Possible water lubricated grain movement in the circumpolar region of Mars

Possible water lubricated grain movement in the circumpolar region of Mars

Authors:

Kereszturi et al

Abstract:

In this work we evaluate a new model on the possibility, could microscopic liquid water supported grain movement on Mars happen at the circumpolar region (in Richardson crater) today, combined with the analysis of new HiRISE ESP images. We confirmed earlier (PSP images based) findings on the morphology, sequential growth and two separate phased formation method of flow features emanate from Dark Dune Spots (1: gas-jet driven streaks toward different directions, 2: flow-like streaks downward). We also identified that the gas-jet ejected and back fallen grains surrounded by water ice produce local enrichment of H2O, forming local water ice layer.

Several model scenarios were developed and evaluated to exploit the possibilities of liquid supported flow, including the increased thickness of interfacial liquid layer by salts and impurities, the collapse and movement of loose stratum of air-fallen dust-salt mixture with interbedded liquid layers, the mechanical force to kick-off the movement by hydration/dehydration cycles, and the migrating phase change plus the seeping of thin liquid film around interconnected grains. Selecting the most relevant elements among them, which are also compatible to our current knowledge of Mars, a comprehensive model was built that could be tested. This best model contains four interconnected and subsequent elements: 1. deposition of airfall dust in autumn and winter producing a loose surface layer, 2. spatial concentration of H2O ice by gas-jet activity during the CO2 sublimation phase, 3. mechanical kick-off by daily expansion/contraction cycles to mix the components, 4. engulfed hygroscopic salts and dust grains to enlarge the ratio of liquid to support the flow. The emerged self-amplifying process could produce daily movement in theory. The scenario contains realistic elements; it is in agreement with the observations, and also being testable by laboratory modelling. The analyzed locations are important because of the joint occurrence of concentrated water ice, elevated temperature and moving flow-features; and it also provides insight into the possible current action of liquid water on Mars.

Melas Chasma MAY Have had Prolonged Periods of Near Surface Water

Implications for the aqueous history of southwest Melas Chasma, Mars as revealed by interbedded hydrated sulfate and Fe/Mg-smectite deposits

Authors:

Liu et al

Abstract:

Using visible and near infrared data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), we identified a sequence of hydrated sulfates and Fe/Mg-smectites in southwest Melas Chasma. Specifically, these hydrated sulfate and semectite deposits are interbedded and have been highly deformed. Equilibrium thermodynamic calculations of coupled basalt weathering and fluid evaporation predict that sequential formation of Fe/Mg-smectites and sulfate evaporites in similar quantities, as observed in the interbedded smectite-sulfate sequences, is chemically plausible. The Fe/Mg-smectite-sulfate deposits may have thus formed through in situ basalt weathering and fluid evaporation, although an origin involving repeated cycles of transport and deposition of detrital clays by a neutral fluid containing Mg and SO4 and subsequent evaporation cannot be ruled out. If the Fe/Mg-smectites are authigenic, the Hesperian (or younger) age Melas Chasma would have experienced prolonged periods with near-surface water, providing potentially habitable conditions.

More Evidence of Martian Ground Water From the Arabia Terra

Monica Pondrelli and colleagues investigated the Equatorial Layered Deposits (ELDs) of Arabia Terra in Firsoff crater area, Mars, to understand their formation and potential habitability. On the plateau, ELDs consist of rare mounds, flat-lying deposits, and cross-bedded dune fields. Pondrelli and colleagues interpret the mounds as smaller spring deposits, the flat-lying deposits as playa, and the cross-bedded dune fields as aeolian. They write that groundwater fluctuations appear to be the major factor controlling ELD deposition.

Pondrelli and colleagues also note that the ELDs inside the craters would likely have originated by fluid upwelling through the fissure ridges and the mounds, and that lead to evaporite precipitation. The presence of spring and playa deposits points to the possible presence of a hydrological cycle, driving groundwater upwelling on Mars at surface temperatures above freezing. Pondrelli and colleagues write that such conditions in a similar Earth environment would have been conducive for microbial colonization.

