The set of spherules that Opportunity came across in 20183.
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Instead of finding foraminifera, Schaller and his team found the glassy spherules.
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And lodged inside the fossilized paddlefish's gills were more of the glass spherules.
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The asteroid's possible size was determined by analyzing the size of the spherules, Glikson told CNN.
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Glikson and his team are basing their assessment on the discovery of tiny glass beads called spherules.
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The spherules are iron-heavy "concretions formed by action of mineral-laden water inside rocks," according to NASA.
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He'd also like to find more spherules, as his team has only a few dozen to work with.
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In addition, the researchers performed comparative analyses with other microtektites, cosmic spherules (also known as micrometeorites), and volcanic rocks.
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Such spherules are believed to form when a huge comet or asteroid sprays droplets of molten rock into the air.
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One of Opportunity's first big finds, in April 2004 was small, round "spherules," photographed by its microscopic imager near Fram Crater.
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To confirm that the spherules were indeed micrometeorites Mr Larsen needed both expertise and more heavyweight equipment than he had at home.
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Altogether, he found about 500 of these "spherules", each around 300-400 microns in diameter (a few times the width of a human hair).
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These spherules, detailed today in the journal Science, are thought to be impact leftovers — rock debris that the comet or asteroid ejected when it hit Earth.
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The rover also came across an abundance of tiny spherical objects called Martian spherules, nicknamed "blueberries," created by multiple processes including volcanic eruptions, meteor impacts, and contact with water.
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Out of the 661 pounds of rooftop debris the team analyzed, 48 samples were confirmed as "cosmic spherules," formed by extreme melting as a meteorite heats up in Earth's atmosphere.
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The timing of the two events is pretty tantalizing for researchers The evidence the researchers found are tiny glassy spheres, known as spherules, inside ocean rocks along the US East Coast.
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The research team only found spherules near New Jersey and Florida, but these glassy objects need to be found in more ocean rocks to see how far the impact debris spread.
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The outcrop erodes away as it gets sandblasted, and the spherules (which seem to resist erosion better than the rest of the outcrop does) fall out and roll down the hill. Weird.
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The column has a number of iridescent blue spherules armed with nematocysts.
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Melted micrometeorites (cosmic spherules) were first collected from deep-sea sediments during the 1873 to 1876 expedition of HMS Challenger. In 1891, Murray and Renard found "two groups [of micrometeorites]: first, black magnetic spherules, with or without a metallic nucleus; second, brown-coloured spherules resembling chondr(ul)es, with a crystalline structure". In 1883, they suggested that these spherules were extraterrestrial because they were found far from terrestrial particle sources, they did not resemble magnetic spheres produced in furnaces of the time, and their nickel- iron (Fe-Ni) metal cores did not resemble metallic iron found in volcanic rocks. The spherules were most abundant in slowly accumulating sediments, particularly red clays deposited below the carbonate compensation depth, a finding that supported a meteoritic origin.
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Spherules still in their originating strata Martian spherules (also known as blueberries due to their blue hue in false-color images released by NASA) are the abundant spherical hematite inclusions discovered by the Mars rover Opportunity at Meridiani Planum on the planet Mars.
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It included nanodiamonds (including the hexagonal form called lonsdaleite), carbon spherules, and magnetic spherules. Multiple hypotheses were examined to account for these observations, though none were believed to be terrestrial. Lonsdaleite occurs naturally in asteroids and cosmic dust and as a result of extraterrestrial impacts on Earth.
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In addition to those spheres with Fe-Ni metal cores, some spherules larger than 300 µm contain a core of elements from the platinum group. Since the first collection of HMS Challenger, cosmic spherules have been recovered from ocean sediments using cores, box cores, clamshell grabbers, and magnetic sleds. Among these a magnetic sled, called the "Cosmic Muck Rake", retrieved thousands of cosmic spherules from the top 10 cm of red clays on the Pacific Ocean floor.
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Spherules are found lying unconformably over Carboniferous limestone in Wickwar Quarry. These are possibly tektite deposits, formed as molten material ejected by a meteorite impact that may have fallen back to Earth.Kirkham, A. 2003. Glauconitic spherules from the Triassic of the Bristol area, SW England: probable microtektite pseudomorphs.
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Close-up of a rock outcrop. Thin rock layers, not all parallel to each other. spherules. spherules. The Mars Exploration Rovers, Spirit and Opportunity found a great deal of evidence for past water on Mars. The Spirit rover landed in what was thought to be a large lake bed.
