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Author Topic: What's new in Greenland?  (Read 82884 times)

crandles

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Re: What's new in Greenland?
« Reply #250 on: May 22, 2017, 01:18:08 PM »
Greenland melting quite high 18th & 19th May- especially on SW coast.

Does Greenland Melting Season deserve a thread of its own?


I suggest multiyear images from
http://nsidc.org/greenland-today/greenland-surface-melt-extent-interactive-chart/

such as attached

Neven

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Re: What's new in Greenland?
« Reply #251 on: May 22, 2017, 01:51:19 PM »
Greenland melting quite high 18th & 19th May- especially on SW coast.

Does Greenland Melting Season deserve a thread of its own?


Good idea. We've had one every year so far, I believe. Here it is: Greenland 2017 melt season
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gerontocrat

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Re: What's new in Greenland?
« Reply #252 on: May 22, 2017, 02:00:27 PM »
Greenland melting quite high 18th & 19th May- especially on SW coast.

Does Greenland Melting Season deserve a thread of its own?


Good idea. We've had one every year so far, I believe. Here it is: Greenland 2017 melt season

Cor! Thanks. I hope there are chances of images where melting is biting hard.

VeliAlbertKallio

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Re: What's new in Greenland?
« Reply #253 on: May 25, 2017, 04:19:04 AM »
I was referring to this landscape on the Geikie Peninsula which is definitely volcanic as you can see (and NASA article put it quite nicely). What still bothers me is that these volcanoes go there beneath the ice sheet almost forever (!) and then you cannot see every volcano on the surface - much like the Gamburtseve Range they are hidden deep in Antarctic ice.

It bothers me how uniform the volcanic rocks there are and what faults in the rocks might be therein. Just like Toba and Yellowstone aren't really very active volcanic systems today to fear, there is some tiny bit of beast still left in them (this justifying some fear of future supereruptions).

My concern or fear is that if huge ablation of ice takes place stresses by ice-forced subsidence reverberates to the old faults or creates new ones and incursion of hot water or rocks would come active under ice just like Nanortalik hot springs. The partial melting of Peridotite isn't easy to come, I admit, but the weight of ice sheet influences bedrocks and has a very deep footprint which I think is generally underestimated:

I see here a clear connection between central Greenland subglacial depression, volcanic incursions on the east coast of Greenland and proximity of the vast volcanic shield of Iceland nearby all in connection. Whilst I am aware of the drifting of a volcanic hotspot and believe it to be the strongest today in Iceland, I do not see an absolute reason why not residual activity pockets could not exist in Greenland. True, in Hawaii the volcanic activity diminishes towards North East.

There are extinct volcanoes in Antarctica, but also some others that aren't and keep wondering if any system is left in limbo in Greenland that could start playing up due to wet solidus damage strengthening regional plumes in mantle due to ablation and then nucleation of gases within magma reservoirs (if there were any near surface).

After all, I also note that if these volcanoes really are so old (those NASA guys did not walk on the mountains but flew over in altitude, sic), in many of them appears far too little erosion if they were millions of years old as you follow NASA argument - but sharp volcanic forms appear not always planed smooth by ice. Long periods of ice and glaciation tends to smoothen the rocks round but I can't see often rocks smoothened by ice in this volcanic region, do you have any explanation to that? This isn't Grand Canyon region carved by river, but area which ought to be carved by ice. Look at the rocks elsewhere Greenland and see how rounded ice has made them.

So, I am still afraid that they could cause Jokullhaups and contribute as ice sheet mass balance is impacted. For example, looking at the Gamburtsev Range volcanoes profiles in ice, it has been claimed that the ice sheet on that region was "growing from bottom up" by ice upwell (ice sheet growing from its base upwards).

I have interpreted these Gamburtsev features the other way round: the volcanoes have dumped latent heat during the ice sheet by melting ice and so destroying the ice sheet stratification there as the compacted snow melted and then turned next into frozen water ice (rather than compacted snow what it was before the heat incursion event I suspect occurring there). I support heat possibility because we have seen Vatnajokull producing Jokullhaups with huge bursts of water by volcano melting, but if the water could not escape out and once the effusive eruption fizzles out the water will freeze just the way the Gamburtsev Range soundings look like.

I would not take NASA airborne people's expedition at face value, I would rather see them going on foot and kicking stones around to come to conclusions like mine that the ice has not sufficiently shaped the mountains to justify them a greatly different age and origins to those in Iceland. I did not say that I have seen live volcanoes, but can feel suspicious of lack of planing effect of ice.

