Rover "Perseverance" on Mars
The new search of the "missing link" of life

Norbert Brügge, Germany
Dipl.-Geol.

Upload: February 2021


Unique on Mars: Spread of olivine/Mg-carbonate

USGS
"Jezero is a crater basin at the western edge of the Isidis Basin. It is characterized by fluvial/deltaic sediment deposition into a paleolake. A western and northern delta have been observed from orbit.The western delta is dominated by Fe/Mg smectites and exhibits well defined sedimentary layering, including bottomset deposits. The northern delta is dominated by Mg-carbonates and associated olivine, but is less well preserved than the western delta. The basin fill is also dominated by olivine and Mg-carbonates, though it is unclear whether this represents primary detrital deposition, re-working of prelacustrine sediments, or exposure of the regional Mg-carbonate/olivine unit observed more broadly in Nili Fossae (also of unknown origin). A volcanic unit (~3.5 Ga) overlies most of the basin fill, embays the eroded delta scarps, and surrounds deltaic remnants which have been separated from the main delta bodies by aeolian deflation at some time prior to volcanism."

 


Newest insights:

 

The first pictures of the rover's landing site (below) unfortunately led to misleading assumptions. In the meantime we have a lot of new knowledge, which has been persistently interpreted in this direction due to the paradigm of a former lake in the Jezero crater. As a geologist, I have to come to completely different conclusions, which are documented on my pages and can be summarized as follows:

Jezero Crater is likely a collapsed dome of an ultramafic magma that solidified long ago. The current state of the surface of the crater was caused by violent tectonic movements. The destructive activity can be recognized by the outcropping bedrock.

A former lake or any activities of water have not yet been proven. The delta is interpreted as the remnant of the moraine from a dry ice glacier. The original extent of the moraine has not yet been clarified. An wide extension in the crater would mean that the tectonic movements in the bedrock are of more recent. The boulders left behind by the already eroded moraine have mixed with the broken bedrock.

 

1.) My newest analysis of the groundmass and texture in the consistently magmatic bouldes has resulted in surprising results.
       
(Note: The pumice is in truth a disintegrated ultramafic rock, enriched with holes of decomposed olivine aggregates).

  

2.) Now, I suspect that the Jezero Crater is a landscape of a wind-eroded glacier moraine, and the deposits of the delta are remnants of the former larger moraine.

 

3.) Rover "Perseverance" on the way  to interesting tectonic structures in the Jezero crater

 

4.) The riddle of the "Paving Stones" in the Jezero Crater -- Older moraine or bedrock ?

 

5.) What are the stratified deposits in the linear elevation in the Jezero Crater ?

 

6.) Rover "Perseverance"  in the enigmatic landscape "South Seitah"

 

 

 

The first photos after landing on the planet on 02/18/2021 show a plain on which there are debris of all sizes that are very similar to volcanic pumice stone. If it is actually pumice deposits, that's not good news. These pumice deposits could have a significant thickness as the photos suggest. Aeolian sands on the floor seem to be only a thin blanket.
The hoped-for sediments of a lake bottom would be difficult to find because were blown out. Outcrops of (basaltic) pumice appear to be very common in the crater, as seen in the video during the rover's descent and in the landing zone. One stone is particularly interesting because it has a peeled  crust that could document smectite formation. It could explain the previously measured slightly clayey portion in the young aeolian sands.
It will be interesting whether such pumice deposits in the Jezero crater can also be found in the deposits of the delta, and in what context and conditions. According to the measurements, layered smectites are also expected. Smectite are created by the weathering of basaltic material on the earth (with atmospheric conditions and water). Smectites are a mineral mixture of different layered silicates (phyllosilicates) and belong to the clay minerals.
Measurements from orbit have found on the Nili Fossae region Mg-carbonates with olivine on the surface (high terrain). Tectonic faults on the Nili Fossae terrain are obious. Pumice material in the deposits of the delta can come from higher elevations outside the crater.
At the moment, many scenarios are possible for the chronological sequence of the filling in the Jezero crater. The great hope for trace of life on Mars is in the delta. Some lander have found some prerequisites for possible life on Mars, but the ultimate proof is lacking.

 

    

             

First details from the surface of landing place

  

Earthly pumice