11/13/2019
After a 6 month break from working on this web site, I developed a new hypothesis based on information first explored on my Space Rocks page 111. I have a plausible hypothesis for the asteroid belt's formation. Within this hypothesis, I may have also found an explanation for Mars' strange topography. This page is an attempt to dig into and explore this idea.
Several concepts need to be understood in order to appreciate my hypothesis.
Several concepts need to be understood in order to appreciate my hypothesis.
- The Grand Tack Hypothesis
- Asteroid Belt Formation
- Jupiter's Roche Radius
- Tidal Flex
- Jupiter's Trojans
- Pallasite Meteorites
- Olivine Deposits on Mars
- My Roche A-Tack Hypothesis
- The Grand Tack Theory
My hypothesis is built around the Grand Tack Theory which goes something like this.
- Jupiter was the first planet to form, as such, it grew to be the largest since it had the most solar system stuff available to eat.
- Jupiter formed around 3.5 AU from the Sun (one AU equals Earth distance to Sun, (149.6 million km, 92,584,307 miles)).
- Jupiter then migrated inward to within Mars' orbital zone 1.5 AU, (Mars perihelion = 1.381 AU, aphelion = 1.666 AU).
- Saturn and Jupiter entered into an orbital resonance which pulled Jupiter back to a higher orbit eventually settling at its current location of 5.2 AU. Hence, Jupiter crossed the asteroid belt twice.
- The asteroid belt resides between 2 and 3.25 AU.
- The asteroid belt zone was originally inhabited by 6 or 7 planetesimals with a combined mass equal to Earth's mass.
- Jupiter's gravity caused the 6-7 planetesimals to collide and self destruct ejecting 99.9% of the material from this zone.
- Jupiter also removed most of the material from Mars' orbital zone making it smaller than it should be. Mars should be basically the mass of Earth but is instead 10.7% (ten percent basically) or one tenth Earth's mass.
The asteroid belt, long purported to be just a jumbled hodge podge of rocks orbiting between Mars (1.5 AU) and Jupiter (5.2 AU) is now known to have been formed from a family of 6 or 7 preexisting large parent bodies. Isotopic studies show there were at least 6 ancient parent bodies in the asteroid belt zone while mineralogic studies point to 7 distinct bodies. |
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Science models indicate the asteroid belt should contain material equal to at least one Earth mass but instead it has less than one tenth of one percent. Jupiter's grand tack trip, twice crossing the asteroid belt, is used to explain the loss of all this material due to impacts and ejections via gravitational perturbations.
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In other words, there used to be 7 large bodies smaller than Mars which were driven to self-destruction by collisions.
We partially know these parent bodies existed because pallasite meteorites like Fukang could only develop inside a body with specific pressure and heat conditions. Additional corroborating evidence comes from spectrographic similarity, resonance, inclination and the orbital eccentricity that these groups of objects share. The current prevailing assumption is that when Jupiter crossed the asteroid belt zone it caused "six" planets to collide, the collisions were responsible for their destruction, |
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Jupiter, then, gravitationally scattered more than 99.9% of the debris toward the Sun or outward forming the Oort cloud. When the Grand Tack Theory was created, six planets were thought to have originally existed in the asteroid belt because of six distinct isotopic variations found inside pallasite meteorites. But today, mineralogic evidence shows seven distinct planets existed. What are the odds all 7 objects (not 6) serendipitously collided, completely destroying each other?
There were 7 large bodies driven to self destruction, the question is how, not if.
My question is, "Is collision impact alone a reasonable explanation for all seven of the planetesimal's annihilation?"
There were 7 large bodies driven to self destruction, the question is how, not if.
My question is, "Is collision impact alone a reasonable explanation for all seven of the planetesimal's annihilation?"
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No, absolutely not!
Not in my opinion. How do I explain their destruction?
The Roche Radius is a zone where a planet's tidal forces tear apart orbiting bodies. The Roche radius is the distance at which a satellite is torn apart by the larger body's gravitational force. This distance depends on the densities of the two bodies but as a general rule it is about 2.44 times the radius of the parent body. |
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All the gas giant planets, Jupiter, Saturn, Uranus and Neptune have rings and all of these rings reside inside their respective Roche limits. In essence, the Roche Radius is what creates ring debris around planets.
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Any satellite that reaches the Roche limit of a planet, will be destroyed and turned into ring fodder for the planet (assuming the planet is gravitationally strong enough to do so).
