The Murray Springs Clovis site, Pleistocene extinction, and the question of extraterrestrial impact

Haynes, C. Vance; Boerner, J.; Domanik, K.; Лауретта, Д. С.; Ballenger, Jesse; Goreva, J. S.

doi:10.1073/pnas.0908191107

Cited by 60 publications

(50 citation statements)

References 18 publications

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“…Bement et al (2014) concluded from sedimentological evidence that the peak ND accumulations in the YDB and younger strata did not result from changes in climate, deposition rates, lag deposits, or human site usage. Their results refute the hypothesis that the NDs simply resulted from cosmic influx that deposited them as a lag deposit at the YDB over an extended interval of time (Haynes et al 2010;Pinter et al 2011;Boslough et al 2012). Instead, Bement et al (2014) concluded the evidence is consistent only with cosmic-impact events.…”

Section: Introductioncontrasting

confidence: 50%

“…In North America and the Middle East, Bunch et al (2012) identified YDB melt-glass that formed at high temperatures (1730Њ to 12200ЊC), as also reported by three independent groups, Mahaney et al (2010) in South America and Fayek et al (2012) and Wu et al (2013) in North America. This study focuses solely on nanodiamonds (NDs), and so, for independent discussions of other proxies, see Haynes et al (2010) and Paquay et al (2009), who found no evidence for the platinum-group elements iridium or osmium. Alternately, Wu et al (2013) found large YDB anomalies in osmium, as discussed below.…”

Section: Introductionmentioning

confidence: 99%

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Nanodiamond-Rich Layer across Three Continents Consistent with Major Cosmic Impact at 12,800 Cal BP

Kinzie¹,

Hee

Stich

et al. 2014

The Journal of Geology

170

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. A B S T R A C TA major cosmic-impact event has been proposed at the onset of the Younger Dryas (YD) cooling episode at ≈12,800 ‫ע‬ 150 years before present, forming the YD Boundary (YDB) layer, distributed over 150 million km 2 on four continents. In 24 dated stratigraphic sections in 10 countries of the Northern Hemisphere, the YDB layer contains a clearly defined abundance peak in nanodiamonds (NDs), a major cosmic-impact proxy. Observed ND polytypes include cubic diamonds, lonsdaleite-like crystals, and diamond-like carbon nanoparticles, called n-diamond and i-carbon. The ND abundances in bulk YDB sediments ranged up to ≈500 ppb (mean: 200 ppb) and that in carbon spherules up to ≈3700 ppb (mean: ≈750 ppb); 138 of 205 sediment samples (67%) contained no detectable NDs. Isotopic evidence indicates that YDB NDs were produced from terrestrial carbon, as with other impact diamonds, and were not derived from the impactor itself. The YDB layer is also marked by abundance peaks in other impact-related proxies, including cosmic-impact spherules, carbon spherules (some containing NDs), iridium, osmium, platinum, charcoal, aciniform carbon (soot), and high-temperature melt-glass. This contribution reviews the debate about the presence, abundance, and origin of the concentration peak in YDB NDs. We describe an updated protocol for the extraction and concentration of NDs from sediment, carbon spherules, and ice, and we describe the basis for identification and classification of YDB ND polytypes, using nine analytical approaches. The large body of evidence now obtained about YDB NDs is strongly consistent with an origin by cosmic impact at ≈12,800 cal BP and is inconsistent with formation of YDB NDs by natural terrestrial processes, including wildfires, anthropogenesis, and/or influx of cosmic dust.

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Section: Introductioncontrasting

confidence: 50%

Section: Introductionmentioning

confidence: 99%

Nanodiamond-Rich Layer across Three Continents Consistent with Major Cosmic Impact at 12,800 Cal BP

Kinzie¹,

Hee

Stich

et al. 2014

The Journal of Geology

170

View full text Add to dashboard Cite

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“…Based on the published methodology adopted by Surovell et al, we suggest that their study may have suffered from this effect because size-sorting was not conducted. Finding a single spherule among 10,000 magnetic grains is such a tedious endeavor that some have claimed that any results may be highly subjective and therefore unreliable (14). In light of the above difficulties, we considered whether magnetic spherule counting is a quantitative science, or rather, a subjective art as suggested by Haynes et al (14).…”

