The Geology of Jezero Crater, Observations & Findings |
The Geology of Jezero Crater, Observations & Findings |
Feb 24 2021, 01:41 AM
Post
#1
|
|
Merciless Robot Group: Admin Posts: 8784 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
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!
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
|
|
|
Feb 25 2021, 02:16 AM
Post
#2
|
|
Senior Member Group: Members Posts: 1045 Joined: 17-February 09 Member No.: 4605 |
The consensus seems to be that the crater floor was flooded by lava some 300 million years after the lake dried up which embayed sedimentary/deltaic deposits. There has been some erosion of the delta material since then so a proportion of the aeolian deposit that JRehling noted drapes underlying topography could well be of deltaic origin. The area west of the Isidis basin, including Jezero crater reveals olivine‐carbonate lithology; in Jezero crater concentrated at the Western rim with some deposits in the delta. Given the dearth of carbonates elsewhere despite what seems to have been plentiful water in a CO2 atmosphere it will be really interesting if Perseverance can determine why it was preserved in this particular area.
JRehling...." 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." Most possible, but using that term here is akin to lighting a blue touch paper. |
|
|
Feb 25 2021, 04:29 PM
Post
#3
|
|
Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
One detail in the Sol 3 panorama that's especially informative is the northernmost (furthest right) delta face. I cropped it and moreover turned up contrast in the red channel to bring out a subtle color contrast.
The first thing I notice is that here, as elsewhere, the delta's eastern slopes are mainly smooth, with the expected sedimentary layers covered. The layers are visible, though, more than in other places in the delta. The route plans we've seen would never bring Perseverance close to this area, instead heading well south, where outcroppings are – from the landing site – hard to see. The mission team may gamble that with any route that ascends the delta, the layers will nonetheless make themselves apparent closer up. I'm also struck by the fact that the layers are not horizontal. There has been tilting since the lake dried up. My manipulation of the color contrast was intended to explore the smooth mantling of the delta slope, and I think the patchy variation speaks to two types of material. The darker, greener material appears to be talus derived from the delta itself, while the brighter, redder material is the global coating of dust, which is universally present in this photo in the near distance, the far distance, and atop the delta. What's not clear is how much the contrast seen in the patchiness has to do with changes in texture versus abundance of one material versus the other, but that may be one and the same: Where larger pieces of talus exist, we see the rough sides of them, and elsewhere, the global dust unit covers it up. As Perseverance approaches the delta, we will begin to see more pieces of the delta that moved downslope. However, the area just east of and below the delta will likely be a jumble of pieces from different layers, and while each of those rocks will be individually interesting, the jumbling will deny us information about which piece came from which layer, and may be something the mission planners choose to move past fairly quickly, opting to get sooner up and to the layers themselves, where each unit studied will come with the context provided of which unit in the delta is that unit's home. |
|
|
Feb 25 2021, 06:15 PM
Post
#4
|
|
Member Group: Members Posts: 684 Joined: 24-July 15 Member No.: 7619 |
I'm also struck by the fact that the layers are not horizontal. There has been tilting since the lake dried up. Most river delta deposits slope downward when they hit a much larger lake or ocean. Similarly, the first sediment to drop out of the current is the heaviest- the largest and most incompressible gravel and grit. The further from the delta mouth you get, the finer, and more "hydrated" the sediment becomes. When the delta is eventually compressed or dries out, there's more "shrinkage" in the more distant sediment beds. |
|
|
Lo-Fi Version | Time is now: 6th June 2024 - 08:14 AM |
RULES AND GUIDELINES Please read the Forum Rules and Guidelines before posting. IMAGE COPYRIGHT |
OPINIONS AND MODERATION Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators. |
SUPPORT THE FORUM Unmannedspaceflight.com is funded by the Planetary Society. Please consider supporting our work and many other projects by donating to the Society or becoming a member. |