Seasonal deposition

Time for a half-baked hypothesis. Please feel free to shoot this down:

Could some of the layers that we see in Endurance Crater be explained in terms of an (past) annual cycle of aeolian sedimentation?

In other words seasonal aeolian deposition of loose deposits during the spring storms, then finer 'loess' like materials as winds drop, followed by in-situ consolidation (permacrust) by upward migrating brines during the summer, surface oxidation by UV radiation for the rest of the year, and so on?

The graded bedding would be consistent with coarser material during heavy wind, followed by finer material during calmer periods.

The finer material with higher surface area would also tend to absorb more brine salts, including iron, and would result in annually deposited layers with a higher iron content.

Now if we have a climate change induced by a catastrophic event, this could result in this material being soaked (pickled)in groundwater/brine for longer periods, giving rise to diagenitic processes/post depositional transformation.

Hi Aldebaran,

Sounds sensible to me and it is in part consistant with some of my previous posts.

Mars rains from below and likely creates pockets of brine liquid in the subsurface it "rains".
In addition, the global Mars dust storms seem to be a periodic event. So, perhaps, the layers are cemented after seasonal/periodic dust storms (while Mars is raining from below).

Another possibility is that liquid brine surface bodies were present during the periodic dust storms (and/or possible tides)and the layers represent material that settled out in the brine surface bodies during periodic dust storms.

rpage,

What you say about ponding makes sense, and we would probably get at least seasonally frozen ponds depending on the atmospheric pressure. What would the presence of frozen ponds do to the bedding on a local basis? I'd suggest very little near the edges, but away from the edges, there would be an interruption to saltation type drift. Finer material would be deposited preferentially over the water or ice surface. The ice might melt on a seasonal basis, giving rise to quite uniform varve-like features, without any organic implications.

Taking into account the faint young sun, it's difficult to come up with a scenario that includes a warm wet Mars.

The eccentric orbit of Mars has probably been around since the earliest times. If not, what event could have caused Mars to move into an eccentric orbit more recently?

This eccentricity would always result in considerable seasonal variation in climate between perihelion and aphelion.

Now the tough question, open to everyone - We have the Northern Hemisphere of Mars that shows lower topographical elevation and relief than the Southern Highlands.

Are these features evidence of a once extensive ocean, or some kind of glacial feature, something totally different, or do we need more data?

We have evidence of alteration giving rise to 'andesite' or altered shergottite type material in these regions . We have evidence of ancient dendritic network systems elsewhere on Mars.

Are we any closer to filling in the gaps?

Aldebaran, I think if periodic volcanic outgassing is thrown in to account for S and Fe, you may have something. Are the upward migrating brines hydrothermal, does it need to be briny? The evaporite basins (whether ground or surface water in origin) were probably flanked by dune fields that migrated over and around anything in their way (one grain at a time based on some layers we see). We know migrating dune fields can exist.

The relief of mars can in a way be compared to the moon, where one side (the far side) is topographically higher then the near side. The difference is due to the very large impact basins located on the near side (e.g., lunar maria). More then likely mars had these large impacts creating the relief differential we see in the northern lats. And as basins tend to do, they probably filled with water (and ice) at one time.

The migrating liquids need to be briny certainly for some of the processes. The deposition of calcium sulphate requires a calcium halide brine, or some other soluble calcium salt.

The upwards migration could include hydrothermal fluids, but I'm suggesting some kind of seasonal seepage due to the change in temperatures and capillary action through the upper level of regolith.

I agree with the point on migrating dune fields.

The sulfur would most likely have come from volcanic offgassing.

http://mars4.jpl.nasa.gov/mgs/msss/camera/images/10_19_98_polar_release/10_19_98_npld_rel/46103_sub_50perc.gif

In your mentioning of varves, I can't help but think of the layered deposits of the northern lats that no doubt are repeating sequences of ice and sand (or dust), and which could have some seasonal component. If there was a active volcanic source for atmospheric Fe and S on mars today we MAY see the formation of a deposit similar to something like we've seen at meridiani. The materials are there.

Atmospheric iron? So are you still looking at aerial oxidation as a possibility?

Why do we need atmospheric Fe, when we have fine red hematite dust deposited by the wind.

