Dilemma posed by uranium-series dates on archaeologically significant bones from Valsequillo, Puebla, Mexico

Szabo, B. J.; Malde, Harold E.; Irwin-Williams, Cynthia

doi:10.1016/0012-821x(69)90163-0

Cited by 52 publications

(19 citation statements)

References 10 publications

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“…Activity ratios of 234 U/ 238 U, ( 234 U/ 238 U), are generally greater than 1 in natural waters due to the ''hot atom effect'' whereby 234 U is preferentially leached from minerals because of damage caused to the crystal lattice during the decay of 238 U to 234 U [6]. ( 234 U/ 238 U) is therefore variable from site to site, and has been found to range from 0.5 to 3.3 in uncontaminated waters, yet local values can be relatively constant [15]. Therefore, variation from a local background ( 234 U/ 238 U) signature can be used to detect non-natural additions to the system [17].…”

Section: Theory Uranium Isotope Systematicsmentioning

confidence: 96%

Analysis of a sugar maple tree core for monitoring environmental uranium contamination

McHugh

Widom

Spitz

et al. 2015

J Radioanal Nucl Chem

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Concentrations and isotopic ratios of metals in tree rings can be employed to resolve temporal changes in contamination, but few studies have explored the behavior of uranium (U). This study measured U abundance and isotopic compositions of sugar maple (Acer saccharum) tree rings near the former Fernald Feed Materials Production Center (FFMPC), a U purification facility in Ohio. U concentrations, 235 U/ 238 U, and 234 U/ 238 U are generally consistent with known events in FFMPC history. Additionally, the outermost rings have compositions consistent with contemporary soil. These results suggest that sugar maple may be reliable for monitoring past and present environmental U contamination.

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Section: Theory Uranium Isotope Systematicsmentioning

confidence: 96%

Analysis of a sugar maple tree core for monitoring environmental uranium contamination

McHugh

Widom

Spitz

et al. 2015

J Radioanal Nucl Chem

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“…Equations (11) and (17) [3] present EU dates on bones sandwiched between speleothems from Grant Hall of Victoria Cave, South Australia, which are clearly younger than the constraints. The EU dates of 12 bones ranged between 25 and 59 kyrs, whereas the upper speleothem yielded ages of 46 and 73 kyrs and the lower 220-260 kyrs.…”

Section: Discussionmentioning

confidence: 99%

“…The model combines both 238 U and 235 U decay schemes into a single equation and assumes the 234u/ 238 u ratio of the migrating uranium is equal to that measured in the sample. Szabo and his colleagues later applied the model to fossil bones (see for example, [17][18][19]), from which reasonable finite ages could be often be derived from samples that showed excess activities of 231 Pa and 230 Th.…”

Section: Other Modes Of Open-system Behaviormentioning

confidence: 99%

U-series Age Equations for Uranium Assimilation by Fossil Bones

et al. 1995

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Because of the general abundance of fossil bone in archeological deposits, U-series chronologists are often forced to resort to bone studies in the absence of more reliable material such as autogenic carbonate. Bone is less reliable than authigenic phases because living bone contains no uranium, and fossil bone readily acquires uranium post-depositionally. In the ideal case, uranium is assimilated into bone from soil fluids soon after burial in early uptake (EU), and the bone remains a closed system thereafter. At the other extreme is a gradual, linear uptake of uranium (LU) in which the bone assimilates uranium more or less continuously with time.We derive age equations and nomographs for both the LU process and for the special case of EU followed by linear uptake of 234 U to provide semi-quantitative upper limits on the age of many fossil bones. The equations show that LU ages are about twice the EU ages for EU ages up to about 50 kyrs, are about 2.5 times mid-range EU dates, and approaching about 3 times EU as isotopie equilibrium is approached. Thus the limit of LU dates is on the order of 1 my compared to about 350 kyrs for EU. Ages calculated for the linear uptake of 23 *U increases the EU dates by only 10% for EU dates up to about 50 kyrs, increasing to 50% in mid-range, and approaches 100% as isotopie equilibrium is approached.

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“…No obstante, la polémica se acrecentó en 1969 cuando los doctores Barney J. Szabo, Harold E. Malde y Cynthia Irwin-Williams publicaron un artículo donde dieron a conocer que mediante nuevas técnicas de datación, los artefactos encontrados en Valsequillo ofrecían una edad superior a los 200 000 años, edad fuera de toda proporción respecto a lo aceptado por la comunidad científica sobre la antigüedad del hombre temprano en América. Sin embargo, los investigadores atribuyeron esta anomalía a lo reciente de las nuevas técnicas ya que aún estaban en fase experimental (Szabo et al, 1969).…”

Section: Historia De La Ciencia En Méxicounclassified

Investigaciones paleontológicas en el Valle de Puebla durante el siglo XX

Flores¹

2017

Cienc. ergo sum

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Dilemma posed by uranium-series dates on archaeologically significant bones from Valsequillo, Puebla, Mexico

Cited by 52 publications

References 10 publications

Analysis of a sugar maple tree core for monitoring environmental uranium contamination

Analysis of a sugar maple tree core for monitoring environmental uranium contamination

U-series Age Equations for Uranium Assimilation by Fossil Bones

Investigaciones paleontológicas en el Valle de Puebla durante el siglo XX

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