Enigmatic rock layer in Mars’ Gale crater awaits measurements by the Curiosity rover

Enigmatic Rock Layer in Mars’ Gale Crater Awaits Measurements by the Curiosity Rover
The marker horizon (yellow arrow) is darker, smoother, and tougher than the sulfate-bearing rocks surrounding it. HiRISE picture merged to a Digital Terrain Model (DTM) perspective view exhibiting roughly 1 kilometer of topography throughout Mount Sharp. Image options 3 times vertical exaggeration. Credit: NASA/University of Arizona.

Scientists have been finding out the sediments inside Mars’ Gale crater for a few years utilizing orbital information units, however due to the Curiosity rover driving throughout these deposits we are able to additionally acquire up-close observations and detailed measurements of the rocks, much like area work finished by geologists on Earth.

A brand new paper led by Planetary Science Institute Senior Scientist Catherine Weitz takes a brand new have a look at an enigmatic function seen in orbital information of Mount Sharp, a 5.5-kilometer-high mound in Gale crater: a darker, stronger, flatter, easy rock layer or weathering horizon that stands out from the sulfate-bearing rocks wherein it happens. Because the darker horizon could be distinguished in orbital information from the encircling brighter sulfate-bearing rocks, it may be traced throughout a lot of Mount Sharp and it marks a selected time interval inside the crater, which is why it’s known as a “marker horizon.”

The marker horizon seems to be both a number of rock layers or a zone of weathering with a unique look from the sulfate-bearing rocks wherein it happens. Marker horizons are discovered on Earth too, with volcanic ash being a typical marker horizon as a result of it might probably seem completely different from the encircling sediments and it may be traced throughout variable landscapes. Geologists can use marker horizons as time-stratigraphic options, which means that the marker horizon fashioned throughout a single occasion or a selected time interval, so by tracing the marker horizon throughout giant areas we are able to all the time know what rocks had been deposited both earlier than or after it in stratigraphy.

“Some event occurred within Gale crater during the deposition of sulfate-bearing sediments that resulted in a different kind of rock unit. The marker horizon is distinct in appearance from the sulfate-bearing rocks above and below it, indicating an environmental change occurred for a brief time, such as a drier period, or perhaps a regional event like an explosive eruption from a nearby volcano that deposited ash across a large area which included Gale crater,” Weitz stated.

Enigmatic Rock Layer in Mars’ Gale Crater Awaits Measurements by the Curiosity Rover
Context Camera (CTX) mosaic of Mount Sharp (middle) in Gale Crater with exposures of the marker horizon proven in purple. Surrounding the CTX mosaic are HiRISE enhanced colour picture subsets of the marker horizon (m) taken all through Mount Sharp, with blue arrows exhibiting approximate areas the place every subset happens in Mount Sharp. The yellow scale bar in every subset picture is 50 meters. A distinct stretch has been utilized to every subset picture so the colours aren’t comparable between photos. Credit: NASA/MSSS/University of Arizona

“We used orbital data collected from the High Resolution Imaging Science Experiment (HiRISE), Context Camera (CTX), and Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instruments on the Mars Reconnaissance Orbiter (MRO) to map out where this marker horizon occurs throughout Mount Sharp and study its appearance and composition. We found that the marker horizon varies in its elevation by 1.6 kilometers across Mount Sharp, that it dips between 1 and 5 degrees away from the center of Gale crater, and it has a mafic composition similar to other basaltic materials including aeolian sands,” stated Weitz, lead creator of “Orbital Observations of a Marker Horizon at Gale Crater” that seems within the Journal of Geophysical Research: Planets.

“We explored several different formation mechanisms for the marker horizon. It could be composed of the same materials as the sulfate-bearing rocks above and below it, but became harder and more resistant to erosion either during formation or subsequently by water carrying minerals to cement it. The marker horizon could also be a sandstone or lag deposit that formed when it was drier in Gale crater relative to when the sulfates formed. Another possibility is that the horizon contains volcanic ash that was deposited when a nearby volcano explosively erupted ash into the Martian atmosphere that later became hardened. All of these potential origins require the presence of at least some water to cause cementation that hardened the horizon,” Weitz stated. “Our orbital observations currently favor an indurated sulfate or volcanic ash origin, but we will have to wait until the Curiosity rover reaches the horizon in the coming months before determining which origin is most plausible.”

Closer observations will enable scientists to higher perceive why the marker horizon seems so completely different from the close by sulfate outcrops. “We are fortunate that the Curiosity rover is planning to reach the marker horizon in the coming months as it traverses up Mount Sharp through the sulfate-bearing rocks, providing valuable ground measurements that can be used to evaluate the different origin scenarios. Currently the Curiosity rover is approximately 700 meters away from the marker horizon, crossing from the Greenheugh pediment to the clay-sulfate transition region. Exploration of the marker horizon by Curiosity will enable detailed analyses of sedimentological properties, including grain sizes, any unconformities, internal structures, textures, and chemical composition,” stated Weitz, a Co-Investigator on the HiRISE digicam and a science staff member on the Curiosity rover.

“These in situ observations and measurements that Curiosity can make are critical to distinguish between the multiple proposed formation scenarios. Of course, Mars can throw us a curveball and it may turn out that the origin of the marker horizon could be the result of something we did not anticipate from the orbital data sets,” Weitz stated. “Only when Curiosity begins its own investigation of the marker horizon will the data be sufficient to hopefully unravel the origin of this enigmatic marker horizon and help us further understand the intriguing sedimentary history of Gale crater.”

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More info:
Catherine M. Weitz et al, Orbital Observations of a Marker Horizon at Gale Crater, Journal of Geophysical Research: Planets (2022). DOI: 10.1029/2022JE007211

Enigmatic rock layer in Mars’ Gale crater awaits measurements by the Curiosity rover (2022, April 28)
retrieved 28 April 2022

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