Hyper Velocity Asteroids and Mantle Plumes

[Reality Check]

The measurement of interest (but not really ) is the radial velocity. I would expect this to be relatively small since nearby stars are in similar orbits to the Sun.
Astrometric radial velocities III. Hipparcos measurements of nearby star clusters and associations has maximum radial velocities of ~35 km/s of the clusters.

The reason why the radial velocity of stars is uninteresting is because the chance of any object hitting us from them is tiny. The reason that asteroids , meteoroids and comets hit the Earth is because there are lots and lots of them. They also happen to be in orbits in the same plane as the Earth, i.e. their orbits often cross the Earth's orbit.

 

[DeathDart]

The Stable Earth Model

Where do mantle plumes get their energy? Does it come up from the mantle? If it does come up through the mantle what form would it take and how high would the overpressure be?

Overpressure is necessary to get the mantle plume to erupt through the surface. So if the mushroom model is correct then the area of overpressure would be several hundred miles in diameter and penetrate the crust in multiple places if not hundreds of places. Then the eruptions would stop, forever. Hardly anything will extrude out onto the surface. Why couldn't this model produce a large area of flood basalts or a long lasting plume? This model might account for some local volcanic activity but it doesn't account for the massive flood basalts.

The model fails because no matter how intense and localized the heating was at the lower mantle, by the time the plume rose to the crust, the energy had diffused in all directions. It took too long getting to the surface and it spread out before it got there.

A hyper velocity impact of a stony asteroid traveling at 100 kilometers per second. The origin of this asteroid is from the Milky Way Galaxy, that big bright band in the sky (if you live in the country).

It is extremely unlikely that any of the planets of our Solar System will break loose and strike Earth. Also the asteroid belt is becoming depleted and the big rocks that are still out there could cause some serious damage, but they have a relatively low velocity. Some of the big ones could cause localized eruptions but the eruption life spans should be brief. More likely Jupiter sends them into the Sun or deeper into space.

The galaxy isn't like our Solar System. The stars locally are not in lockstep with the Sun. The Hipparcos Survey shows what could be described (over millions of years) as a shooting gallery. Most, but not all, the local stars have modest 20-50 kms relative motions. The preferred direction is along the general orbital path. Some stars are moving into and out of the galactic central plane. Because the Milky Way Galaxy is not a very flat disk, a lot of stars have orbital planes which are tilted compared to the main plane of the galaxy. So a star moves above (or below) the galactic plane and then comes through the galactic plane. Each time it enters the plane it does so in a completely different neighborhood. When it went above the galactic plane, it slowed down so when it goes through the galactic plane again the stars that it passed through on the way up have moved ahead of it.

A slow motion shooting gallery, but it is a shooting gallery. Some models of galactic motion suggest the operation of a blender with periods of massive positional changes as the galactic arm swings about. Remember the windup argument? We know the velocities are not able to explain the spiral arm structure since it would wind up very quickly. The spiral arms may indicate a wobble that is aggravated by non-linear effects in gravity. As the central bar turns, it pulls in the arms and as the bar passes, the arms move outward. It gives the appearance of a spiral without having the windup problem.

You could say that the Milky Way Galaxy sloshes a lot. So we have a picture of a galactic neighborhood where stars could easily pass very close 1/10 light year to the Solar System if we look at long periods of time. Without a correct and complete record of the impacts on Earth, we are making guesses and probabilities with a very limited database. Shell or Texaco probably have a database for the continental United States with dozens if not hundreds of impact structures. Fat chance of getting it from them.

So while the asteroid threat from within the Solar System is declining, the threat from the Milky Way Galaxy is constant when averaged over a billion years.

If an asteroid comes from the Milky Way Galaxy, it tends to have a higher velocity than local asteroids. A fraction of the Milky Way asteroids can have velocities from 100 to over 500 kilometers per second. How can we get an estimate on how often that happens? Easy, mantle plumes from impacts have a life span of 2 to 80 million years depending on their depth and the amount of energy deposited. So how many mantle plumes have been detected?

Iceland (the whole country), Hawaii, Yellowstone, New Madrid, The Rhine Graben 95%, the Colorado Plateau (extinct mantle plume?). Gravity trefoils? on the Isostatic Gravity Map of the United States in Wyoming, South and North Dakota, and Montana. I can't even guess their ages.

