Types Of Spherules Research Articles

Chemical classification of spherules recovered from the Pacific Ocean site of the CNEOS 2014-01-08 (IM1) bolide

We have conducted an extensive towed-magnetic-sled survey during the period of June 14–28, 2023, over the seafloor about 85 km north of Manus Island, Papua New Guinea, centered around the calculated path of the bolide CNEOS 2014-01-08 (IM1). We found about 850 spherules of diameter 0.1–1.3 mm in our samples. The samples were analyzed by micro-XRF, Electron Probe Microanalyzer and ICP Mass spectrometry. Here we report major and trace element compositions of the samples and classify spherules based on that analysis. We identified 78 % of the spherules as primitive, in that their compositions have not been affected by planetary differentiation. We divided these into four groups, three of which correspond to previously described cosmic spherule types. Spherules in the fourth group, comprising 22 % of the collection, appear to all reflect planetary igneous differentiation and are all different from previously described spherules. We call them D-type spherules. At least five of the D-type spherules are suggested to be terrestrial in origin, although many spherules exhibit elemental ratios that are distinct from known planetary bodies and their origins are undetermined. A subset of the D-spherules show an excess of Be, La and U, by up to three orders of magnitude relative to the solar system standard of CI chondrites. Detailed mass spectrometry of 12 of these “BeLaU”-type spherules, the population of which may constitute up to ∼10 % of our entire collected sample, suggests that they are derived from material formed by planetary igneous fractionation. Their chemical composition is unlike any known solar system material. We compare these compositions to known differentiated bodies in the solar system and find them similar to those of evolved planetary materials–with lunar KREEP the closest in terms of its trace element enrichment pattern, but unusual in terms of their elevated CI-normalized incompatible elements. The “BeLaU”-type spherules reflect a highly differentiated, extremely evolved composition of an unknown source.

Metallic and glass spherules in the loose deposits of the Put river head (Middle Urals)

Research subject. The article examines exotic mineral formations - spherules (balls) of various composition and structure, found in the Neogene sediments of the interfluve of the Put-Bisert rivers within the eastern wing of the Yurizan-Sylva de-pression.Materials and methods. The work was carried out using the authors' research results, the available data on similar formations both from the modern soil-vegetation layer, including peat and technogenic formations, and from more ancient Phanerozoic sedimentary, magmatic and ore complexes. The article uses the results of studies obtained by a scanning electron microscope “EVO MA 15” from ZEISS with an energy-dispersive attachment EDS “X-MAX 80” at the JSC “Mekhanobr” analytical laboratory.Results. A detailed study of the surface morphology, dimensions, chemical and mineral composition of three types of spherules - magnetite, iron-chromium composition and barium and titanium oxide, similar to the stoichiometric formula of sanbornite - was carried out. The surface of the balls of the second type is heterogeneous in structure and contains growths, some of which have the form of a flat, flattened, square, skeletal crystal of a sectorial structure. The inner surface of the crystal has a fine-mesh structure. The cells have a complex, elongated structure. At the periphery of the crystal, the cells transform into hollow channels, indicating growth from the gas phase. In composition, the sectoral crystal corresponds to a solid solution between magnesio-chromite and herzenite with an admixture of nickel, calcium and silicon. The internal microstructure of iron-chromium spherules has a myrmekite, two-phase structure.Conclusions. The obtained data indicate that such heterogeneous formations can be formed only in specific deep fluid-saturated high-temperature magmatic systems and delivered to the surface by hydrothermal fluids along weakened tectonic zones. The detection of these formations in the overlying sediments of the western wing of the Artinskaya anticline may indicate the proximity of large fluid-supplying deep structures that control the Bukharovskoye gas show.

Morphological aspects, textural features and chemical composition of spherules from the Colônia impact crater, São Paulo, Brazil