I don't think aerial oxidation is necessary, but the atmospheric iron I mention (not so clearly by the way) would be contained in volcaniclastic debris probably in the form of olivine. Klingelhoefer (Johannes Gutenberg U) is not sure where the iron for hematitie comes from, but he leans to olivine. But your point on red hematite source doesn't seem to be considered by Klingelhoefer, is the red hematite phase a dead end for reactiveness?

It is certainly a dead end for reactiveness on the surface of Mars today.

Reactiveness depends on the environment, but red hematite is found all over Mars, and forms a significant proportion of wind-born dust. However, reducing and hydrating environments can alter red hematite.

Link

The source of that air-borne hematite is probably olivine too.

There is a strong indication that the grey hematite is derived from Goethite which is derived from Jarosite. Certainly Goethite has been detected at Gusev.

It could be that we had volcanic sulfur outgassing to form FeS. This could later dissolve in basic solutions to form gelatinous FeOH, and it could oxidize directly to form Fe SO4.

3D L456/R1 Sand ripple:

Full L4/L5/L6 of ripple:

Speaking of half-baked, whenever you rock guys start getting wordy, I would like to smack you in the head with a picture, pepper you with questions, sprinkle on some spices and cook till done.

OK, this image is guaranteed to drive you crazy -- if you actually look at it closely for more than 10 seconds.

Lots and lots of lines and circles of millimeter and submillimeter grains on the side of the ripple.

Frost heave? I think there are similiar ( although much larger -- maybe more water?) patterns in the Arctic tundra regions.

JPL did a curious thing with this image: they did a full filter sequence -- but sent back only L4/L5/L6/R1 as full frames. The rest were sent back cropped and centered on a little circular feature...

Hmmm.

If anyone is interested. I will crop the full frame images too and do a full filter image.

Sorry about the PNGs. It's the only way to show you all that is there.

This appears to be a surface aeolian phenomenon. The fines clearly cover up the desert pavement. If we were to remove the fines, the original surface would be undisturbed, or that's how I read it. I can't see any evidence of frost-heave.

Alde, I'm fence sitting when it comes to the origin of the non-granular layers examined at meridiani, were they gelatinous when deposited or is diagenesis to blame for the resemblence. Some cycle (climatic/seasonal, depositional, volcanic) is revealed by the laminae.

Explain further "This could later dissolve in basic solutions to form gelatinous FeOH, and it could oxidize directly to form Fe SO4." Basic ?

ArizonaSt - Sorry, the last reply was a bit vague.

I was considering a possible scenario starting with FeS being produced under anaerobic, reducing conditions.

If we then had some displaced basic (alkaline) solutions coming into contact with this (as a result of impacts or volcanic activity for example), the basic solution could have dissolved and mobilised the FeS to produce gelatinous FeOH. (FeS is quite soluble in basic solutions.)

Another separate reaction is the oxidation of FeS, eventually forming Ferric sulphate. There are a number of other possible reactions.

In essence, I'm talking about changing groundwater conditions giving rise to the precipitation of minerals such as Jarosite.

Aldebaran brought up an interesting idea on Epsomite in the Biology Forum that I think might be applicable to this thread on seasonal deposition.

Epsomite is a mineral that contains 7 water molecules as a part of it's molecular composition.

[Link]

/R

marsman

The only point I was making was the possible lack of free water in the equatorial region. If there are substantial quantities of Magnesium sulfate on Mars, the stable monohydrate will act to mop up any potentially free groundwater (within limits) to form Epsomite, the heptahydrate.

The anomalies in the equatorial zone may be explained entirely by stable hydrated minerals, and there may be no sub-surface ice.

Aldebaran, we now have *visual* evidence that there is atmospheric deposition of free water/ice near the equator.