My PhD is in geochemistry so I know some pretty weird things. For a nice short write up about volcanic rocks in Greenland check out this NASA blog post.
https://blogs.nasa.gov/icebridge/2013/04/16/post_1366140794166/

FredBear

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Re: What's new in Greenland?
« Reply #254 on: May 25, 2017, 12:12:44 PM »
VeliAlbertKallio, the landscape looks similar to Spitsbergen (pointed mountains) and the "layer-cake" of rocks have obviously been eroded for some considerable time. In my opinion the layers are not distorted as they might  be in more active zones (but this is just a snap-shot)?

lifeblack

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Re: What's new in Greenland?
« Reply #255 on: May 25, 2017, 07:35:59 PM »
VelliAlbertKallio, while the peaks in the picture have an overall shape that suggests they are younger than suggested elsewhere, the features that are visible are clearly all erosional, and none of the pyramidal shapes in view were erupted as cone shaped mountains  (ie, none of the features are from a partially eroded cascade-type stratovolcano).  As evidence, look at the stacked layers of lava that are visible - they were clearly emplaced as (apparently) continuous sheets on a nearly level landscape, and they remain nearly horizontal today.
As for the height of the mountains after so many millions of years of glaciation, I might be going out on a limb here, but I think that as the rock gets eroded away, the crust will rebound upwards in response to the removal of the top layers.

I would definitely be interested in whether there are any moribund volcanic sources in Greenland that may be reactivated by decompression melting, but the landscape in  the picture doesn't seem to be good evidence of anything recent

Tor Bejnar

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Re: What's new in Greenland?
« Reply #256 on: May 25, 2017, 08:34:08 PM »
The following information is from a geologic map of Greenland, with my leading comments:
It appears the youngest igneous rocks in Greenland are on the order of 50 million years old.  I wouldn't expect the removal of all Greenlandic ice to re-energize significant (or actually any) volcanic activity. From here: "Extinct: It takes a lot to be an “extinct” volcano. The rule of thumb I use is about 1 million years since the last eruption … "


Chart describing last 100 million years of igneous rocks in Greenland (see time line screen shots):
(references are to time line reference numbers)

 
[6] Paleocene tholeiitic lavas, central West Greenland.
[7] Paleocene picritic lavas, central West Greenland.
[48] Eocene tholeiitic plateau basalts in East Greenland.
[49] Paleocene–Eocene tholeiitic basalts with picritic intervals. East Greenland.
[53] Tertiary felsic intrusions in East Greenland.
[57] Tertiary mafic to intermediate intrusive complexes in East Greenland.
[58] Upper Cretaceous gabbroic intrusion. Pearya terrane, Ellesmere Island (Canada).
« Last Edit: May 25, 2017, 08:46:52 PM by Tor Bejnar »
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VeliAlbertKallio

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Re: What's new in Greenland?
« Reply #257 on: May 26, 2017, 04:48:40 AM »
Very many thanks for the highly constructive points raised! Please note that  I raise these here as highly speculative stipulations and as a sort of brainstorming attempt and I do not see - at least for now any evidence - of geological activity. Yet, I wish to raise further detailed points for your consideration.)

I'm enclosing a very typical scenery of glacier-shaped rocks and boulders from Greenland. Even volcanic rocks, as hard they may be, are impacted and subjected to the milling of ice domes from above (if rocks were covered by one). I have seen many volatile structures on that region (unlike the Svalbard) that do not appear in any way round but look like a frozen in time, a still frame. The overall appearance is similar to water-flooding impacted strata of the Grand Canyon region, not an ice sheet gourged one. For me, the region has perhaps undergone strong isostatic uplift, but it was impacted by water floods, Jokullhaups, turning it to the Grand Canyon of Greenland. It is not geomorphic according to the ice sheet planing, if it were the volcanic mountains would have a distinctive smooth rise facing the direction ice sheet had flowed, with steep rear sides.

Source of these floods would then be Jokullhaups.

The volatile structures preserved is, therefore, suggestive to me that the rocks were hot when the ice sheet was forming (and hence expelling the local ice development unlike elsewhere). As Jokullhaups periodically discharged water and lahar, the loose, slushy stratum eroded rapidly.

If so, then the volcanic incursion is associated with the Central Greenland's subsidence when the ice dome was being deposited onto the Precambrian granites across Greenland. Thus, the incursion of magma is a result of ice sheet compressing subglacial magma reservoir and driving a partial melting of asthenosphere beneath the glaciating region - with the partial melting breakdown products being driven out here near this edge area of Greenland continental plate (where plate's weaknesses are greatest). The only option is for me to go and collect more volatile rock structure evidence which would dispel the idea of ice having carved out this peculiar area. That's a future project for me and these expeditions are costly!

There are earthquakes and the Nantortalik hot spring. I suspect that there must be more hot springs hidden beneath ice sheet as the faults are myriad. Hot springs could be behind some of the subglacial heat anomalies are found in various parts of Greenland. Today more pressurized water is fed into subglacial faults by water from moulins that are becoming increasingly active over perimetrical subglacial bedrock. Moulins one day number in millions over perimeter shield.

