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Unmanned Spaceflight.com _ Mars _ Ancient Ocean that covered 1/3 of Mars with Water

Posted by: Bobby Jun 15 2010, 12:33 AM

I found this article about Mars being covered with Water and found it interesting.
June 13, 2010

Here is the article:
http://www.colorado.edu/news/r/f9b2e81224758e6b422b6bb0735f7098.html

Posted by: Paolo Jun 15 2010, 04:24 AM

It will be interesting to see how they solve the mystery of why (to my knowledge) all of the sites having clays or other water-modified rocks and minerals are found in the ancient cratered highlands and not in the smooth northern plains

Posted by: ngunn Jun 15 2010, 08:59 AM

The ocean froze and we see the stuff deposited on top, not the seabed sediments?

Posted by: serpens Jun 15 2010, 09:20 AM

That explains very well why the underlying strata is heavily cratered, but covered by the smooth northern basin. Given the Comanche find and the ph at the Phoenix site could we anticipate that the ocean was a neutral or high ph and that there are carbonates down there? Or is that too much of a leap of faith.

Posted by: Bill Harris Jun 15 2010, 12:41 PM

There are many processes and environments involved in the formation of carbonates. Until we know more about the type of carbonate involved and the depositional environment, we don't know many of the fine details. It's just one data point, one piece of the jigsaw puzzle.

My take on Comanche is that it is a hydrothermal feature, whci is a whole 'nuther critter from aquatic deposition.

--Bill

Posted by: schaffman Jun 16 2010, 11:59 AM

There are likely at least two different "oceans" in Mars history. The DiAchille paper, cited in Bobby's post, analyzed valley networks and deltas from the Noachian period (>3.5 billion years ago.) when climatic conditions were very different than today. Some temporary bodies of water (or mud) probably formed much later in the northern hemisphere in association with the hugh outflow channels carved during the Hesperian (maybe 500 to 1,000 million years after the earlier ocean--absolute dates are uncertain). The chemical environments (pH etc.) were likely very different during each.

What's puzzling to me is that an ancient, cratered Noachian surface is preserved at realtively shallow depths in the northern hemisphere, suggesting that the sediment layers from both oceanic events are fairly thin. Mars is such a fascinating enigma.

Tom

Posted by: tharrison Jul 2 2010, 06:32 PM

QUOTE (ngunn @ Jun 15 2010, 12:59 AM) *
The ocean froze and we see the stuff deposited on top, not the seabed sediments?


If there were seabed sediments in the northern plains, they're certainly not what's at the surface right now. Young craters on the northern plains have very bouldery ejecta, which implies that the material they impacted into is hard like a basalt rather than soft marine sediments.

Posted by: tim53 Jul 29 2010, 04:54 PM

QUOTE (schaffman @ Jun 16 2010, 03:59 AM) *
There are likely at least two different "oceans" in Mars history. The DiAchille paper, cited in Bobby's post, analyzed valley networks and deltas from the Noachian period (>3.5 billion years ago.) when climatic conditions were very different than today. Some temporary bodies of water (or mud) probably formed much later in the northern hemisphere in association with the hugh outflow channels carved during the Hesperian (maybe 500 to 1,000 million years after the earlier ocean--absolute dates are uncertain). The chemical environments (pH etc.) were likely very different during each.

What's puzzling to me is that an ancient, cratered Noachian surface is preserved at realtively shallow depths in the northern hemisphere, suggesting that the sediment layers from both oceanic events are fairly thin. Mars is such a fascinating enigma.

Tom


My own current thinking on this subject is that the ocean grew after accretion, reaching it's maximum extent in the late Noachian, was initially largely unfrozen, then was frozen over and covered with debris as it monotonically declined over time, with transgressive pulses producing the "shorelines" I identified in Viking images. The ocean is still there, but likely frozen solid (and less extensive).

Blocks at the surface in the putative ocean basin interior can be explained in a number of ways. "Sorting" and concentrating of blocks at the surface through periglacial processes; Marine sediment layer overlying basement rocks (and craters) is thin or absent; fines have been selectively winnowed out by aeolian (or aqueous) processes.

If you dried up the Earth's oceans, much of the exposed ocean floor would be basalt.

-Tim.

Posted by: schaffman Aug 1 2010, 10:31 AM

Thanks for clarifying, Tim.
I was thinking oceans (plural) in terms of the differing chemistry, areal extent, and climatic conditions under which standing bodies of water may have formed. Given how ancient the dichotomy appears to be, it seems reasonable that the northern lowlands have been the major sink for water throughout Martian history, and as such would have been the location of the true martian "ocean" (ultimate base level) since very early in the Noachian.

Tom

Posted by: Den Oct 19 2010, 10:04 PM

Indeed, we have two near certainties which contradict each other:

(1) Mars *had to* have a lot of water early on and thus, had to have fairly extensive ocean.
(2) But we don't see much of sedimentary rocks.

