Formation of spinels in cosmic objects during atmospheric entry: a clue to the Cretaceous-Tertiary boundary event

Robin, Éric; Bonte, Ph.; Froget, L.; Jèhanno, C.; Rocchia, R.

doi:10.1016/0012-821x(92)90021-m

Cited by 112 publications

(42 citation statements)

References 18 publications

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“…Since the original discovery of anomalous amounts of Ir at the Cretaceous/Tertiary boundary (K/T) by Alvarez et aL (1980), impact-derived minerals (e.g., shock metamorphosed quartz, tektites, spinels, soot) and the Ir anomaly have been identified at the K/T boundary worldwide, and these data have greatly supported K/T boundary meteorite impact hypothesis (e.g., Alvarez et al, 1982;Bohor et al, 1984Bohor et al, , 1987aBohor et al, , 1987bSmit and Kyte, 1984;Kyte and Smit, 1986;Wolbach et al, 1987;Izett et al, 1990Izett et al, , 1991Izett, 1991;Kring and Boynton, 1991;Sigurdsson et aL, 1991;Smit et al, 1992;Robin et al, 1992aRobin et al, , 1992b. The discoveries of these impact-derived minerals and the Ir anomalies are striking.…”

Section: Introductionmentioning

confidence: 93%

Origin of the Mg-Smectite at the Cretaceous/Tertiary (K/T) Boundary at Stevns Klint, Denmark

Elliott

1993

Clays and clay miner.

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Abstract--The clay mineralogy and major element geochemistry of four distinct layers within the Cretaceous/Tertiary (K/T) boundary marl (i.e., II, IIIa, IIIb, and IV) at Stevns Klint, Denmark, including "impact layer" (layer IIIa), were examined, and there was not a marked change in the clay mineralogy throughout this K/T boundary marl. A magnesium smectite (i.e., Mg-smectite) was the predominant clay mineral at the K/T boundary not only at Stevns Klint and at Nye Klov; it was also found to be the predominant clay mineral in the K/T boundary at Karlstrup Quan-y. In addition, Mg-smectite was found in a smectitic marl 32 meters below the K/T boundary at the Limhamn Quarry (near Malm6, Sweden), and it did not have anomalous concentrations of iridium or other siderophile trace elements. Given its occurrence in a Maastrichtian marl, it is therefore argued that the Mg-smectite is not derived from meteorite impact.The rare earth element (REE) signatures of the Mg-smectites ranged from being comparable to the North American Shale Standard (NASC) to being one-half an order of magnitude depleted relative to NASC. One Mg-smectite collected from layer IIIb, immediately above the "impact/red layer," was depleted in REE by one order of magnitude relative to NASC, and these levels of REE are comparable to those of smectite and illite/smectite (I/S) formed authigenically in bentonites and K-bentonites, respectively. Thus, the REE data suggest this Mg-smectite in all likelihood was formed authigenically from a glassy precursor. The presence of the low levels of REE of the Mg-smectite in the layer IIIb has no particular significance other than to suggest that this Mg-smectite separate was the least contaminated with illite or apatite having higher REE levels. With better separation, the other Mg-smectites would be expected to have comparably low levels of REE. Given the presence of the Mg-smectite throughout the K/T boundary and in Maastrichtian and Danian marls, the Mg-smectite is thought to be of volcanic origin. However, is not certain whether the Mg-smectite formed from volcanic glass deposited at the K/T boundary or whether it was formed from volcanic glass as young as late Cretaceous.

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Section: Introductionmentioning

confidence: 93%

Origin of the Mg-Smectite at the Cretaceous/Tertiary (K/T) Boundary at Stevns Klint, Denmark

Elliott

1993

Clays and clay miner.

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“…Montmorillonite and nontronite are the main minerals of both the Lechówka boundary clay and its spherules. Ni-rich spinel grains with high nickel contents and high ferric ratios indicate highly oxidizing conditions during crystallization in the atmosphere (Robin et al 1992).…”

Section: Discussionmentioning

confidence: 99%

“…High contents of Ir and platinumgroup elements (Ganapathy 1980), the presence of glassy spherules (Smit and Klaver 1981;Izett 1987;Montanari 1991;Olsson et al 1997;Norris et al 1999), shocked quartz (Bohor and Betterton 1990) and unusual Ni-rich spinels (Kyte and Smit 1986;Robin et al 1991Robin et al , 1992 at K-Pg boundary sites worldwide, have been attributed to the impact of an asteroid-sized bolide 10 km in diameter. The finding of a piece of the projectile in the North Pacific Ocean (Kyte 1998) indicates that the impactor was a carbonaceous chondrite.…”