Obviously most of the destroyed satellite's material will become ring debris eventually falling into the planet some will be ejected away from the planet but a very small amount will escape both processes. Perhaps less than one tenth of one percent of the original satellite body will escape Jupiter's cannibalism and/or ejection to remain mostly near its original orbital trajectory. |
Saturn's Roche Limit
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Tidal flex energy is a relatively new concept (1979), as such, its not an idea incorporated into much of the scientific interpretations related to the energy induction process of proto-planet, planetesimal, embryo and planetary formation. Instead most science papers written about moons or planetary rounded bodies (in hydrostatic equilibrium) tend to utilize the concept of radioactive decay and/or accretion (impact) processes to explain a planet's internal heat source. However, tidal flex is a very dominant energy source in the solar system its more relevant than accretion (impact) heat energy and I'm suggesting its even more relevant than radioactive decay energy. |
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I say this because unlike radioactive decay and impact energy, tidal flex energy is ongoing. Its a persistent regular relatively stable form of input energy its not typically reducing or decaying over time, in fact it can increase over time depending on dynamic orbital parameters.
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Mercury
NASA's probe, Mariner 10, in 1974 flew past Mercury and discovered something that had been assumed to be impossible. Since Mercury (2,440 km) is such a small planet, it's core should have cooled into a solid ball of metal by now. In essence, it doesn't have enough radioactive material or residual accretion heat energy to have a hot core after 4.5 billion years. Hence, it was naturally assumed to be a dead planet but we didn't know about or consider the effect of tidal flex energy as a constant input energy source induced by its orbital eccentricity. |
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Turns out Mercury is not only geologically active but it also has a magnetic field which means it has a churning molten core due to its orbital eccentricity with the Sun which induces tidal flex into the planet. Mercury's eccentric orbit of 0.205 is the largest of all the planets except for Pluto.
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Jupiter's moons Io, Europa & Ganymede Jupiter has three geologically active moons, Ganymede which is similarly sized to Mercury and Io and Europa which are smaller than Mercury. All of these moon's cores are heated by tidal flex energy. Io (1,815 km radius) is heated by tidal flex such that it's rocky surface is the most volcanically active in the solar system spewing out ultramafic lava (really hot), (much hotter than Earth's lava). Mercury is only 5.5% the mass of Earth while Io is only 1.5% Earth's mass and yet Io (via tidal flex) is far more volcanically active, hot and energetic than Earth. Tidal flex is a significant source of current, consistent, regular induced energy. |
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Europa Europa (1,569 km radius) is less than 1% the mass of Earth and has evidence of an active core from tidal flex energy. Europa has an icy outer shell with deposits of sulfur salt minerals lining its surface ice fractures. These brown minerals are delivered to Europa's surface through hydrothermal vents contained inside a very thin layer of salty ocean water below the icy outer shell. The hydrothermal vent energy source is explained by tidal flex energy induced into Europa by Jupiter |
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Ganymede Ganymede (as moons go) is quite large (2,634 km radius), its 2.5% the Earth's mass, it is physically slightly larger than the planet Mercury but it is half Mercury's mass. In other words it has less than half the radiogenic material as Mercury. It has a magnetic field which means it has a churning molten hot core created by (you guessed it) tidal flex energy not radiogenic or impact energy, rather flexing and stretching caused by its orbital relationship to Jupiter. Ganymede has auroras similar to Earth's created by its magnetosphere's interaction with Jupiter's radiation belt. |
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Saturn moon Enceladus
Enceladus is puny (252 km radius), its less than half the size of Pluto's dead moon Charon. Enceladus is so small it's near the boundary where a body can gravitationally make itself round. It is only geologically active because of induced tidal flex energy. It is tidally stretched by Saturn and as such is geologically active. Enceladus is spewing out guessers of ice crystals from its south pole which are forming Saturn's E ring. |
Enceladus should not, by any radiogenic or impact scenarios be geologically active but it is because of regular tidal flexing induced by its orbit around Saturn.
Location of rings, Enceladus and Mimas
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Enceladus forming the E ring
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To put Enceladus' small size in perspective, it has a radius of 252 km while Neptune's moon Proteus is 210 km. This is Proteus, its orbit is circular not eccentric, no tidal flexing. Proteus' shape is irregular not round. Its density is 1.3 g/cm³, Enceladus' density is 1.6. They have similar amounts of rocky, potentially radioactive, material. Proteus is dead. Enceladus is not. |
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Saturn moon Mimas
Mimas (198 km radius) is only one of two known rounded solar system bodies smaller than Enceladus. Mimas is the smallest rounded body in the solar system and is considered shaped due to tidal flexing forces. Wiki quote; Due to the tidal forces acting on it, Mimas is noticeably prolate; its longest axis is about 10% longer than the shortest. 