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Cribrinopsis fernaldi is a large anemone that can be crimson red, orange or white. This species has zigzag transverse lines on its tentacles, white tubercles on its column, and spherules just below the tentacles. These spherules can be especially hard to see as they are often withdrawn. The column is up to in diameter and around high.
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The presence of lightning-induced volcanic spherules may provide geological evidence for volcanic lightning when the lightning itself was not observed directly.
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South Africa's Kaapvaal craton and Western Australia's Pilbara craton have similar early Precambrian cover sequences. Kaapvaal's Barberton granite- greenstone terrane and Pilbara's eastern block show evidence of four large meteorite impacts between 3.2 and 3.5 billion years ago. (Similar greenstone belts are now found at the margins of the Superior craton of Canada.) The high temperatures created by the impact's force fused sediments into small glassy spherules. Spherules of 3.5 billion years old exist in South Africa and spherules of a similar age have been found in Western Australia, they are the oldest-known terrestrial impact products.
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Several relatively large matrix spherules, about 0.1 to 0.3 mm across, are present as a bead-like girdle, band, or sheath inside the periphery of the chondre.
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Malhmoodite is a creamy-white mineral with a silky luster. It exhibits a 3 on the Mohs hardness scale. The spherules of Malhmoodite are made up of thin, flat, radiating, optically homogeneous crystals and seem to form in a parallel extinction and positive elongation. The cores of the spherules appear to be loose material, making up about one-third to one-half of the radius of the spherule.
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Early in the mission, mission scientists were able to prove that the abundant spherules at Eagle crater were the source of hematite in the area discovered from orbit.
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Researchers from the University of Utah have explored the similarities between the blueberries and spherical concretions discovered within “Jurassic Navajo Sandstone” in southern Utah. They have concluded Mars must have had previous ground water activity to form the blueberries. However, they do note the spherules are more spherical in the Martian sample due to the lack of “joints, fractures, faults, or other preferential fluid paths,” unlike the Utah sample. A team of researchers from Japan studied the spherules found in Utah as well as spherules that were later discovered in Mongolia, in the Gobi. They found evidence that the concretions found in these locations are first formed as “spherical calcite concretions” in sandstone.
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Acicular crystals from the Wessels Mine in South Africa Bultfonteinite is transparent and pale pink to colorless. The mineral occurs as radiating prismatic acicular crystals and radial spherules up to .
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Any difference in the measured data was then attributed to the material in the spherules. A large difference in the obtained "spectra" was found. "This is the fingerprint of hematite, so we conclude that the major iron-bearing mineral in the berries is hematite," said Daniel Rodionov, a rover science team collaborator from the University of Mainz, Germany. This discovery seems to strengthen the conclusion, that spherules are concretions, grown in wet condition with dissolved iron.
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The pyroclastics at Laco Sur contain spherules of magnetite. An age of 2.1±0.1 million years has been found for ore by fission track dating. The lavas contain veins likely generated by hydrothermal activity.
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Glass resembling rock samples were collected and investigated. These spherules contain very high percentage of iron, along with very high ratios of nickel and cobalt. This high ratios suggests a meteorite strike or extraterrestrial rocks.
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Then he discovered that drill cuttings from the earlier gas well were archived at the New York State Geological Survey museum. These cuttings were examined carefully, during which graduate students working for him found microscopic iron spherules — to him irrefutable evidence of an impact crater. However, questions from crater specialists at a conference in Budapest sent him back to look more closely at the cuttings. One attendee pointed out that he hadn't ruled out the possibility that the spherules had merely been deposited by a passing meteorite or comet.
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Experimental studies and investigation of volcanic deposits have shown that volcanic lighting creates a by-product known as "lightning-induced volcanic spherules" (LIVS). These tiny glass spherules form during high-temperatures processes such as cloud-to- ground lightning strikes, analogous to fulgurites. The temperature of a bolt of lightning can reach 30,000 °C. When this bolt contacts ash particles within the plume it may do one of two things: (1) completely vaporize the ash particles, or (2) cause them to melt and then quickly solidify as they cool, forming orb shapes.
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It occurs in fumaroles, as a result of combustion metamorphism and coal seam fires, in glass spherules related to meteorite impacts, and as accessory phase in kimberlites and carbonatites. It has been reported from Vesuvius and Stromboli, Italy.
