RESULTS OF A DATING ATTEMPT -CHEMICAL AND PHYSICAL MEASUREMENTS RELEVANT TO THE CASE OF THE CRETACEOUS TERTIARY EXTINCTIONS

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In Gubbio, Italy, a l em layer of clay between extensive limestone formations marks the boundary between the Cretaceous and Tertiary Periods. This clay layer was known to have been deposited about 65 million years ago when many life forms became extinct, but the length of time associated with the deposition was not known. In an attempt to measure this time with normally deposited meteoritic material as a clock, extensive measurements of iridium abundances (and those of many other elements) were made on the Gubbio rocks. Neutron activation analysis was the principal tool used in these studies. About 50 elements ... continued below

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15 p.

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Asaro, Frank; Michel, Helen V.; Alvarez, Luis W. & Alvarez, Walter September 1, 1980.

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Description

In Gubbio, Italy, a l em layer of clay between extensive limestone formations marks the boundary between the Cretaceous and Tertiary Periods. This clay layer was known to have been deposited about 65 million years ago when many life forms became extinct, but the length of time associated with the deposition was not known. In an attempt to measure this time with normally deposited meteoritic material as a clock, extensive measurements of iridium abundances (and those of many other elements) were made on the Gubbio rocks. Neutron activation analysis was the principal tool used in these studies. About 50 elements are searched for in materials like the earth's crust, about 40 are detected and about 30 are measured with useful precision. We were not able to determine exactly how long the clay deposition took. Instead the laboratory studies on the chemical and physical nature of the Cretaceous-Tertiary boundary led to the theory that an asteroid collision with the earth was responsible for the extinction of many forms of life including the dinosaurs.

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15 p.

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  • American Chemical Society Symposium on"Nuclear and Chemical Dating Techniques", Houston, TX, March 23-28, 1980

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  • Report No.: LBL-11613
  • Grant Number: DE-AC02-05CH11231
  • Office of Scientific & Technical Information Report Number: 1077843
  • Archival Resource Key: ark:/67531/metadc837925

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

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  • September 1, 1980

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  • May 19, 2016, 9:45 a.m.

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  • July 5, 2016, 1:43 p.m.

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Asaro, Frank; Michel, Helen V.; Alvarez, Luis W. & Alvarez, Walter. RESULTS OF A DATING ATTEMPT -CHEMICAL AND PHYSICAL MEASUREMENTS RELEVANT TO THE CASE OF THE CRETACEOUS TERTIARY EXTINCTIONS, article, September 1, 1980; Berkeley, California. (https://digital.library.unt.edu/ark:/67531/metadc837925/: accessed May 20, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.