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Evidence of Fluctuating Ground Water Levels in the Mawrth Vallis on Mars

Detection of copiapite in the northern Mawrth Vallis region of Mars: Evidence of acid sulfate alteration

Authors:

Farrand et al

Abstract:

The Mawrth Vallis region on Mars is associated with extensive layered deposits containing a stratigraphic sequence of Fe/Mg smectites overlain by Al phyllosilicates. Earlier studies have reported restricted exposures of the ferric sulfate mineral jarosite on top of the sequence. In this paper we have used CRISM data covering the northern portion of the Mawrth Vallis region to find a new jarosite exposure and multiple occurrences of the mixed valence Fe-sulfate mineral copiapite (Fe2+Fe3+4(SO4)6(OH)2·20(H2O)). HiRISE imagery indicate that the copiapite exposures lie on top of the Al phyllosilicates and thus post-date that unit either as a coating or as extensive veins. The presumed copiapite exposures are associated with high values of a “SINDX” parameter derived from CRISM data. Application of several spectral matching metrics over a spectral subsection indicated several candidates for the high SINDX phase including copiapite, ferricopiapite and metavoltine (another mixed valence Fe-sulfate mineral). Visible and near infrared CRISM spectra of the high SINDX areas are most consistent with the phase being copiapite. On Earth copiapite generally occurs as efflorescent coatings in acid mine drainage environments or in association with acid sulfate soils. The presence of jarosite and copiapite indicates the presence of acidic waters. Such acid waters could have contributed to the formation of the underlying Al phyllosilicate minerals. A possible mode of origin for these minerals in this region would involve a fluctuating ground water table and the weathering of Fe sulfide minerals.

New Mexico Chile Production Falls Sharply

While red and green chili peppers still sit on top of the list as New Mexico's favorite food crop, commercial production fell sharply last year according to a USDA year-end crop production report and confirmed by the latest crop statistics from the New Mexico Department of Agriculture.

The official report indicates fewer acres of chili peppers planted and harvested in 2013, down about 16 percent from the previous year. USDA says 65,000 tons of New Mexico chili peppers were produced in 2013 compared to nearly 78,000 tons in 2012. Over a decade ago New Mexico chili pepper farmers were harvesting over 100,000 tons of green and red peppers each fall.

link.

Oy! Not the Best Use of Water Resources!

In Saudi Arabia...

In the UAE....

In China...

In the USA...

oy.

Why is the Sea Level Rising Faster Than Projected?

Sea levels are rising faster than expected from global warming, and University of Colorado geologist Bill Hay has a good idea why. The last official IPCC report in 2007 projected a global sea level rise between 0.2 and 0.5 meters by the year 2100. But current sea-level rise measurements meet or exceed the high end of that range and suggest a rise of one meter or more by the end of the century.

"What's missing from the models used to forecast sea-level rise are critical feedbacks that speed everything up," says Hay. He will be presenting some of these feedbacks in a talk on Sunday, 4 Nov., at the meeting of The Geological Society of America in Charlotte, North Carolina, USA.

One of those feedbacks involves Arctic sea ice, another the Greenland ice cap, and another soil moisture and groundwater mining.

"There is an Arctic sea ice connection," says Hay, despite the fact that melting sea ice -- which is already in the ocean -- does not itself raise sea level. Instead, it plays a role in the overall warming of the Arctic, which leads to ice losses in nearby Greenland and northern Canada. When sea ice melts, Hay explains, there is an oceanographic effect of releasing more fresh water from the Arctic, which is then replaced by inflows of brinier, warmer water from the south.

"So it's a big heat pump that brings heat to the Arctic," says Hay. "That's not in any of the models." That warmer water pushes the Arctic toward more ice-free waters, which absorb sunlight rather than reflect it back into space like sea ice does. The more open water there is, the more heat is trapped in the Arctic waters, and the warmer things can get.

Then there are those gigantic stores of ice in Greenland and Antarctica. During the last interglacial period, sea level rose 10 meters due to the melting of all that ice -- without any help from humans. New data suggests that the sea-level rise in the oceans took place over a few centuries, according to Hay.

"You can lose most of the Greenland ice cap in a few hundred years, not thousands, just under natural conditions," says Hay. "There's no telling how fast it can go with this spike of carbon dioxide we are adding to the atmosphere."

This possibility was brought home this last summer as Greenland underwent a stunning, record-setting melt. The ice streams, lubricated by water at their base, are speeding up.

Hay notes, "Ten years ago we didn't know much about water under the Antarctic ice cap." But it is there, and it allows the ice to move -- in some places even uphill due to the weight of the ice above it.

"It's being squeezed like toothpaste out of a tube," explains Hay. The one thing that's holding all that ice back from emptying into the sea is the grounded ice shelves acting like plugs on bottles at the ends of the coastal glaciers. "Nobody has any idea how fast that ice will flow into the oceans once the ice shelves are gone."

Another missing feedback is the groundwater being mined all over the world to mitigate droughts. That water is ultimately added to the oceans (a recent visualization of this effect in the U.S. was posted by NASA's Earth Observatory).

All of these are positive feedbacks speeding up the changes in climate and sea-level rise.