Section: Resultsmentioning

confidence: 99%

“…Finding a single spherule among 10,000 magnetic grains is such a tedious endeavor that some have claimed that any results may be highly subjective and therefore unreliable (14). In light of the above difficulties, we considered whether magnetic spherule counting is a quantitative science, or rather, a subjective art as suggested by Haynes et al (14). Cognitive neuroscience might reveal whether limitations in human perception affect the ability of an operator to discriminate spherules among numerous non-spherulitic distractors.…”

Section: Resultsmentioning

confidence: 99%

Independent evaluation of conflicting microspherule results from different investigations of the Younger Dryas impact hypothesis

LeCompte

Goodyear

Demitroff

et al. 2012

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

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Firestone et al. sampled sedimentary sequences at many sites across North America, Europe, and Asia [Firestone RB, et al. (2007) Proc Natl Acad Sci USA 106:16016–16021]. In sediments dated to the Younger Dryas onset or Boundary (YDB) approximately 12,900 calendar years ago, Firestone et al. reported discovery of markers, including nanodiamonds, aciniform soot, high-temperature melt-glass, and magnetic microspherules attributed to cosmic impacts/airbursts. The microspherules were explained as either cosmic material ablation or terrestrial ejecta from a hypothesized North American impact that initiated the abrupt Younger Dryas cooling, contributed to megafaunal extinctions, and triggered human cultural shifts and population declines. A number of independent groups have confirmed the presence of YDB spherules, but two have not. One of them [Surovell TA, et al. (2009) Proc Natl Acad Sci USA 104:18155–18158] collected and analyzed samples from seven YDB sites, purportedly using the same protocol as Firestone et al., but did not find a single spherule in YDB sediments at two previously reported sites. To examine this discrepancy, we conducted an independent blind investigation of two sites common to both studies, and a third site investigated only by Surovell et al. We found abundant YDB microspherules at all three widely separated sites consistent with the results of Firestone et al. and conclude that the analytical protocol employed by Surovell et al. deviated significantly from that of Firestone et al. Morphological and geochemical analyses of YDB spherules suggest they are not cosmic, volcanic, authigenic, or anthropogenic in origin. Instead, they appear to have formed from abrupt melting and quenching of terrestrial materials.

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“…18-21. Many of the impact markers reported in YD black mats have been widely discredited (22)(23)(24)(25)(26)(27) with the exception of the enigmatic nanodiamonds.…”

Section: Uring the End Of The Last Glacial Period In The Northernmentioning

confidence: 99%

No evidence of nanodiamonds in Younger–Dryas sediments to support an impact event

Daulton

Pinter

Scott

2010

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

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The causes of the late Pleistocene megafaunal extinctions in North America, disappearance of Clovis paleoindian lithic technology, and abrupt Younger-Dryas (YD) climate reversal of the last deglacial warming in the Northern Hemisphere remain an enigma. A controversial hypothesis proposes that one or more cometary airbursts/ impacts barraged North America ≈12,900 cal yr B.P. and caused these events. Most evidence supporting this hypothesis has been discredited except for reports of nanodiamonds (including the rare hexagonal polytype) in Bølling-Ållerod-YD-boundary sediments. The hexagonal polytype of diamond, lonsdaleite, is of particular interest because it is often associated with shock pressures related to impacts where it has been found to occur naturally. Unfortunately, previous reports of YD-boundary nanodiamonds have left many unanswered questions regarding the nature and occurrence of the nanodiamonds. Therefore, we examined carbon-rich materials isolated from sediments dated 15,818 cal yr B.P. to present (including the Bølling-Ållerod-YD boundary). No nanodiamonds were found in our study. Instead, graphene-and graphene/ graphane-oxide aggregates are ubiquitous in all specimens examined. We demonstrate that previous studies misidentified graphene/graphane-oxide aggregates as hexagonal diamond and likely misidentified graphene as cubic diamond. Our results cast doubt upon one of the last widely discussed pieces of evidence supporting the YD impact hypothesis.archaeology | paleoclimate | Quaternary extinctions | carbon spherules | fungal sclerotia

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The Murray Springs Clovis site, Pleistocene extinction, and the question of extraterrestrial impact

Cited by 60 publications

References 18 publications

Nanodiamond-Rich Layer across Three Continents Consistent with Major Cosmic Impact at 12,800 Cal BP

Nanodiamond-Rich Layer across Three Continents Consistent with Major Cosmic Impact at 12,800 Cal BP

Independent evaluation of conflicting microspherule results from different investigations of the Younger Dryas impact hypothesis

No evidence of nanodiamonds in Younger–Dryas sediments to support an impact event

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