A wide variety of spherules and aluminum-silicate accretionary particles are found associated to allochthonous breccia deposits within the Colônia impact crater, SE Brazil. Using morphological, textural and compositional variation parameters, four types of spherules can be identified: (i) iron spherules and (ii) silicate-iron spherules, both dominant, and scarce (iii) titanium-silicate-iron spherules and (iv) copper-nickel-iron spherules. The spherules range in size from 0.1 mm up to 0.5 mm, and exhibit noticeable splash kinematic shapes with variations for spherical, oval, prolate and droplet. Textural patterns include granular massive, polygonal junctions, and several types of dendritic growth. Iron spherules are mainly pure iron oxides (magnetite and/or hematite) and contain low contents in Mg, Na, K, P and also in REE; occasionally, they may contain Si and Mn. Silicate-iron spherules differ for the higher concentrations in Si and in a few times in Ti and Ca. The accretionary particles have nothing in common with the spherules, except for its close spatial and temporal occurrence. In terms of morphology, they do not show symmetric splash-form shapes and some of them are clearly composed of different parts of fine pieces of mineral fragments mechanically aggregated in a partially molten state before the deposition. Chemical composition of accretionary particles reveals abundance of the elements Si, Fe and Al, presence of K and less commonly of Ti, Ca, Na and P. Because these elements are found in great amounts in minerals of the regional country rocks, it is assumed that the formation of both splash-form spherules and accretionary particles is probably related to the melting of metamorphic lithologies of the crystalline basement due to hypervelocity impact event.

Volcanic spherules condensed from supercritical fluids in the Payenia volcanic province, Argentina

Spherules can be formed by high-temperature processes during volcanic eruptions, lightning strikes and meteorite impacts. Here we report four different types of spherules and spheroidal particles associated with tephra deposits from two separate volcanic fields in the southern Payenia province of Argentina. These silicate and carbonate spherules represent <0.01% of the sampled material, with individual spherules <200 µm in size. Thirty particles were imaged. Only the transparent spherules are smooth, perfect spheres; other morphologies include ellipsoids and aggregated dumbbells. The spheroids are either hollow or solid. Major element analyses show that the spherules and spheroids have silica-rich, Fe-rich, carbonate and basaltic compositions. Chemical analysis of the carbonate spheroids shows some variability in the trace element content between the cores and rims, suggesting element mobility and loss towards the margins. All the analysed carbonate spheroids have elevated Sr/Y, La/Y and La/Ce ratios outside the range for sedimentary carbonates. All four spherule types are considered to be volcanic in origin, with the excess CO 2 required for the formation of the carbonate spherules potentially sourced from the basement lithologies. Based on the major and trace element analyses, we conclude that the silica-rich and carbonate spherules formed by instantaneous condensation from supercritical CO 2 -rich hydrous fluids saturated with dissolved silicates. Supplementary material : Appendix A, containing the full analytical dataset collected by electron probe microanalysis and secondary ion mass spectrometry, is available at https://doi.org/10.6084/m9.figshare.c.5108689

An urban collection of modern-day large micrometeorites: Evidence for variations in the extraterrestrial dust flux through the Quaternary

Abstract We report the discovery of significant numbers (500) of large micrometeorites (>100 μm) from rooftops in urban areas. The identification of particles as micrometeorites is achieved on the basis of their compositions, mineralogies, and textures. All particles are silicate-dominated (S type) cosmic spherules with subspherical shapes that form by melting during atmospheric entry and consist of quench crystals of magnesian olivine, relict crystals of forsterite, and iron-bearing olivine within glass. Four particles also contain Ni-rich metal-sulfide beads. Bulk compositions are chondritic apart from depletions in the volatile, moderately volatile, and siderophile elements, as observed in micrometeorites from other sources. The reported particles are likely to have fallen on Earth in the past 6 yr and thus represent the youngest large micrometeorites collected to date. The relative abundance ratio of barred olivine to cryptocrystalline spherule types in the urban particles of 1.45 is shown to be higher than a Quaternary average of ∼0.9, suggesting variations in the extraterrestrial dust flux over the past 800 k.y. Changes in the entry velocities of dust caused by quasi-periodic gravitational perturbation during transport to Earth are suggested to be responsible. Variations in cosmic spherule abundance within the geologic column are thus unavoidable and can be a consequence of dust transport as well as major dust production events.