One crazy-ish idea from me: what if Mars indeed had a lot of water, but it always was mostly solid?

Even here on Earth, with beefy atmosphere (-> greenhouse effect) and higher insolation, we had pretty bad glaciations. At Mars distance, it should have been colder. What if Mars "ocean" was mostly frozen solid, like continuous ice age with only short periods of catastrophic melting and floods, when polar tilt, greenhouse effect and volcanic heat happen to work together?

After billions of years of slow water loss, especially from surface closer to equator, this will give us today outwardly "dirty", but inside pretty "icy" Mars (lots of ancient river/flood valleys, glaciers, lots of permafrost at latitudes +/-40 and up to poles), yet not much of sediments. Sedimentation doesn't happen in solid water, right?

Re "icy" Mars: http://www.uahirise.org/PSP_008809_2215
this glacier(-like?) feature is at 41.3 N.lat. Why is it _white_ in RGB? Was is covered with water frost when this image was taken?

Posted by: ngunn Oct 19 2010, 10:45 PM

The view from my armchair is that I like your scenario. I suspect a lot of the water related landforms on Mars will turn out to have formed at the bottom of ice sheets, not at the surface.

Posted by: brellis Oct 20 2010, 01:14 AM

POST DELETED - SEE FORUM GUIDELINES 1.3 - ADMIN

Posted by: AndyG Oct 20 2010, 11:34 AM

Den, I've got two armchairs. rolleyes.gif

From one, given that solar output has increased by several tens of percent since the birth of the solar system, an early Mars - one with noticeably less insolation - could have been an appreciably colder planet than today's, thus supporting this idea.

From the other, I suppose an early Mars' thicker atmosphere and more tectonic activity works in favour of warming the place up.

Quite which chair wins is not something I feel at all qualified to comment on.

Andy

Posted by: serpens Oct 21 2010, 02:52 AM

Actually are there not 3 variables (armchairs) to consider?
1. Output from the sun (insolation at the upper atmosphere) increasing with time,
2. Atmospheric make-up and heat from impact/volcanic activity (decreasing with time), and
3. Distance from the sun (given the apparent instability of the early solar system as evidenced by the LHB, possibly increasing early on).

Ok - just a blip at the edge of the probability distribution but isn't a warmer wetter Mars a possibility worth consideration?

Posted by: schaffman Oct 21 2010, 11:57 AM

QUOTE (Den @ Oct 19 2010, 05:04 PM) *
One crazy-ish idea from me: what if Mars indeed had a lot of water, but it always was mostly solid?

Even here on Earth, with beefy atmosphere (-> greenhouse effect) and higher insolation, we had pretty bad glaciations. At Mars distance, it should have been colder. What if Mars "ocean" was mostly frozen solid, like continuous ice age with only short periods of catastrophic melting and floods, when polar tilt, greenhouse effect and volcanic heat happen to work together?

After billions of years of slow water loss, especially from surface closer to equator, this will give us today outwardly "dirty", but inside pretty "icy" Mars (lots of ancient river/flood valleys, glaciers, lots of permafrost at latitudes +/-40 and up to poles), yet not much of sediments. Sedimentation doesn't happen in solid water, right?


Not crazy at all. Your scenario resembles the one that Jeff Kargel discusses in Mars: A Warmer Wetter Planet.

Surface water on Earth is mostly liquid with with ocassional climactic excursions producing widespread surface ice (glaciations). Mars, being colder, is the opposite: Water is frozen most of the time and only ocassionally do conditions exist to produce liquid water. Such conditions became much less frequent and of lower intensity over time.

Tom

Posted by: AndyG Oct 21 2010, 12:11 PM

Not happy not knowing with which of the chairs to pick, I felt the need for a quick play with Excel.

Mars' average temperature today is around 210K. All things being equal, a 70%-as-bright Sun only knocks about 18K off that - a figure which I find a little suprising in terms of how relatively undramatic a change that is.

I can dial in a current-Earth-like atmosphere for this early Mars, and almost regain that 18K. Still cold and dry!

But consider a short-lived, even thicker atmosphere, one loaded with CO2 and water vapour pumped out by those gigantic volcanoes, and then the temperature starts to rise markedly. Is this the way to a warm, wet Mars? Sadly I don't think so, since this atmosphere comes at a price: it's going to seriously raise the albedo, dropping the temperature.

It's hard work to reach an Earth-like 288K.

Indeed, only towards the limits of Venusianess does the planet become balmy, which I think is extremely unlikely to have occured or extremely short-lived if it ever did.

So - for most of Mars' history - it's definitely the cold, dry chair for me.