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They appear in nodular patches, concentrated along bedding planes, protruding from weathered cliffsides, randomly distributed over mudhills or perched on soft pedestals. Small hematite concretions or Martian spherules have been observed by the Opportunity rover in the Eagle Crater on Mars.
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The evidence given by proponents of a bolide or meteorite impact event includes "black mats", or strata of organic-rich soil that have been identified at dozens of Clovis culture archaeological sites in North America. Proponents have reported materials including nanodiamonds, metallic microspherules, carbon spherules, magnetic spherules, iridium, platinum, platinum/palladium ratios, charcoal, soot, and fullerenes enriched with helium-3 that they interpret as evidence for an impact event that marks the beginning of the Younger Dryas. Proponents of the hypothesis claim that these data cannot be adequately explained by volcanic, anthropogenic, or other natural processes.
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The article claimed that no nanodiamonds were found and that the supposed carbon spherules could be fungus or insect feces and included modern contaminants. In response, in June 2013 some of the original proponents published a re-evaluation of spherules from eighteen sites worldwide that they interpret as supporting their hypothesis. Skepticism increased with the revelation of documentation demonstrating misconduct and past criminal conduct. In 2012, scientists reported evidence supporting a modified version of the Younger Dryas impact hypothesis—involving a much smaller, non-cometary impactor—was found in lake bed cores dating to 12,900 YBP from Lake Cuitzeo in Guanajuato, Mexico.
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Several other sites also showed hematite, such as Aureum Chaos. Because terrestrial hematite is typically a mineral formed in aqueous environments or by aqueous alteration, this detection was scientifically interesting enough that the second of the two Mars Exploration Rovers was sent to a site in the Terra Meridiani region designated Meridiani Planum. In-situ investigations by the Opportunity rover showed a significant amount of hematite, much of it in the form of small spherules that were informally named "blueberries" by the science team. Analysis indicates that these spherules are apparently concretions formed from a water solution.
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Unlike other species which may accumulate matter, the tubercles do not attach to ocean debris such as bits of shell. The column is red in colour. No special spherules are present around the external rim of the oral disk beyond the tentacles.
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Granulocytes apparently develop from plasmatocytes and are also amoeboid, although no phagocytosis has been observed. They may act as storage cells. Spherulocytes are up to 15 µm long seem to be non-motile. They contain many spherules, whose composition changes over time, but the function is not known.
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The soils consist of fine-grained basaltic sand and a surface lag of hematite-rich spherules, spherule fragments, and other granules. Underlying the thin soil layer, are flat-lying sedimentary rocks. These rocks are finely laminated, are rich in sulfur, and contain abundant sulfate salts.S. Squyres, et al.
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Gilalite is a copper silicate mineral with chemical composition of Cu5Si6O17·7(H2O). It occurs as a retrograde metamorphic phase in a calc- silicate and sulfide skarn deposit. It occurs as fracture fillings and incrustations associated with diopside crystals. It is commonly found in the form of spherules of radial fibers.
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These blueberries were found to be composed almost entirely of the mineral hematite. It was decided that the spectra signal spotted from orbit by Mars Odyssey was produced by these spherules. After further study it was decided that the blueberries were concretions formed in the ground by water.Bell, J (ed.) The Martian Surface. 2008.
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A spherical structure for allophane. Nature 281, 339 only Transmission electron micrographs show that it is generally made up of aggregates of hollow spherules ~3–5 nm in diameter. Allophane can alter to form halloysite under resilicating aqueous conditions and can alter to form gibbsite under desilicating conditions. A copper containing variety cupro-allophane has been reported.
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In 2016 a new study showed that flat roofs in urban areas are fruitful places to extract micrometeorites. The "urban" cosmic spherules have a shorter terrestrial age and are less altered than the previous findings. Amateur collectors may find micrometeorites in areas where dust from a large area has been concentrated, such as from a roof downspout.
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This color-enhanced image shows spherical granules. Microscopic images of the soil taken by Opportunity revealed small spherically shaped granules. They were first seen on pictures taken on Sol 10, right after the rover drove from the lander onto martian soil. When Opportunity dug her first trench (Sol 23), pictures of the lower layers showed similar round spherules.
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Kutnohorite occurs as aggregates of bundled blades of white through rose pink to light brown crystals. Also as simple rhombs with curved faces, polycrystalline spherules and in massive and granular habits. It has perfect rhombohedral cleavage, typical of carbonates. It is brittle with a subconchoidal fracture and it is quite soft, with hardness to 4, between calcite and fluorite.
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Perhamite can range in color from white to brown and can be translucent to opaque. Its luster is said to be earthy, but vitreous to pearly along fractures. It occurs as radial discoidal, platy hexagonal crystals, in rough spherules up to 1mm thick. The specific gravity of perhamite is measured at 2.64 with a calculated density of 2.53.
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Over time, these concretions weathered from what was overlying rock, and then became concentrated on the surface as a lag deposit. The concentration of spherules in bedrock could have produced the observed blueberry covering from the weathering of as little as one meter of rock.Squyres, S. et al. 2004. The Opportunity Rover's Athena Science Investigation at Meridiani Planum, Mars.
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The name is derived from xocomecatl, the Nahuatl word for "bunches of grapes", and alludes to the mineral's appearance as a set of green spherules. It occurs in the oxidized zone of gold-tellurium veins in altered rhyolite. It occurs associated with other rare tellurate minerals: parakhinite, dugganite, tlapallite, mcalpineite, leisingite, jensenite; the sulfate - phosphate minerals: hinsdalite–svanbergite; and the oxide goethite.
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"A number of straightforward geological processes can yield round shapes," says Hap McSween. These include accretion under water, meteor impacts, or volcanic eruptions. The principal investigator, Steve Squyres, indicates they could alternately be concretions, or accumulated material, formed by minerals coming out of solution as water diffused through rock. Mosaic shows some spherules partly embedded, spread over the (smaller) soil grains.
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Wu, Y., Sharma, M., LeCompte, M.A., Demitroff, M.N. and Landis, J.D., 2013. Origin and provenance of spherules and magnetic grains at the Younger Dryas boundary. Proceedings of the National Academy of Sciences, 110(38), pp.E3557-E3566. A later paper argues that their interpretation is based on the misreading of preliminary results, including a radiocarbon date, published in a conference abstract.
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The rock "Berry Bowl". On March 18 the results of the investigation of the area called "Berry Bowl" was announced. This site is a large rock with a small, bowl-shaped depression, in which a large number of spherules had accumulated. The MIMOS II Mössbauer spectrometer was used to analyze the depression and then the area of the rock right beside it.
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He also conducted a wide range of research at the crater, discovering impactite, iron-nickel spherules related to the impact and vaporization of the asteroid, and the presence of many features still unique to the crater, such as half-melted slugs of meteoric iron mixed with melted target rock. Nininger's discoveries were compiled and published in a seminal work, Arizona's Meteorite Crater (1956).
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Opportunity rover found that the soil at Meridiani Planum was very similar to the soil at Gusev Crater and Ares Vallis; however in many places at Meridiani the soil was covered with round, hard, gray spherules that were named “blueberries.”Yen, A., et al. 2005. An integrated view of the chemistry and mineralogy of martian soils. Nature. 435.: 49-54.
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Cambridge University Press. Over time, these concretions weathered from what was overlying rock, and then became concentrated on the surface as a lag deposit. The concentration of spherules in bedrock could have produced the observed blueberry covering from the weathering of as little as one meter of rock.Squyres, S. et al. 2004. "The Opportunity Rover’s Athena Science Investigation at Meridiani Planum, Mars".
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The rock "Berry Bowl". Opportunity Rover found that the soil at Meridiani Planum was very similar to the soil at Gusev crater and Ares Vallis; however in many places at Meridiani the soil was covered with round, hard, gray spherules that were named "blueberries."Yen, A., et al. 2005. An integrated view of the chemistry and mineralogy of martian soils. Nature. 435.
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Spheres at Kirkwood, each are about 3 mm across In the fall Opportunity headed south, exploring Matijevic hill and searching for phyllosilicate minerals. Some data was sent to Earth directly using X-Band radio signals, as opposed to orbiter relays. Finally, the number of power cycles on the rover's Inertial Measurement Unit were reduced. Science work included testing various hypotheses about the newly discovered spherules.
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Before differentiating into adiaspores, the conidia measure 2-4 μm in diameter and are shaped either ovoid, subglobose or pyriform with glabrous walls. After growth at 40 °C the conidia morph into their adiaspore form enlarging to approximately 25 μm in vitro and 40 μm in vivo. These adiaspores are uninucleate and they do not replicate. They are occasionally mistaken for spherules of the organism Coccidioides immitis.
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Changbaiite has a trigonal crystal system and a space group of R3m. Its lattice dimensions are a= 10.499 Å c = 11.553 Å. Changbaiite can be found as a small crystal with a tabular or spherules crystal shape. It can get up to 5mm in size and averages from 0.2 to 0.4 mm. Changbaiite's trigonal crystals show 3m symmetry and is bounded, in sequence of lessening prominence.
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The Placozoa normally propagate asexually, dividing in the middle to produce two (or sometimes, three) roughly equal-sized daughters. These remain loosely connected for a while after fission. More rarely, budding processes are observed: spherules of cells separate from the dorsal surface; each of these combines all known cell types and subsequently grows into an individual of its own. Sexual reproduction is thought to be triggered by excessive population density.
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The K–Pg boundary exposure in Trinidad Lake State Park, in the Raton Basin of Colorado, shows an abrupt change from dark- to light-colored rock. White line added to mark the transition. This hypothesis was viewed as radical when first proposed, but additional evidence soon emerged. The boundary clay was found to be full of minute spherules of rock, crystallized from droplets of molten rock formed by the impact.
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The petrified wood of this tree is frequently referred to as "Rainbow wood" because of the large variety of colors some specimens exhibit. The red and yellow are produced by large particulate forms of iron oxide, the yellow being limonite and the red being hematite. The purple hue comes from extremely fine spherules of hematite distributed throughout the quartz matrix, and not from manganese, as has sometimes been suggested.
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Chondrules in a chondrite meteorite. A millimeter scale is shown. Meteorites contain a record of accretion and impacts during all stages of asteroid origin and evolution; however, the mechanism of asteroid accretion and growth is not well understood. Evidence suggests the main growth of asteroids can result from gas-assisted accretion of chondrules, which are millimeter-sized spherules that form as molten (or partially molten) droplets in space before being accreted to their parent asteroids.
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Xocomecatlite is a rare tellurate mineral with formula: Cu3(TeO4)(OH)4. It is an orthorhombic mineral which occurs as aggregates or spherules of green needlelike crystals. It was first described in 1975 for an occurrence in the Oriental mine near Moctezuma, Sonora, Mexico. It has also been reported from the Centennial Eureka mine in the Tintic District, Juab County, Utah and the Emerald mine of the Tombstone District, Cochise County, Arizona in the United States.
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However, recent analyses have shown that isolated particles of non- biogenic origin make up the majority of the magnetic particles in the thick clay unit. A 2016 report in Science describes the discovery of impact ejecta from three marine P-E boundary sections from the Atlantic margin of the eastern U.S., indicating that an extraterrestrial impact occurred during the carbon isotope excursion at the P-E boundary. The silicate glass spherules found were identified as microtektites and microkrystites.
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Sewardite has only been found at three locations, in the Tsumeb mine in Tsumeb, Namibia, Mina Ojuela, Mapimi, Durango, Mexico, and La Mur, Las Animas mine, Sonora, Mexico. At the site in Durango, Mexico, it occurs as a dark, reddish spherules and rosettes of very thin, flaky crystals. This newly discovered mineral (confirmed as a species in 1998) has been determined as rare, since only 1–2 mg of it were found in the Tsumeb mine.
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Mosaic shows spherules, some partly embedded, spread over (smaller) soil grains on the Martian surface. Concretions are found in a variety of rocks, but are particularly common in shales, siltstones, and sandstones. They often outwardly resemble fossils or rocks that look as if they do not belong to the stratum in which they were found. Occasionally, concretions contain a fossil, either as its nucleus or as a component that was incorporated during its growth but concretions are not fossils themselves.
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Micrometeorites found in polar sediments are much less weathered than those found in other terrestrial environments, as evidenced by little etching of interstitial glass, and the presence of large numbers of glass spherules and unmelted micrometeorites, particle types that are rare or absent in deep-sea samples. The MMs found in polar regions have been collected from Greenland snow, Greenland cryoconite, Antarctic blue ice Antarctic aeolian (wind-driven) debris, ice cores, the bottom of the South Pole water well, Antarctic sediment traps and present day Antarctic snow.
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Not even a weak initial charge is needed to start the machine; the self-excitation system automatically starts by turning the mobile disk clock- wise (when viewed from the front of the machine) using the special crank. The quantity of charge captured through induction by the combs is collected by the two mobile, brass collection rings, the terminal spherules of the spark-gap are each charged by the opposite sign with respect to the sign of the comb with which they are in contact.