Nondestructive spectroscopic and petrochemical investigations of Paleoarchean spherule layers from the ICDP drill core BARB5, Barberton Mountain Land, South Africa

AbstractA Paleoarchean impact spherule‐bearing interval of the 763 m long International Continental Scientific Drilling Program (ICDP) drill core BARB5 from the lower Mapepe Formation of the Fig Tree Group, Barberton Mountain Land (South Africa) was investigated using nondestructive analytical techniques. The results of visual observation, infrared (IR) spectroscopic imaging, and micro‐X‐ray fluorescence (μXRF) of drill cores are presented. Petrographic and sedimentary features, as well as major and trace element compositions of lithologies from the micrometer to kilometer‐scale, assisted in the localization and characterization of eight spherule‐bearing intervals between 512.6 and 510.5 m depth. The spherule layers occur in a strongly deformed section between 517 and 503 m, and the rocks in the core above and below are clearly less disturbed. The μXRF element maps show that spherule layers have similar petrographic and geochemical characteristics but differences in (1) sorting of two types of spherules and (2) occurrence of primary minerals (Ni‐Cr spinel and zircon). We favor a single impact scenario followed by postimpact reworking, and subsequent alteration. The spherule layers are Al2O3‐rich and can be distinguished from the Al2O3‐poor marine sediments by distinct Al‐OH absorption features in the short wave infrared (SWIR) region of the electromagnetic spectrum. Infrared images can cover tens to hundreds of square meters of lithologies and, thus, may be used to search for Al‐OH‐rich spherule layers in Al2O3‐poor sediments, such as Eoarchean metasediments, where the textural characteristics of the spherule layers are obscured by metamorphism.

In situ oxygen isotope compositions in olivines of different types of cosmic spherules: An assessment of relationships to chondritic particles

Cosmic spherules collected from deep sea sediments of the Indian Ocean having different textures such as scoriaceous (4), relict-bearing (16), porphyritic (35) and barred olivine (2) were investigated for petrography, as well as high precision oxygen isotopic studies on olivine grains using secondary ion mass spectrometry (SIMS). The oxide FeO/MgO ratios of large olivines (>20μm) in cosmic spherules have low values similar to those seen in the olivines of carbonaceous chondrite chondrules, rather than matching the compositions of matrix. The oxygen isotope compositions of olivines in cosmic spherules have a wide range of δ18O, δ17O and Δ17O values as follows: −9 to 40‰, −13 to 22‰ and −11 to 6‰. Our results suggest that the oxygen isotope compositions of the scoriaceous, relict-bearing, porphyritic and barred spherules show provenance related to the carbonaceous (CM, CV, CO and CR) chondrites. The different types of spherules that has experienced varied atmospheric heating during entry has not significantly altered the Δ17O values. However, one of the relict-bearing spherules with a large relict grain has Δ17O=5.7‰, suggesting that it is derived from 16O-poor material that is not recognized in the meteorite record. A majority of the spherules have Δ17O ranging from −4 to −2‰, similar to values in chondrules from carbonaceous chondrites, signifying that chondrules of carbonaceous chondrites are the major contributors to the flux of micrometeorites, with an insignificant fraction derived from ordinary chondrites. Furthermore, barred spherule data shows that during atmospheric entry an increase in ∼10‰ of δ18O value surges Δ17O value by ∼1‰.

Characterization of particulate matter in attic and settled dusts collected from two buildings in Budapest, Hungary

Abstract We have investigated two buildings covered with Zsolnay glazed architectural ceramics in Budapest (Hungary), one located in the densely built-up area of the city centre with a high traffic rate and one in a city quarter with moderate traffic and more open space. A black crust layer, containing a large amount of artificial particulate matter with different size and chemical composition, was observed on the ceramic material of both buildings, whereas weathered glaze was detected only on the ceramics of the building situated in the city centre. In this paper, our goal is to reveal the role of the particulate matter in the degradation of architectural ceramics. For this reason the attic dust and settled dust from the roofs of the studied buildings were collected. In the attic dust, besides the natural particles of geological origin, three types of artificial particles typically with spherical shape (spherules) were also distinguished: aluminosilicate (two subtypes), carbonaceous, and iron-rich fly-ash. The appearance of gypsum crystallites around the particulate matter in association with all spherule types suggests that the particulate matter greatly contributes to the degradation process.