Andy

Posted by: Vultur Oct 21 2010, 02:21 PM

If Mars ever had an Earth-density atmosphere, though, it would have had far more CO2 and thus a stronger greenhouse effect. Earth's atmosphere is unstable, maintained that way by life. Before plants, Earth had much more CO2 and less O2.

Posted by: Den Oct 23 2010, 07:29 PM

QUOTE (Vultur @ Oct 21 2010, 02:21 PM) *
If Mars ever had an Earth-density atmosphere, though, it would have had far more CO2 and thus a stronger greenhouse effect. Earth's atmosphere is unstable, maintained that way by life. Before plants, Earth had much more CO2 and less O2.


I believe the gist of AndyG's post is that even thick CO2 atmosphere doesn't raise temperature enough to make liquid ocean possible.

Posted by: ngunn Oct 23 2010, 09:29 PM

QUOTE (Den @ Oct 23 2010, 08:29 PM) *
even thick CO2 atmosphere doesn't raise temperature enough to make liquid ocean possible.


The pressure required to maintain the liquid state doesn't have to depend on a thick atmosphere; it can come from the weight of 'sea ice'. Most of the water oceans in the solar system have such caps, but I think any ancient martian ocean would have had a much thinner cap than that of Europa or the other galileans, more like 'snowball Earth'.

Posted by: Den Oct 25 2010, 01:36 PM

QUOTE (ngunn @ Oct 23 2010, 09:29 PM) *
The pressure required to maintain the liquid state doesn't have to depend on a thick atmosphere; it can come from the weight of 'sea ice'. Most of the water oceans in the solar system have such caps, but I think any ancient martian ocean would have had a much thinner cap than that of Europa or the other galileans, more like 'snowball Earth'.


Sea ice would be unstable in current Mars conditions - it would sublimate.

With thicker atmosphere in the past, it looks plausible. So my mental picture needs to be corrected: ancient Mars ocean, where it was liquid, was covered by permanent thick ice cover (many meters). Over the eons, atmosphere was lost, water was partly sublimating and escaping to space and to colder, higher latitudes, and partly "escaping" to permafrost and deep underground aquifers. Surface of ex-frozen-ocean was gradually covered by dust.

Bear in mind that this description of "cold Mars" is too simplistic. In 3 billion years, a lot of interesting events happened. Largish impacts. Changing tilt of the rotational axis. And first of all, volcanic eruptions and lava floods are prime candidates to make a lot of water liquid, at least for some geologically short time, but enough to cause catastrophic floods, carve river valleys, etc...

Posted by: Fran Ontanaya Oct 25 2010, 02:04 PM

Are you taking into account the salinity of the sea, and also more methane than is currently observed?

Posted by: Den Oct 25 2010, 02:36 PM

QUOTE (Fran Ontanaya @ Oct 25 2010, 02:04 PM) *
Are you taking into account the salinity of the sea, and also more methane than is currently observed?


Consider this: on Mars equator, average temperatures are below -40C. This is at least 20C colder than on North Pole of the planet Earth. The Earth has thick atmosphere with some CO2, with traces of methane, and its ocean is saline, and yet, ice at North Pole is 2-3 meters thick.

Posted by: Fran Ontanaya Oct 26 2010, 11:47 AM

The hypersaline lakes in the McMurdo Dry valleys remain ice free most of the year, and without tectonics the martian ocean could have been shallower than on Earth.

Posted by: Den Oct 26 2010, 06:30 PM

QUOTE (Fran Ontanaya @ Oct 26 2010, 12:47 PM) *
The hypersaline lakes in the McMurdo Dry valleys remain ice free most of the year, and without tectonics the martian ocean could have been shallower than on Earth.


http://en.wikipedia.org/wiki/Lake_Vida -

"Lake Vida is one of the largest lakes in the McMurdo Dry Valley region and is a closed-basin endorheic lake. The top waters of Lake Vida are frozen year-round to a depth of at least 19 m forming an ice-seal over briny waters that are seven times as saline as seawater. ... The high salinity allow for the lake bottom waters to remain liquid at an average yearly water temperature of -10°C."

Is this wiki article incorrect about 19 thick ice cover?

Posted by: schaffman Oct 27 2010, 02:58 AM

Which raises an interesting question. Could ice-covered lakes (like Lake Vostok, for example) still be present on Mars? How would one search for them? The ice would likely be mantled with dust and lag deposits. They would most likely occur at mid latitudes where ice is more stable. And they would likely be Amazonian in age (?). It seems if the zone of liquid water were shallow enough that MARSIS or SHARAD could detect the ice-water boundary. All questions I don't know the answer to. Does anyone know if anyone has looked into this?

Tom

Posted by: Fran Ontanaya Oct 27 2010, 03:22 PM

http://mars.jpl.nasa.gov/express/mission/sc_science_marsis02.html

QUOTE
Scientists should be able to see the top of a liquid zone somewhere in the upper 2-3 kilometers (1-2 miles) fairly easily, and may be able to go down to 5 km (about 3 miles) or more.

