At Paleo-Indian kill sites throughout North America abundant fossil evidence exists for Mammoths,... more At Paleo-Indian kill sites throughout North America abundant fossil evidence exists for Mammoths, dated to ≈11,000 rcy BP (13,000 cal yr BP), often fully articulated and partly butchered, whose remains could not have been exposed to the elements for more than a short time. They appear to be the victims of a sudden, catastrophic event. At several sites a black mat lies in direct contact with the bones. No evidence for Mammoths, or the Paleo-Indians who hunted them, is found in later sediments. We have investigated Paleo-Indian sites at Gainey, MI, Murray Springs, AZ, and Blackwater Draw, NM where we discovered a layer of abundant, rounded, ferromagnetic particles in direct contact with the Mammoth fossils. These particles can readily be extracted from the sediment with a strong permanent magnet. Many of the particles from the Gainey, MI site appear to be meteoritic and shocked, as shown in Figure 1.
We have analyzed the elemental content of sediments, magnetic grains and microspherules found in ... more We have analyzed the elemental content of sediments, magnetic grains and microspherules found in the 12.9 ka Younger Dryas boundary layer (YDB) at eight North American Clovis-age sites, a site in Belgium, and 16 Carolina Bays using Prompt Gamma-ray Activation Analysis (PGAA), Instrumental Neutron Activation Analysis (INAA), X-ray fluorescence (XRF), Inductively Coupled Plasma Mass Spectrometry (ICP-MS), and low- background gamma-ray
ABSTRACT The debate surrounding the late Pleistocene megafaunal extinctions in North America and ... more ABSTRACT The debate surrounding the late Pleistocene megafaunal extinctions in North America and the possible cause being related to an impact (asteroid or cometary) event at the Younger Dryas boundary (YDB) some ~12,900 ka, has recently been renewed with the discovery of nanodiamonds (lonsdaleite) and other diamond polymorphs in several YDB locations worldwide(1). While the discovery of lonsdaleite is certainly exciting, it is unclear whether or not this diamond allotrope would form during shock processes diagnostic of an impact event. Moreover, there are combustion related processes (e.g. CVD and anoxic combustion) that can lead to the production of nanodiamonds. Nevertheless, the presence of nanodiamonds coupled to other impact tracers (e.g. magnetic spherules, iridium) in the YDB layer suggests that these nanodiamonds may be related to an impact event. In previous studies of some North American YDB sitesm we searched for fullerenes with trapped noble gases. Fullerenes (C60 to C200) from Clovis age sites at Murray Springs, AZ, Blackwater Draw, NM and Daisy Cave, San Miguel Channel Island, contain trapped helium and argon with isotope ratios similar to the planetary component of carbonaceous chondrites, indicative of their formation in an extraterrestrial environment. In addition, polycyclic aromatic hydrocarbons (PAHs) were also identified in the same layer along with charcoal and soot that are attributed to widespread wildfires associated with the impact event. In an effort to better understand the true nature of the nanodiamonds, we have collected some charcoal spherules related to a younger impact crater and some modern day wildfires. The results of all of these studies will be presented.
