Main Sequence – The Outer Iron Core

Main Sequence - The Outer Iron Core

The previous posting introduced the pivotal role played by the outer iron core in the evolution of planetary objects formed by planetary differentiation.

In planetary science, planetary differentiation is the process of separating out different constituents of a planetary body as a consequence of their physical or chemical behaviour, where the body develops into compositionally distinct layers; the denser materials of a planet sink to the center, while less dense materials rise to the surface.

Such a process tends to create a core and mantle.

The liquid outer core

The outer core of the Earth is a liquid layer about 2,266 km (1,408 mi) thick composed of iron and nickel which lies above the Earth’s solid inner core and below its mantle.

Its outer boundary lies 2,890 km (1,800 mi) beneath the Earth’s surface.

The transition between the inner core and outer core is located approximately 5,150 km (3,200 mi) beneath the Earth’s surface.

The process of planetary differentiation concentrates the elements that are denser than iron in the planetary inner core.

Elemental abundances
Relative abundance of the chemical elements in the Earth’s upper continental crust, on a per-atom basis.

The process of planetary differentiation is an intrinsic feature of planetary formation driven by either:
1) Centripetal separation during accretion of a planetary object in a spinning dust cloud.
2) The binary fission of a molten planetary object.

Heating due to radioactivity, impacts, and gravitational pressure melted parts of protoplanets as they grew toward being planets.

In melted zones, it was possible for denser materials to sink towards the center, while lighter materials rose to the surface.

The compositions of some meteorites (achondrites) show that differentiation also took place in some asteroids (e.g. Vesta), that are parental bodies for meteoroids.

The short living radioactive isotope Al26 was probably the main source of heat.

Thus, the process of planetary differentiation created the Earth’s inner core which contains dense primordial nuclides such as Thorium and Uranium.

Radioactive primordial nuclides

These 34 primordial nuclides represent radioisotopes of 28 distinct chemical elements (cadmium, neodymium, tellurium, and uranium each have two primordial radioisotopes, and samarium has three).

The radionuclides are listed in order of stability, with the longest half-life beginning the list.

The subsequent gradual cooling [towards a temperature sustainable by nuclear decay] of a newly formed planetary object enables the outer iron core to slowly solidify around the primordial nuclides that are concentrated within the inner core.

This gradual cooling process enables Widmanstätten Patterns to develop in the outer iron core.

Widmanstätten patterns, also called Thomson structures, are unique figures of long nickel-iron crystals, found in the octahedrite iron meteorites and some pallasites.

They consist of a fine interleaving of kamacite and taenite bands or ribbons called lamellae.

Commonly, in gaps between the lamellae, a fine-grained mixture of kamacite and taenite called plessite can be found.

Widmanstätten Pattern

Iron and nickel form homogeneous alloys at temperatures below the melting point, these alloys are taenite.

At temperatures below 900 to 600°C (depending on the Ni content), two alloys with different nickel content are stable: kamacite with lower Ni-content (5 to 15% Ni) and taenite with high Ni (up to 50%).

Octahedrite meteorites have a nickel content intermediate between the norm for kamacite and taenite, this leads under slow cooling conditions to the precipitation of kamacite and growth of kamacite plates along certain crystallographic planes in the taenite crystal lattice.

The formation of Ni-poor kamacite proceeds by diffusion of Ni in the solid alloy at temperatures between 700 and 450°C, and can only take place during very slow cooling, about 100 to 10,000 °C/Myr, with total cooling times of 10 Myr or less.

This explains why this structure cannot be reproduced in the laboratory.

The eventual formation of a solid iron outer core [surrounding the nuclear inner core] slowly generates a pressurised inner core that can trigger fission and subsequent fusion reactions.

The heat and pressure generated by these nuclear reactions in the inner core will [if you’re lucky] lead to the fracturing and re-melting of the outer iron core.

The heat and pressure released by the fractured outer iron core drives planetary volcanism [plus planetary outgassing when fusion reactions have been triggered] and the quiescence of the nuclear reactions until the outer iron core has cooled sufficiently to re-solidify [and re-pressurise the inner core].