Posted by: tharrison Oct 27 2010, 05:43 PM

QUOTE (schaffman @ Oct 26 2010, 06:58 PM) *
Which raises an interesting question. Could ice-covered lakes (like Lake Vostok, for example) still be present on Mars? How would one search for them? The ice would likely be mantled with dust and lag deposits. They would most likely occur at mid latitudes where ice is more stable. And they would likely be Amazonian in age (?). It seems if the zone of liquid water were shallow enough that MARSIS or SHARAD could detect the ice-water boundary. All questions I don't know the answer to. Does anyone know if anyone has looked into this?


Both the MARSIS and SHARAD folks have looked for stuff like this, as well as evidence of subsurface liquid water aquifers. So far they haven't found anything conclusive...they've found lots of subsurface ice in various places around the planet (i.e. the aprons in the Deuteronilus Mensae), but nothing suggesting liquid water.

Posted by: schaffman Oct 28 2010, 03:42 PM

QUOTE (tharrison @ Oct 27 2010, 12:43 PM) *
Both the MARSIS and SHARAD folks have looked for stuff like this, as well as evidence of subsurface liquid water aquifers. So far they haven't found anything conclusive...they've found lots of subsurface ice in various places around the planet (i.e. the aprons in the Deuteronilus Mensae), but nothing suggesting liquid water.


Thanks for the info.

Tom

Posted by: serpens Jul 28 2013, 04:15 AM

The evidence for a substantial ocean keeps on trickling in.

http://www.caltech.edu/content/evidence-martian-ocean


Posted by: RichforMars Aug 20 2013, 01:35 PM

And at this particular time in Martian history, how was reality on the planet we live on?

Posted by: ElkGroveDan Aug 20 2013, 04:33 PM

QUOTE (RichforMars @ Aug 20 2013, 06:35 AM) *
And at this particular time in Martian history, how was reality on the planet we live on?


Reality on Earth? It was tangible but alas there was no one around to quantify it.

Posted by: centsworth_II Aug 20 2013, 05:53 PM

QUOTE (RichforMars @ Aug 20 2013, 09:35 AM) *
And at this particular time in Martian history, how was reality on the planet we live on?
There are so many theories about how Earth was and how Mars was 3.5 to 4 billion years ago that I don't think we can know now on which planet oceans formed first. But I would guess that oceans likely existed on both planets at the same time at some point.


Posted by: nprev Aug 20 2013, 09:00 PM

There's some evidence (D/H ratio, I think) that Venus once had oceans as well, BTW.

But, machts nicht. If Mars OR Venus indeed did have oceans there's just no way to positively tell if they coexisted with those of the Earth, really. Terrestrial geological evidence from that era is at best fragmentary; the LHB was beating the hell out of the entire inner Solar System for a lot of that time.


Posted by: serpens Aug 21 2013, 11:02 PM

The evidence is fragmentary yes, but compelling for continental crusts and oceans at 4.4 Mya ago (detrial zircons - Yilgarn Craton, Western Australia). At that stage Earth was just a baby and the LHB was just getting into stride. There is no certainty as to the LHB time scale or the impact intensity distribution over the period, but given the evidence from the moon and Mars for hefty impactors a cycle of ocean vaporisation and condensation, for both Earth and Mars seems more likely than not.

Posted by: Chmee Aug 22 2013, 05:18 PM

Strange to think that at one point Venus, Earth, and Mars, may have all had oceans at the same time. Three planets who may have started similarly, but have diverged dramatically since then. Also, given how new the surface of Venus is (i.e. 100 million years old?), perhaps its ocean lasted until relatively recently (in geologic terms). Maybe less then a billion years ago the oceans evaporated, than the plate tectonics stopped, and than the surface got covered in magma?

Posted by: elakdawalla Aug 22 2013, 05:52 PM

Regarding Venus, it's better to assume that we are *not* living in a special time in its history. The simplest explanation for its youthful surface age is of a stagnant lid with periodic overturn -- every several hundred million years the cold lithosphere (which is denser than the hot stuff below it) founders and sinks into the mantle, producing a global paroxysm of volcanic activity that wanes and then quiets for a long time until it all happens again. This isn't the only possible explanation, of course, but you have to make a very strong case for an ad-hoc explanation before you can convince people that the uniformitarian explanation is false. This is an odd duck though, a uniform process of repeated catastrophes. I wonder what Hutton would think smile.gif

Posted by: serpens Dec 10 2013, 10:21 PM

Well Curiosity seems to have confirmed that there was significant water during the Hesperian lasting millions to tens of millions of years. This is clear empirical evidence of a warmer, wetter Mars with neutral pH water.

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