Syrtis Major quadrangle

MC-13

Syrtis Major

0–30° N

45–90° E

Quadrangles

Atlas

• 
• 

The Syrtis Major quadrangle covers latitudes 0° to 30° N and longitudes 270° to 315° W (45-90E). Syrtis Major quadrangle includes some other named regions: Syrtis Major Planum, and parts of Terra Sabaea and Isidis Planitia. Geologically, Syrtis Major is an ancient shield volcano with a central depression that is elongated in a north-south direction. Calderas are large openings at the top of volcanoes. Syrtis Major contains the calderas named Meroe Patera and Nili Patera. Other geologically interesting features in the area include dikes and inverted terrain. The Beagle 2 lander crashed in this quadrangle in December 2003. In January 2015, NASA reported the Beagle 2 that had found it in Isidis Planitia (location is about 11.5265 N and 90.4295E. It was imaged by HiRISE onboard the Mars Reconnaissance Orbiter. Beagle 2 looked intact. In November 2018, NASA announced that Jezero crater was chosen as the landing site for the planned Mars 2020 mission. Jezero Crater is located at 18.855N and 77.519 E The rest of this article will cover significant scientific discoveries and show what the landscape looks like close up. We will be learning and hearing much more about this area when Mars 2020 lands in Jezero Crater.

How named

Syrtis Major is named after the classical Roman name Syrtis maior for the Gulf of Sidra that is found on the coast of Libya (classical Cyrenaica). Interestingly, Syrtis Major is near Cyrene which accoding to the Bilbe is the place where "Simon" who carried the cross of Jesus was from.

Discovery and history

Syrtis Major is the main marking that people see when they look at Mars through a backyard telescope. It was discovered by Christiaan Huygens, who included it in a drawing of Mars in 1659 and was originally known as the "Hourglass Sea.” Different cartographers have given it different names over centuries. Johann Heinrich von Mädler in 1840 called the feature “Atlantic Canale.” Richard Proctor called it “Kaiser Sea” in 1867. A little later, Camille Flammarion called it the “Mer du Sablier” (French for "Hourglass Sea") when he updated Proctor's naming system in 1876. Syrtis Major, the name that has stock was picked by Giovanni Schiaparelli when he created a map based on observations made during Mars' close approach to Earth in 1877.

Igneous rocks

The Syrtis Major region is of great interest to geologists since several types of igneous rocks have been found there with orbiting spacecraft. Besides basalt, dacite and granite have been found there with orbiting satellites. Dacite originates under volcanoes in magma chambers. In magma chambers new minerals and rocks are put together. After heavy minerals (olivine and pyroxene) containing iron and magnesium have settled to the bottom, Dacites form at the top of the chamber. Granite is formed by an even more complex process. Some areas of Syrtis Major contain large amounts of the mineral olivine. Olivine turns into other minerals very rapidly in the presence of water, so if we find olivine, we know that the place has been dry for a long time.

Minerals

A variety of important minerals have been discovered near Nili Fossae, a major trough system in Syrtis Major. Besides olivine, other minerals found there include carbonates, aluminum smectite, iron/magnesium smectite, hydrated silica, kaolinite group minerals, and iron oxides. In December 2008, NASA's Mars Reconnaissance Orbiter found carbonate minerals, a geologically significant discovery. Later research published in October 2010, described a large deposit of carbonate rocks found inside Leighton Crater. The rocks at one time were buried 4 miles below the surface. This discovery has great importance in understanding the history of the planet. Finding carbonates in an underground location means that Mars may have been warmer and may have had atmospheric carbon dioxide and ancient seas. Because the carbonates were found near silicate minerals and clays, hydrothermal systems like the deep sea vents on Earth may have been present. Other minerals found by the Mars Reconnaissance Orbiter are aluminum smectite, iron/magnesium smectite, hydrated silica, kaolinite group minerals, iron oxides, and talc. NASA scientists have also discovered that Nili Fossae is the source of plumes of methane, raising the question of whether this source originates from biological sources.

Dikes

Narrow ridges occur in some places on Mars. They may be formed by different means, but some are probably caused by molten rock moving underground and moving along cracks or faults in the rock. When they cool, walls of hard rock may be formed after being exposed by the erosion of softer, surrounding materials. Such a feature is termed a dike. They are common on Earth—a famous one is Shiprock, New Mexico;

• 

  Dikes near Shiprock, New Mexico

Mapping the presence of dikes allows us to understand how magma (molten rock under the ground) travels and where it could have interacted with surrounding rock, thus producing valuable ores. Deposits of important minerals are also made by dikes and other types of magma movements. These superhot liquid rocks heat water. The hot water dissolves minerals that are deposited in cracks in nearby rock. This process has given us many sources of important minerals. One would expect a great deal of intrusive igneous activity (molten rock under the ground) to occur on Mars because it is believed there is more igneous activity under the ground than on top, and Mars has many huge volcanoes. In other words, more liquid rock was under the surface than in the many massive Martian volcanoes.

Dike

Linear Ridge Networks

Some crater floors in the Syrtis Major area show elongated ridges arranged in a complex pattern. Scientists are still debated over the exact origin of these features. Some have suggested that they are dikes made up of molten rock; others have advanced the idea that other fluids such as water were involved. The ridges are found where there has been erosion.