Section: Introductionmentioning

confidence: 99%

Spherules associated with the cretaceous–paleogene boundary in Poland

Brachaniec¹,

Karwowski²,

Szopa³

2014

Acta Geologica Polonica

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ABSTRACT:Brachaniec, T., Karwowski, Ł. and Szopa, K. 2014. Spherules associated with the Cretaceous-Paleogene boundary in Poland. Acta Geologica Polonica, 64 (1), 99-108. Warszawa.The succession of the Lechówka section near Chełm in south-eastern Poland presents the first complete record of the Cretaceous-Paleogene (K-Pg) boundary in Poland. Samples of the boundary clay were examined for microtektites and shocked minerals to confirm the impact origin of the sediment. The spheroidal fraction reveals morphological and mineralogical features, e.g., spherules, similar to material from the K-Pg boundary as described from elsewhere. The impact genesis of the spherules is confirmed by the presence of nickel-rich spinel grains on their surfaces. The spinels are considered to be primary microlites and, thus, the spherules at Lechówka can be classified as microkrystites. No shocked minerals were noted. The deposits with spherules comprise Aland Mg-rich smectite (Cheto smectite). This almost pure Mg-rich smectite, forming up to 100% of the clay fraction, derived from the weathering of the impact glass. It is proposed that the spherules isolated from the Cretaceous-Paleogene boundary clay at Lechówka come from the Chicxulub crater in Mexico.

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“…Ni-rich magnesioferrite spinels are known to occur in many types of spherules, including cosmic spherules (e.g., Robin et al, 1992) and impact spherules such as at the K-T boundary (Smit and Kyte, 1984), in Eltanin ejecta (Margolis et al, 1991), and even in an Archean spherule bed (Byerly and Lowe, 1994). These spinels are often considered to be hightemperature phases that have survived diagenetic alteration and record processes involved in formation and evolution of at least one K-T boundary component (e.g., Kyte and Smit, 1986;Robin et al, 1992;Kyte and Bostwick, 1995). Very little is known about the trace element chemistry of these spinels.…”

Section: Physical Tracersmentioning

confidence: 99%

Tracers of the extraterrestrial component in sediments and inferences for Earth's accretion history

Kyte¹

2002

Catastrophic Events and Mass Extinctions: Impacts and Beyond

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The study of extraterrestrial matter in sediments began with the discovery of cosmic spherules during the HMS Challenger Expedition (1873-1876), but has evolved into a multidisciplinary study of the chemical, physical, and isotopic study of sediments. Extraterrestrial matter in sediments comes mainly from dust and large impactors from the asteroid belt and comets. What we know of the nature of these source materials comes from the study of stratospheric dust particles, cosmic spherules, micrometeorites, meteorites, and astronomical observations.The most common chemical tracers of extraterrestrial matter in sediments are the siderophile elements, most commonly iridium and other platinum group elements. Physical tracers include cosmic and impact spherules, Ni-rich spinels, meteorites, fossil meteorites, and ocean-impact melt debris. Three types of isotopic systems have been used to trace extraterrestrial matter. Osmium isotopes cannot distinguish chondritic from mantle sources, but provide a useful tool in modeling long-term accretion rates. Helium isotopes can be used to trace the long-term flux of the fine fraction of the interplanetary dust complex. Chromium isotopes can provide unequivocal evidence of an extraterrestrial source for sediments with high concentrations of meteoritic Cr.The terrestrial history of impacts, as recorded in sediments, is still poorly understood. Helium isotopes, multiple Ir anomalies, spherule beds, and craters all indicate a comet shower in the late Eocene. The Cretaceous-Tertiary boundary impact event appears to have been caused by a single carbonaceous chondrite projectile, most likely of asteroid origin. Little is known of the impact record in sediments from the rest of the Phanerozoic. Several impact deposits are known in the Precambrian, including several possible megaimpacts in the Early Archean.

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Formation of spinels in cosmic objects during atmospheric entry: a clue to the Cretaceous-Tertiary boundary event

Cited by 112 publications

References 18 publications

Origin of the Mg-Smectite at the Cretaceous/Tertiary (K/T) Boundary at Stevns Klint, Denmark

Origin of the Mg-Smectite at the Cretaceous/Tertiary (K/T) Boundary at Stevns Klint, Denmark

Spherules associated with the cretaceous–paleogene boundary in Poland

Tracers of the extraterrestrial component in sediments and inferences for Earth's accretion history

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