Recently discovered 3.42-3.23 Ga impact layers, Barberton Belt, South Africa: 3.8 Ga detrital zircons, Archean impact history, and tectonic implications

The Barberton greenstone belt (BGB) includes eight known layers containing spherical particles (spherules) that condensed from rock vapor clouds formed by the impact of large meteorites or asteroids 3.47–3.23 Ga. Previous studies have inferred that the spherules represent bolides at least 20–70 km across. Spherule beds S1–S4 have been previously characterized in detail: we provide here the first detailed analysis of more recently discovered beds S5–S8. All eight beds are composed of the same basic compositional and textural spherule types, including nearly pure silica spherules representing nonaluminous melt precursors, nearly pure phyllosilicate spherules representing mostly mafic and ultramafic liquids, and compositionally mixed spherules. Evidence of spherule amalgamation and surface corrosion within the rock vapor clouds is developed in some beds. Bed S6, which occurs within a thick sequence of ultramafic volcanic rocks, is overlain by a tsunami layer containing zircons as old as 3811 ± 7 Ma, suggesting deep, possibly impact-related crustal uplift and erosion in distant areas. The formation of at least 8 major impact layers representing bolides 20–70 km in diameter over an interval of ∼240 m.y. suggests impact rates greatly exceeding those of later geologic time, and provides direct evidence that terrestrial bombardment by large bolides did not end abruptly at 3.8 Ga, but waned gradually until 3.0 Ga or even later. The coincidence of at least four large impact layers and the initiation of BGB deformation at 3.26–3.23 Ga suggests that an impact cluster at this time may have disrupted a long-lived earlier geodynamic system and triggered the development of a contrasting, more modern plate tectonic regime.

Refractory metal nuggets in different types of cosmic spherules

Out of the three basic cosmic spherule types collected from the seafloor, RMNs (refractory metal nuggets) have been reported from I-type spherules commonly, rarely from S-type spherules and never from the G-type spherules. Nuggets in the I-type cosmic spherules have formed by melting and complete oxidation during atmospheric entry, whereas no clear understanding emerged so far regarding the formation of the rare nuggets in S-type spherules. We collected cosmic spherules by raking the deep seafloor with magnets, and carried out systematic and sequential grinding, polishing and electron microscopic investigations on 992 cosmic spherules to identify RMNs. Fifty-four nuggets (RMNs) are identified, out of which 23, 26, and 5 nuggets are recovered from 23 I-, 21 S- and 5 G-type cosmic spherules, respectively.The nuggets in all the three spherule types follow a pattern indicative of their formation by metal segregation during atmospheric entry due to heating and oxidation, however, there are differences in their elemental distribution patterns. The refractory metal elements (RMEs) in the I-type spherules show a sequence of volatilization from a chondritic source, however, the relatively volatile RMEs in these spherules seem to be either depleted or distributed in numerous smaller nuggets. However, RMNs in the G-type spherules show closer conformity to CI chondrites and do not have a large volatile RME depletion. Whereas, the RMEs in the nuggets found in the S-type spherules are enriched in the volatile as well as the refractory elements. Also all the spherules show enrichment patterns and elemental ratios that are close to CI composition for refractory elements suggesting a common mechanism of formation. Pulse heating during atmospheric entry seems to be an efficient mechanism for RME segregation into nuggets. The patterns of RME enrichment and elemental ratios when compared with the nuggets in CAIs, show marked variations, outlining their differences in the process of formation. In addition, we also discovered a fremdling-like object in a cosmic spherule which has a nugget encased in Fe–Ni and sulfide phases, similar to those typically observed in CAIs of CV or CO chondrites. The atmospheric entry for this rare cosmic spherule appears to have taken place at a high zenith angle with a low entry velocity, so that its volatile phases are well preserved.

Micro-chemical analysis of anthropogenic spherules and its role in spherule type discrimination

Spherules of anthropogenic, biogenic, geogenic and cosmogenic origins are difficult to distinguish based on their size, shape, surface features despite their importance to elucidate large scale geological events such as mass ex- tinction, palaeoclimate change, and meteoritic impacts etc. Rapid industrialization and vehicular emissions have added several other types of spherules. However, chemical analysis of different types of spherules, especially major element chemistry, has been found useful to differentiate spherules of diverse origins.

Meteoritic ablation debris from the Transantarctic Mountains: Evidence for a Tunguska-like impact over Antarctica ca. 480 ka ago

