Rover "Perseverance": First significant petrological results

explored along the traverse between the landing place and "South Seitah"


Norbert Brügge, Germany
Dipl.-Geol.

Update:
15.03.2022
 

My analysis is based on a number of insights into the groundmass and texture of the rocks, captured by the rover's cameras.

The photos published so far by NASA allow the conclusion that the massive boulders and the layered tephra-loke deposits are all of igneous or volcanic origin. The masive boulders are chaotic deposited on tectonically uplifted elevations. The layered deposits are tephra-like and mostly in the state of disintegration.

A main component of the matrix in all type of rocks is hornblende (amphibole). This explains the many reflections that emanate from the crystal surfaces when light is incident. Another component are obviously bright-colored high calcium-pyroxes (HCP). Strong concentrations of magnesium and calcium are detected in a single spectrogram published so far.

It has been found that in holes residues of decomposed olivine can be found in various distributions in boulders, but often there are only empty holes. The stones at the rover's landing place which I originally referred as deposits of pumice are in reality remnants of rocks in final stage of disintegration. In retrospect, the "holes" in the supposedly blistered structure are empty nests of decomposed olivine. Such holes in high concentration leads to the conclusion that olivine is also part of the groundmass.

 If the rocks are actually basalt, then is it a hornblende and olivine rich basalt. But it is more likely that it is an ultramafic magma (kimberlite, peridotite?),  because the almost complete lack of quartz is noticeable.
 

 

First datasets from the Visible and InfraRed (VISIR) sensor and Raman spectrometer instruments of the SuperCam were now published. VISIR uses reflected sunlight to examine the mineral compositions of rocks and soils. The Raman spectrometer uses a green laser beam for its observations. The result: Clear peaks of Mg and Ca were found in the spectrogram from an outcropd stone in the ground (Sol 12). It could be an indication of Ca- rich pyroxene.
 

Zoom with the SuperCam on a stone in the ground that is identified
as basaltic (?). Clear peaks of Mg and Ca were found in a spectrogram.


Source: NASA/JPL-Caltech/LANL/CNES/CNRS

    


S
eptember 10: After a long waiting now from NASA (JPL-Caltech) new datasets recorded with the instruments of the SuperCam from a abraded stone at "Artuby ridge".
 

The guesswork continues. According to the investigations, some of the bright inclusions in the "basalt" are supposed to be sulfate and phosphate "salts". Contrary to this assumption of NASA scientists, it is inconceivable, that secondary salts can form in the dense matrix of the crystalline rock if they are laying in the water of a lake. In addition, it has not been proven that they are salts. Only the elements sulfur and phosphor were detected, which is an indication of volcanism. Note the high amount of calcium and aluminum in the rock.

 

Composition of groundmass and phenocrysts

Hornblende and High Calcium Pyroxe in the groundmass

                       
First published photos by the SherlocCams from the surface of unspecified stones shows some details from the groundmass, included dark areas therein.
 The probability that this dark areas are
hornblende is high. The bright parts in the matrix could be Ca-pyroxene and olivine


       
               
Reflexions on hornblende crystals when exposed to light

Olivine in the groundmass and as phenocrysts

An exposed rock (Sol-37) is described as puzzling. It has a smooth surface (almost vitreous) on which numerous rounded depressions can be seen. Upon closer inspection of the photo, I notice that some of the depressions still have a brownish (not secondary) filling. Obviously these are the typical remnants of decomposed olivine aggregates, which are already missing in most of the holes.

    

Sol-37 (Lava bomb !?)

Several holes from phenocrysts

Decomposed olivine






Decomposed olivine

High concentration of holes from decomposed olivine in the groundmass of debris

 

First great details from sol-160 (crumbly "Paving stones")


            

It are to see hornblende (dark brown), decomposed olivine (brownish) and probably Ca-pyroxene (bright) . The dark holes symbolize broken-out hornblende

The white parts are still a mystery.
 If it is actually high calcium-pyroxene, it would
be a surprise.
High calcium-pyroxe found e.g. in S-type asteroids:

The HCP mystery


           


Second details from sol-183 (abraded solid boulder "of Artuby Ridge" )
 

The same composition:
Hornblende, olivine and the conspicuous bright parts, but all less weathered.

 






Third details from sol-206 (abraded solid boulder of "South Seitah")
 

The same composition as before:

Small white grains that are scattered everywhere and do not seem to belong to the matrix. They are still clearly visible in blurred photos of the abraded surface. The origin of these grains remains a mystery for the time being.  Perhaps it are splinters of crystals that were created during the abrasion.



 



 
Fourth details from the abraded spot sol-253 ("South Seitah")

 

Details from abraded spot sol 292 ("South Seitah")

 

Significantly are the HCP's

Details from abraded spot sol-346 ("Artuby Ridge")

              

Spectacular details from sol-367 (abraded solid boulder in the "Landing area"
Clearly visible for the first time: Bright elongated rectangular pyroxene crystals !


Drilling cores


Sol-190: First drill core
 "Artuby Ridge"


Sol-196: Second drill core
 "Artuby Ridge"


Sol-262 Third drill core
 "South Seitah"


Sol-271: Fourth drill core
"South Seitah"


Sol-295: Fifth drill core
Nearby the depression


Sol-298: Sixth drill core (?)
Nearby the depression


Sol-303: Seventh drill core
Nearby the depression


Sol-337: Eighth drill core
Nearby the depression


Sol-371: Ninth drill core
Landing area