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The Geology of Jezero Crater, Observations & Findings
nprev
post Feb 24 2021, 01:41 AM
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This thread is for those rockhounds among us to discuss the new terrain we'll see as Perseverance scoots around her new home. Let's get dirty & technical! laugh.gif


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HSchirmer
post Feb 24 2021, 01:51 AM
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QUOTE (nprev @ Feb 24 2021, 02:41 AM) *
This thread is for those rockhounds among us to discuss the new terrain we'll see as Perseverance scoots around her new home. Let's get dirty & technical! laugh.gif

Rule #1
The physical processes of weathering can cause rocks to move in ways you don't expect.
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dougkeenan
post Feb 24 2021, 02:13 AM
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Is it indeed "Geology" and not "Aresology" or some-such?
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HSchirmer
post Feb 24 2021, 02:31 AM
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QUOTE (dougkeenan @ Feb 24 2021, 03:13 AM) *
Is it indeed "Geology" and not "Aresology" or some-such?

testing the mod's patience I've gone with the rule that "*-ology" is research done by an on site "*-ologist".

By my measure, we have lots of "geologists", only 12 Apollo "seleneologists", and we're eagerly waiting for "aresologists".
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Phil Stooke
post Feb 24 2021, 02:52 AM
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This has been a discussion since the 1960s. I remember a very good piece on it in a paper about Mars by Luciano B. Ronca in about 1965.

This is how it works. 'geo-' means land, not planet Earth, though it can be used for the planet by extension from the main idea. Geography is the study and depiction of different lands (around the Mediterranean, originally, for the Greeks). Geology is the study of what the land is made of. Geomorphology is the study of the shape of the land and how it is shaped. Geodesy of course is extending the concept to the planet, but at its root 'geo-' means land.

And another point if that's not enough. If geology is the study of the Earth, we can have Selenology for the Moon and Areology for Mars, but how far do you want to take it? A different word for the study of every planet, moon and asteroid? Will Callistologists meet Ceresologists and Enceladologists at LPSC? Ultimately that is a ludicrous situation for people who are all doing the same kind of work, so a common term is desirable, and the one we use is 'geology'.

Phil


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Don1
post Feb 24 2021, 03:11 AM
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Some resources:

A recent USGS geological map of the Jezero Crater region (big pdf)

LPSC 2021 abstract: Mineralology of Jezero

LPSC 2021 abstract: Jezero floor unit

LPSC 2021 abstract: Carbonates in Jezero
(Final link now corrected)
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HSchirmer
post Feb 24 2021, 03:32 AM
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QUOTE (Phil Stooke @ Feb 24 2021, 03:52 AM) *
And another point if that's not enough. If geology is the study of the Earth, we can have Selenology for the Moon and Areology for Mars, but how far do you want to take it? A different word for the study of every planet, moon and asteroid? Will Callistologists meet Ceresologists and Enceladologists at LPSC? Ultimately that is a ludicrous situation for people who are all doing the same kind of work, so a common term is desirable, and the one we use is 'geology'.
Phil

Well said.
However, I DO look forward to a time when we have "A different word for the study of every planet, moon and asteroid."
In much the same way we say "Doctor" in general but then differentiate between phlebotomist, proctologist and optometrists.

Ideally, we have "*-ologists" who work on site. However, if we get to the wonderful stage where people can devoting their careers to the research of an individual world, with unique combinations of composition and what components are solid, liquid or gas (e.g. water on Mercury, Earth, Pluto) then we should call the people who "learn that world" by the name of that place they know like a second home.

If we can accept about 75 medical "specialties", we can accept world-specific "specialties."
QUOTE
PHYSICIAN CODING
• Adult Intensivist
• Allergy
• Anesthesia
• Bariatric Medicine/Surgery
• Burn/Trauma
• Cardiac Catheterization
• Cardiology
• Cardiovascular Surgery
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• Dermatology
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• Emergency Medicine
• Endocrinology
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• Hospitalist
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• Neurology
• Neurosurgery
• Nuclear Medicine
• Obstetrics & Gynecology
• Occupational Medicine
• Ophthalmology
• Oral Surgery
• Orthopedics
• Otolaryngology / Head & Neck Surgery
• Pain Management
• Palliative Care
• Pain Management
• Palliative Care
• Pathology: Surgical & Anatomic
• Pediatric Intensivist
• Pediatrics
• Pediatric Surgery
• Physical Medicine

• Plastic & Reconstructive Surgery
• Podiatric Surgery
• Psychiatry
• Pulmonary Medicine
• Radiation Oncology
• Radiology
• Rheumatology
• Surgical Oncology
• Thoracic Surgery
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• Urology
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• Wound Care
ASC SPECIALTIES
• Bariatric Surgery
• ENT
• General Surgery
• Gastroenterology
• Neurosurgery
• Obstetrics & Gynecology
• Ophthalmology
• Oral/Dental Surgery
• Orthopedic Surgery
• Pain Management
• Pediatric Surgery
• Plastic Surgery
• Podiatric Surgery
• Urology
• Vascular Surgery
HOSPITAL CODING
• Ambulatory Clinics
• Cardiac Catheterization Labs
• Diagnostic Radiology
• Emergency Department
• GI Endoscopy Labs
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HCC AUDITS
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stevesliva
post Feb 24 2021, 04:32 AM
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Because this forum is now old enough to drive, there is of course a thread for this topic of semantics:
http://www.unmannedspaceflight.com/index.php?showtopic=6615
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Pando
post Feb 24 2021, 04:41 AM
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QUOTE (HSchirmer @ Feb 23 2021, 07:32 PM) *
However, I DO look forward to a time when we have "A different word for the study of every planet, moon and asteroid."
Ideally, we have "*-ologists" who work on site. However, if we get to the wonderful stage where people can devoting their careers to the research of an individual world,