Bob Clark

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From: rgregorycl...@yahoo.com (Robert Clark)
Newsgroups: sci.astro,alt.sci.planetary,sci.physics,sci.geo.geology,sci.geo.meteorology
Subject: Further evidence for current liquid water near the equator on Mars.
Date: 25 Nov 2004 00:37:34 -0800

In this post to the Habitablezone.com/space/ bbs I discuss seasonal
changes observed by the Gamma Ray Spectrometer on Mars Odyssey in near
equatorial water on Mars:

Latest Mars Odyssey observations prove free water at equator.
Posted by Robert Clark on 6/27/2003 8:03:48 AM.
[link]

A report presented to October, 2004 Vernasky/Brown Conference
provides further evidence of these seasonal changes:

47 - EVIDENCE OF THE SEASONAL REDISTRIBUTION OF WATER IN THE SURFICIAL
MARTIAN REGOLITH BASED ON ANALYSIS OF THE HEND MAPPING DATA. R.O.
Kuzmin, E.V. Zabalueva, I.G. Mitrofanov, M.L.Litvak, A.V. Parshukov,
V.Yu.Grin'kov, W. Boynton, R.S. Saunders.
http://www.geokhi.ru/~planetology/theses/47_kuzmin_et_al.pdf

The authors note an increase in northern near equatorial regions of
the water content during the northern Summer and southern Summer. They
argue this should be due to transport of water vapor to the equator
from northern polar regions during northern Summer and from the
southern polar regions during southern Summer. Evidence for this is
its seasonal nature but also the fact the highest increase is shown in
the measurements closest to the surface. These are figures 1d and 1c,
which show the water content within 10cm (4 inches) and 20-30cm (8-12
inches), respectively. Note the highest increase in the measurements
occurs within 10cm (4 inches) of the surface.
The authors suggest either the water vapor is deposited as frost on
the surface or incorporated into clathrates or evaporates near
surface:

"The observing maximum value of the reduction of the higher energy
fast neutrons flux (in the period with Ls=270°-330°) approaches ~
20%.That is the abundance of the water (in form of water ice or
clathrate CO2·6H2O) in ~ 10 cm thickness surface layer could be
increased notably in the period on. As water source for this
apparently serves the water vapor mass transferred meridionally to
here from residual southern polar cap due to the significantly lower
partial pressure of H2O over the cold surface of the northern seasonal
cap and its surrounding region. We suggest that the visible reduction
of the neutrons flux outside of the seasonal cover of the CO2-ice (up
to the equatorial regions), may to be associated with both
condensation of the H2O frost on the surface and hydration of a salts
minerals (mostly sulfates and chlorides) contained in the surface
layer of the regolith. The neutrons flux reduction observing in the
period Ls=130°-170° is rather associated with hydration process in the
surface regolith due to high atmospheric humidity in the period."
EVIDENCE OF THE SEASONAL REDISTRIBUTION OF WATER IN THE SURFICIAL
MARTIAN REGOLITH BASED ON ANALYSIS OF THE HEND MAPPING DATA, p. 2

However, note that if it is frost then there are locations near the
equator at low altitude and it would be expected to melt to liquid
water at these low elevations sites as seasonal daytime temperatures
increased. (Temperatures near the equator can reach 80 degrees
Fahrenheit during daytime in Summer.)
Also important to realize is that either the clathrate or evaporate
explanations would require liquid water for their formation and within
4 inches of the surface and occurring currently and seasonally.

Bob Clark
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From: "Robert Clark"
Newsgroups: sci.astro, alt.sci.planetary, sci.physics, sci.geo.geology, sci.geo.meteorology
Subject: Re: Further evidence for current liquid water near the equator on Mars.
Date: 14 Dec 2004 08:14:54 -0800

Whoa! Frost on the Mars rover solar panels?

>From the Mars rover press release:

December 13, 2004
Mars Rovers Spot Water-Clue Mineral, Frost, Clouds
"A portion of Mars' water vapor is moving from the north pole toward
the south pole during the current northern-summer and southern-winter
period. The transient increase in atmospheric water at Meridiani, just
south of the equator, plus low temperatures near the surface,
contribute to appearance of the clouds and frost, Wolff said. Frost
shows up some mornings on the rover itself. The possibility that it has
a clumping effect on the accumulated dust on solar panels is under
consideration as a factor in unexpected boosts of electric output from
the panels."
[link]