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The impact is thought to have happened in the Holocene period, around 3,500 years ago.Bianca Mikovitš. Teadlaste töö tulemus Kaali kraatri vanuse määramisel ühtib vana regilauluga Maaleht, January 26, 2016 The estimates of the age of the Kaali impact structure (Saaremaa Island, Estonia) provided by different authors vary by as much as 6,000 years, ranging from ~6,400 to ~400 years before current era (BCE). Analysis of silicate spherules in Estonian bogs show that the possible age of the impact craters could be approximately 7,600 years.
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For ease of identification, its etching tests are as follows; With HNO3 it slowly produces a weak brown variegated deposit that acts as a protector to the surface and can be removed completely; with aqua regia it effervesces and produces a weak deposit that can be rubbed off and white, radiating spherules are formed, reaction with FeCl3 yields a browning of the surface at different rates and produces black rims of droplet.Ramdohr, P. (1980) The Ore minerals and their intergrowths. Second edition. Volume II, Pergamon Press. p. 524. .
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21736 The site contains both human made lithic artifacts and megafauna remains–including gomphotheres. All the horizons containing megafauna and evidence of human activity date to the late Pleistocene. The calibrated radiocarbon dates indicate human evidences between 16,400 and -12,800 cal years B.P. The site is claimed to contain evidence for the Younger Dryas impact hypothesis. This evidence include sediment layers with charcoal and pollen assemblages both indicating major disturbances as well as rare metallic spherules, and a Pt. Au and Pd peak anomaly originating from claimed to be derivative of airbursts or impacts.
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General depiction of (+)ssRNA viral replication with spherules formed from the membrane of the endoplasmic reticulum After virus entry, the protein capsid is degraded by the host cell, and this allows the unpackaging of the viral RNA. RNA1 and RNA2 encode for protein 1a and 2a-polymerase, respectively, both of which are expressed to produce viral replication proteins within the cell. The actual replication process occurs in membrane vesicles created from invaginations of the host endoplasmic reticulum membrane. The viral RNA is replicated into a dsRNA genome utilizing an RNA dependent-RNA polymerase.
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The spherules resemble the glassy chondrules (rounded granules) in carbonaceous chondrites, which are found in carbon-rich meteorites and lunar soils. Remarkably similar lithostratigraphic and chronostratigraphic structural sequences between these two cratons have been noted for the period between 3.5 and 2.7 billion years ago. Paleomagnetic data from two ultramafic complexes in the cratons showed that at the two cratons could have been part of the same supercontinent. Both the Pilbara and Kaapvaal cratons show extensional faults which were active about during felsic volcanism and coeval with the impact layers.
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The evidence for the Alvarez impact hypothesis is supported by chondritic meteorites and asteroids which contain a much higher iridium concentration than the Earth's crust. The isotopic ratio of iridium in meteorites is similar to that of the Cretaceous–Paleogene boundary layer but significantly different from the ratio in the Earth's crust. Chromium isotopic anomalies found in Cretaceous–Paleogene boundary sediments are similar to that of an asteroid or a comet composed of carbonaceous chondrites. Shocked quartz granules, glass spherules and tektites, indicative of an impact event, are common in the Cretaceous–Paleogene boundary, especially in deposits from around the Caribbean.
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In 2018, some researchers interpreted the undated Hiawatha Glacier impact crater in Greenland as evidence for the Younger Dryas impact event due to its location. Two papers were published dealing with an "extraordinary biomass-burning episode" associated with the Younger Dryas Impact. In 2019, scientists reported evidence in sediment layers with charcoal and pollen assemblages both indicating major disturbances at Pilauco Bajo, Chile in sediments dated to 12,800 BP. This included rare metallic spherules, melt glass and nanodiamonds thought to have been produced during airbursts or impacts. Pilauco Bajo is the southernmost site where evidence of the Younger Dryas impacts has been reported.
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This reveals a dark matrix embedded throughout with mm-sized, lighter-colored chondrules, tiny stony spherules found only in meteorites and not in earth rock (thus it is a chondritic meteorite). Also seen are white inclusions, up to several cm in size, ranging in shape from spherical to highly irregular or "amoeboidal." These are known as calcium-aluminum-rich inclusions or "CAIs", so named because they are dominantly composed of calcium- and aluminum-rich silicate and oxide minerals. Like many chondrites, Allende is a breccia, and contains many dark-colored clasts or "dark inclusions" which have a chondritic structure that is distinct from the rest of the meteorite.
