Tectonic Complexity in Mercury's Impact Features

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

Victoria Rupes

This image is a portion of the MDIS global mosaic basemap that was acquired during MESSENGER's first year in orbit. The scene, with north to the right, shows a geological feature termed Victoria Rupes -- a long cliff or scarp that formed when Mercury shrank slightly as its core cooled. Rupes on Mercury are named for ships of discovery, and Victoria Rupes is named for the Victoria that formed part of Ferdinand Magellan's fleet in his 1519-1522 effort to circumnavigate Earth.

This geologic feature is of particular interest to MESSENGER scientists because it is part of a larger, linear set of contractional structures that may correspond to what is termed a fold-and-thrust (FAT) belt on Earth. FAT belts are common terrestrial surface features, and form when the crust is shortened due to compressional tectonism. Identifying FAT belts on Mercury will help scientists understand in more detail how that planet's crust has deformed through time.

Date Created: February 10, 2012
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
Latitude Range: 47° N to 59° N
Longitude Range: 321° E to 331° E
Resolution: 250 meters/pixel
Scale: The crater just left of center is approximately 42 km (26 mi.) in diameter
Projection: Azimuthal equidistant

Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Mercury Landscape

When MESSENGER first flew by Mercury on January 14, 2008, MDIS acquired images of a large portion of Mercury's surface that had never previously been seen by spacecraft. This mosaic of NAC images shows some of the geologic features discovered during that first flyby that have been subsequently named: the curving cliff face of Beagle Rupes, the elongated crater Sveinsdottir, and the craters Izquierdo and Kunisada flooded with lava.

This year, the MESSENGER spacecraft is positioned once again to visit the Solar System's innermost planet. However, this time, the spacecraft won't just pass by. On March 18, 2011, a 15-minute maneuver will place MESSENGER in orbit about Mercury, making it the first spacecraft ever to do so. The MESSENGER mission will then begin an extensive year-long science campaign to unravel Mercury's mysteries. 2011 promises to be an exciting year of further discoveries for the MESSENGER mission.

Date Acquired: January 14, 2008
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Scale: Izquierdo Crater is 170 kilometers (106 miles) in diameter.

Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Long Scarp

Extending from the left edge of this image diagonally toward the lower right corner is a long scarp (cliff) face. This scarp runs through a large ancient crater in the center of the frame and was seen for the first time during MESSENGER's second Mercury flyby. Planetary geologists use the Latin term "rupes" for scarps on Mercury. Scarps such as this one have been identified all over the planet. The presence of many long and high scarps suggests a history for Mercury that is unlike that of any of the other planets in the Solar System. These giant scarps are believed to have formed when Mercury's interior cooled and the entire planet contracted slightly as a result, causing the surface rocks to fracture and some blocks of crust to thrust over others along great faults. Determining the geometry of such scarps on Mercury and information on the times that deformation occurred can thus be used to understand the thermal history of the planet. Next year, when the MESSENGER spacecraft is in orbit around Mercury, MDIS will acquire for the first time global imaging coverage of Mercury's surface with lighting conditions optimal for identifying such scarps.

Date Acquired: October 6, 2008
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Scale: The large crater crosscut by the scarp is approximately 110 kilometers (70 miles) in diameter.

Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington