YD IMPACT COMET CRUST

Sectioned igneous slab with metallic-iron inclusions
Suggested YD-impact comet crust

The attendant alternative solar system ideology predicts a siderophile-depleted igneous crust on hot classical Kuiper belt objects, but, whether this material is that material is more problematic.

Abstract:

    Comet-crust meteorites are suggested here to be a new class of outer solar system meteorites, composed of the igneous crust of hot-classical Kuiper belt objects (KBOs). KBO comets are rare in the inner solar system, compared to inner solar system asteroids and chondrites, therefore comet crust meteorites should be proportionately rare in present-day meteorite falls. But 12,800 years ago, a ‘YD impact hypothesis’ or ‘Clovis comet hypothesis’, suggests that a 100+ km KBO was perturbed into the inner solar system where it fragmented, exponentially increasing the impact hazard to Earth. The Laurentide ice sheet was apparently struck by several fragments of the YD comet, which impacted in the vicinity of the Great Lakes and Hudson Bay, causing the extinction of 90 genera of megafauna in the Americas, and precipitating a 1000 year period of cooling, known as the Younger Dryas. The YD comet is suggested here to have had an igneous crust that was scattered across North America and beyond, when large ice-sheet fragments were launched into ballistic trajectories as part of the ejecta curtain of multiple primary impacts on the ice sheet.

    Comet-crust meteorites requires an alternative solar system ideology that predicts a siderophile-depleted igneous crust for hot classical KBOs, which is also depleted in silicates. Hot-classical KBOs are suggested here to have condensed from a siderophile-depleted ’trifurcation debris disk’, > 4,567 Ma, that lay on the 3-oxygen-isotope terrestrial fractionation line, resulting in siderophile-depleted comet crust material, depleted in iridium and nickel, unlike inner solar system meteorites.
    Large KBOs presumably underwent spontaneous ’aqueous differentiation’ at formation by streaming instability (gravitational collapse), internally melting water ice, which precipitated authigenic sedimentary cores with a gneissic composition. The liquid water refroze to form icy mantles surrounding sedimentary gneissic cores, with the icy mantles depleted in gneissic silicates.
    An igneous crust on hot-classical KBOs presupposes a former binary-Sun, whose binary components spiraled in to merge in a luminous red nova (LRN) at 4,567 Ma. The solar-merger LRN briefly enveloped the solar system out to and including the Kuiper belt, melting the surface regolith into an igneous ‘comet crust’.
    LRN solar plasma partially reduced iron oxides in the igneous crust to metallic iron, causing metallic iron to rain through the igneous crust, forming the millimeter- to centimeter-scale metallic-iron blebs characteristic of comet-crust meteorites. Additionally some comet-crust meteorites exhibit fusion crust and occasionally flow lines that formed during atmospheric ablation.
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High-density rock with cratered surface from City Island, Harrisburg, PA
Suggested YD-impact Clovis-comet meteorite

Introduction:

    Sedimentary cores dated to the onset of the Younger Dryas, 12,800 BP, from the Americas, Europe, and Asia exhibit iron-rich spherules, glass-like carbon, glass spherules, nanodiamonds, and platinum enrichments.  Additionally, closely-dated glacial cores exhibit platinum enrichments and numerous markers for extreme biomass burning.  Some sedimentary horizons from this time period are so enriched in black carbon/soot deposits as to engender the term ‘black mat’ for their distinctive appearance.  Significantly, 90 genera of megafauna went extinct in the Americas by 12,700 BP.  A thousand year period of glacial conditions known as the Younger Dryas followed the brief warming of the Late Glacial Interstadial at the end of the Last Glacial Maximum.
    A group of 63 scientists from 55 universities in 16 countries have created the Comet Research Group to pursue the likelihood that a comet impact on or over the Laurentide ice sheet 12,800 BP was the cause for this unusual combination of anomalies.

    Petaev et al., 2013 analyzed Greenland ice sheet cores from the Greenland Ice Sheet Project 2 and discovered a large platinum anomaly at the onset of the Younger Dryas,  not accompanied by an iridium anomaly, with the Pt/Ir ratios at the Pt peak exceeding those in known terrestrial sediments.  The Pt concentrations rise by at least 100 fold over ~ 14 years before dropping back during the subsequent ~ 7 years.  The Pt anomaly precedes the ammonium and nitrate spike in the GISP2 ice core (2) by 30 y and, thus, this event is unlikely to have triggered the biomass burning and destruction thought to be responsible for ammonium increase in the atmosphere and the Greenland ice (11).”
    Subsequently, a platinum anomaly was documented in bulk sedimentary sequences from 11 widely-separated sites across the continental United States.  (Moore, West et al., 2017)  This article constrains the Greenland ice core Pt anomaly, from Petaev et al. 2013, to ~12,836–12,815 cal BP.

    In a recent study measuring biomass burning proxies, 23 sites with previous YD impact markers were examined across North America and northern Europe, including one site in northern South America and one site in the Middle East.  The study revealed a major peak in biomass burning at the YD onset that appears to be the highest during the latest Quaternary.  (Wolbach et al.,2., 2018)

    In a related article, biomass-burning aerosols were discovered in 4 ice-core sequences from Greenland, Antarctica, and Russia.  The perturbations on CO2 records from Taylor Glacier, Antarctic suggest the combustion of ~9% of Earth’s terrestrial biomass.  (Wolbach et al.,1., 2018)
    This 2018 paper, which includes 24 scientists from the Comet Research Group, states that the “cosmic-impact hypothesis is based on considerable evidence that Earth collided with fragments of a disintegrating 100 km-diameter comet, the remnants of which persist within the inner solar system ~12,800 y later”.  (Wolbach et al.,1., 2018)  Elsewhere, Comet Encke and the Taurid meteor stream are suggested as the possible debris stream of a former KBO that fragmented in the inner solar system in the last 20,000 to 30,000 years, whose debris stream once included the former YD comet.
    No crater has been positively identified for the one or more posited Younger Dryas (YD) impacts on the Laurentide ice sheet in the Great Lakes Region, circa 12,800 BP.  This absence of a primary impact crater reduces the likelihood of recognizing primary bolide material, particularly if it belongs to a new class of outer solar system meteorites that is radically different from inner solar system asteroids and chondrites.
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45 kg metallic-iron ‘ring-of-flames’ from Conshohocken, PA
Suggested YD impact comet-crust meteorite

YD impact comet-crust overview:

    The former YD impact bolide is suggested to have possessed an igneous crust that constitutes a new class of siderophile-depleted (low nickel, < 2 ppb iridium) meteorites on Earth.  This suggested comet crust contains frequent millimeter-to-centimeter-scale metallic-iron inclusions that appear to have solidified in a microgravity environment, and thus extraterrestrial.
    The primary impact was presumably on the Laurentide ice sheet, with comet crust ferried into SE PA and elsewhere as bolide contamination within a secondary ejecta curtain of Laurentide ice sheet fragments.  Indeed, a chunk of apparent comet crust was found in California.

    Comet crust was fortuitously preserved on Earth impact by the cushioning effect of the relatively-compressible target ice of the Laurentide ice sheet. The relative compressibility of water ice, compared to bedrock silicates, presumably clamped the impact shock wave pressure below the melting point of silicates, preserving bolide material from melting on impact, with the relative endothermic compressibility of water absorbing the lion’s share of the impact energy. The target ice sheet absorbed the lion’s share of the energy in the form of PdV compressive heating, likely raising the temperature of the target ice to thousand of Kelvins. Thus in addition to atmospheric ablation, some of the surface scorching observed on comet-crust material may have occurred at impact

    As many as 500,000 elliptically-shaped Carolina bays are located along the Atlantic Seaboard and Gulf Coast of the US, which have been suggested by members of the Comet Research Group to have been caused by secondary impacts from an ejecta curtain of Laurentide ice sheet fragments from a primary impact on the ice sheet, circa 12,800 BP. Many ice sheet fragments apparently traveled over 1000 km in ballistic trajectories above Earth’s atmosphere at 3 km/s and impacted with 1% of the specific kinetic energy of primary YD comet fragments traveling at 30 km/s.

    Presumably a similar density of secondary ice-sheet-fragment impacts occurred inland from the coastal Carolina bays, but secondary ice-fragment impacts on harder inland terrain caused less collateral damage, which has been visually erased by subsequent weathering during the intervening millennia.
    The impulse of secondary ballistic impacts of ice-sheet fragments on exposed bedrock or thin soil over bedrock is suggested here to have fractured target bedrock, occasionally forming discrete boulder fields, particularly when ice-sheet fragments hit the leeward side of mountains and slopes, where the forward momentum of the ice-sheet fragment was directed downhill, promoting downhill debris flows. (See section, YD IMPACT BOULDER FIELDS). In Eastern Pennsylvania, the Hickory Run boulder field and the Ringing Rocks boulder fields are both suggested to be YD impact boulder fields, where the several Ringing Rocks bounder fields are largely in situ bounder fields, while the larger Hickory Run boulder field is most-likely a debris-flow bounder field. And innumerable smaller concentrations of sharp-edged boulders that are nominally-weathered could also be secondary impact sites.
    There is some indication, from the orientation of Carolina bays, that ice-sheet-fragment ballistic trajectories over Central and Southeastern Pennsylvania came from primary impacts in the Hudson bay region, much-further north than the Great Lakes region, resulting in higher-speed ballistic trajectories, as indicated on the following figure from Richard Firestone, 2009. And these higher ballistic speeds may be necessary, or at least significant, in creating sufficient impact brecciation to form impact bounder fields. Additionally, if these same ice-sheet fragments from Hudson bay region were particularly contaminated with comet crust, this could explain the convergence of impact boulder fields and comet crust in Southeast Pennsylvania.

From Firestone, 2009, Figure 3, predicting the locations of primary strikes on the Laurentide ice sheet, 12,800 B.P., derived from the orientations of Carolina bays, The ballistic trajectories of ice-sheet-fragment ejecta curtains are indicated in red and blue. Red trajectories point back to a suggested primary impact over Hudson bay, with a cluster of red trajectories passing over Eastern Pennsylvania (bordered in green) Ice-sheet-fragment impacts from the Hudson Bay Region are suggested here to have formed a cluster of ‘YD impact boulder fields’ in Eastern Pennsylvania.

    If the YD comet fragment included any of its gneissic KBO core, its indistinguishably from metamorphic Earth rocks would render it inconspicuous, where the metamorphic basement rock of the continental tectonic plates on Earth are suggested HERE to be the authigenic sedimentary cores of hot-classical KBOs, emplaced on Earth during the late heavy bombardment. And ironically, the similarity of suggested igneous comet crust to industrial iron furnace slag also renders igneous comet crust inconspicuous, particularly in light of its economic exploitation for its iron content, which frequently mingles pristine comet crust with an industrial slag waste stream. Finally, multiple primary impacts on a transitory multi-kilometer-thick ice sheet that launched a lively trajectory curtain of secondary impacts, resulting in a fantastic distribution of secondary impacts across the North American continent and beyond, with the ejecta curtain overwhelmingly composed of fresh-water ice that disappeared without a trace.
    All aspects of the suggested YD comet impact deviate from the classical understanding of rocky-iron asteroids/chondrites on target bedrock, from its suggested siderophile-depleted gneissic core composition and igneous composition of comet crust, to its multiple impacts on a transitory ice sheet, generating a singular spray of secondary ice-sheet fragments in ballistic trajectories above Earth’s atmosphere.

YD comet-crust exhibits a number of typical features that occur with variable frequency:
– Gray igneous matrix; constituting variable-sized chunks of dense, gray igneous matrix, having a particularly-high calcium-oxide content, with specimens often containing variable-sized metallic-iron inclusions. Some matrix material is highly-vesicular, like scoria, while some matrix material lacks vesicles altogether.
– Metallic iron; consisting of variable-sized masses of metallic iron, from millimeter-scale inclusions in the gray igneous matrix to isolated masses of metallic iron as large as 100 kg. Some iron is massive (cast) and some is nodular, where nodular iron often appears in aggregates that appear to be sintered together, with little or no accompanying matrix material.
– Magnetite/hematite; while metallic iron was evidently molten, while associated magnetite/hematite appears to have formed by aqueous deposition, likely by metasomatism in internal fissures.
– Some matrix material exhibits one smooth undulating surface, with a typical 10-15 cm undulation radius, with the matrix material typically fractured into pie-shaped ‘slices’, having one rounded smooth surface, with the other surfaces being fractured, resembling a slice of pie.
– Some matrix material exhibits apparent fusion crust, and a small percentage of fusion crust exhibits apparent flow lines.
– All types of YD comet crust are typically coated with a white, gritty cement-like coating, to the extent that this cement-like coating is one of the best indicators of comet crust.
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Aqueous differentiation of KBOs:

    Large KBOs presumably underwent aqueous differentiation during formation by streaming instability, a form of gravitational instability, with aqueous differentiation defined here as the melting of water ice by the conversion of potential energy to heat during gravitational collapse. Large KBOs in which all water ice either melted or sublimed presumably processed all their trifurcation-debris-disk dust and ice through internal saltwater oceans, largely dissolving nebular dust suspended in saltwater, and/or with nebular dust acting as nucleation sites for mineral crystallization. In the microgravity of internal KBO oceans, authigenic mineral grains grew by crystallization until falling out of aqueous suspension at a sand grain size or larger, forming sedimentary cores with a bulk gneissic composition. Gneissic banding is attributed to intermittent KBO-quake subsidence events that modulated mineral-species solubilities by way of pH variations, where subsidence shock waves caused CO2 to bubble out of solution, sharply raising the pH.
    Over time heat loss caused internal KBO oceans to freeze solid, trapping solutes and suspended mineral grains in the saltwater ice, with the solutes deficient in the bulk chemistry of the gneissic sediments (and siderophile depleted). This depletion of gneissic silicates left the icy mantle and crust highly-enriched in water-soluble solutes, notably salts, iron, magnesium, carbonates, and calcium oxides.

    The subsequent plasma immersion of old-classical KBOs in the 4,567 Ma binary spiral-in solar merger LRN is suggested here to have sublimed the volatiles and melted the remaining volatiles into an igneous crust, with gaseous volatiles percolating through the igneous crust, creating voids in the igneous crust.

    The chemically-reducing nature of ionized hydrogen and carbon monoxide in the LRN solar plasma chemically reduced exposed iron oxides to metallic iron, with iron droplets merging into centimeter-scale metallic iron inclusions in comet crust before falling out of suspension within percolating igneous matrix. Coincidently, carbon monoxide is the reducing agent for converting iron oxide to metallic iron in industrial iron-smelting furnaces.

(see section, AQUEOUS DIFFERENTIATION OF KUIPER BELT OBJECTS (KBOs))
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Alternative solar system model:

Symmetrical flip-flop fragmentation:
    An alternative star formation mechanism, designated ‘symmetrical flip-flop fragmentation’, is suggested to have ‘condensed’ a twin-binary pair of disk instability objects around a large brown-dwarf-mass protostellar core, where the twin disk instability (DI) objects were much-more massive than the diminutive core. Orbital interplay progressively transferred kinetic energy and angular momentum from the massive twin DI-objects to the diminutive brown dwarf by the mechanism of equipartition of kinetic energy, which evaporated the former brown-dwarf-mass core into a circumbinary orbit around the twin-binary DI-objects, as the DI-objects spiraled inward, conserving potential energy and angular momentum. The DI-objects evolved into our former binary-Sun.

Trifurcation and the trifurcation debris disk:
    It’s well known that equipartition of kinetic energy transfers orbital kinetic energy and angular momentum from more massive objects to less massive objects in close orbital encounters, which is the principle used in ‘gravity assist’ routinely used by spacecraft, and equipartition in triple-star systems causes unstable chaotic orbits to evolve into stable hierarchical systems, with the least massive component in a circumbinary orbit around the more-massive central binary pair.
    Equipartition is suggested here to also transfer rotational energy and angular momentum from more-massive to less-massive objects in close orbital encounters, increasing rotation rate, causing them to ‘spin up’. Equipartition is suggested to have caused our former brown-dwarf-mass protostar to spin up until it distorted into a tri-axial Jacobi ellipsoid and then into a bar-mode instability. Additional pumping of rotational energy caused the bar-mode instability to centrifugally fragment in a well constrained manor, designated ‘trifurcation’, for its suggested fragmentation into 3 components. Bar-mode-instability fragmentation occurs when the self gravity of the bar-mode arm pinches off into a twin-binary pair of objects orbiting a diminutive residual core at the center of rotation.
    First-generation trifurcation creates a Mini-Me version of the original brown dwarf core orbited by a much-more massive pair of disk-instability objects (protostars), such that first-generation trifurcation promotes second-generation trifurcation, and etc., like a set of Russian nesting dolls, where the residual core of the previous generation becomes the trifurcating core of the next generation. Thus, 4 trifurcation generations created the twin-binary objects in our solar system;
– 1st gen. ― ‘binary-Companion’ (with super-Jupiter-mass components)
– 2nd gen. ― Jupiter-Saturn
– 3rd gen. ― Uranus-Neptune
– 4th gen. ― Venus-Earth + Mercury (residual core)
    Trifurcation is presumably an inefficient process, spinning off or vaporizing a substantial percentage of trifurcating objects in the form of gas and dust debris. Assuming that our trifurcated brown-dwarf-mass protostar had been internally differentiated into an iron-nickel (siderophile) core, the resulting spin-off debris would necessarily have been siderophile depleted. Thus, four generations of trifurcation created a siderophile-depleted ‘trifurcation debris disk’ from the homogeneous brown dwarf reservoir, which lay on the 3-oxygen-isotope, brown dwarf fractionation line, which we know as the terrestrial fractionation line.
    And the trifurcation debris disk condensed siderophile-depleted (hot-classical) Kuiper belt objects (KBOs), presumably by streaming instability, against Neptune’s outer 2:3 mean motion resonance.

Binary-Sun spiral-in merger luminous red nova (LRN) at 4,567 Ma:
    Secular perturbation between former binary-Sun and former binary-Companion caused binary-Sun to spiral in and merge in at 4,567 Ma in a luminous red nova (LRN), which briefly created a plasma fireball that apparently enveloped the classical Kuiper belt, vaporizing volatiles from the surface of KBOs and melting the refractory regolith into an igneous, siderophile-depleted rocky-iron crust.
    The red giant phase of (stellar-merger) luminous red nova LRN M85OT2006-1 would have reached far into the Kuiper belt, with a fireball estimated at R = 2.0 +.6-.4 x 10^4 R☉, and a peak luminosity of about 5 x 10^6 L☉. (Rau et. al. 2007) “Previously published line indices suggest that M85 has a mean stellar age of 1.6+/-0.3 Gyr. If this mean age is representative of the progenitor of M85 OT 2006-1, then we can further constrain its mass to be less than 2 M☉.” (Ofek et al. 2007) If the size of the less than 2 M☉ LRN M85OT2006-1 fireball was in the range of 74–121 AU (R = 2.0 +.6-.4 x 10^4 R☉), then it’s readily conceivable that our greater than 1 M☉ LRN fireball, at 4,567 Ma, should easily have scorched a preexisting Kuiper belt reservoir centered around 43 AU.
    The solar-merger LRN quickly retreated, leaving a low-angular-momentum ‘LRN debris disk’ in the inner solar system that ‘condensed’ rocky-iron asteroids by streaming instability, presumably against the Sun’s greatly expanded magnetic corotation radius, and later condensed chondrites by streaming instability against Jupiter’s strongest inner resonances, but the low angular momentum content of the solar-merger debris disk precluded forming a high angular momentum debris disk at the distance of the Kuiper belt.
    The dynamic temperature profile of the luminous red nova may partly explain the large centimeter-scale metallic-iron inclusions, which are too large to have been held in molten igneous suspension within the supporting matrix, even in the microgravity of a KBO. The LRN temperature profile over time caused top down melting of the surface regolith, followed by bottom up solidification, during the exponential cooling phase, measured in months. Once reaching a peak melt depth, the receding solar plasma allowed the igneous crust to gradually solidify (cool) from the bottom up, even as iron oxide was still being chemically reduced to a molten metallic-iron state at the surface. Thus as metallic-iron globules rained down onto the rising matrix solidification front, the iron spherules piled up, but since the melting point of iron is higher than the melting point of the surrounding (basaltic) mafic matrix, the iron spherules would be solid at the matrix solidification front; however, prolonged exposure to elevated temperatures may have sintered these iron spherules into solid iron masses below the melting point of iron.

Binary-Companion spiral-in merger at 650 Ma:
    Almost 4 billion years after the binary-Sun merger at 4,567 Ma, the super-Jupiter components of binary-Companion spiraled in to merge at about 650 Ma in an asymmetrical merger explosion that gave the newly-merged Companion escape velocity from the Sun. The resulting ‘Companion-merger debris disk’ presumably condensed a young (650 Ma), cold, classical KBO population against Neptune’s outer 2:3 resonance. And this Companion-merger debris disk may have coated the old (> 4,567 Ma) hot, classical KBO population with a thin veneer of binary-Companion merger dust and ice that was not siderophile depleted. This late veneer on otherwise siderophile-depleted hot classical KBOs may be the origin of the platinum spike found in black mats across North America and in the Greenland ice sheet, dating to 12,800 Ka.

The three debris disks of our highly-unusual solar system:
– Trifurcation debris disk―>4,567 Ma―forming siderophile-depleted hot-classical KBOs
– Solar-merger debris disk―4,567 Ma―forming inner solar system asteroids and chondrites
– Companion-merger debris disk―650 Ma―forming cold classical KBOs

(See section, STARS, PLANETS, MOONS, MINOR PLANETS AND COMETS)
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Ragnarok: The Age of Fire and Gravel:

    In 1883 Ignatius L. Donnelly, US congressman from Minnesota, wrote a treatise on a suggested comet strike 12,000 years ago. For evidence he points to an often unstratified layer of “drift”, “till”, or “hard-pan”, composed of clay and gravel, with occasional inclusions of larger cobbles and boulders. Allochthonous cobbles and boulders in the till are often scored with striations, as from being scraped with great force. Donnelly descriptions indicate that unstratified drift is often overlain with stratified drift.
    Ignatius Donnelly is not merely describing well-defined terminal moraine that is deposited at the maximum reach of ice sheets during glacial maxima, which is frequently marked on geologic maps, but Donnelly describes a much-more widespread phenomenon that is different in kind and extent. This drift may represent material deposited by the sudden collapse (melting) of the Laurentide ice sheet precipitated by the YD comet impact, flushing Canadian sediments into the contiguous northern states of the USA. Unprecedented flooding would have been accompanied by unprecedented debris flows, as ice dams repeatedly formed and catastrophically failed.
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INAA/mass spec analysis of suggested YD impact comet-crust meteorites