Aggregates of microscopic spherules broadly similar in texture and composition to cosmic spherules or meteorite ablation spheres were discovered within the ∼ 1 Ma-old Transantarctic Mountain micrometeorite traps at Miller Butte, Victoria Land, Antarctica. Mineralogical and geochemical data obtained by means of field emission-scanning electron microscopy, electron microprobe analyses, synchrotron X-ray diffraction, and magnetization measurements show that they consist of a porous aggregate of quench-textured spherules, with individual spherules ranging from less than 1 to 65 µm in diameter. Spherule types include porphyritic olivine plus magnesioferrite spherules, dendritic magnesioferrite spherules, barred and feathered olivine spherules, and cryptocrystalline spherules. In contrast to the textural variations, the bulk composition of the individual spherules is fairly homogeneous and broadly chondritic. Likewise olivine has a nearly homogeneous composition Fa 16.3 ± 2.7 . Olivine and magnesioferrite are characterized by high NiO contents (2.72 ± 1.6 and 4.68 ± 0.68 wt.%, respectively), as typically observed in ablation debris and meteorite fusion crusts. The bulk composition of the aggregates is similar to the fusion crust of ordinary and carbonaceous chondrites. We interpret the spherulitic aggregates as meteorite ablation debris formed during the atmospheric entry of a large meteorite of ordinary or carbonaceous chondritic composition. Comparison with the available literature data shows that the ablation debris found at Miller Butte is most likely paired with the extraterrestrial dust found in a ∼ 480 ka-old ice layer in the EPICA-Dome C and Dome Fuji ice cores (East Antarctic ice sheet), thereby documenting a continental-scale distribution of ablation debris associated with a major meteoritic impact event which occurred ∼ 480 ka ago. Based on estimates of the projectile mass (> 10 8 kg) and numerical simulation of small-scale impacts from literature, we propose that the continental-scale distribution of the ablation debris was generated by the deceleration of a giant impact plume associated with a Tunguska-like impact over Antarctica. Tunguska-like impacts have global frequencies on the order of 10 3 to 10 5 yr, consistent with several being recorded in the Antarctic ice sheet. Finally, our detailed petrographic description of the spherulitic aggregates could serve as guide to the search for Tunguska-like events in the geological record.

Fundamental Research for Forensic Characterization of Soil Samples by Using Instrumental Analysis

Soil can be one of the most important physical evidence in a criminal investigation which contributes to prove a linkage between the suspect and the crime scene. In this work, the validity of multiple instrumental analytical techniques for forensic soil identification was studied using 148 soil samples collected from the Tokyo metropolitan area. The samples were characterized by X-ray diffraction (XRD) analysis, X-ray fluorescence (XRF) analysis, magnetic susceptibility determination, scanning electron microscopy with an energy dispersive X-ray spectrometer (SEM-EDS) and high-energy synchrotron radiation X-ray fluorescence (SR-XRF) analysis. It was found that soil samples collected from railway stations and roadside dust showed higher magnetic susceptibilities (≧0.5×10-4 m3 kg-1 for 25% of the samples collected ) than those of soil samples collected from rivers, ponds, and lakes (<0.1×10-4 m3 kg-1 for 40% of the samples colleted). Microscopic examination of the soil samples revealed three kinds of characteristic spherules: i.e., transparent, white, and black particles. The SEM-EDS analyses of the spherule samples showed the following compositional characteristics. The transparent spherules exhibited two compositional types: Na-Ca-Si-O and Ba-Ti-Si-O types. On the other hand, black ones were either Fe-O or Si-Mg-O types and white ones were either Al-O or Sr-Al-O types. It was concluded that these six types of spherules were found at characteristic points and consequently, they can be used as forensic soil identification.

Compositional grading in an 3.24 Ga impact-produced spherule bed, Barberton greenstone belt, South Africa: A key to impact plume evolution

Compositional grading of spherules in the ~3.24 Ga spherule bed S3, Barberton greenstone belt, South Africa, provides constraints on the evolution of the impact-generated rock vapor plume within which the spherules formed. Two fall-deposited sections of S3, 40 km apart, are both about 30 cm thick and composed almost entirely of spherules. These spherules are diverse in size, composition and texture. Although they have been chemically altered, primary textures and some mineralogy is preserved. Both sections show a similar compositional grading, which includes five stratigraphic zones, each composed of a distinctive assemblage of spherule types. Petrographic and geochemical data suggest that this stratigraphic layering is the same in both sections. This regionally consistent grading suggests large-scale compositional and thermal layering in the impact plume. REE data indicate that the basal part of S3 in these sections contains the most refractory material and that the upper part contains the most basaltic components. Overall, the beds show a temporal evolution consistent with the condensation sequence predicted for a fractionation-modified mixing of chondritic and basaltic materials.