How would you then distinguish a volcanologist from a geologist on Mars, just to name one? Or how about meteorologist? They are all *-ologists.

I think just adding the name of the rock in front of the field of study is sufficient: "Mars geologist". Simple, effective, everyone knows the subject. No need to invent new words. Absent the name and it's implicit that it's Earth.
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nprev
post Feb 24 2021, 07:16 AM
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....aaaand, were done with the pedantry.

Let's talk about rocks. On Mars.


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serpens
post Feb 24 2021, 07:34 AM
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QUOTE (nprev @ Feb 24 2021, 07:16 AM) *
....aaaand, were done with the pedantry.

Let's talk about rocks. On Mars.


Thank you nprev!
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Eutectic
post Feb 24 2021, 09:48 AM
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QUOTE (Don1 @ Feb 23 2021, 09:11 PM) *



The link above to the abstract on carbonates in Jezero is an inadvertent duplicate of link to the the Jezero floor abstract. This is the correct link to the abstract on carbonates in Jezero: LPSC 2021 abstract: Carbonates in Jezero
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JRehling
post Feb 24 2021, 05:00 PM
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For now, we have a mission that'll be exploring that floor unit, which isn't the reason why Perseverance came to Jezero but it's a matter of fate that we'll have the best set of instruments ever to reach another planet rolling over and exploring that. We're going to read the history of Mars in reverse, which is quite different from Curiosity, which hit oldest units in Gale early, then rolled upwards and forwards in time.

I like the Hundal, et al paper that compares the Jezero layering with that of Isidis. I wonder about Jezero vs. Gusev. For Spirit, the floor unit was a showstopping barrier that prevented the rover from making any direct contact with the history of the river+lake environment. The Columbia Hills ended up being a bit of a consolation prize, and a surprise, where water vented upwards after the lake was gone. I don't know if Perseverance will find anything similar in Jezero, and I doubt it, since we can see the 2km to the delta and it looks flat, but maybe there'll be some equivalent. In the short term, I think we're going to learn about the nature of a sort of "impact gardening" that took place on a massive scale on Mars, flinging rocks and boulders long distance, mantling the ancient landscapes. As such, I can't see any reason why it would be very different here than in Gusev, but maybe the individual regional impacts will make for a different story.

I'm struck by how many rocks peeking up through the sand and dust seem to hold to one general contour just at or very slightly above the surface. Does this mean that erosion has worn a once-deeper layer down a bit, and if so, what was so effective in planing these rocks down? Chemical or aeolian erosion?
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HSchirmer
post Feb 24 2021, 08:06 PM
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QUOTE (JRehling @ Feb 24 2021, 05:00 PM) *
I'm struck by how many rocks peeking up through the sand and dust seem to hold to one general contour just at or very slightly above the surface. Does this mean that erosion has worn a once-deeper layer down a bit, and if so, what was so effective in planing these rocks down? Chemical or aeolian erosion?

I'd guess a basin wide layer of hard sediment, could also be "natural cement" or caliche.

I'm in the "Newark Basin" area that stretches from Lancaster Pa to New York City. Material laid down in anaerobic deep lakes during wet conditions is very hard stone, while material laid down in shallow oxidizing water on the dry lake is very soft stone. There are several very hard layers of rock laid down in paleo lake Newark which you can easily trace for over 70 miles. You'd expect a similar effect in Jezro for large areas of horizontal sediment- material laid down in wet times should be harder and form resistant "terraces".

Interesting, in Newark basin, they're tracing climate variations / Milankovich cycles by reading oxidation states of the rock. They're actually THEN using that data to recreate what Earth's orbit, precessions and tilts were. This circumvents the chaos / "the butterfly effect" which generally precluded accurate simulations of Earth's orbital characteristics backward more that about 60 million years ago, by actually "reading" what the values were from 223 million to 199 million years ago. It should be VERY interesting to see if Curiosity and Perseverance can achieve something similar on Mars!

QUOTE
Mapping Solar System chaos with the Geological Orrery
https://www.pnas.org/content/pnas/116/22/10664.full.pdf
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JRehling
post Feb 24 2021, 09:55 PM
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What we see now in the near distance is not thought to be sedimentary layers formed in the lake. It is material emplaced as ejecta from impacts and aeolian deposits. Perseverance is not resting on the bottom of the lake. It is resting on material that is covering the bottom of the lake.

https://pubs.er.usgs.gov/publication/sim3464

"Volcanic ash or eolian airfall deposit that drapes underlying topography."
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