YD comet crust characterization:

    In another unfortunate coincidence with industrial iron-smelting slag, YD comet crust has a high calcium oxide content. The fire assay of two comet crust samples yielded 25.69% and 40.28%, which is in line with industrial iron-smelting slag (41.7%) (Chemical composition of iron and steel slag). The high iron and calcium content of YD comet crust are suggested to be the refractory solutes of the saltwater ocean after precipitation of the gneissic sediments, and after volitalization by the solar plasma of the binary-Sun merger LRN.

Gray igneous matrix with metallic-iron inclusions:
    Comet crust is highly variable regarding specimen size, density, matrix to metallic iron ratio, void prevalence, void size, and surface texture. Specimen size ranges from millimeter- to centimeter-scale gravel up to igneous boulders more than a meter across. Igneous matrix density is highly variable, varying by iron-oxide concentration, void prevalence and metallic-iron concentration, but its density is noticeably greater than industrial iron-furnace slag, which has very little remaining iron content. Sectioned slabs of mafic matrix have a greasy appearance, with smearing sometimes evident after cutting with a wet saw.
    Metallic-iron inclusions typically range in size from millimeter- to centimeter-scale, with isolated iron masses up to 100 kg (and maybe much higher).
    Internal voids in gray igneous matrix range in size, and prevalence from millimeter-scale voids, with almost the appearance of volcanic scoria, to centimeter-scale voids, to specimens with a complete absence of voids.

Massive and nodular metallic iron:
    The centimeter-scale of metallic-iron inclusions, which are nearly 2-½ times as dense as the surrounding comet-crust matrix, have too much negative buoyancy to remain suspended in molten igneous matrix, even in the microgravity of KBOs, and certainly on Earth, given the low-viscosity of mafic melts (compared to felsic melts). Thus Special conditions are required for the formation of suspended centimeter-scale metallic-iron inclusions anywhere but in zero gravity. These special conditions are suggested to be the prolonged (months-long) exposure to reducing conditions that chemically reduced iron oxide to metallic iron, with an underlying floor, against which spherules of metallic iron could fall out of suspension and aggregate into larger masses, and in sufficient time to sinter together. In KBOs immersed in LRN plasma, the effective floor was the phase transition between molten matrix and underlying solidified matrix, which cooled from the bottom up, once reaching maximum melt depth. The spherules may have variably sintered together over time, with incomplete sintering creating masses of nodular iron.
    The contorted shapes of many iron inclusions and masses is notable, with many 3-dimensional shapes that would typically have to be cast in a 3-dimensional mold on Earth, due to the high density and low viscosity of molten iron.
    Metallic iron falls into several categories,
1) metallic iron inclusions completely surrounded by gray igneous matrix,
2) massive metallic iron, often with little or no associated igneous matrix, and
3) nodular metallic iron composed of nodules that appear to be sintered together, also with little or no accompanying igneous matrix.
    Compared to the millimeter- to centimeter-scale metallic-iron blebs in suggested comet crust, glassy iron furnace slag from historic Joanna furnace, PA contains only microscopic iron spherules clearly evident in thin glass flakes, backlit under 40X magnification, with the spherules appearing to have a distinct upper size limit.

Nodular metallic iron
Suggested YD-impact comet crust (meteorite)

Sectioned igneous slab with metallic-iron inclusions
Suggested YD-impact comet crust

Broken boulder with magnet attached to metallic-iron inclusion
Suggested YD-impact comet crust

Nodular metallic-iron mass with gritty, whitish, cement-like coating
Suggested YD-impact comet crust

Metallic-iron specimens from Doe Run, PA
Suggested YD-impact comet crust

Gritty, whitish, cement-like coating as a reliable YD comet crust indicator:
    Comet crust meteorites typically exhibit a whitish, gritty, cement-like coating. Calcium carbonate may constitute the glue holding authigenic mineral grains together, because the coating fizzes when exposed to weak acids like vinegar. The cement-like coating is apparently surface contamination acquired at impact, at primary and/or secondary impact, since it often coats surfaces apparently broken on impact. Cement-like coating often overlies fusion crust, but occasionally is melted into the fusion crust itself.
    Cement-like coating is common on both grey igneous matrix and on comet-crust hematite/magnetite, but it’s uncommon on massive and nodular metallic iron, likely because of rust exfoliation. Cement-like coating is suggested to be one of the most reliable indicators of YD comet crust; however, its absence is not proof against membership, because weathering can remove it. Whitish cement-like coating is can be helpful in discriminating between comet crust and iron furnace slag, when the two are mixed in the waste stream.
    Gritty cement-like coating contains variable concentrations of shiny black magnetic spherules, which are visually similar to spherules found at the bottom of the 12,800 year old (YD) black mat across North America and elsewhere, but curiously, the cement-like coating does not also contain transparent glassy spherules, which are also common at the bottom of the YD black mat. The significance of the presence of black spherules and absence of clear glassy spherules has not been fathomed.
    Finally, ‘steam cleaning’ at impact may be partly responsible for bleaching cement-like coating white. Bleached-white sand white has been noted in the rims of Carolina bays.