The crystalline lunar spherules: Their formation and implications for the origin of meteoritic chondrules

Abstract— Crystalline lunar spherules (CLS) from three thin sections of Apollo 14 regolith breccias (14318,6; 14318,48 and 14315,20) have been examined. The objects have been classified and their abundances, size distributions, bulk compositions, and (where possible) plagioclase compositions determined. By number, 64% consist predominantly of very fine‐grained equant plagioclase grains but can also contain larger (∼50 μm) feldspar crystals (type X), while 22% contain plagioclase lathes in a fine‐grained mafic mesostasis (type Y). Plagioclase in both spherule types displays bright yellow cathodoluminescence that is conspicuous among the blue CL of the normal feldspar of the breccias. Type Z spherules (5%) contain feldspar with blue CL and minor amounts of olivine and pyroxene. Type Q spherules (4%) contain feldspar with yellow CL but in a luminescent mesostasis (of quartz or feldspar?). A few spherules are mixtures of type Y and type X textures. Most type X spherules, and a few type Y spherules, have fine‐grained opaque rims. Compound objects were also found and consist of two or more CLS that appear to have collided while still plastic or molten. The CLS are thought to be impact spherules that crystallized in free flight, their coarse textures suggesting fairly slow cooling rates (∼ &lt;1 °C/s). The abundance of the CLS resembles that of chondrules in the CM chondrite Murchison, and their cumulative size‐frequency distributions are very similar to those of the chondrules in several meteorite classes. The bulk compositions of the CLS do not resemble regoliths at any of the Apollo sites, including Apollo 14, or any of the common impact glasses, but they do resemble the bulk compositions of several lunar meteorites and the impact glasses they contain. The Apollo 14 site is located on a region containing Imbrium ejecta, and we suggest that the CLS derive from the Imbrium impact. Ballistic calculations indicate that only impact events of this size on the Moon are capable of producing melt spherules with the required free flight times and slow cooling rates. Smaller impacts produce glassy spherules and agglutinates. As has been pointed out many times, the CLS have many properties in common with meteoritic chondrules. While much remains unclear, difficulties with a nebular origin and new developments in chondrule chronology, studies of asteroid surfaces and impact ejecta behavior, and the present observations indicate that meteoritic chondrules could have formed by impact.

Origin and diagenesis of K/T impact spherules—From Haiti to Wyoming and beyond

Abstract— Impact spherules in Cretaceous/Tertiary (K/T) boundary clays and claystones consist of two types; each type is confined to its own separate layer of the boundary couplet in the Western Hemisphere. The form and composition of each of the spherule types result from its own unique mode of origin during the K/T event. Type 1 splash‐form spherules occur only in the melt‐ejecta (basal) layer of the K/T couplet. This layer was deposited from a ballistic ejecta curtain composed of melt‐glass droplets transported mostly within the atmosphere. In contrast, Type 2 spherules are accreted, partially crystalline, spheroidal bodies that formed by condensation of vaporized bolide and target‐rock materials in an expanding fireball cloud, from which they settled out of buoyant suspension to form the fireball layer. Dendritic and skeletal Ni‐rich spinel crystals are unique to these Type 2 spherules in the fireball layer.Compositions of relict glasses found in Type 1 K/T spherules from Haiti indicate that they were derived from intermediate silicic target rocks. These melt‐glass droplets were deposited into an aqueous environment at both continental and marine sites. We propose that the surfaces of the hot melt droplets hydrated rapidly in water and that these hydrated glass rims then altered to palagonite. Subsequent alteration of the palagonite rims to smectite, glauconite, chlorite, kaolinite, or goyazite occurred later during various modes of progressive diagenesis, accompanied by dissolution of some of the glass cores in spherules from continental sections and from marine sections that were subsequently raised above sea level. In many of the nonmarine sections in the Western Interior, the glass cores altered to kaolinite instead of dissolving.Directly comparable spherule morphologies (splash forms), textural features of the altered shells, and scalloping and grooving of relict glass cores or secondary casts demonstrate that the Haitian and Wyoming spherules are equivalent altered Type 1 melt‐droplet bodies. The spherules at both locations were deposited in a melt‐ejecta layer as part of the K/T impact event.Previously, two types of relict impact glasses had been identified in the Haitian spherule beds: black glass of andesitic composition and high‐Ca yellow glass with an unusually high S content. Most workers agree that the latter probably formed by impact melting and mixing of surficial carbonate (and minor anhydrite) rocks with the more deeply‐buried crystalline parent rocks of the black glasses. However, some workers have suggested that an intermediate compositional gap exists between the two groups of glasses, implying a different origin than simple mixing of end members during impact. We report glass compositional analyses with values extending throughout this intermediate range, lending support to the impact‐mixing model. Inclusions of CaSO4 found by us in relict yellow glasses further support this model.

