Geochemical constraints on source region of Cretaceous/Tertiary impact glasses

Sigurdsson, Haraldur; Bonte, Ph.; Turpin, Laurent; Chaussidon, M.; Métrich, Nicole; Steinberg, M.; Pradel, P.; Dhondt, Steven

doi:10.1038/353839a0

Cited by 89 publications

(49 citation statements)

References 17 publications

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“…The impact ejecta (microtektites) in Haiti and northeastern Mexico (5,6) and melt rock in the Chicxulub cores have similar geochemistry, and the 39Ar͞40Ar ages are within Ϯ200,000 years (200 ky) of the K-T boundary (7,8). These observations made a convincing case for Chicxulub as the long-sought K-T boundary impact crater and cause for the end-Cretaceous mass extinction.…”

mentioning

confidence: 56%

Chicxulub impact predates the K-T boundary mass extinction

Keller

Adatte

Stinnesbeck

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

142

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Since the early l990s the Chicxulub crater on Yucatan, Mexico, has been hailed as the smoking gun that proves the hypothesis that an asteroid killed the dinosaurs and caused the mass extinction of many other organisms at the Cretaceous-Tertiary (K-T) boundary 65 million years ago. Here, we report evidence from a previously uninvestigated core, Yaxcopoil-1, drilled within the Chicxulub crater, indicating that this impact predated the K-T boundary by Ϸ300,000 years and thus did not cause the end-Cretaceous mass extinction as commonly believed. The evidence supporting a pre-K-T age was obtained from Yaxcopoil-1 based on five independent proxies, each with characteristic signals across the K-T transition: sedimentology, biostratigraphy, magnetostratigraphy, stable isotopes, and iridium. These data are consistent with earlier evidence for a late Maastrichtian age of the microtektite deposits in northeastern Mexico.T he search for the K-T impact crater effectively ended in the early l990s with the discoveries of the Chicxulub crater and its estimated diameter between 180 and 280 km (1-4). The impact ejecta (microtektites) in Haiti and northeastern Mexico (5, 6) and melt rock in the Chicxulub cores have similar geochemistry, and the 39Ar͞40Ar ages are within Ϯ200,000 years (200 ky) of the K-T boundary (7,8). These observations made a convincing case for Chicxulub as the long-sought K-T boundary impact crater and cause for the end-Cretaceous mass extinction. But doubts persisted regarding the precise age and size of the impact crater (2-4, 9), the origin of the so-called megatsunami deposits (5,(10)(11)(12), and the nature of the mass extinction (13,14). To resolve these issues, the International Continental Scientific Drilling Program (ICDP) supported the drilling of a new core within the Chicxulub crater (Yaxcopoil-1 drilled between December 2001 and February 2002) with the stated objectives to determine the precise age of the crater and its link to the global K-T boundary layer, to unravel Chicxulub's role in the K-T mass extinction, and to study the cratering event and size of the impact crater (15).Chicxulub Core Yaxcopoil-1 (Yax-1) Yax-1 is located 40 km southwest of Merida, Mexico, and Ϸ60 km from the center of the Chicxulub structure (Fig. 1). A continuous core sequence was recovered from 400 to 1,511 m below the surface (15). † † ‡ ‡ Between 794.65 and 894 m, a 100-m-thick impact (suevite) breccia overlies a 617-m-thick sequence of horizontally layered shallow-water lagoonal to subtidal Cretaceous limestones, dolomites, and anhydrites. The first 85 m of the impact (suevite) breccia consist primarily of clasts from these underlying shallow-water lithologies, some crystalline rocks of continental basement origin, and devitrified glass (Cheto smectite) fragments and spherules. † † The upper 15 m of the breccia are stratified with alternating layers of upward fining clasts (3-5 cm at the base to 2-5 mm at the top), coarse cross-bedding structures, and gray friable sand layers in the top meter, all of which indicate...

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mentioning

confidence: 56%

Chicxulub impact predates the K-T boundary mass extinction

Keller

Adatte

Stinnesbeck

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

142

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“…These black and yellow impact glasses display compositions similar to those of the upper continental crust (Izett 1991;Sigurdsson et al 1991a, b;Koeberl and Sigurdsson 1992;Bohor and Glass 1995). The yellow glasses are is rich in Ca (~25 wt% CaO), S (~0.6 wt% SO 3 ), and Sr, which is most likely the result of a carbonate and/or anhydrite contributions (Izett 1991;Sigurdsson et al 1991b). Sigurdsson et al (1992) have shown, from comparison with experimental glasses, that the Haitian glasses have been quenched from temperatures much higher than those of typical volcanic processes.…”

Section: Introductionmentioning

confidence: 89%

Yellow impact glass from the K/T boundary at Beloc (Haiti): XANES determination of the Fe oxidation state and implications for formation conditions

