Significance of thorium, uranium and potassium in some Early Precambrian graywackes from Wyoming and Minnesota

J. J W Rogers; K. C. Condie; S. Mahan

doi:10.1016/0009-2541(70)90053-7

Significance of thorium, uranium and potassium in some Early Precambrian graywackes from Wyoming and Minnesota

J. J W Rogers^*, K. C. Condie, S. Mahan

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

5 Citations (Scopus)

Abstract

Thorium, uranium, and potassium concentrations have been measured by gamma-ray spectrometry in graywacke sequences from the Wind River Mountains of Wyoming and the Knife Lake area of Minnesota. Thorium concentrations are compatible with the clay, quartz, and lithic contents of the rocks, but the uranium contents are low, thus yielding Th/U ratios in the neighbourhood of 5 or above. Assuming that all post-depositional elemental abundance variations in the graywackes have been caused solely by radioactive decay since the rocks were formed (about 3 · 10⁹ years ago), the initial Th/U ratios would have been in the range of 3-4. If the graywackes are random samples of the continental crust at their time of formation, them these data support the data of Fahrig and Eade (1968) to the effect that the continental crust 3 · 10⁹ years ago had a Th/U ratio significantly higher than that of the whole earth.

Original language	English
Pages (from-to)	207-213
Number of pages	7
Journal	Chemical Geology
Volume	5
Issue number	3
DOIs	https://doi.org/10.1016/0009-2541(70)90053-7
Publication status	Published - 1970
Externally published	Yes

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title = "Significance of thorium, uranium and potassium in some Early Precambrian graywackes from Wyoming and Minnesota",

abstract = "Thorium, uranium, and potassium concentrations have been measured by gamma-ray spectrometry in graywacke sequences from the Wind River Mountains of Wyoming and the Knife Lake area of Minnesota. Thorium concentrations are compatible with the clay, quartz, and lithic contents of the rocks, but the uranium contents are low, thus yielding Th/U ratios in the neighbourhood of 5 or above. Assuming that all post-depositional elemental abundance variations in the graywackes have been caused solely by radioactive decay since the rocks were formed (about 3 · 109 years ago), the initial Th/U ratios would have been in the range of 3-4. If the graywackes are random samples of the continental crust at their time of formation, them these data support the data of Fahrig and Eade (1968) to the effect that the continental crust 3 · 109 years ago had a Th/U ratio significantly higher than that of the whole earth.",

author = "Rogers, {J. J W} and Condie, {K. C.} and S. Mahan",

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doi = "10.1016/0009-2541(70)90053-7",

language = "English",

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pages = "207--213",

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TY - JOUR

T1 - Significance of thorium, uranium and potassium in some Early Precambrian graywackes from Wyoming and Minnesota

AU - Rogers, J. J W

AU - Condie, K. C.

AU - Mahan, S.

PY - 1970

Y1 - 1970

N2 - Thorium, uranium, and potassium concentrations have been measured by gamma-ray spectrometry in graywacke sequences from the Wind River Mountains of Wyoming and the Knife Lake area of Minnesota. Thorium concentrations are compatible with the clay, quartz, and lithic contents of the rocks, but the uranium contents are low, thus yielding Th/U ratios in the neighbourhood of 5 or above. Assuming that all post-depositional elemental abundance variations in the graywackes have been caused solely by radioactive decay since the rocks were formed (about 3 · 109 years ago), the initial Th/U ratios would have been in the range of 3-4. If the graywackes are random samples of the continental crust at their time of formation, them these data support the data of Fahrig and Eade (1968) to the effect that the continental crust 3 · 109 years ago had a Th/U ratio significantly higher than that of the whole earth.

AB - Thorium, uranium, and potassium concentrations have been measured by gamma-ray spectrometry in graywacke sequences from the Wind River Mountains of Wyoming and the Knife Lake area of Minnesota. Thorium concentrations are compatible with the clay, quartz, and lithic contents of the rocks, but the uranium contents are low, thus yielding Th/U ratios in the neighbourhood of 5 or above. Assuming that all post-depositional elemental abundance variations in the graywackes have been caused solely by radioactive decay since the rocks were formed (about 3 · 109 years ago), the initial Th/U ratios would have been in the range of 3-4. If the graywackes are random samples of the continental crust at their time of formation, them these data support the data of Fahrig and Eade (1968) to the effect that the continental crust 3 · 109 years ago had a Th/U ratio significantly higher than that of the whole earth.

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VL - 5

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JO - Chemical Geology

JF - Chemical Geology

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ER -

Significance of thorium, uranium and potassium in some Early Precambrian graywackes from Wyoming and Minnesota

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