Although much has been written about a cosmic impact event in the Western Alps of the Mt. Viso ar... more Although much has been written about a cosmic impact event in the Western Alps of the Mt. Viso area, the event closely tied with the Younger Dryas Boundary (YDB) of 12.8 ka and onset of the Younger Dryas (YD), the affected land surface is considered to contain a similar black mat suite of sediment found on three continents. While work elsewhere has focused on recovered sediment from lake and ice cores, buried lacustrine/alluvial records, and surface glacial and paraglacial records, no one has traced a mountain morphosequence of deposits with the objective of investigating initial weathering/ soil morphogenesis that occurred in ice recessional deposits up to the YDB when the surface was subjected to intense heat, presumably, as hypothesized by Mahaney et al. (2016a) from a cosmic airburst. With the land surface rapidly free of ice following glacial retreat during the Bølling-Allerød interstadial, weathering processes ~13.5 to 12.8 ka led to weathering and soil morphogenesis in a slow progression as the land surface became free of ice. To determine the exposed land character in the mid-to late-Allerød, it is possible to utilize an inverted stratigraphic soil morphogenesis working backward in time, from known post-Little Ice Age (LIA) (i.e. time-zero) through LIA (~0.45 to ~0.10 ka), to at least the middle Neoglacial (~2 ka), to answer several questions. What were the likely soil profile states in existence at the end of the Allerød just prior to the cosmic impact/airburst (YDB)? Assuming these immature weathered regolith sections of the Late Allerød approximated the <1 ka old profiles seen today, and assuming the land surface was subjected to a hypothesized instant temperature burst from ambient to ~2200 o C at ~12.8 ka, what would be the expected effect on the resident sediment? To test the mid-LG (YDB) to YD relationship we analyzed the paleosols in both suites of deposits-mid-LG to YD-to test that the airburst grains are restricted to Late Allerød paleosols and using relative-age-determination criteria, that the overlapping YD to mid-LG moraines are closely related in time. These are some of the questions about the black mat that we seek to answer with reference to sites in the upper Guil and Po rivers of the Mt. Viso area.
Oceanic impacts are a growing source of concern for the scientific community. Though the Earth is... more Oceanic impacts are a growing source of concern for the scientific community. Though the Earth is ~70 percent covered with water, and logic would therefore dictate that ~70 percent of impacts occur in the oceans, scientific investigations have focused on continental events. This is in part due to the difficulties inherent in examining submarine impact structures. Oceanic impacts lack many
ABSTRACT Nanodiamonds (NDs), including hexagonal diamonds (lonsdaleite) have been discovered at t... more ABSTRACT Nanodiamonds (NDs), including hexagonal diamonds (lonsdaleite) have been discovered at the Tunguska impact site and in the Cretaceous-Tertiary (K/T) boundary layer, which also contains cubic diamonds. Similarly, for the Younger Dryas boundary layer (YDB) that dates to the onset of the Younger Dryas (YD) cooling event at ~12.9 ka, NDs (cubics and lonsdaleite) are found broadly at multiple locations over North America and Europe. The NDs are proposed to result from a cosmic impact event that triggered widespread biomass-burning, which produced peaks at multiple sites in charcoal, grape-cluster soot, carbon spherules (CS), glass-like carbon, ammonium, and nitrate at the onset of the YD. The question is whether or not a cosmic impact is the best or only explanation for the YDB nanodiamonds. For example, could volcanism or intense wildfires have produced them? WILDFIRES: There is evidence for widespread fires at 12.9 ka: (1) The YDB also contains variable concentrations and sizes of CS, which are carbon-rich spheres produced through intense heat in high-stand wildfires. (2) Greenland ice cores exhibit spikes in ammonium and nitrate at the YD onset, that are interpreted as proxies for biomass-burning and collectively form the largest such peak known from late Quaternary ice cores. (3) Nearly all of 74 North American lakes examined exhibit peaks in charcoal representing evidence for wildfires at or close to ~12.9 ka, within the limits of radiocarbon dating. (4) High levels of soot have been detected in the YDB layer at five sites across North America (CA, AZ, OK, TX, and SC). NANODIAMONDS: For Tunguska, K/T sites, and the YDB, NDs have been found either embedded within or closely associated with CS. Experimental research demonstrates that ND formation requires extreme physical conditions generated either in the laboratory or during an ET impact, and not otherwise found on Earth&amp;#39;s surface. These conditions include transient high temperatures, hypoxic atmospheric conditions, and rapid quenching, thus excluding regular wildfires, where oxic conditions would destroy NDs. The available evidence supports formation of nanodiamonds by cosmic impact at 12.9 ka for the following reasons: (A) Lonsdaleite has never been found associated with any volcanic or igneous rocks or with mantle-derived terrestrial diamonds; (B) Lonsdaleite has been found only inside meteorites or impact craters; (C) NDs have never been found in association with non-impact wildfires; (D) No CS that contain NDs have been observed above or below known impact boundaries, e.g., the K/T and Tunguska layers; (E) In the entire geologic record, there are only two known continental layers containing both NDs and soot - the K/T boundary and the YDB. Thus, existing aggregate evidence supports an as-yet undefined cosmic event as the most compelling explanation for the YDB, and it argues against wildfires or volcanism as alternative causes.