Note the typical gritty, whitish, cement-like coating characteristic of suggested YD impact comet-crust meteorites

Spherules embedded in cellular matrix gleaned from whitish cement-like coating on surface of suggested YD impact comet crust

Shiny black spherules gleaned from whitish cement-like coating on the surface of suggested YD impact comet crust

Shiny black spherules gleaned from whitish cement-like coating on the surface of suggested YD impact comet-crust meteorite

Shiny black spherules gleaned from whitish cement-like coating on the surface of suggested YD-impact comet crust

High-density magnetite/hematite:
    Some comet-crust iron is in the metallic state, some blended into igneous matrix, and some concentrated in iron ore with varying degrees of purity. Comet-crust iron ore comes in two forms, hematite, which is slightly ferrimagnetic with a reddish-brown streak, and magnetite, which is strongly ferrimagnetic with a black streak, both which typically exhibit gritty, whitish cement-like coating.
    Magnetite in an igneous context on Earth is often a cumulate rock, where dense cumulate crystals precipitate out of a fractionating magma chamber, but cumulate precipitation can not occur in the brief time frame and not in microgravity. Instead, comet-crust magnetite and hematite are suggested to have formed by metasomatism. The continuous cover of molten igneous rock during the LRN created a pressure cooker environment underneath, with temperatures and pressures likely above the triple point (273.16 K, 611.657 Pa) of water, creating supercritical conditions that may have been particularly adept at the physical transport of dissolved mineral species necessary for metasomatism. With a cooler floor, supercritical water may have condensed below, dumping its solute load in the form of precipitation/crystallization. Comet crust iron ore is not found in physical contact with metallic iron or igneous matrix, which might be expected if comet-crust iron ore is metasomatic, while comet-crust matrix and metallic iron is igneous.
    Comet-crust iron ore may exhibit a sinewy surface in hematite, a reniform shape in goethite, a blocky appearance characteristic of pegmatites, or millimeter-sized magnetite grains that are reflective like glitter.

Magnetite with cement-like coating
Suggested metasomatic YD-impact comet crust

Magnetite and hematite with cement-like coating
Suggested metasomatic YD-impact comet crust

Comet crust with one rounded surface:
    Many comet-crust specimens from Phoenixville, PA are roughly triangular in cross section, with one rounded side, resembling a thick slice of pie. The rounded surface was presumably the outer surface of the KBO, directly exposed to LRN plasma, while the other surfaces are fractured. The brief multi-month immersion of KBOs in LRN plasma presumably caused significant volatile loss to the YD KBO, accompanied by densification of the surface regolith during igneous melting. This volatile loss and densification caused subsidence that may have expressed itself in the form of wrinkling, causing the observed degree of undulation in the surface. The radius of the rounding is typically in the range of 10-15 cm.
    Specimens with rounded surfaces have only been found in Phoenixville, which seems suspicious for a natural source; however, specimens exhibiting fusion crust are also more prevalent in Phoenixville, which suggests that the Phoenixville material is from the surface of the former YD KBO, which had greater exposure to ablation during atmospheric transit, hence more fusion crust.

Large metallic-iron mass with gray igneous rocky matrix. The undulating top surface is suggested to be the surface crust of the former Kuiper belt object, wrinkled due to subsidence while exposed to solar plasma
Suggested YD impact comet crust

Pie-slice-shaped specimen, with the rounded side as a fragment of the undulating wrinkled surface of the former Younger Dryas (YD) Kuiper belt object
Suggested YD-impact comet crust

Pie-slice-shaped specimen, with the rounded side as a fragment of the undulating wrinkled surface of the former Younger Dryas (YD) Kuiper belt object
Suggested YD-impact comet crust

Absent to strongly vesicular:
    Suggested comet crust is often dismissed by meteorite experts due to the prevalence of vesicles, since vesicles are very uncommon in inner solar system meteorites. Some comet-crust specimens are so saturated with vesicles as to resemble terrestrial volcanic scoria, and presumably formed in a similar fashion, from pressurized outgassing through weak spots in the molten surface of the YD KBO, whereas some comet crust specimens exhibit no vesicles at all. The observed millimeter- to centimeter-scale variability in vesicle size, when present, does not seem like a likely range of variability in a well-regulated industrial process.

Large vesicles in specimen from Harrisburg, PA
Suggested YD-impact comet crust (meteorite)

Fusion crust, some with flow lines:
    Suggested fusion crust on comet-crust specimens varies in coloration from brown to jet black, where black coloration may be pristine, whereas brown coloration may represent subsequent oxidation. Fusion crust is relatively rare, suggesting that most comet crust was physically protected from the ablative atmosphere during its entry through Earth’s atmosphere. Of small hand-sample-sized specimens exhibiting fusion crust, the fusion crust is frequently evident on all sides, whereas on larger (> 10 cm) specimens that fractured upon impact, the impact-fractured surfaces contain no fusion crust. An industrial iron-furnace slag origin can not readily explain a fusion-crust-like surface on all sides of small hand-sample-sized specimens.
    Fusion crust is common on well-documented inner solar system meteorites, as are regmaglypts on iron-nickel meteorites. While there does seem to be some indication of regmaglypts on comet-crust magnetite, there are no comet-crust iron specimens exhibiting apparent regmaglypts.
    Additionally, several comet-crust mafic-matrix specimens with fusion crust specimens appear to exhibit flow lines as well.

Front and back of specimen showing complete coverage by fusion crust. Note that cement-like coating covers fusion crust.

