Fwd: Curiosity rover finds evidence of Mars’ primitive continental crust

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Date: July 15, 2015 at 10:29:42 AM CDT
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Subject: FW: Curiosity rover finds evidence of Mars' primitive continental crust

 

14-Jul-2015

Curiosity rover finds evidence of Mars' primitive continental crust

DOE/Los Alamos National Laboratory

 

The ChemCam laser instrument on NASA's Curiosity rover has turned its beam onto some unusually light-colored rocks on Mars, and the results are surprisingly similar to Earth's granitic continental crust rocks. This is the first discovery of a potential 'continental crust' on Mars.

Nature Geoscience

 

 

Curiosity rover finds evidence of Mars' primitive continental crust

This is the first discovery of a potential "continental crust" on Mars.

July 13, 2015

 

Igneous clast named Harrison embedded in a conglomerate rock in Gale crater, Mars, shows elongated light-toned feldspar crystals. The mosaic merges an image from Mastcam with higher-resolution images from ChemCam's Remote Micro-Imager. Credit: NASA/JPL-Caltech/LANL/IRAP/U. Nantes/IAS/MSSS.

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"Along the rover's path we have seen some beautiful rocks with large, bright crystals, quite unexpected on Mars" said Roger Wiens

LOS ALAMOS, N.M., July 13, 2015—The ChemCam laser instrument on NASA's Curiosity rover has turned its beam onto some unusually light-colored rocks on Mars, and the results are surprisingly similar to Earth's granitic continental crust rocks. This is the first discovery of a potential "continental crust" on Mars.

"Along the rover's path we have seen some beautiful rocks with large, bright crystals, quite unexpected on Mars" said Roger Wiens of Los Alamos National Laboratory, lead scientist on the ChemCam instrument. "As a general rule, light-colored crystals are lower density, and these are abundant in igneous rocks that make up the Earth's continents."

Mars has been viewed as an almost entirely basaltic planet, with igneous rocks that are dark and relatively dense, similar to those forming the Earth's oceanic crust, Wiens noted. However, Gale crater, where the Curiosity rover landed, contains fragments of very ancient igneous rocks (around 4 billion years old) that are distinctly light in color, which were analyzed by the ChemCam instrument.

French and U.S. scientists observed images and chemical results of 22 of these rock fragments. They determined that these pale rocks are rich in feldspar, possibly with some quartz, and they are unexpectedly similar to Earth's granitic continental crust. According to the paper's first author, Violaine Sautter, these primitive Martian crustal components bear a strong resemblance to a terrestrial rock type known to geologists as TTG (Tonalite-Trondhjemite-Granodiorite), rocks that predominated in the terrestrial continental crust in the Archean era (more than 2.5 billion years ago).

The results were published this week in Nature Geoscience, "In situ evidence for continental crust on early Mars."

Gale crater, excavated about 3.6 billion years ago into rocks of greater age, provided a window into the Red Planet's primitive crust. The crater walls provided a natural geological cut-away view 1-2 miles down into the crust. Access to some of these rocks, strewn along the rover's path, provided critical information that could not be observed by other means, such as by orbiting satellites.

ChemCam, a laser-induced breakdown spectrometer (LIBS), provides chemical analyses at a sub-millimeter scale; detailed images were provided by its Remote Micro Imager.

 

 

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Mars may have once had a continental crust

Scientists say the Red Planet's higher elevation southern hemisphere more and more recalls the continental crust of an early Earth.

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LOS ALAMOS, N.M., July 14 (UPI) -- A team of researchers, including scientists in France and the United States, say new data beamed by back Mars rover Curiosity suggests the Red Planet once possessed a continental crust.

In a new paper, published this week in the journal Nature Geoscience, scientists describe 20 rocks recently analyzed by Curiosity. The rocks, which researchers expected to reveal large samples of basalt, are mostly rich in silica, suggesting a different geological history than ones previously ascribed to Mars -- one more like Earth's.

The newly studied rocks, sourced from inside Gale Crater, feature varying concentrations of alkaline compositions -- some with fine-grained and porphyritic textures, others with larger fragments of quartz diorite and granodiorite. The rocks are 3.6 billion years old.

"Along the rover's path we have seen some beautiful rocks with large, bright crystals, quite unexpected on Mars" Roger Wiens, a researcher at the Los Alamos National Laboratory, said in a press release. Wiens is the lead scientist on the team dedicated to Curiosity's ChemCam instrument.

"As a general rule, light-colored crystals are lower density, and these are abundant in igneous rocks that make up the Earth's continents," Wiens added.

Most scientists believed Mars to be without magmatic activity, which is why researchers expected to find large expanses of basalt, as is found on Earth's ocean floors. But the silica-rich rocks suggests a more dynamic geologic and magmatic history that includes a crust and even plate tectonics.

"We conclude that silica-rich magmatic rocks may constitute a significant fraction of ancient Martian crust and may be analogous to the earliest continental crust on Earth," scientists wrote in their paper.

Scientists say they haven't found direct evidence of shifting plates on Mars, but that the Red Planet's higher elevation southern hemisphere more and more recalls the continental crust of an early Earth.

"There's a bit of evidence for the precursor to tectonics, because there are magnetic domains that were found in parts of the southern hemisphere on the surface of Mars," Wiens told Australia's ABC Science. "The planet doesn't have a magnetic field now, but it suggests that it did have one in the past."             

 

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