Giuli

Eeckhout

Koeberl

et al. 2008

Meteorit & Planetary Scien

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Yellow impact glass from the K/T boundary at Beloc (Haiti): XANES determination of the Fe oxidation state and implications for formation conditionsAbstract-We determined the iron oxidation state and coordination number in five samples of yellow impact glass from the Cretaceous-Tertiary (K/T) boundary section at Beloc, Haiti, which formed as the result of impact melting during the Chicxulub impact event. The samples were analyzed by Fe K-edge XANES spectroscopy and the results were compared with published data on eight black impact glasses and one high Si-K impact spherule from the same impact layer. The pre-edge peak of our high-resolution XANES spectra displays evident variations indicative of significant changes in the Fe oxidation state, spanning a wide range from about 75 to 100 mole% Fe 3+ . Yellow K/T glasses have significantly higher Fe 3+ /(Fe 2+ + Fe 3+ ) ratios compared to black K/T impact glasses (from 20 to 75 mole% Fe 3+ ) and high Si-K glass (20 mole% Fe 3+ ). In particular, all the pre-edge peak data on these three types of impact glasses plot between two mixing lines joining a point calculated as the mean of a group of tektites studied so far (consisting of [4] Fe 2+ and [5] Fe 2+ ) to [4] Fe 3+ and [5] Fe 3+ , respectively. Thus, the XANES spectra of the yellow K/T glasses can be interpreted as a mixture of [4] Fe 2+ , [5] Fe 2+ , [4] Fe 3+ , and [5] Fe 3+ . Our observations can be explained by a very large range of oxygen fugacity conditions during melt formation. Furthermore, there is a clear positive relationship between the Fe 3+ /(Fe 2+ + Fe 3+ ) ratio and the Ca content of these glasses, suggesting that the Fe oxidation state was influenced by the relative contribution of Ca-sulfate-and Ca-carbonate-bearing sedimentary rocks at the impact site.

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“…This conclusion is supported by geological evidence from several sources. About 2-6% of the impact glass droplets produced by the Chicxulub impact and found in the K/T boundary are composed of a Caand S-rich yellow glass, which is best explained by an impact into a sulfate target [Bohor and Glass, 1995;Izett, 1991;Sigurdsson et al, 1991aSigurdsson et al, , b, 1992. Analyses of sulfur isotopes and major and minor elements in these yellow glasses suggest that the melting that produced them released about 18% SO2 (by weight) [Chaussidon et al, 1996].…”

Section: Sulfate Vaporizationmentioning

confidence: 99%

Energy, volatile production, and climatic effects of the Chicxulub Cretaceous/Tertiary impact

Pope¹,

Baines²,

Ocampo³

et al. 1997

J. Geophys. Res.

195

170

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Abstract. A comprehensive analysis of volatiles in the Chicxulub impact strongly supports the hypothesis that impact-generated sulfate aerosols caused over a decade of global cooling, acid rain, and disruption of ocean circulation, which contributed to the mass extinction at the Cretaceous/Tertiary (K/T) boundary. The crater size, meteoritic content of the K/T boundary clay, and impact models indicate that the Chicxulub crater was formed by a short period comet or an asteroid impact that released 0.7-3.4 x 103• ergs of energy. Impact models and experiments combined with estimates of volatiles in the projectile and target rocks predict that over 200 gigatons (Gt) each of SO2 and water vapor, and over 500 Gt of CO2, were globally distributed in the stratosphere by the impact. Additional volatiles may have been produced on a global or regional scale that formed sulfate aerosols rapidly in cooler parts of the vapor plume, causing an early, intense pulse of sulfuric acid rain. Estimates of the conversion rate of stratospheric SO2 and water vapor to sulfate aerosol, based on volcanic production of sulfate aerosols, coupled with calculations of diffusion, coagulation, and sedimentation, demonstrate that the 200 Gt stratospheric SO2 and water vapor reservoir would produce sulfate aerosols for 12 years. These sulfate aerosols caused a second pulse of acid rain that was global. Radiative transfer modeling of the aerosol clouds demonstrates (i) that if the initial rapid pulse of sulfate aerosols was global, photosynthesis may have been shut down for 6 months and (2) that for the second prolonged aerosol cloud, solar transmission dropped 80% by the end of first year and remained 50% below normal for 9 years. As a result, global average surface temperatures probably dropped between 5' and 3 IøK, suggesting that global near-freezing conditions may have been reached. Impactgenerated CO2 caused less than IøK greenhouse warming and therefore was insignificant compared to the sulfate cooling. The magnitude of sulfate cooling depends largely upon the rate of ocean mixing as surface waters cool, sink, and are replaced by upwelling of deep ocean water. This upwelling apparently drastically altered ocean stratification and circulation, which may explain the global collapse of the delta •3C gradient between surface and deep ocean waters at the K/T boundary.

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Geochemical constraints on source region of Cretaceous/Tertiary impact glasses

Cited by 89 publications

References 17 publications

Chicxulub impact predates the K-T boundary mass extinction

Chicxulub impact predates the K-T boundary mass extinction

Yellow impact glass from the K/T boundary at Beloc (Haiti): XANES determination of the Fe oxidation state and implications for formation conditions

Energy, volatile production, and climatic effects of the Chicxulub Cretaceous/Tertiary impact

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