• 

  Ridges, as seen by HiRISE under HiWish program These may be the result of dikes or faults.

• 

  Close, color view of ridges, as seen by HiRISE under HiWish program

• 

  Close, color view of ridges, as seen by HiRISE under HiWish program

• 

  Ridges, as seen by HiRISE under HiWish program

Dunes

Sand dunes are found all over Mars, especially in low spots like craters and the floors of old river valleys.Dunes on the floor of Arnus Vallis, an old river valley are visible in a picture below. Dunes in valleys on Mars usually lie at right angles to the valley walls.

• 

  Wide view of dunes, as seen by HiRISE under HiWish program

• 

  Dunes, as seen by HiRISE under HiWish program

• 

  Color view of dunes

Streaks

Many areas of Mars change their shape and/or coloration. For many years, astronomers observing regular changes on Mars when the seasons changed, thought that what they saw was evidence of vegetation growing. After close-up inspection with a number of spacecraft, other causes were discovered. Basically, the changes are caused by the effects of the wind blowing dust around. Sometimes, fine bright dust settles on the dark basalt rock making the surface appear lighter, at other times the light-toned dust will be blown away; thus making the surface darken—just as if vegetation were growing. Mars has frequent regional or global dust storms that coat the surface with fine bright dust. In the THEMIS image below, white streaks are seen downwind of craters. The streaks are not too bright; they appear bright because of contrast with the dark volcanic rock basalt which makes up the surface.

• 

  Bright Streaks in Syrtis Major caused by the wind, as seen by THEMIS.

• 

  Light-toned streak on the lee ward side of a crater, as seen by HiRISE under HiWish program

Inverted relief

Some places on Mars show inverted relief. In these locations, a stream bed may be a raised feature, instead of a valley. The inverted former stream channels may be caused by the deposition of large rocks or due to cementation. In either case erosion would erode the surrounding land and leave the old channel as a raised ridge because the ridge would be more resistant to erosion. Images below, taken with HiRISE show sinuous ridges that are old channels that have become inverted.

• 

  Inverted Stream Channels in Antoniadi Crater, as seen by HiRISE

• 

  Inverted Channel with many branches in Syrtis Major quadrangle

• 

  Possible inverted streams, as seen by HiRISE under HiWish program

Layers

Many places on Mars show rocks arranged in layers. Rock can form layers in a variety of ways. Volcanoes, wind, or water can produce layers. A detailed discussion of layering with many Martian examples can be found in Sedimentary Geology of Mars.

• 

  Wide view of rock layers, as seen by HiRISE under HiWish program

• 

  Tilted rock layers, as seen by HiRISE under HiWish program

• 

  Rock layers in Flammarion (Martian crater), as seen by HiRISE under HiWish program

• 

  Close view of layers, as seen by HiRISE under HiWish program Part of the image is in color. HiRISE images only show a middle part in color.

• 

  Wide view of layers, as seen by HiRISE under HiWish program

• 

  Layers around crater, as seen by HiRISE under HiWish program

• 

  Layers, as seen by HiRISE under HiWish program

• 

  Layers, as seen by HiRISE under HiWish program

• 

  Wide view of layers, as seen by HiRISE under HiWish program

• 

  Close view of layers, as seen by HiRISE under HiWish program

Channels

There is enormous evidence that water once flowed in river valleys on Mars. Images of curved channels have been seen in images from Mars spacecraft dating back to the early seventies with the Mariner 9 orbiter. Indeed, a study published in June 2017, calculated that the volume of water needed to carve all the channels on Mars was even larger than the proposed ocean that the planet may have had. Water was probably recycled many times from the ocean to rainfall around Mars.

• 

  Channel, as seen by HiRISE under HiWish program

• 

  Peridier Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter).

• 

  Channels along wall of Peridier Crater, as seen by CTXcamera (on Mars Reconnaissance Orbiter). Note: this is an enlargement of the previous image of Peridier Crater.

• 

  Channel, as seen by HiRISE under HiWish program

• 

  Channel, as seen by HiRISE under HiWish program

• 

  Channels, as seen by HiRISE under HiWish program

• 

  Valleys, as seen by HiRISE under HiWish program

• 

  Channels and ridges, as seen by HiRISE under HiWish program

• 

  Close view of ridges, as seen by HiRISE under HiWish program

Hollows

• 

  Hollows that formed in crater floor deposit, as seen by HiRISE under HiWish program Hollows probably formed as ice left the ground.

• 

  Close, color view of hollows on crater floor, as seen by HiRISE under HiWish program many cracks are visible. Ground rich in ice often forms cracks. When a crack appears, there is enhanced loss of ice from the ground. Eventually, a small crack may evolve into a hollow.

• 

  Eroding mesa in Syrtis Major. It would be rough to walk across this feature. Image was taken with Mars Global Surveyor, under the MOC Public Targeting Program.

• 

  Close-up of crater deposit that shows both impact craters and pit craters caused by collapse. Image taken by HiRISE under the HiWish program.

• 

  Crater with eroding floor deposit, as seen by HiRISE under HiWish program

• 

  Close view of pits forming in crater floor deposit. The box shows the size of a football field for scale.