Cosmic spherules in the geologic record

Abstract— Cosmic spherules obtained from the Greenland ice cap, deep‐sea sediments, and ancient oceanic deposits of Eocene and Jurassic age were chemically and texturally compared. The proportions of spherule types were found to change as a function of time, with the number of iron spherules increasing as the age of the sample increased. It is not yet possible, however, to determine if the variation in spherule types represents a real change in the meteoroid complex or is a result of differential weathering of the spherules in the Earth's environment.The age of these spherules ranges from less than 3000 years to about 190 million years. Although only a few spherules older than 500 000 years are chemically unaltered, textural information is available even from the oldest spherules and, by comparison with contemporary spherules, gives some insight into the original compositions of the particles.

New types of spherules from Antarctica: Meteoritic impact origin?

Spherules collected form Antarctic ice have been studied by using instrumental neutron activation analysis, energy dispersive X‐ray spectrometry and X‐ray diffration photography. Peculiar spherules, Ca‐Ti‐rich (perovskite) type (CTS) and Fe‐Cr‐Ni‐rich type (FCN), were found in the Mizuho ice core at depths of 32 to 33.5 m. Both types have rare earth element (REE) abundances; i.e., significant relative enrichment of light REE over heavy REE, which is commonly seen for terrestrial perovskite, however, with anomalous enrichment of Nd and Sm. In the Allan Hills bare ice, only a "chondritic" type without depletion of Au and S (CAS) was recognized. Size distributions and influx rates of spherules for these ices and the Mizuho surface snow indicate that Antarctic spherules are composed of steady‐falling and occasional populations. All the results combine to suggest that CTS and FCN may be droplets strewn by the impact of a huge meteorite, and CAS must be debris from one of the chondrites that fell on the source region of the Allan Hills bare ice and survive terrestrial alterations.

Trace element analyses of spheres from the melt zone of the Greenland Ice Cap using synchrotron X ray fluorescence

Synchrotron X ray fluorescence spectra of unpolished iron and chondritic spheres extracted from sediments collected on the melt zone of the Greenland ice cap allow the analysis of Ni, Cu, Zn, Ga, Ge, Pb, and Se with minimum detection limits on the order of several parts per million. All detected elements are depleted relative to chondritic abundance with the exception of Pb, which shows enrichments up to a factor of 500. An apparent anticorrelation between the Ni‐content and trace element concentration was observed in both types of spherules. The fractionation patterns of the iron and chondritic spheres are not complementary and consequently the two iron spheres examined in this study are unlikely to result from the ejection of globules of Fe/Ni from parent chondritic micrometeoroids.

Authigenic “spherules” in K-T boundary sediments at Caravaca, Spain, and Raton Basin, Colorado and New Mexico, may not be impact derived

The K-T boundary interval at Barranco del Gredero, Caravaca, Spain, consists of three units: a light gray Cretaceous marl, a 1- to 3-mm-thick ferruginous clay called the “K-T boundary impact layer” because of its content of shock-metamorphosed quartz grains, and an overlying greenish-gray clay. A conspicuous feature of the impact layer is its content of potassium-feldspar particles called “sanidine spherules” by some authors. The particles consist of a porous mesh-work of prismatic potassium-feldspar crystals clearly of authigenic origin. Their shape, distribution, and texture suggest that they are not altered basaltic melt droplets formed during impact of an extraterrestrial object as advocated by some proponents of the impact-extinction theory of Alvarez. Moreover, authigenic spherules also occur in a thin kaolinitic claystone layer at the K-T boundary in continental sedimentary rocks of the Raton Basin, Colorado and New Mexico. This layer is overlain by another claystone (5–8 mm thick) that records the abrupt appearance of shock-metamorphosed quartz grains in the local stratigraphic section. Four compositional types of spherules (kaolinite, goyazite, layered goyazite/kaolinite, and jarosite) occur in the lower of the two claystone layers. Because the spherules are (1) not in a bed containing shock-metamorphosed minerals, (2) common at some and rare at other localities, and (3) hollow and form peculiarly shaped intergrown masses suggest that they are not altered microtektites or melt droplets.