Oblate --------------------------------- Prolate
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Mimas' density is only 1.15 g/cm³, its almost completely ice (lacking radiogenic material) and is smaller than Proteus but is rounded by tidal flex energy alone.
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Uranus moon Miranda
Miranda (235 km radius) Wiki Quote Precisely how a body as small as Miranda could have enough internal energy to produce the myriad geological features seen on its surface is not established with certainty,[18] though the currently favoured hypothesis is that it was driven by tidal heating during a past time when it was in 3:1 orbital resonance with Umbriel.[20] The resonance would have increased Miranda's orbital eccentricity to 0.1, and generated tidal friction due to the varying tidal forces from Uranus.[21] As Miranda approached Uranus, tidal force increased; as it retreated, tidal force decreased, causing flexing that would have warmed Miranda's interior by 20 K, enough to trigger melting.[21][12][13] |
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Neptune moon Triton
Triton is basically Pluto's twin and is a moon thought to be captured by (not accreted around) Neptune. When Voyager 2 flew past Triton it actually took images of actively spewing plumes erupting from the surface. Triton has active volcanism or perhaps better described as cryovolcanism taking place on its surface. Care to guess how scientists explain this phenomenon? Yep! Tidal flex from its off center equatorial orbit around Neptune. |
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Earth and it's Moon
Scientists have been baffled by Earth's core remaining so hot after 4.5 byr as they are mentally tied to the concept that the core could only have been heated by radioactive decay and heat from the original accretion (impacts) process.
Scientists have been baffled by Earth's core remaining so hot after 4.5 byr as they are mentally tied to the concept that the core could only have been heated by radioactive decay and heat from the original accretion (impacts) process.
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But I would suggest the Earth is still being heated by the eccentric orbit of the Moon as well as Earth's own eccentric orbit around the Sun.
When NASA landed on the Moon, scientists left behind seismic sensors and these sensors sound off once per month due to the Moons orbital eccentricity with the Earth. In other words, the Moon registers regular seismic activity as a direct result of its orbital characteristics around the Earth. Or you could say the Moon is tidally flexed every month due to its eccentric orbit around Earth. The moon is receding from the Earth (3.8 cm (1.49 in) per year) meaning its tidal flexing was previously much stronger. This same gravitational flexing energy is induced into Earth by the Moon. Older science theories suggest the Mare (dark flat planes) on the Moon were created by impacts but more recent, more accurate information shows how these Mare were created by volcanic processes. The dark Mare blotches are volcanic lava flows. |
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The near and far side of the Moon look completely different. The near side is much smoother than the far side.
The near side of the moon is much younger than the far side as there are noticeably fewer impact craters inside the Mare. This suggests, in part, that the Mare formed once the Moon locked its near side toward the Earth, then the Earth's gravity focused its pull on the dense lava raising it to the surface. |
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The crustal thickness of the far side of the moon is as much as 60 km thicker than the near side. While the near side of the Moon is more dense than the far side its depth is more shallow.
The dense side of the Moon always faces the Earth since the Moon is tidally locked to Earth. This suggests that after the Earth stopped the moon's rotation, it gravitationally pulled the moon's dense magma to the surface. The smoother younger more dense near side Mare on the Moon display some similarities to Mars' surface as well as its northern hemisphere (NH). |
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Mars This brings us to my whole point about tidal flex. Since Jupiter, during the grand tack model, was once within Mars' orbital zone it, would have tidally flexed Mars. 
Tharsis region
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Mars topographic map
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National Geographic quote
There are three basic types of magma: basaltic, andesitic, and rhyolitic, each of which has a different mineral composition. All types of magma have a significant percentage of silicon dioxide. Basaltic magma is high in iron, magnesium, and calcium but low in potassium and sodium. It ranges in temperature from about 1000oC to 1200oC (1832oF to 2192oF). Andesitic magma has moderate amounts of these minerals, with a temperature range from about 800oC to 1000oC (1472oF to 1832oF). Rhyolitic magma is high in potassium and sodium but low in iron, magnesium, and calcium. It occurs in the temperature range of about 650oC to 800oC (1202oF to 1472oF). Both the temperature and mineral content of magma affect how easily it flows.
The viscosity (thickness) of the magma that erupts from a volcano affects the shape of the volcano. Volcanoes with steep slopes tend to form from very viscous magma, while flatter volcanoes form from magma that flows easily.
Olympus Mons is a shield volcano with low slopes indicating it expelled a hot magma (ultramafic) that flowed easily. Mars' surface gravity is one third that of Earth (viscous lava would flow really slow) and it is far colder than Earth (lava would cool much faster) yet massive outflows of really hot magma occurred over extreme time frames.