Until the announcements of a possible impact event (Firestone et al. 2007; Kennett et al., 2009a;... more Until the announcements of a possible impact event (Firestone et al. 2007; Kennett et al., 2009a; 2009b) at the beginning of the Younger Dryas (YD) around 12.9 ka, the KT impact layer (KTB) that resulted from the Chicxulub impact at 65 mya was the only geological boundary layer known to contain coeval peaks in various impact markers, including diamonds. Here,
We report abundant nanodiamonds in sediments dating to 12.9 ± 0.1 thousand calendar years before ... more We report abundant nanodiamonds in sediments dating to 12.9 ± 0.1 thousand calendar years before the present at multiple locations across North America. Selected area electron diffraction patterns reveal two diamond allotropes in this boundary layer but not above or below that interval. Cubic diamonds form under high temperature-pressure regimes, and n-diamonds also require extraordinary conditions, well outside the range of Earth's typical surficial processes but common to cosmic impacts. N-diamond concentrations range from 10 to 3700 parts per billion by weight, comparable to amounts found in known impact layers. These diamonds provide strong evidence for Earth's collision with a rare swarm of carbonaceous chondrites or comets at the onset of the Younger Dryas cool interval, producing multiple airbursts and possible surface impacts, with severe repercussions for plants, animals, and humans in North America.
<p>The Younger Dryas cooling episode came about in the Northern Hemisphere in an abrupt man... more <p>The Younger Dryas cooling episode came about in the Northern Hemisphere in an abrupt manner atypical of deglaciation events. This cooling resulted in the Pleistocene extinctions of many genera of faunas and coincided with the disappearance of the Clovis culture. The Younger Dryas Cosmic Impact of 12.8 kya is then considered as a hypothesis that explains these dramatic and enigmatic events. As a nonlinear climate episode, the YDB Impact Hypothesis can have explanatory power in accounting for the associated environmental and cultural changes.</p>
Controversy over the alpine route taken by the Hannibalic Army from the Rhône Basin into Italia i... more Controversy over the alpine route taken by the Hannibalic Army from the Rhône Basin into Italia in 218 BC (2168 cal BP) has raged amongst classicists for over two millennia. Because Hannibal crossed the Alps, the significance for identifying the route taken by the Punic Army lies more in its potential for identifying sites of historical archaeological significance than a resolution of one of history's most enduring questions. While compelling stratigraphic, geochemical and microbiological evidence has been recovered from an alluvial floodplain mire in the upper Guil Valley, located below the Col de la Traversette (about 3000 masl) on the French-Italian border, it potentially identifies the invasion route as the one originally proposed by Sir Gavin de Beer in 1974. The dated layers in several sections, termed the MAD (mass animal deposition) beds based on disrupted/churned bedding and key/specialized
Weathering rinds have been used for decades as relative age indicators to differentiate glacial d... more 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.