Fusion crust on suggested YD-impact comet crust

Fusion crust on specimens from Phoenixville, PA
Suggested YD-impact comet-crust meteorites

Fusion crust on specimen from Phoenixville, PA
Suggested YD-impact comet-crust meteorite

Fusion crust with flow lines and embedded spherules in YD-impact Clovis-comet-crust meteorite

Fusion crust with flow lines
Suggested YD-impact comet-crust meteorite

Industrial-slag imitation of comet crust:
    Early 18th century industrial bloomers slag can resemble comet-crust iron ore, but bloomery slag never exhibits the gritty cement-like coating that marks comet crust as genuine.  In Phoenixville, PA, early bloomery slag (likely from the 1716 Pool Bloomery Forge near Pottstown) is mixed with later blast-furnace slag and comet-crust material in the waste stream dumped over the south bank of French Creek.
    Comet crust was apparently sometimes melted (rather than smelted) for its metallic-iron component in small auxiliary furnaces to larger iron-smelting blast furnaces, leaving behind high-density slag with a high iron-oxide content, but minus its metallic-iron component.  Comet crust melted for its metallic iron content will not exhibit the gritty, whitish cement-like coating.

Early colonial bloomery slag, early 18th century

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Comet crust as a mimic of industrial iron-furnace slag:

    Comet crust concentrations are almost invariably associated with historical iron manufacturing, due to the high iron content. Complicating matters, some comet crust appears to have been melted rather than smelted for its metallic-iron content, creating high-density ‘comet-crust slag’, which still contains the original iron-oxide content, but is devoid of its metallic-iron and is often rife with broken fire brick inclusions. Comet-crust slag, however, will never possess the whitish, gritty cement-like coating, which almost ubiquitous on large chunks of pristine comet crust. Comet-crust melting, rather than smelting, for its metallic-iron content likely occurred in small ad hoc furnaces on the grounds of larger smelting operations, creating cast iron with embrittling contaminants for undemanding ballast applications like window sash counterweights. Indeed, broken chunks of window sash counterweights can still be found on the west bank of the Schuylkill River in West Conshohocken, PA.

    Another unfortunate coincidence is the similarity in chemistry. Siderophile depletion at trifurcation, followed by gneissic sediment depletion at aqueous differentiation, followed by volatile depletion during solar plasma immersion has concentrated the iron and calcium oxides in comet crust, which are the very oxides most concentrated in iron ore and in industrial iron-furnace slag respectively. The high density of typical comet crust in the form of high iron oxide content and high metallic-iron content should raise eyebrows, but this glaring inefficiency would likely be dismissed as primitive processing in early colonial manufacturing. Two assayed comet-crust specimens measured 12.31% and 9.61% for Fe2O3.

    The extreme variability of comet-crust material across its various types argues against an industrial origin, where repeatability is critical for consistent outcomes and thus, profitability. Manufacturing strives to reduce variability and reduce waste, where the high iron content in the waste stream at multiple sites telegraphs a natural origin.
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Locations in Southeastern Pennsylvania:

Conshohocken, PA:
    A large volume of comet crust has been dumped on a triangle of land just off Light Street, Conshohocken, PA (40.0807, -75.3127), readily identifiable on Google satellite due to the herbicide properties of granulated comet crust. West Conshohocken also exhibits numerous diabase boulders with sharp edges formed by relatively-recent catastrophic fracturing, rather than gradual weathering, suggesting brecciation by a secondary impact of an ice-sheet fragment. Conshohocken combines two elements of secondary impacts; relatively-recently fractured boulders with evidence of catastrophic fracturing and comet crust material.
    Comet-crust material in Conshohocken is variably mixed with iron furnace slag and comet-crust slag. Broken window sash weights on the west bank of the Schuylkill River point to possible small-scale melting, rather than smelting, of comet crust.
    Calvary Cemetery in West Conshohocken has diabase boulders with sharp edges, indicating recent catastrophic fracturing. Also, comet crust specimens can be found in the wooded areas (40.0613, -75.3271).

Mound of granular material with a high ferromagnetic content from from Conshohocken, PA (40.0807, -75.3127)
Suggested YD-impact ‘comet-crust slag’. Pristine comet crust was presumably processed by melting (rather than smelting) for its metallic-iron content, then sprayed with cold water to fracture it to form the observed granular material. Melting removes only the metallic iron, leaving behind high-density slag with a high iron-oxide content. The tan foreground material (of the inset image) is pristine, while the grey mound material was presumably industrially processed.
Note the herbicidal properties of granular comet crust.

Loose metallic-iron nodules from Conshohocken, PA
Suggested YD impact comet-crust metallic-iron

Doe Run, PA (East Fallowfield Township):
    Park at the Speakman Number 1 Covered bridge (39.9293, -75.8228), and particularly scout the high side of Covered Bridge Rd., where the farmer appears to have tossed comet crust matrix and metallic iron to the edge of his field, some of which has tumbled down the slope to the road’s edge.

Phoenixville, PA:
    In Phoenixville, PA, a significant quantity of triangular chunks of comet crust, with one rounded surface like slices of pie, are mixed with a smaller quantity of industrial iron furnace slag from the nearby historic Phoenixville iron works. Here, the industrial slag appears to be of two types, low-density slag smelted in the primary Phoenixville iron works blast furnace, and high-density slag, presumably melted comet crust in small adjunct furnaces with its iron oxide content intact. The high incidence of pie-shaped slices of comet crust in the waste stream may be due to the low iron content of comet crust from the surface of the former YD KBO.
    The slag and comet-crust material has been tumbled into the French Creek ravine along the south bank, between N. Main St. and Ashland St. (40.135, -75.513), just east of the Phoenixville Foundry.

Harrisburg Area:
    As elsewhere, comet crust has been used as clean fill in the Harrisburg Area. Comet crust in combination with iron-furnace slag has been used to build what appears to be an abandoned road spur off Paxton Ave. between Paxton Ministries and Faulkner Honda (40.2545, -76.8505).
    Comet crust has also been used as clean fill on the East Shore of the Susquehanna River for residential parking on the river side of Front St. in Enola, PA, and the material has been spotted as far west as Wesley Dr. in Mechanicsburg, PA.

