The Cretaceous-Tertiary boundary on the Pacific plate: Composition and distribution of impact debris

Kyte, Frank T.; Bostwick, Jennifer A.; Zhou, Lei

doi:10.1130/0-8137-2307-8.389

Cited by 22 publications

(26 citation statements)

References 46 publications

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“…This scenario has been proposed to explain the regional trends in spinel compositions observed over the entire Pacific basin at the Cretaceous/Paleogene boundary (Kyte et al 1996) and is supported by recent theoretical considerations showing that the Chicxulub vapor cloud might have produced the kind of environment required for spinel crystallization (Ebel and Grossman 2005).…”

Section: Different Mode Of Formation?mentioning

confidence: 64%

Chronostratigraphy, composition, and origin of Ni-rich spinel from the Late Eocene Fuente Caldera section in Spain: One impact or more?

Robin

Molina

2006

Meteoritics &Amp; Planetary Science

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Abstract-Here we report on the stratigraphic distribution and chemical composition of Ni-rich spinel, a specific mineral tracer of meteorite impacts, in the Fuente Caldera section in Spain. A major peak in spinel abundance is observed in a biostratigraphic interval defined by the last occurrence of the planktic foraminifera Porticulasphaera semiinvoluta and the first occurrence of the planktic foraminifera Turborotalia cunialensis. Two other peaks of lower abundances are observed higher up in the same biostratigraphic interval, but geochemical considerations suggest that they likely originate from redeposition by turbiditic currents. Biostratigraphic correlations with the global stratotype section and point for the Eocene/Oligocene boundary of Massignano in Italy give an age of 35.4 ± 0.2 Ma (1σ) for the major peak. This age is indistinguishable from the age of the impact horizon at Massignano (35.5 ± 0.2 Ma) and within the age uncertainties for the Popigai (35.7 ± 0.2 Ma) and Chesapeake Bay (35.5 ± 0.5 Ma) craters. The Fuente Caldera spinel, as the Massignano spinel, is assumed to be a relic mineral of microkrystites, which are believed to derive from a unique source related to the Popigai impact crater. The morphologies and Cr compositions of the Fuente Caldera and Massignano spinel crystals are markedly different, however: the Fuente Caldera spinel occurs mostly as octahedral and skeletal crystals with 85% of the grains belonging to the Cr-rich magnetite series and 15% to the Fe-rich chromite series, whereas the Massignano spinel occurs mostly as dendritic crystals with 90% of the grains belonging to the Cr-poor magnetite series. It is unlikely that these differences are the result of post-depositional alteration processes because the compositions of the crystals, as well as their morphologies, are in general very similar to those reported for primary spinel crystals, i.e., spinel crystals present in meteorite fusion crust or synthetized from meteoritic material. In addition, spinel crystals have quite homogeneous compositions except for a few grains (<10%) showing Cr zonations, but these are assigned to primary crystallization processes. One possible explanation that is consistent with a single impact event producing spatial variations in spinel compositions and morphologies is that microkrystites are locally generated by the ablation in the atmosphere of impact debris. An alternative explanation is that Fuente Caldera and Massignano microkrystites derive from two closely spaced impact events, which however requires another, so-far unknown source crater for microkrystites.

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Section: Different Mode Of Formation?mentioning

confidence: 64%

Chronostratigraphy, composition, and origin of Ni-rich spinel from the Late Eocene Fuente Caldera section in Spain: One impact or more?

Robin

Molina

2006

Meteoritics &Amp; Planetary Science

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“…MgO does not appear to have been preferentially incorporated into the impactites as both the SEMY and the CEMY do not show substantial concentrations of MgO (4.23 and 5.51 wt%, respectively) compared to the CTIY (13.62 wt%). The unusual and unique MgO-rich composition of magnesiow¸stite spinels found in K/T boundary ejecta of the Pacific Ocean region compared to all other K/T boundaries (Kyte et al 1996;Ebel and Grossman 2005) may account for some of this missing MgO.…”

Section: Carbonate End-membermentioning

confidence: 99%

Geochemical and petrographic characteristics of impactites and Cretaceous target rocks from the Yaxcopoil‐1 borehole, Chicxulub impact structure, Mexico: Implications for target composition

Tuchscherer

Reimold

Koeberl

et al. 2005

Meteorit & Planetary Scien

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All tables for this article are available online at http://meteoritics.org.Abstract-We present major and trace element data as well as petrographic observations for impactites (suevitic groundmass, bulk suevite, and melt rock particles) and target lithologies, including Cretaceous anhydrite, dolomite, argillaceous limestone, and oil shale, from the Yaxcopoil-1 borehole, Chixculub impact structure. The suevitic groundmass and bulk suevite have similar compositions, largely representing mixtures of carbonate and silicate components. The latter are dominated by melt rock particles. Trace element data indicate that dolomitic rocks represented a significant target component that became incorporated into the suevites; in contrast, major elements indicate a strong calcitic component in the impactites. The siliceous end-member requires a mafic component in order to explain the low SiO 2 content. Multicomponent mixing of various target rocks, the high alteration state, and dilution by carbonate complicate the determination of primary melt particle compositions. However, two overlapping compositional groups can be discerned-a high-Ba, low-Ta group and a high-Fe, high-Zn, and high-Hf group. Cretaceous dolomitic rocks, argillaceous limestone, and shale are typically enriched in U, As, Br, and Sb, whereas anhydrite contains high Sr contents. The oil shale samples have abundances that are similar to the North American Shale Composite (NASC), but with a comparatively high U content. Clastic sedimentary rocks are characterized by relatively high Th, Hf, Zr, As, and Sb abundances. Petrographic observations indicate that the Cretaceous rocks in the Yaxcopoil-1 drill core likely register a multistage deformation history that spans the period from preto post-impact. Contrary to previous studies that claimed evidence for the presence of impact melt breccia injection veins, we have found no evidence in our samples from a depth of 1347-1348 m for the presence of melt breccia. We favor that clastic veinlets occur in a sheared and altered zone that underwent intense diagenetic overprint prior to the impact event.

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“…3. A -One of the spherules found at the base of the boundary clay at Lechówka; B -Detail of spherule surface with a thin, characteristic coating of smectite (Sm); C -Arrows indicate small and regular cavities; D -Cluster of what are probably three distorted spherules; E -probable Ni-rich spinel as suggested by EDS spectrum 1986; Kyte et al 1996). These kinds of morphologies indicate rapid crystallization and cooling from a hightemperature melt (Bohor et al 1986;.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, microtektites from Chicxulub can be expected all over the earth (180 km × 280 = 50400 km). Altered microtektites from the K-Pg boundary have been reported in North Pacific cores (Kyte et al 1996), in Europe and Asia (Republic of Georgia; Smit 1999) at distances up to < 10000 km, i.e., c. 53 crater diameters from Chicxulub. Based on this reasoning, the Lechówka spherules could easily have derived from the Chicxulub impact structure.…”

Section: Source Of Spherulesmentioning

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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The Cretaceous-Tertiary boundary on the Pacific plate: Composition and distribution of impact debris

Cited by 22 publications

References 46 publications

Chronostratigraphy, composition, and origin of Ni-rich spinel from the Late Eocene Fuente Caldera section in Spain: One impact or more?

Chronostratigraphy, composition, and origin of Ni-rich spinel from the Late Eocene Fuente Caldera section in Spain: One impact or more?

Geochemical and petrographic characteristics of impactites and Cretaceous target rocks from the Yaxcopoil‐1 borehole, Chicxulub impact structure, Mexico: Implications for target composition

Spherules associated with the cretaceous–paleogene boundary in Poland

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