I expect the volcanic region (potentially) evolving to the Mascarene volcanism. A two-phase volcanism where a low viscosity, vast lava floods are followed by a long non-active interval to the previous episodes of vast effusive volcanic eruptions. Then a smaller secondary episode re-emerges a new bout of different type of volcanism which shatters the old crust and causes mountain incursions to pierce the old, lava field by the extremely high viscosity (cool) secondary lavas. This renewal of eruptivity thus shatters the solidified ('extinct') flat lava volcano field. The secondary volcanism in the Mascarene volcanos had so high viscosity that many eruptions caused vertically rising lava floods (like a toothpaste comes out of the tube when it is pointed upwards).

In the Mascareane volcanism, the force of high viscous rock oozing through flat lava field was so great that nearly all secondary volcanoes go vertigo through the plain, lava rising vertically skyward. Even parts of the old solidified lava crust sitting as a tip of the newly oozing highly viscous lava with the old solid blocks of lava becoming a mushroom-like 'hat' shapes for the volcano, i.e. Peter Both 'hat' cap. https://upload.wikimedia.org/wikipedia/commons/b/b3/Pieter_Both%2C_mountain.jpg These vertical formations rising from flat lava landscapes.

The question is of course how solid is the high viscous incursion and whether such incursions could make way up once Greenland ice sheet melts. What drives high viscous lava up is not exactly clear but some disassociation of gases must have happened, maybe further afield, pressure change reverberated from nucleating lavas elsewhere to make cool rocks to cause secondary Mascarene eruptivity. In the case of deglaciation, this could be the secondary trigger, whereas the low viscous eruptivity would have been the primary trigger, a forming ice sheet.

It is my view that the secondary Mascarene volcanism was driven by gaseous disassociating within low viscous magmas in long distance, perhaps when the hot spot was already transiting from Mauritius to nearby Reunion. Events in Iceland and/or deep partial melting in asthenosphere under Greenland could be the source to force old cool lavas in Greenland once the ice sheet mass balance losses become large enough to create Mauritian style new volcanic life on the old volcanic region.

By the way, whilst climbing to study Mount Lepus I came also across old continental blocks of rock embedded in these high viscous plumes of semi-solid rocks that had broken through the primary plain of solidified lavas and seabed. (Only years after people theorized this sunken continent.)


« Last Edit: May 26, 2017, 04:59:15 AM by VeliAlbertKallio »

Hyperion

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Re: What's new in Greenland?
« Reply #258 on: May 26, 2017, 12:22:47 PM »


Certainly some spectacular igneous pancaking in the Geike Area.



This seems to be the Skaergaard intrusion some 55 million years ago. Possibly ASSOCIATED with the PETM.
Wikipedia:
The Skaergaard intrusion is a layered igneous intrusion in the Kangerlussuaq area, East Greenland. It comprises various rock types including gabbro, ferro diorite, anorthosite and granophyre.

Discovered by Lawrence Wager[1] in 1931 during the British Arctic Air Route Expedition led by Gino Watkins, the intrusion has been important to the development of key concepts in igneous petrology, including magma differentiation and fractional crystallisation[2][3] and the development of layering.[4][5] The Skaergaard intrusion formed when tholeiitic magma was emplaced about 55 million years ago,[6] during the initial opening of the North Atlantic Ocean. The body represents essentially a single pulse of magma, which crystallized from the bottom upward and the top downward. The intrusion is characterized by exceptionally well-developed cumulate layering defined by variations in the abundance of crystallizing olivine, pyroxene, plagioclase and magnetite.

The Skaergaard is perhaps the simplest and smallest of a group of gabbroic complexes of similar age that occur along the central coast of East Greenland, which together with coeval flood basalts are part of the North Atlantic large igneous province.


I say associated because looking at the some 50ma glaciated alternating with some 100ma hothouse approximate periodicity of the last about 500ma. These Large Igneouse events seem very much clustered in the transition of meltdown. Quite plausibly causation is the deglaciation. rather than the result. Or more precisely a cyclic melt loading and unloading process causing the repeated addition of sills. Both under the ice sheets during mass loss cycles. And at distances where the super heated fluid basalt emerges through deep dyke conduits from the glaciated continent keels as hot spots or super-swells. Or from rift zones to allow spreading  when the rebuilding of icecaps as ice mass starts to destabilize and oscillate.

Heres a list from wikipedia. And a picture of the Longest seamount chain in the world left by the hotspot thats thought to have caused the biggest eruption we know of. The Ontong-Java event. The Louisville hotspot probably connects with central West Antarctica. And whats left of WAs bum is the Hikurangi,  Manihiki, Ontong Java Plateaus, and Sth Pacific Superswells. Whether Greenlands bum is going to keep feeding Iceland, or Nth Canada and Iceland feed Greenlands bum in the near future, who can say.