Previously, a large platinum (Pt) anomaly was reported in the Greenland ice sheet at the Younger ... more Previously, a large platinum (Pt) anomaly was reported in the Greenland ice sheet at the Younger Dryas boundary (YDB) (12,800 Cal B.P.). In order to evaluate its geographic extent, fire-assay and inductively coupled plasma mass spectrometry (FA and ICP-MS) elemental analyses were performed on 11 widely separated archaeological bulk sedimentary sequences. We document discovery of a distinct Pt anomaly spread widely across North America and dating to the Younger Dryas (YD) onset. The apparent synchroneity of this widespread YDB Pt anomaly is consistent with Greenland Ice Sheet Project 2 (GISP2) data that indicated atmospheric input of platinum-rich dust. We expect the Pt anomaly to serve as a widely-distributed time marker horizon (datum) for identification and correlation of the onset of the YD climatic episode at 12,800 Cal B.P. This Pt datum will facilitate the dating and correlating of archaeological, paleontological, and paleoenvironmental data between sequences, especially those with limited age control.
At Paleo-Indian kill sites throughout North America abundant fossil evidence exists for Mammoths,... more At Paleo-Indian kill sites throughout North America abundant fossil evidence exists for Mammoths, dated to ≈11,000 rcy BP (13,000 cal yr BP), often fully articulated and partly butchered, whose remains could not have been exposed to the elements for more than a short time. They appear to be the victims of a sudden, catastrophic event. At several sites a black mat lies in direct contact with the bones. No evidence for Mammoths, or the Paleo-Indians who hunted them, is found in later sediments. We have investigated Paleo-Indian sites at Gainey, MI, Murray Springs, AZ, and Blackwater Draw, NM where we discovered a layer of abundant, rounded, ferromagnetic particles in direct contact with the Mammoth fossils. These particles can readily be extracted from the sediment with a strong permanent magnet. Many of the particles from the Gainey, MI site appear to be meteoritic and shocked, as shown in Figure 1.
We have analyzed the elemental content of sediments, magnetic grains and microspherules found in ... more We have analyzed the elemental content of sediments, magnetic grains and microspherules found in the 12.9 ka Younger Dryas boundary layer (YDB) at eight North American Clovis-age sites, a site in Belgium, and 16 Carolina Bays using Prompt Gamma-ray Activation Analysis (PGAA), Instrumental Neutron Activation Analysis (INAA), X-ray fluorescence (XRF), Inductively Coupled Plasma Mass Spectrometry (ICP-MS), and low- background gamma-ray
ABSTRACT The debate surrounding the late Pleistocene megafaunal extinctions in North America and ... more ABSTRACT The debate surrounding the late Pleistocene megafaunal extinctions in North America and the possible cause being related to an impact (asteroid or cometary) event at the Younger Dryas boundary (YDB) some ~12,900 ka, has recently been renewed with the discovery of nanodiamonds (lonsdaleite) and other diamond polymorphs in several YDB locations worldwide(1). While the discovery of lonsdaleite is certainly exciting, it is unclear whether or not this diamond allotrope would form during shock processes diagnostic of an impact event. Moreover, there are combustion related processes (e.g. CVD and anoxic combustion) that can lead to the production of nanodiamonds. Nevertheless, the presence of nanodiamonds coupled to other impact tracers (e.g. magnetic spherules, iridium) in the YDB layer suggests that these nanodiamonds may be related to an impact event. In previous studies of some North American YDB sitesm we searched for fullerenes with trapped noble gases. Fullerenes (C60 to C200) from Clovis age sites at Murray Springs, AZ, Blackwater Draw, NM and Daisy Cave, San Miguel Channel Island, contain trapped helium and argon with isotope ratios similar to the planetary component of carbonaceous chondrites, indicative of their formation in an extraterrestrial environment. In addition, polycyclic aromatic hydrocarbons (PAHs) were also identified in the same layer along with charcoal and soot that are attributed to widespread wildfires associated with the impact event. In an effort to better understand the true nature of the nanodiamonds, we have collected some charcoal spherules related to a younger impact crater and some modern day wildfires. The results of all of these studies will be presented.
