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Mahaney W.C.,York University | Allen C.C.R.,Queen's University of Belfast | Pentlavalli P.,Queen's University of Belfast | Kulakova A.,Queen's University of Belfast | And 21 more authors.
Archaeometry | Year: 2017

Controversy over the alpine route that Hannibal of Carthage followed from the Rhône Basin into Italia has raged amongst classicists and ancient historians for over two millennia. The motivation for identifying the route taken by the Punic Army through the Alps lies in its potential for identifying sites of historical archaeological significance and for the resolution of one of history's most enduring quandaries. Here, we present stratigraphic, geochemical and microbiological evidence recovered from an alluvial floodplain mire located below the Col de la Traversette (~3000 m asl—above sea level) on the French/Italian border that potentially identifies the invasion route as the one originally proposed by Sir Gavin de Beer (de Beer). The dated layer is termed the MAD bed (mass animal deposition) based on disrupted bedding, greatly increased organic carbon and key/specialized biological components/compounds, the latter reported in Part II of this paper. We propose that the highly abnormal churned up (bioturbated) bed was contaminated by the passage of Hannibal's animals, possibly thousands, feeding and watering at the site, during the early stage of Hannibal's invasion of Italia (218 bc). © 2016 The Authors. Archaeometry published by John Wiley & Sons Ltd on behalf of University of Oxford

Mahaney W.C.,Quaternary Surveys | Mahaney W.C.,York University | Keiser L.,University of Oklahoma | Krinsley D.H.,University of Oregon | And 10 more authors.
Journal of the Geological Society | Year: 2013

Weathering rinds have been used for decades as relative age indicators to differentiate glacial deposits in long Quaternary sequences, but only recently has it been shown that rinds contain long and extensive palaeoenvironmental records that often extend far beyond mere repositories of chemical weathering on both Earth and Mars. When compared with associated palaeosols in deposits of the same age, rinds often carry a zonal weathering record that can be correlated with palaeosol horizon characteristics, with respect to both abiotic and biotic parameters. As demonstrated with examples from the French and Italian Alps, rinds in coarse clastic sediment contain weathering zones that correlate closely with horizon development in associated palaeosols of presumed Late Glacial age. In addition to weathering histories in both rinds and palaeosols, considerable evidence exists to indicate that the black mat impact (12.8 ka) reached the European Alps, a connection with the Younger Dryas readvance supported by both mineral and chemical composition. Preliminary metagenomic microbial analysis using density gradient gel electrophoresis suggests that the eubacterial microbial population found in at least one Ah palaeosol horizon associated with a rind impact site is different from that in other Late Glacial and Younger Dryas surface palaeosol horizons. © 2013 The Geological Society of London.

Mahaney W.C.,Quaternary Surveys | Mahaney W.C.,York University | Keiser L.,University of Oklahoma | Krinsley D.,University of Oregon | And 3 more authors.
Journal of Geology | Year: 2013

Previous work has ascribed a cosmic impact origin to black, high-temperature, carbon-encrusted beds (2-3 cm thick), associated with the Younger Dryas readvance of ice at 12.8 ka during the Late Glacial in the northern Andes of Venezuela. The evidence for this includes carbon spherules, aluminosilicate melt rocks, melted coatings of glass-like amorphous carbon, and Fe-Mn on sands and clasts derived from local felsic gneiss and granite. These sediments have been subjected to renewed investigation using high-resolution scanning electron microscopy and energy-dispersive spectrometry, and new data show that spherules at site MUM7B exhibit unique morphologies and compositions. Molar oxide weight percentages prove the spherules are not volcanic and show little overlap with cosmic materials. Spherule microstructures display quench melting and, thus, could not have formed from slow geological authigenic, diagenetic, or metamorphic processes. Instead, geochemical values for the Venezuelan samples plot within the limits of impact-related materials, including tektites, ejecta, and impact spherules from a number of craters and strewnfields (cf. Chicxulub Crater, Chesapeake Bay Crater, Tunguska, Australasian tektite field, Lake Bosumtwi Crater, Ries Crater, and others). These results are identical to previously reported spherules from the Younger Dryas boundary layer (YDB) on three continents, North America, Europe, and Asia, and the most likely origin is from a cosmic impact/ airburst 12.8 ka, as previously proposed. The MUM7B site is one of the two southernmost sites (Venezuela and Peru) in South America, thus extending the evidence supporting the YDB impact event into a new hemisphere on a new continent. © 2013 by The University of Chicago. All rights reserved.