The Titan Hyperion was the first to understand, by diligent attention and observation, the movement of both the sun and the moon and the other stars, and the seasons as well, in that they are caused by these bodies, and to make these facts known to others; — Diodorus Siculus (5.67.1)

RoxTheGeologist

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Re: What's new in Greenland?
« Reply #259 on: May 26, 2017, 04:43:59 PM »

I think Palaeomagnetic evidence places East Greenland at around 60N when the hotspot was causing volcanism.  Is there any evidence of glaciation from that period in Greenland, or the extent of ice sheets if any? I think that the earth was pretty hot at that time, there was a long term warming event that covered the period when Greenland moved over the hotspot, so there was unlikely to be an ice sheet at all.

The North American plate is moving north west relative to the hot spot frame of reference, away from the Icelandic hotspot. Greenland has been moving in the same direction pretty much since the opening of the North Atlantic. The magma chambers that were created in Greenland by the hotspot are cold and eroded, as evidenced from the pictures. Ice unloading will not reawaken any volcanism associated with that hotspot in Greenland. It might increase the activity in Iceland.

RoxTheGeologist

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Re: What's new in Greenland?
« Reply #260 on: May 26, 2017, 04:49:32 PM »

This is worth reading, and shows how the lithosphere below Greenland is now high density, and therefore cold:

https://www.researchgate.net/figure/33681824_fig7_Figure-5-Present-day-tomographic-image-c-of-the-Iceland-hotspot-plume-modified-from

sidd

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Re: What's new in Greenland?
« Reply #261 on: May 26, 2017, 07:56:51 PM »
Fascinating soliton in ice stream going down Rink. May be associated with hi-melt summers. Requires only one bedrock GPS station time series (and some orbiting satellites ...).  The authors clearly share some of Saruman's [1] traits. Wonder if such events can be teased out by ground GPS around Jacobshawn.

Very pretty paper. Read all about it:

https://www.jpl.nasa.gov/news/news.php?feature=6857

open access  doi:10.1002/2017GL073478

I attach Fig 3c), 3d) and S11

The captions for 3c) and d) are

"(c) Pattern of mass deficit transiting the Rink Glacier during 2012 summer. About − 7.1 m of monthly thinning over the optimal domain (blue fill within the glacier trunk outlined by white line) is required to explain the mean monthly displacement (red arrow). Plotted are also the magnitudes and fulcrum positions of monthly mass anomalies (circles) that satisfy the measured monthly displacements (arrows). Notice the down glacier propagation of (negative) mass anomaly that represents the negative phase of mass transport wave. Mean monthly SMB loads are shown in the background. (d) Same as Figure 3c but for the fall/midwinter season that follows. It requires about 2.8 m of monthly thickening over the optimal domain (red fill within the glacier trunk) to explain the mean monthly displacement (blue arrow)."

The caption for S11 is in the image

sidd

[1] "His knowledge was deep, his thought was subtle, and his hands marvellously skilled ... " Tolkien, Lord of the Rings, v III, Ch. X, 1954


Reallybigbunny

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Re: What's new in Greenland?
« Reply #262 on: May 27, 2017, 12:40:21 PM »

johnm33

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Re: What's new in Greenland?
« Reply #263 on: May 27, 2017, 12:53:44 PM »

Hyperion

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Re: What's new in Greenland?
« Reply #264 on: May 31, 2017, 04:20:45 PM »
Dang! This "new mode of glacial acceleration" seems like the slushalanche effect I've been predicting from the spreading and thickening sub surface slushifer discovered in 2011. If this starts to be the new normal behaviour of glacial outflows in Greenland and WA we are looking at big trouble. If a big late summer weather system rains heavily over Greenland. say from a stuck planetary wave in the jets, and a big low in the fram vicinity lifting surfacing gulfstream heat and moisture, with a Greenland/ CAA high. its not difficult to imagine a whole lot going at once. Perhaps 40 days and nights of rain COULD cause abrubt slr.  :o
The Titan Hyperion was the first to understand, by diligent attention and observation, the movement of both the sun and the moon and the other stars, and the seasons as well, in that they are caused by these bodies, and to make these facts known to others; — Diodorus Siculus (5.67.1)

Jester Fish

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Re: What's new in Greenland?
« Reply #265 on: June 06, 2017, 01:09:40 AM »
Above normal temps forecast for June, July, August for Greenland.  I haven't checked out the forecasting verification.
 
http://iri.columbia.edu/our-expertise/climate/forecasts/seasonal-climate-forecasts/