So on the North American Continent we have at least two active amntle plumes. The Yellowstone impact was about 18-20 million years ago. The timing on the New Madrid impact plume is in the range of 35-45 million years ago. The New Madrid mantle plume was created under where the crust split, where those three high gravity arms meet together in northern Texas. That is where the plume formed (the asteroid detonated). Depending on the angle of impact, the actual impact point could be a hundred miles from the intersection of the crust fractures. After the asteroid detonated the material of the mantle thermally expanded , it bulged out the crust producing a three armed radiating fracture. The gravity high trefoil.

Remarkable how the gravity high trefoil produced by a hyper velocity mantle detonation was branded by the Oil Companies as the sign of a failed RIFT????

Let me see lots of mafic magma erupting on to the surface in the middle of a continent and it is a RIFT? Wipe the lipstick off that Oil Company pig, I am not kissing it. The East African Rift hardly has a trefoil appearance, it looks like a linear slash.

After 4+ Billion years how does the Earth produce enough localized energy to create a mantle plume that reaches the surface quickly enough before it dissipates? It can't.

Why do some mantle plumes (Hawaii and Iceland) last so long? One piece of evidence is the material coming out of the Hawaiian volcanoes.

Page 78 The complete guide to rocks and Minerals John Farndon
Although picrite magma forms only under extreme pressures deep in the mantle, it is the one ultramafic rock that normally erupts on the surface as lava, as it did in the 1959 eruption of Kilauea in Hawaii. In this eruption, gigantic fire fountains shot out picrite lavas containing as much as 30% olivine. Yet for picrite to erupt as lava like this, temperatures must be very high indeed.

Page 68 The parasitic cones of the Hawaiian shield volcanoes often ooze trachyte lava.

So some silicates and lighter materials get dragged in by the asteroid. A channel is also formed through the mantle. Even if the heat of detonation dissipates, the material is still erupting because of the buoyancy of the lighter silicate materials that were dragged into the mantle. So the lava coming out of the plume can change as different parts of the mantle and the crust are erupted. These materials were mixed together by a rapid mechanical process, not by some billion year old tectonic process.

So the simplest explanation for the mantle plume? A hyper velocity asteroid punches through the crust traveling hundreds of miles into the mantle before detonating. The crust above the point where the asteroid detonated is forced up by thermal expansion. High density magma rapidly fills the cracks while massively over pressured (Yes a Billion Megatons can easily cause overpressure) magma fountains high into the atmosphere. Pretty, if you are seeing it from a couple of million miles away. The shape of the surface fracture above the mantle detonation usually has threes arms radiating from a central point. Most such trefoil structures are impacts and not rifts.

Actually there is a mechanism for hot mantle material to get to the surface quickly enough to melt surface material. If an impact produces a deep enough channel, it can be fed hot material by the lower mantle. It still has to be started by an impact creating the channel.

 

[Reality Check]

Where do mantle plumes get their energy?
...snipped wall of fantasy...

Mantle plume

There is speculation that some mantle plumes are caused by large-body impacts at hypervelocity.

Hypervelocity refers to velocities in the range from a few kilometers per second to some tens of kilometers per second.

This is not your fantasy of "hyper velocity" (>100km/s) impacts.

 

[Reality Check]

List of the "Milky Way asteroids" that have been detected and their velocities

A fraction of the Milky Way asteroids can have velocities from 100 to over 500 kilometers per second.

Is this an actual fantasy , DeathDart, or do you have evidence?
Start with a list of the "Milky Way asteroids" that have been detected and their velocities.

 

[Reality Check]

How can we get an estimate on how often that happens? Easy, mantle plumes from impacts have a life span of 2 to 80 million years depending on their depth and the amount of energy deposited.

Classical circular reasoning, DeathDart !
You assume that all mantle plumes are formed by impacts and then use this assumption to assert that all mantle plumes are formed by impacts!

 

[Reality Check]

So the simplest explanation for the mantle plume? A hyper velocity asteroid punches through the crust traveling hundreds of miles into the mantle before detonating.

