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Title: Framboidal iron oxide: Chondrite-like material from the black mat, Murray Springs, Arizona

Abstract

At the end of the Pleistocene, many large mammals became extinct in North America1. The three most common theories for this phenomenon include climate change, overkill, or disease. Recently, researchers suggested that an extraterrestrial (ET) event may have caused sudden climate change that devastated these large mammals and had profound effects on the Clovis culture2,3. Critics of the ET event or impact theory note the lack of evidence such as an impact crater, impact material, shocked quartz, or tektites4. Here we present for the first time chemical and textural evidence of impact material from the Clovis-age, Murray Springs black mat layer, Arizona, USA. The impact material contains iron oxide spherules (framboids) in a glassy iron-silica matrix, which is one indicator of a possible meteorite impact. The spherules also contain elevated concentrations of vanadium and little titanium. The chemistry of both the spherules and matrix is consistent with the chemistry of impact material associated with other meteorite impact sites and meteorite showers.

Authors:
 [1];  [1];  [2];  [3];  [1]
  1. University of Manitoba, Canada
  2. {Larry} M [ORNL
  3. University of Arizona
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1074418
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Earth and Planetary Science Letters; Journal Volume: 319-320
Country of Publication:
United States
Language:
English

Citation Formats

Fayek, Mostafa, Hull, Sharon, Anovitz, Lawrence, HaynesJr., C. Vance, and Bergen, Laura. Framboidal iron oxide: Chondrite-like material from the black mat, Murray Springs, Arizona. United States: N. p., 2012. Web. doi:10.1016/j.epsl.2011.11.033.
Fayek, Mostafa, Hull, Sharon, Anovitz, Lawrence, HaynesJr., C. Vance, & Bergen, Laura. Framboidal iron oxide: Chondrite-like material from the black mat, Murray Springs, Arizona. United States. doi:10.1016/j.epsl.2011.11.033.
Fayek, Mostafa, Hull, Sharon, Anovitz, Lawrence, HaynesJr., C. Vance, and Bergen, Laura. 2012. "Framboidal iron oxide: Chondrite-like material from the black mat, Murray Springs, Arizona". United States. doi:10.1016/j.epsl.2011.11.033.
@article{osti_1074418,
title = {Framboidal iron oxide: Chondrite-like material from the black mat, Murray Springs, Arizona},
author = {Fayek, Mostafa and Hull, Sharon and Anovitz, Lawrence and HaynesJr., C. Vance and Bergen, Laura},
abstractNote = {At the end of the Pleistocene, many large mammals became extinct in North America1. The three most common theories for this phenomenon include climate change, overkill, or disease. Recently, researchers suggested that an extraterrestrial (ET) event may have caused sudden climate change that devastated these large mammals and had profound effects on the Clovis culture2,3. Critics of the ET event or impact theory note the lack of evidence such as an impact crater, impact material, shocked quartz, or tektites4. Here we present for the first time chemical and textural evidence of impact material from the Clovis-age, Murray Springs black mat layer, Arizona, USA. The impact material contains iron oxide spherules (framboids) in a glassy iron-silica matrix, which is one indicator of a possible meteorite impact. The spherules also contain elevated concentrations of vanadium and little titanium. The chemistry of both the spherules and matrix is consistent with the chemistry of impact material associated with other meteorite impact sites and meteorite showers.},
doi = {10.1016/j.epsl.2011.11.033},
journal = {Earth and Planetary Science Letters},
number = ,
volume = 319-320,
place = {United States},
year = 2012,
month = 1
}
  • At the end of the Pleistocene a Younger Dryas black mat was deposited on top of the Pleistocene sediments inmany parts of North America. A study of themagnetic fraction ({approx}10,900 50 B.P.) fromthe basal section of the black mat at Murray Springs, AZ revealed the presence of amorphous iron oxide framboids in a glassy iron-silica matrix. These framboids are very similar in appearance and chemistry to those reported from several types of carbonaceous chondrites. The glass contains iron, silicon, oxygen, vanadium and minor titanium, while the framboidal particles contain calcium as well. The major element chemistry of both the spherulesmore » and the glass matrix are consistent with the chemistry of material associated with meteorite impact sites and meteorites. Electron microscopy confirms that the glassy material is indeed amorphous, and also shows that what appear to be individual oxide particles are amorphous as well. The latter appears consistent with their overall morphology that, while euhedral, typically shows significant fracture. Based on these data, we argue that these particles are the product of a hypervelocity impact.« less
  • At the end of the Pleistocene a Younger Dryas black mat was deposited on top of the Pleistocene sediments in many parts of North America. A study of the magnetic fraction (~10,900 50 B.P.) from the basal section of the black mat at Murray Springs, AZ revealed the presence of amorphous iron xide framboids in a glassy iron-silica matrix. These framboids are very similar in appearance and chemistry to those reported from several types of carbonaceous chondrites. The glass contains iron, silicon, oxygen, vanadium and minor titanium, while the framboidal particles contain calcium as well. The major element chemistry ofmore » both the spherules and the glass matrix are consistent with the chemistry of material associated with meteorite impact sites and meteorites. Electron microscopy confirms that the glassy material is indeed amorphous, and also shows that what appear to be individual oxide particles are amorphous as well. The latter appears consistent with their overall morphology that, while euhedral, typically shows significant fracture. Based on these data, we argue that these particles are the product of a hypervelocity impact.« less
  • Isotopic data for C, H and N in acid-resistant residues from carbonaceous chondrites show substantial variability during stepwise pyrolysis and/or combustion. After subtraction of contributions due apparently to inorganic C grains, of probably circumstellar origin, considerable isotopic variability remains, attributable to the kerogen-like organic fraction. That variability may be interpreted in terms of three of four distinct components, based on C, H and N isotopes. The relative proportions of those components vary significantly from sample to sample. The different isotopic components are tentatively identified in terms of specific chemical/structural moieties within the kerogen-like material. This combination of chemical, structural andmore » isotopic information suggests a complex history for meteoritic organic matter. At least three components within the organic population as a whole still carry a signature of apparently interstellar D-enrichment. Part, at least, of the interstellar carrier consisted of reactive entities, not solely polymers.« less