Kinzie C.R.,DePaul University | Hee S.S.Q.,University of California at Los Angeles | Stich A.,DePaul University | Tague K.A.,DePaul University | And 23 more authors.
Journal of Geology | Year: 2014

A major cosmic-impact event has been proposed at the onset of the Younger Dryas (YD) cooling episode at ≈12,800 ± 150 years before present, forming the YD Boundary (YDB) layer, distributed over 150 million km2 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. © 2014 by The University of Chicago. All rights reserved.

Kurbatov A.V.,University of Maine, United States | Mayewski P.A.,University of Maine, United States | Steffensen J.P.,Copenhagen University | West A.,Packer Geoscience Consulting , LLC | And 19 more authors.
Journal of Glaciology | Year: 2010

We report the discovery in the Greenland ice sheet of a discrete layer of free nanodiamonds (NDs) in very high abundances, implying most likely either an unprecedented influx of extraterrestrial (ET) material or a cosmic impact event that occurred after the last glacial episode. From that layer, we extracted n-diamonds and hexagonal diamonds (lonsdaleite), an accepted ET impact indicator, at abundances of up to about 5×106 times background levels in adjacent younger and older ice. The NDs in the concentrated layer are rounded, suggesting they most likely formed during a cosmic impact through some process similar to carbon-vapor deposition or high-explosive detonation. This morphology has not been reported previously in cosmic material, but has been observed in terrestrial impact material. This is the first highly enriched, discrete layer of NDs observed in glacial ice anywhere, and its presence indicates that ice caps are important archives of ET events of varying magnitudes. Using a preliminary ice chronology based on oxygen isotopes and dust stratigraphy, the ND-rich layer appears to be coeval with ND abundance peaks reported at numerous North American sites in a sedimentary layer, the Younger Dryas boundary layer (YDB), dating to 12.9±0.1 ka. However, more investigation is needed to confirm this association.

Mahaney W.C.,Quaternary Surveys | Mahaney W.C.,York University | Keiser L.,University of Oklahoma | Krinsley D.H.,University of Oregon | And 5 more authors.
Geografiska Annaler, Series A: Physical Geography | Year: 2014

Recent analyses of sediment samples from "black mat" sites in South America and Europe support previous interpretations of an ET impact event that reversed the Late Glacial demise of LGM ice during the Bølling Allerød warming, resulting in a resurgence of ice termed the Younger Dryas (YD) cooling episode. The breakup or impact of a cosmic vehicle at the YD boundary coincides with the onset of a 1-kyr long interval of glacial resurgence, one of the most studied events of the Late Pleistocene. New analytical databases reveal a corpus of data indicating that the cosmic impact was a real event, most possibly a cosmic airburst from Earth's encounter with the Taurid Complex comet or unknown asteroid, an event that led to cosmic fragments exploding interhemispherically over widely dispersed areas, including the northern Andes of Venezuela and the Alps on the Italian/French frontier. While the databases in the two areas differ somewhat, the overall interpretation is that microtextural evidence in weathering rinds and in sands of associated paleosols and glaciofluvial deposits carry undeniable attributes of melted glassy carbon and Fe spherules, planar deformation features, shock-melted and contorted quartz, occasional transition and platinum metals, and brecciated and impacted minerals of diverse lithologies. In concert with other black mat localities in the Western USA, the Netherlands, coastal France, Syria, Central Asia, Peru, Argentina and Mexico, it appears that a widespread cosmic impact by an asteroid or comet is responsible for deposition of the black mat at the onset of the YD glacial event. Whether or not the impact caused a 1-kyr interval of glacial climate depends upon whether or not the Earth had multiple centuries-long episodic encounters with the Taurid Complex or asteroid remnants; impact-related changes in microclimates sustained climatic forcing sufficient to maintain positive mass balances in the reformed ice; and/or inertia in the Atlantic thermohaline circulation system persisted for 1kyr. © 2013 Swedish Society for Anthropology and Geography.