Although much has been written about a cosmic impact event in the Western Alps of the Mt. Viso ar... more Although much has been written about a cosmic impact event in the Western Alps of the Mt. Viso area, the event closely tied with the Younger Dryas Boundary (YDB) of 12.8 ka and onset of the Younger Dryas (YD), the affected land surface is considered to contain a similar black mat suite of sediment found on three continents. While work elsewhere has focused on recovered sediment from lake and ice cores, buried lacustrine/alluvial records, and surface glacial and paraglacial records, no one has traced a mountain morphosequence of deposits with the objective of investigating initial weathering/ soil morphogenesis that occurred in ice recessional deposits up to the YDB when the surface was subjected to intense heat, presumably, as hypothesized by Mahaney et al. (2016a) from a cosmic airburst. With the land surface rapidly free of ice following glacial retreat during the Bølling-Allerød interstadial, weathering processes ~13.5 to 12.8 ka led to weathering and soil morphogenesis in a slow progression as the land surface became free of ice. To determine the exposed land character in the mid-to late-Allerød, it is possible to utilize an inverted stratigraphic soil morphogenesis working backward in time, from known post-Little Ice Age (LIA) (i.e. time-zero) through LIA (~0.45 to ~0.10 ka), to at least the middle Neoglacial (~2 ka), to answer several questions. What were the likely soil profile states in existence at the end of the Allerød just prior to the cosmic impact/airburst (YDB)? Assuming these immature weathered regolith sections of the Late Allerød approximated the <1 ka old profiles seen today, and assuming the land surface was subjected to a hypothesized instant temperature burst from ambient to ~2200 o C at ~12.8 ka, what would be the expected effect on the resident sediment? To test the mid-LG (YDB) to YD relationship we analyzed the paleosols in both suites of deposits-mid-LG to YD-to test that the airburst grains are restricted to Late Allerød paleosols and using relative-age-determination criteria, that the overlapping YD to mid-LG moraines are closely related in time. These are some of the questions about the black mat that we seek to answer with reference to sites in the upper Guil and Po rivers of the Mt. Viso area.
Oceanic impacts are a growing source of concern for the scientific community. Though the Earth is... more Oceanic impacts are a growing source of concern for the scientific community. Though the Earth is ~70 percent covered with water, and logic would therefore dictate that ~70 percent of impacts occur in the oceans, scientific investigations have focused on continental events. This is in part due to the difficulties inherent in examining submarine impact structures. Oceanic impacts lack many
ABSTRACT Nanodiamonds (NDs), including hexagonal diamonds (lonsdaleite) have been discovered at t... more ABSTRACT Nanodiamonds (NDs), including hexagonal diamonds (lonsdaleite) have been discovered at the Tunguska impact site and in the Cretaceous-Tertiary (K/T) boundary layer, which also contains cubic diamonds. Similarly, for the Younger Dryas boundary layer (YDB) that dates to the onset of the Younger Dryas (YD) cooling event at ~12.9 ka, NDs (cubics and lonsdaleite) are found broadly at multiple locations over North America and Europe. The NDs are proposed to result from a cosmic impact event that triggered widespread biomass-burning, which produced peaks at multiple sites in charcoal, grape-cluster soot, carbon spherules (CS), glass-like carbon, ammonium, and nitrate at the onset of the YD. The question is whether or not a cosmic impact is the best or only explanation for the YDB nanodiamonds. For example, could volcanism or intense wildfires have produced them? WILDFIRES: There is evidence for widespread fires at 12.9 ka: (1) The YDB also contains variable concentrations and sizes of CS, which are carbon-rich spheres produced through intense heat in high-stand wildfires. (2) Greenland ice cores exhibit spikes in ammonium and nitrate at the YD onset, that are interpreted as proxies for biomass-burning and collectively form the largest such peak known from late Quaternary ice cores. (3) Nearly all of 74 North American lakes examined exhibit peaks in charcoal representing evidence for wildfires at or close to ~12.9 ka, within the limits of radiocarbon dating. (4) High levels of soot have been detected in the YDB layer at five sites across North America (CA, AZ, OK, TX, and SC). NANODIAMONDS: For Tunguska, K/T sites, and the