Rover scientists had speculated that some of this frost may melt to
liquid to contribute to the clumping. Note that actual SURFACE
temperatures can exceed 0 C when the air temperature is below freezing,
when the surface is exposed to direct sunlight (it's southern winter at
the landing sites now.) This would be especially true of a dark surface
like the solar panels specifically designed to absorb sunlight.
What is the expected temperatures of the solar panels during the
hottest portion of the day? Do the cameras actually observe the frost
on solar panels? If so then we may actually be able to observe the
transition to liquid during late morning to early afternoon.
Note that the accumulation of this frost confirms visually what has
been found by the Mars Odyssey HEND hydrogen mapper that water
accumulates on Mars in near equatorial locations during northern and
southern Summer:

Further evidence for current liquid water near the equator on Mars.
Posted by Robert Clark on 11/25/2004 12:39:16 AM
[link]

This visual evidence from the rovers further supports the suggestion by
the authors of the HEND report that this increase is due to atmospheric
deposition. Of the various explanations offered by the authors, it
supports the suggestion the water is in free form, not bound in sulfate
or other evaporite:

47 - EVIDENCE OF THE SEASONAL REDISTRIBUTION OF WATER IN THE SURFICIAL
MARTIAN REGOLITH BASED ON ANALYSIS OF THE HEND MAPPING DATA.
R=2EO. Kuzmin, E.V. Zabalueva, I.G. Mitrofanov, M.L.Litvak, A.V.
Parshukov, V.Yu.Grin'kov, W. Boynton, R.S. Saunders.
http://www.geokhi.ru/~planetology/theses/47_kuzmin_et_al.pdf

The authors suggest frost or ice. My opinion is that during warm
*surface* temperatures this frost can melt to liquid, particularly for
low albedo (dark), low thermal inertia (easy to heat up) materials,
such as the solar panels.

Bob Clark

***********************************************************************
From: "Robert Clark"
Newsgroups: sci.astro, alt.sci.planetary, sci.physics, sci.geo.geology, sci.geo.meteorology
Subject: More on "Frost on the rover solar panels".
Date: 25 Dec 2004 12:58:34 -0800

Imaging at the Opportunity rover landing site in Meridiani Planum
confirms observations using the HEND instrument on Mars Observer that
water/ice is deposited near the equator seasonally on Mars:

Space Sciences
Whoa! Frost on the solar panels?
Posted by Robert Clark on 12/14/2004 7:32:38 AM
In Reply to: Sabkha or playa, take your pick... posted by Nick Hoffman
on 12/13/2004 6:23:08 PM
[link]

However, the HEND instrument shows the greatest amount is deposited
during southern Summer:

47 - EVIDENCE OF THE SEASONAL REDISTRIBUTION OF WATER IN THE SURFICIAL
MARTIAN REGOLITH BASED ON ANALYSIS OF THE HEND MAPPING DATA.
R=2EO. Kuzmin, E.V. Zabalueva, I.G. Mitrofanov, M.L.Litvak, A.V.
Parshukov,
V=2EYu.Grin'kov, W. Boynton, R.S. Saunders.
"As it well seen from fig.1b,c,d, two distinctive "hollows" of
neutrons flux reduction have been appeared in the northern hemisphere
during northern summer at Ls=130 to 170 and in first half of northern
winter at Ls=270 to 330=, being extended from high to low latitudes. At
that, later "hollow" (Ls=270 to 330) is characterized by much
stronger reduction of the neutrons flux and it traces from northern
polar region up to low latitudes in the southern hemisphere. The first
"hollow" is related with periods of the northern middle summer,
while the second one - with of the southern middle summer. In both
case the residual polar caps serve as main source of the water in the
Martian atmosphere."
p=2E 2
http://www.geokhi.ru/~planetology/theses/47_kuzmin_et_al.pdf

Opportunity landed just barely after this time in southern Summer at
about LS 340 (LS stands for solar longitude and indicates Mars
position in its orbit.)
However, it is notable that Spirit did land near the end of the time
period of Ls=270 to 330. Spirit is closer to the southern pole and
this may explain how it could experience deposition during this period
while apparently not during the current northern Summer. Then the
controversial indications of mud at the Spirit landing site early in
the mission may indeed have been indications of this summer-time water
deposition.
Opportunity has observed clouds during the current water deposition
period and since the amount of atmospherically deposited water is
greater during southern Summer, we would expect the cloud density to be
even greater then. Indeed it could be of sufficient density to allow
precipitation which could reach the ground as rain.
The next Ls=270 to 330 period begins in August, 2005.