PubMed | Missouri State University, University of California at Santa Barbara, Kimstar Research, Quaternary Surveys and 18 more.
Type: Journal Article | Journal: Proceedings of the National Academy of Sciences of the United States of America | Year: 2015

The Younger Dryas impact hypothesis posits that a cosmic impact across much of the Northern Hemisphere deposited the Younger Dryas boundary (YDB) layer, containing peak abundances in a variable assemblage of proxies, including magnetic and glassy impact-related spherules, high-temperature minerals and melt glass, nanodiamonds, carbon spherules, aciniform carbon, platinum, and osmium. Bayesian chronological modeling was applied to 354 dates from 23 stratigraphic sections in 12 countries on four continents to establish a modeled YDB age range for this event of 12,835-12,735 Cal B.P. at 95% probability. This range overlaps that of a peak in extraterrestrial platinum in the Greenland Ice Sheet and of the earliest age of the Younger Dryas climate episode in six proxy records, suggesting a causal connection between the YDB impact event and the Younger Dryas. Two statistical tests indicate that both modeled and unmodeled ages in the 30 records are consistent with synchronous deposition of the YDB layer within the limits of dating uncertainty ( 100 y). The widespread distribution of the YDB layer suggests that it may serve as a datum layer.

Anderson D.G.,University of Tennessee at Knoxville | Goodyear A.C.,University of South Carolina | Kennett J.,University of California at Santa Barbara | West A.,Packer Geoscience Consulting , LLC
Quaternary International | Year: 2011

Three approaches are used to test whether or not human populations across North America were affected by abrupt climate change and/or other environmental factors associated with the onset of the Younger Dryas (YD) cooling episode at ca. 12,900 cal BP. They are: (1) frequency analyses of Paleoindian projectile points from across North America; (2) time series of lithic assemblages from eleven Paleoindian quarry sites in the southeastern United States; and (3) summed probability analyses (SPA) of radiocarbon dates from cultural (human-related) sites across North America and parts of the Old World. The results of each analysis suggest a significant decline and/or reorganization in human population during the early centuries of the YD, varying in extent by region. Archaeological settings formerly heavily utilized, such as stone quarries in the southeastern U.S., appear to have been largely abandoned, while over large areas, a substantial decline occurred in the numbers of diagnostic projectile points and cultural radiocarbon dates. Later in the YD, beginning after about 12,600 cal BP, there was an apparent resurgence in population and/or settlements in many areas, as indicated by increases in projectile points, quarry usage, and human-related radiocarbon ages. © 2011 Elsevier Ltd and INQUA.

Mahaney W.C.,Quaternary Surveys | Somelar P.,University of Tartu | Dirszowsky R.W.,Laurentian University | Kelleher B.,Dublin City University | And 7 more authors.
Journal of Geology | Year: 2016

Understanding the mechanism associated with rates of weathering and evolution of rocks→sediment→soil→paleosol in alpine environments raises questions related to the impact of microbial mediation versus various diverse abiotic chemical/physical processes, even including the overall effect of cosmic impact/airburst during the early stage of weathering in Late Glacial (LG) deposits. This study is of a chronosequence of soils/paleosols, with an age range that spans the post–Little Ice Age (post-LIA; <150 yr), the Little Ice Age (LIA; AD 1500–1850), the middle Neoglacial (∼3 ka)–Younger Dryas (YD; <12.8 ka), and the LG (<15 ka). The goal is to elicit trends in weathering, soil morphogenesis, and related eubacterial population changes over the past 13–15 k.yr. The older LG/YD paleosols in the sequence represent soil morphogenesis that started during the closing stage of Pleistocene glaciation. These are compared with undated soils of midto late Neoglacial age, the youngest of LIA and post-LIA age. All profiles formed in a uniform parentmaterial ofmetabasalt composition and in moraine, rockfall, protalus, and alluvial fan deposits. Elsewhere in Europe,North America, and Asia, the cosmic impact/airburst event at 12.8 ka often produced a distinctive, carbon-rich “black mat” layer that shows evidence of high-temperature melting. At this alpine site, older profiles of similar LG age contain scorched and melted surface sediments that are otherwise similar in composition to the youngest/thinnest profiles developing in the catchment today. Moreover, microbial analysis of the sediments offers new insight into the genesis of these sediments: the C and Cu (u = unweathered) horizons in LG profiles present at 12.8 ka (now Ah/Bw) show bacterial population structures that differ markedly from recent alluvial/protalus sample bacterial populations. We propose here that these differences are, in part, a direct consequence of the age/cosmic impact/weathering processes that have occurred in the chronosequence. Of the several questions that emerge from these sequences, perhaps the most important involve the interaction of biotic-mineral factors, which need to be understood if we are to generally fully appreciate the role played by microbes in rock weathering. © 2016 by The University of Chicago. All rights reserved.

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