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Self-portrait of Opportunity near Endeavour Crater on the surface of Mars (January 6, 2014). Cape Tribulation southern end, as seen in 2017 by Opportunity rover The Opportunity rover landed in a small crater, dubbed "Eagle", on the flat plains of Meridiani. The plains of the landing site were characterized by the presence of a large number of small spherules, spherical concretions that were tagged "blueberries" by the science team, which were found both loose on the surface, and also embedded in the rock. These proved to have a high concentration of the mineral hematite, and showed the signature of being formed in an aqueous environment.
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In 2004, Meridiani Planum was the landing site for the second of NASA's two Mars Exploration Rovers, named Opportunity. It had also been the target landing site for Mars Surveyor 2001 Lander, which was cancelled after the failures of the Mars Climate Orbiter and Mars Polar Lander missions. The Eagle crater wall showed layered sandstones, composed of basaltic detritus cemented by sulfate evaporites, and "blue berry" hematite spherules. At Endurance crater, the hematite-sulfate Burns formation showed aeolian dune field cross bedding in the sandstone lower unit, topped by an aeolian sand sheet in the middle unit, and followed by festoon laminations in the upper unit.
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Geological formations recorded are mainly-basaltic volcanic rocks interspersed with tertiary limestones and occasional inter-bedded volcanics overlaid by phosphate-rich soils on the surface in some areas. Along with the highest elevations of Phosphate Hill and Flying Fish Cove, the rocks from Murray Hill summit are characterized as dolomitic limestones, containing between 34 and 41 percent carbonate of magnesia. Analyses of the rocks has shown that the fossils are mostly obliterated, though there are remains of foraminifera, Lithothamnion, and possibly coral. The small, brown spherules of phosphatic matter which occur on the hill in a bed of rock may be explained because of phosphatic fossilization of volcanic rock.
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Linear polymer chains can be regarded as a linear polarizers. If their direction coincides with that of one of the crossed polarizers then little light is transmitted; the transmission is increased when the chains make a non-zero angle with both polarizers, and the induced transmittance is dependent on the wavelength, partly because of the absorption properties of the polymer. A schematic of Maltese cross formation This effect results in the dark perpendicular cones (Maltese cross) and colored brighter regions in between them in the front and right pictures. It reveals that the molecular axis of the polymer molecules in the spherules is either normal or perpendicular to the radius vector, i.e.
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The Younger Dryas impact hypothesis or Clovis comet hypothesis posits that fragments of a large (more than 4 kilometers in diameter), disintegrating asteroid or comet struck North America, South America, Europe, and western Asia about 12,800 years ago. Multiple airbursts/impacts produced the Younger Dryas (YD) boundary layer (YDB), depositing peak concentrations of platinum, high-temperature spherules, meltglass, and nanodiamonds, forming an isochronous datum at more than 50 sites across about 50 million km² of Earth’s surface. Some scientists have proposed that this event triggered extensive biomass burning, a brief impact winter and the Younger Dryas abrupt climate change, contributed to extinctions of late Pleistocene megafauna, and resulted in the end of the Clovis culture.
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Scientists have asserted that the carbon spherules originated as fungal structures and/or insect fecal pellets, and contained modern contaminants and that the claimed nanodiamonds are actually misidentified graphene and graphene/graphane oxide aggregates. An analysis of a similar Younger Dryas boundary layer in Belgium yielded carbon crystalline structures such as nanodiamonds, but the authors concluded that they also did not show unique evidence for a bolide impact. Researchers have also found no extraterrestrial platinum group metals in the boundary layer, which is inconsistent with the hypothesized impact event. Further independent analysis was unable to confirm prior claims of magnetic particles and microspherules, concluding that there was no evidence for a Younger Dryas impact event.
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Chromium isotopic anomalies found in Cretaceous–Paleogene boundary sediments are similar to those of an asteroid or a comet composed of carbonaceous chondrites. Shocked quartz granules and tektite glass spherules, indicative of an impact event, are also common in the K–Pg boundary, especially in deposits from around the Caribbean. All of these constituents are embedded in a layer of clay, which the Alvarez team interpreted as the debris spread all over the world by the impact. Using estimates of the total amount of iridium in the K–Pg layer, and assuming that the asteroid contained the normal percentage of iridium found in chondrites, the Alvarez team went on to calculate the size of the asteroid.