Therefore, planetary bodies will cycle through periods of nuclear activity and quiescence until the inner core has decayed [or been physically depleted via volcanic plumes] to the point where it cannot sustain nuclear reactions.

The planetary bodies that sustain nuclear fission will be volcanic and some traces of the nuclides and the decay products [from the inner core] will be deposited on the planetary surface.

The planetary bodies, such as Earth, that have sustained nuclear fusion will outgas lighter elements [which form the crust, oceans and atmosphere] and will be volcanic. Traces of the nuclides and the decay products [from the inner core] will be deposited on the planetary surface and [with luck] be buried by the subsequent outgassing of the lighter elements that are now found in the crust such a silicon and calcium.

It can be anticipated that the recurrent cycles of nuclear activity followed by quiescence will be associated with the periodic release of nuclides [and decay products] to the surface which will affect the biosphere and render isotope dating techniques invalid.

Roberto Mantovani - The Inflating Earth

The planetary bodies, such as the Gas Giants Jupiter and Saturn, which have sustained nuclear fusion appear more likely to spin off other planetary bodies as moons which, in turn, may eventually support nuclear fusion reactions.

Keplers Third Law - The Saturn System

Wheels within Wheels – Vortex within Vortex

Nuclear fusion is probably currently active with the inner core of Titan [a moon of Saturn] because its atmosphere contains the fusion marker gases: nitrogen, methane and hydrogen.

Like all elements heavier than lithium, the original source of nitrogen-14 and nitrogen-15 in the Universe is believed to be stellar nucleosynthesis, where they are produced as part of the carbon-nitrogen-oxygen cycle.

The atmospheric composition in the stratosphere is 98.4% nitrogen with the remaining 1.6% composed mostly of methane (1.4%) and hydrogen (0.1–0.2%).

True-color image of layers of haze in Titan's atmosphere

True-color image of layers of haze in Titan’s atmosphere

Nuclear fusion appears to be quiescent on Mars because the atmospheric levels of nitrogen and argon are very low.

The atmosphere of Mars consists of about 96% carbon dioxide, 1.93% argon and 1.89% nitrogen along with traces of oxygen and water.

Martian Methane Outgassing

Alternatively, when the outer core of solid iron manages to contain a pressurised fusion reaction [and you’re unlucky] then the planetary body will explosively disintegrate like a hydrogen bomb.

The fragmentation of the outer iron core [caused by the explosive disintegration of a planetary body] generates shrapnel in the form of meteorites which will [eventually] fall onto [or embed themselves within] other planetary bodies in the Solar System.

The Willamette Meteorite is a classic example of shrapnel generated by the explosive disintegration of an outer iron core.

The Willamette Meteorite, officially named Willamette, is an iron-nickel meteorite discovered in the U.S. state of Oregon.

It is the largest meteorite found in North America and the sixth largest in the world.

The meteorite is currently on display at the American Museum of Natural History, which acquired the meteorite in 1906.

Having been seen by an estimated 40 million people over the years, and given its striking appearance, it is among the most famous meteorites known.

Willamett Meteorite

Intriguingly, the Willamette meteorite may have originally landed in “Canada or Montana”.

There was no impact crater at the discovery site; researchers believe the meteorite landed in what is now Canada or Montana, and was transported as a glacial erratic to the Willamette Valley during the Missoula Floods at the end of the last Ice Age (~13,000 years ago).

Willamette, Oregon,+Oregon&hl=es&ie=UTF8&ll=53.592505,-100.283203&spn=29.275482,56.513672&sll=54.110943,-99.931641&sspn=28.930182,90&hnear=Meteorito+Willamette,+West+Linn,+Condado+de+Clackamas,+Oreg%C3%B3n,+Estados+Unidos&t=m&z=4

Therefore, it is not inconceivable that the Willamette meteorite may be associated with a larger fragment of iron shrapnel [which is slowly loosing its magnetism] that is embedded beneath Hudson Bay.

On Earth, a large piece of molten iron is sufficiently denser than continental-crust material to force its way down through the crust to the mantle.

Hudson Bay Magnetics

Tektites: 4 – Primary and Secondary Impact Craters

Unsurprisingly, a “significant heating event” caused a re-crystallisation of the Willamette meteorite.