There are three basic types of magma: basaltic, andesitic, and rhyolitic, each of which has a different mineral composition. All types of magma have a significant percentage of silicon dioxide. Basaltic magma is high in iron, magnesium, and calcium but low in potassium and sodium. It ranges in temperature from about 1000oC to 1200oC (1832oF to 2192oF). Andesitic magma has moderate amounts of these minerals, with a temperature range from about 800oC to 1000oC (1472oF to 1832oF). Rhyolitic magma is high in potassium and sodium but low in iron, magnesium, and calcium. It occurs in the temperature range of about 650oC to 800oC (1202oF to 1472oF). Both the temperature and mineral content of magma affect how easily it flows.
The viscosity (thickness) of the magma that erupts from a volcano affects the shape of the volcano. Volcanoes with steep slopes tend to form from very viscous magma, while flatter volcanoes form from magma that flows easily.
Olympus Mons is a shield volcano with low slopes indicating it expelled a hot magma (ultramafic) that flowed easily. Mars' surface gravity is one third that of Earth (viscous lava would flow really slow) and it is far colder than Earth (lava would cool much faster) yet massive outflows of really hot magma occurred over extreme time frames.
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Olympus Mons is thought to be 2.54 to 3.67 byr old, that's a 1.13 billion year period through which Olympus Mons developed and erupted several times.
Here on Earth, with its churning active hot core, the life span of volcanoes is months to several million years not hundreds of millions of years or even more than a thousand million (billion) years. This makes Olympus Mons' billion year life span unique. Tiny Mars, a tenth the size of Earth, erupted really hot lava over the course of a billion years. If these volcano eruptions are tied to Jupiter's tacking process then Jupiter likely began tacking inward around 4 Ga then outward by around 3 Ga. |
Topography of Mars, MOLA Science Team, NASA
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The grand tack model does not support this time frame, it suggests the tack process took place in a few million years. However, Sean N. Raymond and Alessandro Morbidelli in their paper "The Grand Tack model: a critical review" state the following, We show that some uncertainties remain regarding the Tack mechanism itself; the most critical unknown is the timing and rate of gas accretion onto Saturn and Jupiter.
Mars also has four to five fractured and tectonically raised plates within the Tharsis region.
Mars also has four to five fractured and tectonically raised plates within the Tharsis region.
Mars Tharsis Region with fractured plates
The Tharsis region on Mars looks similar to the bulging spider (expansion fractures) region on Pluto. Mars' crust is made of rock while Pluto's is rock hard ice. The difference in energy to create these two similar features is significant.
Antipodal to Mars' Tharsis region (highest elevation and density) is Hellas Basin with the (lowest collapsed depression) and weakest gravitational zone. 
Pluto's Spider with central cryovolcano
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Pluto's Spider with a cryovolcano at its center
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Similar to how Earth's tidal flexing of the Moon created its Mare and crustal deformation, Jupiter's tidal flexing of Mars, most likely, formed the Tharsis region which subsequently created Valles Marineris and Hellas basin.
Tidal flex is a major contributor to solar system body tectonic formation/deformation processes, differentiation of core/mantel boundaries and induced core heat energy. Impacts and radiogenic decay certainly play a dissipative roll but tidal flex is a significant ongoing persistent energy induction heating process. Over time, processes like radioactive decay and accretion dissipate while a process like tidal flex remains constant or in some cases even increase.
Tidal flex is a major contributor to solar system body tectonic formation/deformation processes, differentiation of core/mantel boundaries and induced core heat energy. Impacts and radiogenic decay certainly play a dissipative roll but tidal flex is a significant ongoing persistent energy induction heating process. Over time, processes like radioactive decay and accretion dissipate while a process like tidal flex remains constant or in some cases even increase.
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Trojans are a collection of asteroids/comets trapped in two zones 60 degrees ahead and behind Jupiter. These two zones are called Lagrange points L4 and L5. I am suggesting, at least some of, these Trojans are debris created by Jupiter when it crossed the asteroid belt zone placing the 7 parent bodies within its Roche limit. My scenario is this. Jupiter migrated inward tearing apart (via Roche radius) the original 7 planetesimals, it ate much of the debris scattered and eject more of it, captured some of it at L4 and L5 and left a very small portion behind as pallasites, rocky asteroids and rocky chondrule dominated carbonaceous meteorites. While impacts may have caused one or two of the original planetesimals to collide and self destruct it is much more likely Jupiter's gravitational force performed the bulk of the destructive work via tidal flexing and Roche radius destruction. |
Space rocks come in three forms; Stony, Iron, and a mix of Iron/Stone. Pallasite is another name for Iron/Stony meteorites. The stony part of pallasite is primarily olivine which is a silicate glassy type of volcanic rock similar to obsidian. The formation process of pallasite is still controversial. The primary area of discussion revolves around the rate at which the iron cooled as knowing this has implications about the depth at which the iron developed inside its parent body. 