YDB, NDs have been found either embedded within or closely associated with CS. Experimental research demonstrates that ND formation requires extreme physical conditions generated either in the laboratory or during an ET impact, and not otherwise found on Earth&amp;#39;s surface. These conditions include transient high temperatures, hypoxic atmospheric conditions, and rapid quenching, thus excluding regular wildfires, where oxic conditions would destroy NDs. The available evidence supports formation of nanodiamonds by cosmic impact at 12.9 ka for the following reasons: (A) Lonsdaleite has never been found associated with any volcanic or igneous rocks or with mantle-derived terrestrial diamonds; (B) Lonsdaleite has been found only inside meteorites or impact craters; (C) NDs have never been found in association with non-impact wildfires; (D) No CS that contain NDs have been observed above or below known impact boundaries, e.g., the K/T and Tunguska layers; (E) In the entire geologic record, there are only two known continental layers containing both NDs and soot - the K/T boundary and the YDB. Thus, existing aggregate evidence supports an as-yet undefined cosmic event as the most compelling explanation for the YDB, and it argues against wildfires or volcanism as alternative causes.
Until the announcements of a possible impact event (Firestone et al. 2007; Kennett et al., 2009a;... more Until the announcements of a possible impact event (Firestone et al. 2007; Kennett et al., 2009a; 2009b) at the beginning of the Younger Dryas (YD) around 12.9 ka, the KT impact layer (KTB) that resulted from the Chicxulub impact at 65 mya was the only geological boundary layer known to contain coeval peaks in various impact markers, including diamonds. Here,
We report abundant nanodiamonds in sediments dating to 12.9 ± 0.1 thousand calendar years before ... more We report abundant nanodiamonds in sediments dating to 12.9 ± 0.1 thousand calendar years before the present at multiple locations across North America. Selected area electron diffraction patterns reveal two diamond allotropes in this boundary layer but not above or below that interval. Cubic diamonds form under high temperature-pressure regimes, and n-diamonds also require extraordinary conditions, well outside the range of Earth's typical surficial processes but common to cosmic impacts. N-diamond concentrations range from 10 to 3700 parts per billion by weight, comparable to amounts found in known impact layers. These diamonds provide strong evidence for Earth's collision with a rare swarm of carbonaceous chondrites or comets at the onset of the Younger Dryas cool interval, producing multiple airbursts and possible surface impacts, with severe repercussions for plants, animals, and humans in North America.
<p>The Younger Dryas cooling episode came about in the Northern Hemisphere in an abrupt man... more <p>The Younger Dryas cooling episode came about in the Northern Hemisphere in an abrupt manner atypical of deglaciation events. This cooling resulted in the Pleistocene extinctions of many genera of faunas and coincided with the disappearance of the Clovis culture. The Younger Dryas Cosmic Impact of 12.8 kya is then considered as a hypothesis that explains these dramatic and enigmatic events. As a nonlinear climate episode, the YDB Impact Hypothesis can have explanatory power in accounting for the associated environmental and cultural changes.</p>
Controversy over the alpine route taken by the Hannibalic Army from the Rhône Basin into Italia i... more Controversy over the alpine route taken by the Hannibalic Army from the Rhône Basin into Italia in 218 BC (2168 cal BP) has raged amongst classicists for over two millennia. Because Hannibal crossed the Alps, the significance for identifying the route taken by the Punic Army lies more in its potential for identifying sites of historical archaeological significance than a resolution of one of history's most enduring questions. While compelling stratigraphic, geochemical and microbiological evidence has been recovered from an alluvial floodplain mire in the upper Guil Valley, located below the Col de la Traversette (about 3000 masl) on the French-Italian border, it potentially identifies the invasion route as the one originally proposed by Sir Gavin de Beer in 1974. The dated layers in several sections, termed the MAD (mass animal deposition) beds based on disrupted/churned bedding and key/specialized
Weathering rinds have been used for decades as relative age indicators to differentiate glacial d... more 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.
