution image of the interior of the Caloris basin. The troughs are graben: structures that developed where horizontal forces pulled the crust apart, causing valleys to form as sections of rock dropped down between two inward-dipping faults. Pulling-apart ("extensional") deformation is much less common on Mercury than is compressional deformation. However, a large number of graben are found within Caloris. This network of graben, named Pantheon Fossae, is the subject of a blog essay recently posted on the website of The Planetary Society.
This image was acquired as a high-resolution targeted observation. Targeted observations are images of a small area on Mercury's surface at resolutions much higher than the 200-meter/pixel morphology base map. It is not possible to cover all of Mercury's surface at this high resolution, but typically several areas of high scientific interest are imaged in this mode each week.
Date acquired: January 19, 2012
Image Mission Elapsed Time (MET): 235472082
Image ID: 1285755
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: 27.3°
Center Longitude: 160.7° E
Resolution: 24 meters/pixel
Scale: The scene is about 43 km (27 mi.) across
Incidence Angle: 76.8°
Emission Angle: 54.9°
Phase Angle: 131.8°
North is up in this image.
Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Lobate scarps are one of the most common types of landform on Mercury, and frequently cross-cut impact craters of all sizes. However, the example in this image, termed Alvin Rupes, is one of only a very small subset of scarps that are accompanied by thin, linear depressions on their upper surfaces. One possibility is that these features are graben -- fault-bounded troughs that form when rock is extended -- like those seen in Caloris basin, for example. If so, then these graben are among the only such structures known to occur outside of volcanically flooded impact basins and craters.
This image was acquired as a high-resolution targeted observation. Targeted observations are images of a small area on Mercury's surface at resolutions much higher than the 200-meter/pixel morphology base map. It is not possible to cover all of Mercury's surface at this high resolution, but typically several areas of high scientific interest are imaged in this mode each week.
Date acquired: July 3, 2013
Image Mission Elapsed Time (MET): 15167012
Image ID: 4372157
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: 7.8°
Center Longitude: 151.1° E
Resolution: 54 meters/pixel
Scale: The crater in the center of the image is about 12 km (7.5 mi.) across
Incidence Angle: 75.6°
Emission Angle: 12.6°
Phase Angle: 88.2°
North is up in this image.
Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Mercury's surface is covered with impact craters, many of which have been flooded by lavas. A subset of flooded impact features host tectonic structures -- graben (shown in red in the figure above) and ridges and scarps (blue) -- that formed during or after volcanic infilling. Such impact features range from so-called "ghost craters" through medium-sized basins such as Mozart, to the largest basins on Mercury, including Rembrandt and the mighty Caloris. Mapping these structures, and so characterizing their nature and spatial and temporal distributions, helps scientists understand the processes responsible for the tectonic complexity within volcanically infilled craters and basins on Mercury.
Date released: February 1, 2013
Center Latitude: (a) 60.3°, (b) 7.8°, (c) -33.5°, (d) 30°
Center Longitude: (a) 36.7° E, (b) 169.6° E, (c) 88°E, (d) 161°E
Projection: Orthographic
Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
This image is a portion of the MDIS global mosaic basemap that was acquired during MESSENGER's first year in orbit. Caloris Basin, the largest young impact crater on Mercury, dominates the scene. With an east-west diameter of 1,640 km, Caloris hosts a wide variety of tectonic features, including graben, ridges, and Pantheon Fossae. MESSENGER team members are in the process of mapping the tectonic features within the Caloris basin and deciphering their complicated relationships.
MESSENGER scientists are interested in the tectonic features of Caloris as the basin shows widespread evidence of both extension and compression, an uncommon tectonic combination on Mercury. Since different processes produce extensional and contractional landforms, the Caloris basin has clearly had a complex and detailed geological history. Understanding how these structures developed will yield an insight into tectonism in Mercury's largest basin, and large impact craters in general.
Date Created: February 10, 2012
Instrument: Mercury Dual Imaging System (MDIS)
Latitude Range: 12° N to 52° N
Longitude Range: 139° E to 187° E
Resolution: 1720 meters/pixel
Scale: The large crater at center right (Atget crater) is 100 km (63 mi.) in diameter
Projection: Azimuthal equidistant
Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
The large Caloris basin hosts a wide variety of tectonic features, including graben, ridges, and Pantheon Fossae. MESSENGER team members are in the process of mapping the tectonic features within the Caloris basin and deciphering their complicated relationships. The tectonic map shown here was published in the abstracts of the 43rd Lunar and Planetary Science Conference, which is being held this week in The Woodlands, Texas. In total, MESSENGER team members are presenting 57 papers at this conference.
Center Latitude: 31°
Center Longitude: 163° E
Scale: Caloris basin has a diameter of 1,550 kilometers (960 miles)
Reference: From abstract #1722 by Paul K. Byrne and coauthors at the 43rd Lunar and Planetary Science Conference
Map credit: Byrne et al. (2012). A tectonic survey of the Caloris basin, Mercury. 43rd Lunar and Planetary Science Conference, The Woodlands, Texas, abstract #1722.
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