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Widmanstatten patterns are linear bands that develop in slow cooling nickel iron alloys while fast cooling metal does not have time to form crystalline linear structures and is amorphous or globular. Widmanstatten patterns indicate slow cooling while non structured nickel iron blobs indicate fast cooling rates. Most pallasites show signs of fast cooling rates while some show signs of both fast and slow cooling rates taking place within one pallasite meteorite. |
Early scientific conclusions about pallasite formation favored slow cooling at greater depths (0.5-2°C per million years, initial temp = 700°-300°C, at 150-300 km depths) processes, however, newer scientific evaluations of pallasite favor shallower depth and faster cooling (20-200°C per year, initial temp = 1100° to 600°C, at 15 km depth) forming processes. The slow cooling rates listed are 2 to 5 orders of magnitude too slow compared to more current values. In other words, the slow cooling rates should range from 5-20°C/100,000 yrs to 5°-20°C per 100 yrs while the fast pallasite cooling rate studies favor cooling on an annual basis.
The cooling rate for pallasite, not just molten to solid but hot solid to cold solid iron would then reduce to the slow cooling rate of about one to ten thousand years and to a fast cooling rate of about 5-20 years. That's a pretty big shift away from 100 million or more years.
Earlier studies by scientists suggest the iron/nickel metal cooled slowly deep inside (150-300 km) parent body in a temperature range of 700-300°C near the metal/rock (core/mantel) boundary while other scientists suggest this can't be the case as the pressures at these depths would have the effect of squeezing molten metal out the bottom of the pallasitic layer and molten mafic silicate out the top resulting in a virtually pure dunitic mantle and an olivine free core. According to Wood [1981], deformation great enough to obliterate the characteristic pallasite geometry would be experienced by olivine crystals at the core-mantle interfaces of planets larger than about 15 km radius. In other words, the density of liquid iron would squeeze the less dense olivine out of the iron if pallasite formed at the core/mantel boundary, thus pallasite could not be formed at this deep zone within a parent body. Makes perfect sense!
Boesenberg et al. (2012)
it should be noted that pallasites do not consist of olivines floating in a metal matrix, as they are often described, but should be more correctly described as metal trapped within an interconnected olivine assemblage. In essence, pallasites were formed by melted metal oozing outwards from the core filling the spaces and intruding into olivine clusters. The less dense olivine did not sink down into a more dense pool of liquid metal.
Andrew Davis & Edward Olsen, Nature.
These patterns are consistent with crystallization of phosphate from a europium-depleted chondritic liquid. This is unlikely to have happened near the base of the differentiating parent-body mantle, because phosphates are late-crystallizing phases; this suggests that some pallasites may come from regions of their parent bodies much nearer the surface than the core–mantle boundary.
M. Miyamoto, Mineralogical Institute, University of Tokyo, Hongo, Tokyo, Japan
The presence of chemical zoning in pallasite olivines suggests a rapid cooling of pallasites at a late stage in their formation, sufficient to escape homogenization of chemical zoning
In order to reconcile the fast cooling rate obtained by chemical zoning of pallasite olivine with the slow cooling rate by Fe-Ni data, a plausible explanation is two-stage cooling, that is fast cooling at high temperatures to form chemical zoning of olivine at the first stage of cooling, and subsequent slow cooling at low temperatures to form the Widmanstatten pattern and to escape homogenization of olivine zoning at the second stage of cooling. A slow cooling rate at the second stage of cooling can be caused by a thick covering of regolith by an impact at a late stage of cooling or reassembly of the parent body [e.g., Taylor et al., 1987].
A likely explanation for the observation is that the parent body was broken apart while still partly molten. The fragments would probably cool rapidly, giving the zoning profile observed. Upon reassembly, most of the objects would be buried deeply, allowing for the metallographic cooling rate to be as slow as that observed.
The presence of chemical zoning of olivines in unequilibrated chondrites may be a similar situation to that of pallasite olivines. Although the cooling rate of chondrites determined by Fe-Ni data is as low as that of pallasites [e.g., Wood, 1979], olivines in unequilibrated chondrites still preserve chemical zoning which formed during initial cooling at high temperatures [e.g., Miyamoto et al., 1986]. Chemical zoning which records a rapid cooling at high temperatures is preserved through slow cooling at low temperatures. However, it should be noted that the metallurgical cooling rates of unequilibrated chondrites may contain large errors because of the metal grains with widely varying Ni compositions (J. T. Wasson, personal communication, 1997).