Come on Opportunity!

Bob Clark
*********************************************************************

From: "Robert Clark"
Newsgroups: sci.astro, alt.sci.planetary, sci.physics, sci.geo.geology, sci.geo.meteorology
Subject: Re: More on "Frost on the rover solar panels".
Date: 28 Dec 2004 08:44:16 -0800

Note that the evaporates (sulfate or carbonate) seen on *top* of rocks
in Gusev also suggests atmospheric deposition of liquid water there:

=================================================
Newsgroups:
sci.astro,alt.sci.planetary,sci.geo.geology,sci.geo.mineralogy
From: rgregorycl...@yahoo.com (Robert Clark)
Date: 2 Jul 2004 04:57:20 -0700
Local: Fri, Jul 2 2004 4:57 am
Subject: Evidence for atmospheric liquid water in Gusev?

In the badastronomy.com forum Daniel Crotty presents an image (below)
showing white colored material on *top* of rocks. This would argue
against the interpretation suggested by Steve Squyres that the
sulfates seen in Gusev might stem from water percolating up from the
subsurface. Instead it would suggest sulfates formed from liquid water
precipitation(rain) or liquid water droplets in a humid atmosphere.
I wondered whether white material on the rocks could be due to the
dust kicked up by a RATTing but Crotty gives other images with no
ratting nearby that also shows white rocks:

Dusty, bright material around Spirit, Sol 165
http://badastronomy.com/phpBB/viewtopic.php?t=14573&sid=7f6b82d247999...

Bob Clark

Uncalibrated color image by Daniel Crotty.

Bob Clark
=================================================

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Similar to ideas generating during Viking, but taken a step further.

I have no problems that there is some ephemeral frost deposition on a seasonal basis, particularly with surfaces of low thermal inertia; however the problem lies with the temperature at which such frost is deposited. The frost itself contains no salt, and it has a snowflakes chance in hell of getting to the temperature needed to melt before it totally subliminates, even if it was sitting on a lump of pure calcium bromide. So how can surface frost realistically be a mechanism for recharge?

The Mars Odyssey data is indicative of hydrogen. The hydrated minerals detected up to now, would in themselves account for the water anomaly.

Where is the evidence of free water, as opposed to water of crystallisation? Epithermal neutron flux is just an indicator of hydrogen.

I haven't had a chance to read all your links, but so far, nothing points conclusively to liquid water.

The clouds themselves would have to be formed of microscopic ice crystals at that temperature and pressure.

Hopefully there may be a chance to observe the southern summer in real time if Opportunity survives that long.

"Also important to realize is that either the clathrate or evaporate
explanations would require liquid water for their formation and within
4 inches of the surface and occurring currently and seasonally."

It would not require liquid water. Haven't you seen a laboratory dessicator ? The water vapour is absorbed direct from the atmosphere into the dessicant. Anhydrous magnesium sulphate is dessicant.

If I don't say this, somebody will say it for me - Here I am discussing the low probability of liquid water forming in Martian equatorial regions on a seasonal basis.

Past events, such as meteorite impacts may have resulted in temporary thickening of the atmosphere to allow formation of liquid water, however that's a different story.

Under current Martian conditions, even for the very short time that water is theoretically stable, water and brine are both highly volatile liquids.

OK, This could be read as raising more questions than answers, but it reveals how complex the phase relationships could be.

The phase diagram below is for magnesium sulfate/ H20. The actual phase diagram will probably be a lot more complicated than this for a ternary or quaternary system which may include calcium and magnesium chlorides. For magnesium sulfate concentrations below 35%, there is a stable phase MgSO4.12H2O that forms between 0 and -5 degrees C.

here is the source of the data:

http://www.phasediagram.dk/index.htm

- and here is the link to the Calcium Chloride/ water binary system:

http://www.phasediagram.dk/binary/calcium_chloride.htm

The maximum theoretical freezing point depression (fpd) for calcium chloride is about -50, with concentrations between 26 and 34% CaCl producing a fpd of less than -40.

The presence of sulfate tends to reduce the overall fpd.