Two distinct volcanic eruptions have flooded this area of Daedalia Planum with lava, flowing around an elevated fragment of ancient terrain.
The images were acquired by ESA’s Mars Express on 28 November 2013 towards the eastern boundary of the gigantic Tharsis Montes volcanic region, where the largest volcanoes on Mars are found.
Two distinct volcanic eruptions have flooded this area of Daedalia Planum on Mars, flowing around an island of ancient terrain. The smooth, fractured terrain to the south (left) predates the rough-textured lava flow that dominates the northern (right) side of the image. The lava flows arose from the giant Arsia Mons volcano, part of the Tharsis complex around 1000 km to the northwest. The blue–grey colour at the bottom left of the image likely reflects a difference in the composition of exposed material: for example, wind-blown ash or dust deposits can easily accumulate in faults or channels. The image was created using data acquired on 28 November 2013 during Mars Express orbit 12 593 using the High Resolution Stereo Camera. The image resolution is about 14 m per pixel. The image centre is at about 25ºS/249ºE. North is right and east down. Copyright ESA/DLR/FU Berlin
The lava flows seen in this image come from Arsia Mons, the southernmost volcano in the Tharsis complex, which lies around 1000 km to the northwest of the region featured here.
This volcanic region is thought to have been active until tens of millions of years ago, relatively recent on the planet’s geological timescale that spans 4.6 billion years.
This region of Daedalia Planum includes Mistretta Crater and sits close to the Claritas Fossae region of Mars. The giant Tharsis Montes volcanoes lie more than 1000 km to the northwest. Copyright NASA MGS MOLA Science Team
The rough elevated terrain at the bottom of the main image is imprinted with three distinct but eroded impact craters, the largest of which is about 16.5 km wide and named Mistretta. The ancient foundation it sits on once belonged to the vast southern highlands, but is now surrounded by a sea of lava, like many other isolated fragments that can be seen in the wider context image.
Close-up view of the two dominant lava flows that reach the foot of the highland terrain (seen at the top of the image in this orientation). The older of the two eruptions produced the smooth lava surface to the south of the island (right), which later experienced extensive faulting. The younger lava flow (left) has a rougher texture and overlies the faulted lava plain, and therefore occurred later, with some of the lava flowing into the troughs. This region was imaged by the high-resolution stereo camera on ESA’s Mars Express on 28 November 2013 (orbit 12 593), with a ground resolution of 14 m per pixel. Copyright ESA/DLR/FU Berlin
Lava flows from two distinct eruptions have reached the foot of this particular feature.
The first eruption produced the lava flow to the south of the island (to the left in the main image and to the right in the close-up perspective image). This flow subsequently experienced extensive faulting due to tectonic forces, resulting in the numerous trough systems.
The younger lava flow (right in the main image, left in the close-up image) must have taken place after the tectonic event that caused the faulting because it overlies both the older lava surface and the tectonic features. Indeed, at the front of the flow, several tongues of lava have flowed preferentially along the lower ground of the troughs.
Colour-coded topography map of Daedalia Planum, featuring a segment of highland terrain that is home to Mistretta Crater, the largest of the three eroded impact craters. White and red show the highest terrains, while blue and purple show the deepest. The image is based on a digital terrain model of the region, from which the topography of the landscape can be derived. The region clearly slopes to the south (left). This region was imaged by the high-resolution stereo camera on ESA’s Mars Express on 28 November 2013 (orbit 12 593), with a ground resolution of 14 m per pixel. The image centre is at about 25ºS/249ºE. North is right and east down. Copyright ESA/DLR/FU Berlin
Another clear indication of the relative ages of the two flows is given by the impact craters: the older, fractured lava flow has more and larger ones than the younger flow.
The younger lava flow also has a rough texture, with many small ridges on the surface. These features form as result of speed gradients within the lava flow due to the difference in temperature between the hot, faster-flowing interior lava and the cooler, slower ‘roof’ of the flow that is exposed to the atmosphere.
Data from the nadir channel and one stereo channel of the high-resolution stereo camera on ESA’s Mars Express have been combined to produce this anaglyph 3D image which can be viewed using stereoscopic glasses with red–green or red–blue filters. This region was imaged on 28 November 2013 (orbit 12 593), with a ground resolution of 14 m per pixel. The image centre is at about 25ºS/249ºE. North is up and east is down. Copyright ESA/DLR/FU Berlin
But neither lava flow travelled unimpeded. The highland ‘island’ in this scene created an obstacle, forcing them to circle its flanks and override its base, most noticeable to the north (to the right in the main colour, topography, and 3D images).
The wider Daedalia Planum region bears witness to numerous lava flows similar to these, each one overlaying the last. By carefully studying the boundaries between overlapping flows, planetary scientists can build up a picture of the eruption history of the Red Planet’s giant volcanoes.