Willamette meteorite - Widmanstätten structure

Willamette Meteorite – a recrystallized octahedrite, a type IIIAB iron meteorite, found at Willamette, Oregon, USA in 1902 (FMNH Me 592, Field Museum of Natural History, Chicago, Illinois, USA).

A significant heating event caused recrystallization of this rock – so Widmanstätten structure is not easily seen in samples.

Unsurprisingly, type IIIAB iron meteorites [like the Willamette Meteorite] are associated with “core formation” and the “crystallization of molten Fe-Ni”.

Iron Meteorites

Iron meteorites: Crystallization, thermal history, parent bodies, and origin
J.I. Goldstein, E.R.D. Scott, N.L. Chabot
Chemie der Erde – Geochemistry – Volume 69, Issue 4, November 2009, Pages 293–325

The type IIIAB Willamette Meteorite probably originated from a planetary body with a “small silicate mantle” which suggests the planetary body experienced nuclear fusion.

The most likely explanation is that the body in which the IIIAB irons cooled had a small silicate mantle that was thicker than the IVA mantle(<1 km), but much thinner than the tens of kilometres expected for an undisturbed differentiated body.

Iron meteorites: Crystallization, thermal history, parent bodies, and origin
J.I. Goldstein, E.R.D. Scott, N.L. Chabot
Chemie der Erde – Geochemistry – Volume 69, Issue 4, November 2009, Pages 293–325

The type IIIAB Willamette Meteorite possibly originated from a planetary body “as large as 1000 km or more in size” possibly located at “1–2AU”.

Contrary to traditional views about their origin, iron meteorites may have been derived originally from bodies as large as 1000 km or more in size.

Most iron meteorites come directly or indirectly from bodies that accreted before the chondrites, possibly at 1–2AU rather than in the asteroid belt.

Iron meteorites: Crystallization, thermal history, parent bodies, and origin
J.I. Goldstein, E.R.D. Scott, N.L. Chabot
Chemie der Erde – Geochemistry – Volume 69, Issue 4, November 2009, Pages 293–325

Therefore, the Willamette Meteorite provides additional supporting evidence for the hypothesise that a planetary object explosively disintegrated in The Other Big Big at about 2 AU.

The Comet Family of Jupiter

Furthermore, the evidence suggests that exploding iron outer cores are ubiquitous in the Solar System because “ungrouped” iron meteorites “probably come from at least 50 other bodies”.

After excluding ungrouped irons weighing < 20 g that may be simple impact melts, silicate-bearing irons, and others loosely linked to group IAB, we infer that the remaining ungrouped irons probably come from at least 50 other bodies that formed in analogous ways to the fractionally crystallized groups.

They have 182W/184W ratios showing they were derived originally from bodies that were melted by 26Al to form cores <1.5Myr after CAI formation and before the formation of chondrites.

These constraints, the evidence for rapid cooling of many irons in a few Myr, the lack of other kinds of meteorites related to the irons, and the small fraction of differentiated bodies in the asteroid belt all suggest that irons could be derived from fragments of planetesimals or protoplanets that formed and broke up at1–2AU and were subsequently scattered into the asteroid belt by protoplanets.

Iron meteorites: Crystallization, thermal history, parent bodies, and origin
J.I. Goldstein, E.R.D. Scott, N.L. Chabot
Chemie der Erde – Geochemistry – Volume 69, Issue 4, November 2009, Pages 293–325

Therefore, it is likely that the next planetary object to explosively disintegrate within the Solar System will be a volcanically dormant moon [or planet] that is “1000 km or more in size”.

Gallery | This entry was posted in Astrophysics, Catastrophism, Earth, Inflating Earth, Inventions and Deceptions, Moon, Science, Solar System. Bookmark the permalink.

3 Responses to Main Sequence – The Outer Iron Core

  1. A C Osborn says:

    Well that is a new Doomsday Scenario to me.
    Or does volcanic activity have to stop before it can occur?
    ie no safety valves.

  2. Pingback: The Embarrassed White Dwarf | MalagaBay

  3. Pingback: Greenland – The Cape York Iron Meteorites | MalagaBay

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