Two stage cooling took place in pallasites, a process that seems self evident based on Widmanstatten patterns (slow cooling linear structures) found encased inside amorphous looking globular molten metal structures (fast cooling).
Miyamoto further suggests, rapid cooling at high temperature evidence is preserved by the slow cooling at low temperature process. I would suggest the inverse is correct, namely, the slow cooling process is preserved by the fast cooling process. For my hypothesis to be correct the fast cooling would have taken place second and the slow cooling first.
The cooling rate for pallasite, not just molten to solid but hot solid to cold solid iron would then reduce to the slow cooling rate of about one to ten thousand years and to a fast cooling rate of about 5-20 years. That's a pretty big shift away from 100 million or more years.
Earlier studies by scientists suggest the iron/nickel metal cooled slowly deep inside (150-300 km) parent body in a temperature range of 700-300°C near the metal/rock (core/mantel) boundary while other scientists suggest this can't be the case as the pressures at these depths would have the effect of squeezing molten metal out the bottom of the pallasitic layer and molten mafic silicate out the top resulting in a virtually pure dunitic mantle and an olivine free core. According to Wood [1981], deformation great enough to obliterate the characteristic pallasite geometry would be experienced by olivine crystals at the core-mantle interfaces of planets larger than about 15 km radius. In other words, the density of liquid iron would squeeze the less dense olivine out of the iron if pallasite formed at the core/mantel boundary, thus pallasite could not be formed at this deep zone within a parent body. Makes perfect sense!
Boesenberg et al. (2012)
it should be noted that pallasites do not consist of olivines floating in a metal matrix, as they are often described, but should be more correctly described as metal trapped within an interconnected olivine assemblage. In essence, pallasites were formed by melted metal oozing outwards from the core filling the spaces and intruding into olivine clusters. The less dense olivine did not sink down into a more dense pool of liquid metal.
Andrew Davis & Edward Olsen, Nature.
These patterns are consistent with crystallization of phosphate from a europium-depleted chondritic liquid. This is unlikely to have happened near the base of the differentiating parent-body mantle, because phosphates are late-crystallizing phases; this suggests that some pallasites may come from regions of their parent bodies much nearer the surface than the core–mantle boundary.
M. Miyamoto, Mineralogical Institute, University of Tokyo, Hongo, Tokyo, Japan
The presence of chemical zoning in pallasite olivines suggests a rapid cooling of pallasites at a late stage in their formation, sufficient to escape homogenization of chemical zoning
In order to reconcile the fast cooling rate obtained by chemical zoning of pallasite olivine with the slow cooling rate by Fe-Ni data, a plausible explanation is two-stage cooling, that is fast cooling at high temperatures to form chemical zoning of olivine at the first stage of cooling, and subsequent slow cooling at low temperatures to form the Widmanstatten pattern and to escape homogenization of olivine zoning at the second stage of cooling. A slow cooling rate at the second stage of cooling can be caused by a thick covering of regolith by an impact at a late stage of cooling or reassembly of the parent body [e.g., Taylor et al., 1987].
A likely explanation for the observation is that the parent body was broken apart while still partly molten. The fragments would probably cool rapidly, giving the zoning profile observed. Upon reassembly, most of the objects would be buried deeply, allowing for the metallographic cooling rate to be as slow as that observed.
The presence of chemical zoning of olivines in unequilibrated chondrites may be a similar situation to that of pallasite olivines. Although the cooling rate of chondrites determined by Fe-Ni data is as low as that of pallasites [e.g., Wood, 1979], olivines in unequilibrated chondrites still preserve chemical zoning which formed during initial cooling at high temperatures [e.g., Miyamoto et al., 1986]. Chemical zoning which records a rapid cooling at high temperatures is preserved through slow cooling at low temperatures. However, it should be noted that the metallurgical cooling rates of unequilibrated chondrites may contain large errors because of the metal grains with widely varying Ni compositions (J. T. Wasson, personal communication, 1997).
Two stage cooling took place in pallasites, a process that seems self evident based on Widmanstatten patterns (slow cooling linear structures) found encased inside amorphous looking globular molten metal structures (fast cooling).
Miyamoto further suggests, rapid cooling at high temperature evidence is preserved by the slow cooling at low temperature process. I would suggest the inverse is correct, namely, the slow cooling process is preserved by the fast cooling process. For my hypothesis to be correct the fast cooling would have taken place second and the slow cooling first.