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There are multiple sites around the world with spikes in levels of platinum that can be associated with the Impact Hypothesis, of which at least 25 are major. Although most of these sites are found in the Northern Hemisphere, a study conducted in October 2019 has found and confirmed another site with high platinum levels located in the Wonderkrater area north of Pretoria in South Africa. This coincides with the Pilauco site in southern Chile which also happens to contain high levels of platinum as well as rare metallic spherules, gold and high-temperature iron that is rarely found in nature and suspected of originating from airbursts or impacts. These Southern Hemisphere high platinum zones further add to the credibility of the Younger Dryas impact hypothesis.
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Sigurðsson worked on monitoring and research of the volcanoes of the Caribbean until 1974, when he was appointed professor at the Graduate School of Oceanography, University of Rhode Island. He is best known for his work on the reconstruction of major volcanic eruptions of the past, including the eruption of Vesuvius in Italy in AD 79 and the consequent destruction of the Roman cities of Pompeii and Herculaneum. In 1991 he discovered tektite glass spherules at the Cretaceous–Paleogene boundary (K–T boundary) in Haiti, providing proof for a meteorite impact at the time of the extinction of the dinosaurs. In 2004 he discovered the lost town of Tambora in Indonesia, which was buried by the colossal 1815 explosive eruption of Tambora volcano.
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The JPL team found many fragmented blueberries and suggested the fracturing occurred after spherule formation. They believe the fracturing either be from meteoric impacts, or the “same process” that “fractured the outcrop.” However, the team note this would not explain the presence of the smallest hematite spherules detected. The smallest are close to perfectly spherical and therefore cannot be explained by fracturing or erosion. NASA’s JPL also found that blueberries uncovered by the Rock Abrasion Tool aboard Opportunity were about 4 mm (0.16 inches) semi-major axis length at Eagle Crater and Endurance crater, about 2.2mm (0.087 inches) at Vostok, and about 3.0 mm (0.12 inches) at Naturaliste (crater). Those found in “the plains” were smaller (1-2mm or 0.04-0.08 inches) than those of Eagle and Endurance craters.
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Eighteen months before publication of the peer-reviewed PNAS paper in 2019 DePalma and his colleagues presented two conference papers on fossil finds at Tanis on 23 October 2017 at the annual meeting of the Geological Society of America. Jan Smit first presented a paper describing the Tanis site, its association with the K-Pg boundary event and associated fossil discoveries, including the presence of glass spherules from the Chicxulub impact clustered in the gill rakers of acipenciform fishes and also found in amber.Smit, J., et al. (2017) Tanis, a mixed marine-continental event deposit at the KPG Boundary in North Dakota caused by a seiche triggered by seismic waves of the Chicxulub Impact Paper No. 113-15, presented 23 October 2017 at the GSA Annual Meeting, Seattle, Washington, USA.
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Analysis of fluvial sediments on Santa Rosa Island by another group also found no evidence of lonsdaleite, impact-induced fires, or extraterrestrial impact. Research published in 2012 has shown that the so-called "black mats" are easily explained by typical earth processes in wetland environments. The study of black mats, that are common in prehistorical wetland deposits which represent shallow marshlands, that were from 6000 to 40,000 years ago in the southwestern USA and Atacama Desert in Chile, showed elevated concentrations of iridium and magnetic sediments, magnetic spherules and titanomagnetite grains. It was suggested that because these markers are found within or at the base of black mats, irrespective of age or location, suggests that these markers arise from processes common to wetland systems, and probably not as a result of catastrophic bolide impacts.
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In front of the buttons, fixed to the edge of the mobile disk towards the horizontal diameter, two brass collection combs, each having 10 points, are positioned in the direction of the disk. The combs are in contact with the inner shields of two Leiden jars, and with the arms of the spark-gap, two brass bars equipped with spherules and insulation handles, into which the sparks are released. The outer shields of the Leiden jars rest on two brass disks electrically connected by a metallic wire, which passes along the base. A second pair of collection combs, facing the mobile disk, each with eight points and a central metal brush that rubs against the buttons, comprises the so-called “diametrical conductor”. The “diametrical conductor” is inclined at 45° with respect to the horizontal diameter and allowed for the polarity of the linings to be maintained unaltered, especially when the exciting dynamos moved farther away than their normal explosive distance.
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