So the simplest explanation for the statement is ignorance, DeathDart !
A hyper velocity asteroid explodes at the surface and forms a crater.

 

[Checkmite]

Where do mantle plumes get their energy? Does it come up from the mantle? If it does come up through the mantle what form would it take and how high would the overpressure be?

Overpressure is necessary to get the mantle plume to erupt through the surface. So if the mushroom model is correct then the area of overpressure would be several hundred miles in diameter and penetrate the crust in multiple places if not hundreds of places. Then the eruptions would stop, forever. Hardly anything will extrude out onto the surface. Why couldn't this model produce a large area of flood basalts or a long lasting plume? This model might account for some local volcanic activity but it doesn't account for the massive flood basalts.

The model fails because no matter how intense and localized the heating was at the lower mantle, by the time the plume rose to the crust, the energy had diffused in all directions. It took too long getting to the surface and it spread out before it got there.

We know that's not true, because of plate tectonics. The mantle convects - heated areas rise, move laterally underneath the crust (pulling portions of the crust along with them), and then sink in areas of lower heat. If as you say it would take very little time for heat to dissipate equally throughout the mantle, this convection should not happen at the scale it does, which requires the mantle to be hotter in some parts and cooler than others for extended periods of time, even at the sub-crust level. If it's possible for that kind of thermal disparity to exist in even the shallow mantle, then it's possible for unusually hot packets of mantle material developed near the core to still be relatively hot when they reach shallower levels.

The rest of your post suggests to me that you might have a misconception of the characteristics of the mantle. The mantle is only liquid where it meets the bottom of extremely thin regions of the crust or the open air. Everywhere else, the mantle is very much quite solid rock. Even the most relatively plastic and ductile portions of it are nevertheless completely solid. It moves around inside the Earth; but almost imperceptibly over short scales of time - we're talking on the order of a handful of millimeters a year. The length of time of the Siberian LIP event - or any plume-related volcanic features if indeed they are such - is actually predicted by the convective speed of the mantle (whether we're talking about actual mantle plumes or other, more shallow-mantle theories).

 

[Dinwar]

We know that's not true, because of plate tectonics.

That, and things like subducted sea floor and fractional melting. The Andies offer a fantastic test of the timing of heat transfer--you've got a subduction zone to the west, and a volcanic chain to the east. The volcanoes are powered by partially melted subducted rock. The heat required to melt the rock was put into the rock during roughly half the time it took to go from "subducted below the MoHo" to "KABOOM!" (It's very rough, but it'll put you in the right order of magnitude I should think.)

Subducted sea floor slabs are an even more serious blow to the idea that the mantle should be one homogenous temperature. They're cold compared to the surrounding rock (they have to be, otherwise they'd melt--they're mafic, not ultramafic like the mantle), and would tend to create cold zones even if the mantle started out homogenous. And we know they exist, and are still quite firm, thanks to a few spectacular earthquakes in recent years.

These demonstrate the flaw in assuming that planet-scale systems operate in the same way that a tea kettle does. These are enormous structures, and that size plays havoc with our intuition.

 

[RenaissanceBiker]

I'm not sure how this thread got started and I don't know enough about the specific geological formations you are talking about, but I am amused by some of these gems.

Because of orbital physics anything going faster than about 50 kms has to come from outside the Solar System. Nothing can enter this Solar System from the universe because the Solar System is protected by a force field.

Nothing can enter our solar system?

Star proper motion for nearby stars converted to linear relative motion can produce a velocity difference of 25 to 400+ kms. Guess who is coming to dinner and it isn’t Sidney Poitier.

Good thing we have that "force field."

An object moving at velocities near or above 100kms may self focus by a very strange mechanism. It may literally collapse into a narrower and denser kinetic object.

100 kms relative to what? I just did the conversion and 100 kms = 0.0003 C.

 

[DeathDart]

I'm not sure how this thread got started and I don't know enough about the specific geological formations you are talking about, but I am amused by some of these gems.


Nothing can enter our solar system?


Good thing we have that "force field."


100 kms relative to what? I just did the conversion and 100 kms = 0.0003 C.