Olivine is produced in volcanic processes that take place deep inside a planet or space body that is able to differentiate its rocky/iron material by way of heat and pressure. 
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On Earth, olivine is delivered to the surface via volcanic eruptions. Top left image is of olivine encased in Hawaiian basaltic lava rock. There are two areas on Mars where volcanic activity was previously focused or targeted, they are called Tharsis and Elysium. If Mars was volcanically ejecting olivine onto its surface, this is where it should be found, yet this is precisely where it is NOT found. |
Above image shows how olivine on Mars is primarily found along its equator or south latitude 30 degrees as if it was orbital debris gravitationally sucked onto the planet along is strongest line of influence. Olivine is also found exclusively inside crater floors in the smooth low elevation northern hemisphere (NH). This strongly suggests the olivine was delivered by meteorites aka pallasites.
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The fact that olivine is completely missing from Tharsis and the Elysium region (above image dotted lines) indicates these volcanic zones spilled material on top of any preexisting evidence of olivine deposits from pallasite meteorites.
This makes the volcanoes younger than the olivine deposits. In other words the olivine packed pallasite meteorites were laid down before the volcanoes erupted and their emplacement was a one time event predating the lava outflow 3.67 Ga. As Jupiter migrated inward, it broke apart the 7 asteroid belt parent bodies hurling pallasite meteorites at Mars and Earth laying down olivine deposits within impact craters. |
Olivine inside impact craters. Ody et al., 2013
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Sometime later, Jupiter migrated outward, it tidally flexed, stretched and deformed Mars while within its orbital zone. This Mars flexing by Jupiter would have caused subsurface heating and internal volcanic activity. Eventually enough pressure built up within Mars to expel the ultramafic lava to the surface while cracking its crust. This is the same process that makes Jupiter's moon Io boil rock, making Io the most volcanic body in the solar system. Mars continued to erupt long after Jupiter's tidal flex influence was felt.
The entire NH of Mars is smoother, younger and at a 10 km lower elevation than the southern hemisphere similar to how our Moon's near side crust is 60 km thinner than the far side. The smoothing of the NH took place earlier than the formation of Tharsis and Elysium volcanic zones because some craters with olivine exist there.
The Tharsis and Elysium zones have no evidence of olivine clusters within craters while the NH while mostly devoid of olivine does have sparse deposits of olivine. This indicates a time sequence where the southern hemisphere is the oldest, NH is middle aged and the volcanic deposits are the youngest. Mars, most likely, barely survived its encounter with Jupiter's gravitation stretching and flexing and this is why its NH is completely different than the southern.
The entire NH of Mars is smoother, younger and at a 10 km lower elevation than the southern hemisphere similar to how our Moon's near side crust is 60 km thinner than the far side. The smoothing of the NH took place earlier than the formation of Tharsis and Elysium volcanic zones because some craters with olivine exist there.
The Tharsis and Elysium zones have no evidence of olivine clusters within craters while the NH while mostly devoid of olivine does have sparse deposits of olivine. This indicates a time sequence where the southern hemisphere is the oldest, NH is middle aged and the volcanic deposits are the youngest. Mars, most likely, barely survived its encounter with Jupiter's gravitation stretching and flexing and this is why its NH is completely different than the southern.
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Jupiter stretched Mars into a prolate shape causing its north pole to break open similar to the tiger stripes on the south pole of Saturn's moon Enceladus or similar to our Moon's Mare or Jupiter's moon Io or Sputnik Planitia on Pluto. |
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Scientists suggest an impact hit Mars' north pole (creating this so called NH Borealis Basin) just like scientists have said the Mare on our Moon were created by impacts. Prior to understanding the power of tidal flex, scientists used impacts as the de facto explanation for misunderstood processes. As examples, take a look at my Basins Page 70 where I talk at length about this type of impact misinterpretation of Hellas basin on Mars, Sputnik Planitia on Pluto Page 95, Elliot crater on Pluto Page 104, Page 71, and a dormant volcano on Pluto I call Kilauea Page 109.
My conclusion
If the grand tack model accurately reflects Jupiter's migration through the solar system (3.5 AU > 1.5 AU > 5.2 AU), it then seems quite reasonable to hypothesize Jupiter's Roche Radius (not just its gravity perturbations) played a major role in forming the asteroid belt (2 to 3.25 AU) and tidal flexing shaped Mars' surface features. I've already laid the groundwork to explain my concept but....
Jupiter migrated inward and crossed the asteroid belt zone. A couple of the preexisting protoplanets/planetesimals in this zone may have been driven to collide and self destruct but certainly not all 7 experienced this fate. Instead, any remaining protoplanets were torn apart by Jupiter's Roche Radius. A small amount of debris remained in this zone forming our asteroid belt but most of the debris was eaten or ejected by Jupiter. Some of the ejected debris landed on Mars and Earth.