Previously, a large platinum (Pt) anomaly was reported in the Greenland ice sheet at the Younger ... more Previously, a large platinum (Pt) anomaly was reported in the Greenland ice sheet at the Younger Dryas boundary (YDB) (12,800 Cal B.P.). In order to evaluate its geographic extent, fire-assay and inductively coupled plasma mass spectrometry (FA and ICP-MS) elemental analyses were performed on 11 widely separated archaeological bulk sedimentary sequences. We document discovery of a distinct Pt anomaly spread widely across North America and dating to the Younger Dryas (YD) onset. The apparent synchroneity of this widespread YDB Pt anomaly is consistent with Greenland Ice Sheet Project 2 (GISP2) data that indicated atmospheric input of platinum-rich dust. We expect the Pt anomaly to serve as a widely-distributed time marker horizon (datum) for identification and correlation of the onset of the YD climatic episode at 12,800 Cal B.P. This Pt datum will facilitate the dating and correlating of archaeological, paleontological, and paleoenvironmental data between sequences, especially those with limited age control.
Airbursts/impacts by a fragmented comet or asteroid have been proposed at the Younger Dryas onset (12.80 ± 0.15 ka) based on identification of an assemblage of impact-related proxies.
Evidence for deposition of 10 million tonnes of impact spherules across four continents 12,800 y ... more Evidence for deposition of 10 million tonnes of impact spherules across four continents 12,800 y ago.
James H. Wittkea , James C. Weaverb , Ted E. Buncha,1, James P. Kennettc , Douglas J. Kennettd , Andrew M. T. Mooree , Gordon C. Hillmanf , Kenneth B. Tankersleyg , Albert C. Goodyearh , Christopher R. Moorei , I. Randolph Daniel, Jr.j , Jack H. Rayk , Neal H. Lopinotk , David Ferrarol , Isabel Israde-Alcántaram, James L. Bischoffn , Paul S. DeCarlio , Robert E. Hermesp,2, Johan B. Kloostermanq,2, Zsolt Revayr , George A. Howards , David R. Kimbelt , Gunther Kletetschkau , Ladislav Nabeleku,v, Carl P. Lipow, Sachiko Sakaiw, Allen Westx , and Richard B. Firestoney.
Airbursts/impacts by a fragmented comet or asteroid have been proposed at the Younger Dryas onset (12.80 ± 0.15 ka) based on identification of an assemblage of impact-related proxies, including microspherules, nanodiamonds, and iridium. Distributed across four continents at the Younger Dryas boundary (YDB), spherule peaks have been independently confirmed in eight studies, but unconfirmed in two others, resulting in continued dispute about their occurrence, distribution, and origin. To further address this dispute and better identify YDB spherules, we present results from one of the largest spherule investigations ever undertaken regarding spherule geochemistry, morphologies, origins, and processes of formation. We investigated 18 sites across North America, Europe, and the Middle East, performing nearly 700 analyses on spherules using energy dispersive X-ray spectroscopy for geochemical analyses and scanning electron microscopy for surface microstructural characterization. Twelve locations rank among the world’s premier end-Pleistocene archaeological sites, where the YDB marks a hiatus in human occupation or major changes in site use. Our results are consistent with melting of sediments to temperatures >2,200 °C by the thermal radiation and air shocks produced by passage of an extraterrestrial object through the atmosphere; they are inconsistent with volcanic, cosmic, anthropogenic, lightning, or authigenic sources. We also produced spherules from wood in the laboratory at >1,730 °C, indicating that impact related incineration of biomass may have contributed to spherule production. At 12.8 ka, an estimated 10 million tonnes of spherules were distributed across ∼50 million square kilometers, similar to well-known impact strewnfields and consistent with a major cosmic impact event.