The force field was a joke. Of course the universe can send anything our way that physics allows. And if human physics is wrong, it can send that stuff too. The sloshing of the galaxy makes encounters murderously complicated.

So arguments about the universe staying outside our Solar System are ludicrous and parochial. Given the local stars have velocities all over the place, many with vectors that can bring them much closer, how can you argue that the Solar System is sacrosanct, untouchable.

Capture of extrasolar material is unlikely. The most probable delivery system for extrasolar material is impact. We have been able to spot small bodies out to Jupiter for about … 20 years. So we run this program for 50,000 times longer we get to a million years. From the impact plumes we know about they occur roughly at intervals of about 5 to 10 million years. Energy seems to be around 100,000 megatons (a guess) At 100kms that is about a 3.7 kilometer wide stony asteroid. If it is carbonaceous, it reflects about 2% of the light back. Traveling at 100kms it will take 73 days after it crosses the orbit of Jupiter to hit. If it is just zooming past, we might be able to see it for about twice that time. Unlike our asteroids they won’t stick around to be discovered. So we haven’t spotted one with our technology in the last twenty years. That is not statistically significant for an event that might happen at 5,000,000 year intervals.

100kms relative to the big blue marble.

 

[DeathDart]

That, and things like subducted sea floor and fractional melting. The Andies offer a fantastic test of the timing of heat transfer--you've got a subduction zone to the west, and a volcanic chain to the east. The volcanoes are powered by partially melted subducted rock. The heat required to melt the rock was put into the rock during roughly half the time it took to go from "subducted below the MoHo" to "KABOOM!" (It's very rough, but it'll put you in the right order of magnitude I should think.)

Subducted sea floor slabs are an even more serious blow to the idea that the mantle should be one homogenous temperature. They're cold compared to the surrounding rock (they have to be, otherwise they'd melt--they're mafic, not ultramafic like the mantle), and would tend to create cold zones even if the mantle started out homogenous. And we know they exist, and are still quite firm, thanks to a few spectacular earthquakes in recent years.

These demonstrate the flaw in assuming that planet-scale systems operate in the same way that a tea kettle does. These are enormous structures, and that size plays havoc with our intuition.

What is the lava production of this volcano chain?

Can it produce 100,000 CUBIC KILOMETERS in less than one year? How long before it can produce 4,000,000 CUBIC KILOMETERS of lava?

I am sure if unbiased measurements were made at the Siberian Traps you would find the intitial event and flood basalts were close to this scale.

Again the energy signature is not of a terrestrial process. Too much energy in too limited an area.

 

[DeathDart]

The convection models are used for plate tectonics. Typical yearly production of magma is less than 10 cubic kilometers per year for the planet.

The convection model doesn’t come close to matching the output of a mantle plume.

So was it thermal convection or chemical convection? They are reaching for anything except an impact event.

After what period of time does the initial perturbation (chemical or thermal) stabilize? Why hasn’t it stabilized after 4.5 billion years? How do you create a new perturbation, a thousand miles below the crust?

A big rock from outside of this Solar System traveling at 100 kms delivers 1000’s of megatons of thermal energy below the crust and deep into the mantle. It really does create a mantle plume with a massive production of flood basalt.

From the geological garbage since 1980 it appears that several small mantle plume events occurred in the American West (last 40 million years). I am always suspicious about Island Arc events, in the middle of a continent?

Instead of follow the money, follow the basalt! A little basalt inside of a continent, no big surprise. A lot of basalt with tracks going in the opposite direction of the NAM tectonic movements, you have a potential impact plume. Especially if the track abruptly starts for no apparent reason, with a lot of flood basalts.

 

[Reality Check]

The convection models are used for plate tectonics. Typical yearly production of magma is less than 10 cubic kilometers per year for the planet.

Citation?

And what has this to do with mantle plumes?

A mantle plume is a posited thermal abnormality where hot rock nucleates at the core-mantle boundary and rises through the Earth's mantle becoming a diapir in the Earth's crust.[2] Such plumes were invoked in 1971[3] to explain volcanic regions that were not thought to be explicable by the then-new theory of plate tectonics. Some of these volcanoes lie far from tectonic plate boundaries, e.g., Hawaii. Others represent unusually large-volume volcanism whether on plate boundaries, e.g., Iceland or basalt floods like the Deccan or Siberian traps.