Prospecting:
    A strong rare earth magnet is the only necessary prospecting tool for finding potential comet crust in Southeastern Pennsylvania and elsewhere. Early spring may be most the productive time to search, before obscuring vegetation begins to grow, and after the fall leaves have compressed over winter.

Rare-earth magnet attached to metallic-iron inclusion in specimen
Suggested YD-impact comet crust (meteorite)

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Association with the iron industry:

    Secondary-impact concentrations of comet crust concentrations exploited in the 19th and 20th century for its iron content were presumably assumed to be poorly-processed 18th century iron-furnace slag.  Native iron is exceedingly rare on Earth, such that slag-like concentrations in the subsoil containing metallic-iron inclusions and posessing elevated calcium-oxide percentages would naturally be mistaken for poorly-processed colonial iron-furnace slag.
    The close connection between comet crust and the iron industry in a siderophile-depleted material so similar to industrial iron furnace slag makes radiometric dating the only chance of establishing comet crust as extraterrestrial.

    Presumably metasomatic comet-crust iron ore has significantly-less contaminating embrittlements compared to igneous comet-crust matrix and igneous comet-crust metallic iron.  The apparent extraction of metallic iron from comet crust matrix by simple melting in dedicated auxiliary furnaces suggests that comet crust matrix material was unsuitable for smelting for its iron oxide content in primary blast furnaces.  The brittle metallic iron in comet-crust matrix was apparently a bonus that could easily be extracted with low technology auxiliary furnaces with low energy expenditure by simply melting rather than smelting comet-crust matrix, but the reason so much comet crust material survives is presumably due to the limited market for non-critical ballast applications of brittle comet-crust iron, such window-sash counterweights.

    A small ‘failed’ iron furnace is moldering in the woods in West Conshohocken.  The home made iron furnace constructed of fire brick contains several cubic feet of cast iron that apparently solidified before it could be tapped to make pig-iron ingots.  A 1938 nickel found in the immediate vicinity suggests the age of the furnace.
    Nearby rests another cottage-industry-scale iron furnace that was considerably more sophisticated, in the form of a 4 ft diameter Bessemer-style furnace.
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Theory weakness:

– The apparent lack of iron tool usage by indigenous peoples of North America is a significant obstacle to the hypothesis, even if the vast majority of comet crust material had been deeply embedded into the subsoil at impact.
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Future work:

– Several comet crust samples were analyzed by INAA, including one analysis on a metallic-iron inclusion, but no iridium was found down to 5 ppb. INAA does not detect platinum, however, which is a prevalent YD black mat marker, and platinum was found in Greenland ice cores from 12,900 B.P., so an assay for platinum-group elements should be made.

– An old age determination (4,567 Ma) for comet crust would be the gold standard for a new class of siderophile-depleted, igneous-origin, outer solar system material that lacks nickel and iridium, but date testing is apparently the exclusive domain of academia—Act Labs in Canada did not answer my email inquires on date testing.
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References:

Dietz, R. S., Barring, J. P., (1973), Hudson Bay arc as an astrobleme: A negative search, Meteoritics, Vol. 8, p. 28-29

Firestone, Richard B., (2009), The Case for the Younger Dryas Extraterrestrial Impact Event: Mammoth, Megafauna, and Clovis Extinction, 12,900 Years Ago, Journal of Cosmology, 2009, Vol 2, pages 256-285, Cosmology, October 27, 2009

Moore, Christopher R.; West, Allen; LeCompte, Malcolm A.; Brooks, Mark J.; Daniel Jr., I. Randolph; Goodyear, Albert C.; Ferguson, Terry A.; Investor, Andrew H.; Feathers, James K.; Kennett, James P.; Tankersley, Kenneth B.; Adedeji, A. Victor; Bunch, Ted E., (2017), Widespread platinum anomaly documented at the Younger Dryas onset in North American sedimentary sequences, Scientific Reports 7, Article number: 44031 (2017)

Ofek, E. O.; Kulkarni, S. R.; Rau, A.; Cenko, S. B.; Peng, E. W.; Blakeslee, J. P.; Cote, P.; Ferrarese, L;. Jordan, A.; Mei, S.; Puzia, T.; Bradley, L. D.; Magee, D.; Bouwens, R., (2007), The Environment of M85 optical transient 2006-1: constraints on the progenitor age and mass, arXiv:0710.3192 [astro-ph]

Petaev, Michail I.; Huang, Sichuan; Jacobsen, Stein B.; Zindler, Alan, (2013), Large Pt anomaly in the Greenland ice core points to a cataclysm at the onset of Younger Dryas, PNAS Aug. 6, 2013 110 (32) 12917-12920

Rau, A.; Kulkarni, S. R.; Ofek, E. O.; Yan, L., (2007), Spitzer Observations of the New Luminous Red Nova M85 OT2006-1, The Astrophysical Journal, Volume 659, Issue 2, pp. 1536-1540

Wolbach, Wendy S. et al, (2018), Extraordinary Biomass-Burning Episode and Impact Winter Triggered by the Younger Dryas Cosmic Impact ~12,800 Years Ago. 1. Ice Cores and Glaciers, The Journal of Geology, Volume 126, Number 2, March 2018

Wolbach, Wendy S. et al, (2018), Extraordinary Biomass-Burning Episode and Impact Winter Triggered by the Younger Dryas Cosmic Impact ~12,800 Years Ago. 2. Lake, Marine, and Terrestrial Sediments, The Journal of Geology, Volume 126, Number 2, March 2018
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