This paper overviews the multiple lines of evidence that collectively suggest a Tunguska-like, co... more This paper overviews the multiple lines of evidence that collectively suggest a Tunguska-like, cosmic airburst event that obliterated civilization-including the Middle Bronze Age (MBA) city-state anchored by Tall el-Hammam-in the Middle Ghor (the 25 km diameter circular plain immediately north of the Dead Sea) ca. 1700 BCE, or 3700 years before present (3.7kaBP). Analyses of samples taken over thirteen seasons of the Tall el-Hammam Excavation Project (TeHEP) have been and are being performed by a team of scientists from New Mexico Tech, Northern Arizona University, North Carolina State University, Elizabeth City (NC) State University, DePaul University, Trinity Southwest University, the Comet Research Group, and Los Alamos National Laboratories, with remarkable results. Commensurate with these results are the archaeological data collected from across the entire occupational footprint (36ha) of Tall el-Hammam, demonstrating a directionality pattern for the high-heat, explosive 3.7kaBP Middle Ghor Event that, in an instant, devastated approximately 500km2 immediately north of the Dead Sea, not only wiping out 100% of the MBA cities and towns, but also stripping agricultural soils from once-fertile fields and covering the eastern Middle Ghor with a super-heated brine of Dead Sea anhydride salts pushed over the landscape by the Event’s frontal shockwaves. Based upon the archaeological evidence, it took at least 600 years to recover sufficiently from the soil destruction and contamination before civilization could again become established in the eastern Middle Ghor.
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Papers by Allen West
James H. Wittkea , James C. Weaverb , Ted E. Buncha,1, James P. Kennettc , Douglas J. Kennettd , Andrew M. T. Mooree , Gordon C. Hillmanf , Kenneth B. Tankersleyg , Albert C. Goodyearh , Christopher R. Moorei , I. Randolph Daniel, Jr.j , Jack H. Rayk , Neal H. Lopinotk , David Ferrarol , Isabel Israde-Alcántaram, James L. Bischoffn , Paul S. DeCarlio , Robert E. Hermesp,2, Johan B. Kloostermanq,2, Zsolt Revayr , George A. Howards , David R. Kimbelt , Gunther Kletetschkau , Ladislav Nabeleku,v, Carl P. Lipow, Sachiko Sakaiw, Allen Westx , and Richard B. Firestoney.
Airbursts/impacts by a fragmented comet or asteroid have been proposed at the Younger Dryas onset (12.80 ± 0.15 ka) based on identification of an assemblage of impact-related proxies, including microspherules, nanodiamonds, and iridium. Distributed across four continents at the Younger Dryas boundary (YDB), spherule peaks have been independently confirmed in eight studies, but unconfirmed in two others, resulting in continued dispute about their occurrence, distribution, and origin. To further address this dispute and better identify YDB spherules, we present results from one of the largest spherule investigations ever undertaken regarding spherule geochemistry, morphologies, origins, and processes of formation. We investigated 18 sites across North America, Europe, and the Middle East, performing nearly 700 analyses on spherules using energy dispersive X-ray spectroscopy for geochemical analyses and scanning electron microscopy for surface microstructural characterization. Twelve locations rank among the world’s premier end-Pleistocene archaeological sites, where the YDB marks a hiatus in human occupation or major changes in site use. Our results are consistent with melting of sediments to temperatures >2,200 °C by the thermal radiation and air shocks produced by passage of an extraterrestrial object through the atmosphere; they are inconsistent with volcanic, cosmic, anthropogenic, lightning, or authigenic sources. We also produced spherules from wood in the laboratory at >1,730 °C, indicating that impact related incineration of biomass may have contributed to spherule production. At 12.8 ka, an estimated 10 million tonnes of spherules were distributed across ∼50 million square kilometers, similar to well-known impact strewnfields and consistent with a major cosmic impact event.