Mantle plumes are an additional mechanism for producing volcanic activity (and thus magma!). The amount of magma produced by plate tectonics has nothing to do with the productions of magma from mantle plumes.

This still means that your idea of the creation of mantle plume from the physically impossible "tunnel" of a meteor impact remains wrong.

So DeathDart- follow the physical facts - impacts create craters, not tunnels !

 

[Reality Check]

DeathDart, are you ignorant of what circular reasoning is

So arguments about the universe staying outside our Solar System are ludicrous and parochial.

The argument that the universe constantly bombards the Solar System with asteroids (and maybe planets and stars ), is ignorant and parochial.

Asteroids are small. Space is very, very, very big.

Given that you have no evidence that local stars have velocities all over the place, many with vectors that can bring them much closer, your argument that the Solar System is touchable. is so far a fantasy.

DeathDart, are you ignorant of what circular reasoning is?
This is the second time that you have used this logical fallacy.
You cannot use your premise to prove your premise !

You especially cannot use a physically impossible premise to prove a premise!

 

[wollery]

Still no calculation for the collisional cross-section of the Earth and other Solar system bodies for an extra-solar rock.

Quelle surprise.

 

[Dinwar]

The convection models are used for plate tectonics. Typical yearly production of magma is less than 10 cubic kilometers per year for the planet.

The convection model doesn’t come close to matching the output of a mantle plume.

And the annual flood height of most rivers isn't anywhere close to what they produce after a once-in-a-lifetime huricane hits the drainage basin. Doesn't mean that our calculations for flooding don't work.

You're talking about two completely different systems here. Plate tectonics doesn't adequately describe magma plumes, but we know that. PT may in part be driven by magma plumes. Your argument assumes that PT drives plume production. It's nonsense.

 

[RenaissanceBiker]

Just to clarify a point. Mantle plumes and volcanoes do not produce magma. They simply allow it to move around. Magma is not really being created by these things.

 

[Dinwar]

Well, considering how much else DeathDart is getting wrong I'm willing to let the difference between magma and lava slide.

 

[DeathDart]

Evidence for Extrasolar Asteroid Impact: Mars

The impact was at Hellas Basin on Mars. The apparent direction of the impact vector was toward the northern (rotation) pole. Approximately 35% of the planet around the northern pole was resurfaced in the last 300 million years. Very little cratering in the Northern Lowlands so it is relatively young.

The asteroid may have entered at the Hellas Basin and detonated somewhere below the northern pole. If it had completely penetrated the planet the superheated (> 50,000 K) asteroid would explosively expand and partially or totally resurface the Northern hemisphere.

Because the Northern Hemisphere is lower by about 4 kilometers than the rest of the planet, it appears that the asteroid carried away a significant portion. About 1/10th of 1 percent of Mar’s mass either, when the asteroid exited, or when the plume fountained material at escape velocity. This indicates that at a minimum that some of the molten material attained Martian escape velocity.

Since my E-Mail server is being spoofed I cannot send e-mail reliably. This is the error that I get.

There is a problem with this website's security certificate.
The security certificate presented by this website was issued for a different website's address.
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This suggests that instead of a com server it is on a .gov or .mil server.

Edited by LashL: 

Removed inappropriate content.

 

[Reality Check]

No Evidence for Extrasolar Asteroid Impact: Mars

The impact was at Hellas Basin on Mars. ...
...snipped strange stuff about email...
...snipped stuff about some moron!...

DeathDart - you presented no evidence for the Hellas Basin being formed from an extra solar asteroid.
Hellas Planitia

Hellas Planitia, also known as the Hellas Impact Basin, is a huge, roughly circular impact basin located in the southern hemisphere of the planet Mars. It is the second or third largest impact crater and the largest visible impact crater known in the Solar System. The basin floor is about 7,152 m (23,465 ft) deep, 3,000 m (9,800 ft) deeper than the moon's South Pole-Aitken basin, and extends about 2,300 km (1,400 mi) east to west.[2][3] It is centered at

WikiMiniAtlas
42°42′S 70°00′E / 42.7°S 70°E / -42.7; 70[4]