Jupiter continued its inward migration until it got close enough to Mars' to tidally flex it to the point that internal heat energy created volcanic activity forming the Tharsis and Elysium regions and northern hemisphere smooth surface/low elevation anomaly. At some point, Jupiter migrated outward and continued to eject any remaining asteroid zone material until less than one tenth of one percent remained.
The late heavy bombardment (LHB) took place from about 4.1 Ga to 3.8 Ga. The LHB may have been the result of Jupiter breaking up the 7 asteroid belt parent bodies. Mars' Olympus Mons is thought to have erupted from 3.67 Ga to 2.54 Ga. Olivine laden pallasites were laid down on Mars prior to 3.67 Ga, most likely between 3.8 and 4.1 Ga.
Slow and fast cooling evidence in a single pallasite displays how a two stage cooling process took place. I would suggest the slow cooling took place while the parent body was intact (pre-Jupiter migration). The slow cooled metal formed inside the olivine clusters then, some time later, Jupiter came along and tidally flexed and heated the parent body causing its metal core to re-melt. The new hotter metal expanded and migrated outward from the core mantel boundary into the cavities within the previously formed olivine/metal clusters. Jupiter continued to stress the parent bodies until they broke apart causing the molten metal to cool rapidly forming pallasites.
That's my basic concept
During its Grand Tack, Jupiter's Roche Radius tore the asteroid belt parent bodies apart forming our current asteroid belt while depositing olivine pallasites on Mars and Earth. Jupiter's migration also tidally flexed Mars heating its core and forming its volcanoes and sunken northern hemisphere.
This hypothesis may be completely wrong but its fun to speculate.
- My Roche A-Tack Hypothesis
My conclusion
If the grand tack model accurately reflects Jupiter's migration through the solar system (3.5 AU > 1.5 AU > 5.2 AU), it then seems quite reasonable to hypothesize Jupiter's Roche Radius (not just its gravity perturbations) played a major role in forming the asteroid belt (2 to 3.25 AU) and tidal flexing shaped Mars' surface features. I've already laid the groundwork to explain my concept but....
Jupiter migrated inward and crossed the asteroid belt zone. A couple of the preexisting protoplanets/planetesimals in this zone may have been driven to collide and self destruct but certainly not all 7 experienced this fate. Instead, any remaining protoplanets were torn apart by Jupiter's Roche Radius. A small amount of debris remained in this zone forming our asteroid belt but most of the debris was eaten or ejected by Jupiter. Some of the ejected debris landed on Mars and Earth.
Jupiter continued its inward migration until it got close enough to Mars' to tidally flex it to the point that internal heat energy created volcanic activity forming the Tharsis and Elysium regions and northern hemisphere smooth surface/low elevation anomaly. At some point, Jupiter migrated outward and continued to eject any remaining asteroid zone material until less than one tenth of one percent remained.
The late heavy bombardment (LHB) took place from about 4.1 Ga to 3.8 Ga. The LHB may have been the result of Jupiter breaking up the 7 asteroid belt parent bodies. Mars' Olympus Mons is thought to have erupted from 3.67 Ga to 2.54 Ga. Olivine laden pallasites were laid down on Mars prior to 3.67 Ga, most likely between 3.8 and 4.1 Ga.
Slow and fast cooling evidence in a single pallasite displays how a two stage cooling process took place. I would suggest the slow cooling took place while the parent body was intact (pre-Jupiter migration). The slow cooled metal formed inside the olivine clusters then, some time later, Jupiter came along and tidally flexed and heated the parent body causing its metal core to re-melt. The new hotter metal expanded and migrated outward from the core mantel boundary into the cavities within the previously formed olivine/metal clusters. Jupiter continued to stress the parent bodies until they broke apart causing the molten metal to cool rapidly forming pallasites.
That's my basic concept
During its Grand Tack, Jupiter's Roche Radius tore the asteroid belt parent bodies apart forming our current asteroid belt while depositing olivine pallasites on Mars and Earth. Jupiter's migration also tidally flexed Mars heating its core and forming its volcanoes and sunken northern hemisphere.
This hypothesis may be completely wrong but its fun to speculate.
| a_petrological_and_chemical_reexamination_of_main_group_pallasite_formation_boesenberg_2012-1.pdf |
| geochemical_relationships_between_some_pallasites_and_iron_meteorites.pdf |
| global_investigation_of_olivine_on_mars_insights_into_crust_and_mantle_compositions_2012je004149.pdf |