;
Descriptors:
URANIUM 234;
Subject Codes
10/5/1147
RADIOACTIVITY;
GEOLOGY;
URANIUM 238;
(NSA):
PHYSICS
WATER
(Item 147 from file:
ROCKS;
SEA;
SOILS;
URANINITES
109)
214772
NSA-17-004718
t
NATURAL VARIATIONS IN THE RATIO OF USsup 2346 TO USsup 23$$sup '8$
Thurber,
D.L.
Columbia Univ., Palisades, N.Y. Lamont Geological Observatory
Publication Date:
Note:
nd
11 p.
’
IAEA Preprint SM-33/12; TID-17377£ For presentation at the IAEA
Symposium on Radioactive Dating,
1962
held at Athens,
Greece, November 19-23,
Journal Announcement: NSA17
Document Type: Book
Language: English
For presentati on at the IAEA Symposium on Radioactive Dating, held at
Athens,
life
Greece,
November 19-23,
(250,000 years)
1962.
Although U/sup 234/ has a good half
for Pleistocene dating,
it was previously ignored
because no reasonable mechanism for separation from its parent, U/sup 238/
seemed to exist. The report of enrichment of U/sup 234/ in ground waters
and secondary minerals by several Russian workers suggests that this
possible chronometer be seriously considered. Using
alpha
spectrometry
the U/sup 234//U/sup 238/ activity ratios of carbonate deposits from two
glacial lake basins and a few selected marine samples were measured. Modern
ocean water has an A/sup U/sup 234//A/sup U/sup 238/ ratio of 1.15 based on
four samples from the Pacific and Atlantic. Since the experimental error on
these measurements is about two per cent, the residual anomaly should be
detectable in samples up to one million years old, providing a dating
method through a period of time not heretofore covered by physical means.
Unrecrystalized coral from an Eniwetok drill hole gave ages based on U/sup
234/U/sup 238/
ratios in agreement with other methods. The oldest sample,
dated as Miocene by paleontologists, was in radioactive equilibrium. Thus
the method appears valid in at least one case.
Six samples from the Lake
Lahontan basin have a U/sup 234//sup 238/ ratio of about 1.5, and six from
Lake Bonneville have values of about 2.0. This anomaly should be detectable
in samples less than 1.5 million years old. Although the available data on
these two glacial lake basins suggest some variations in the ratio with
different lake levels owing to changing drainage patterns, the system does
not appear complicated.
It appears therefore that the anomalous A/sup U/sup
234//A/sup U/sup 238/ ratios in integrating basins such as the ocean, and
playa lakes, provide a very promising geologic dating method for the period
from 100,000 years to 1,000,000 years in both continental and marine
systems. (auth)
Descriptors:
AGE ESTIMATION;
ALPHA SPECTROMETERS;
CARBONATES;
DEPOSITS;
DISTRIBUTION;
ENRICHMENT;
ERRORS;
GEOLOGY;
GROUND WATER;
HALF-LIFE;
MEASURED VALUES;
MINERALS;
QUANTITY RATIO;
SEA;
URANIUM 234
;
URANIUM 238;
VARIATIONS;
WATER
™
Subject Codes (NSA): GEOLOGY, MINERALOGY, AND METEOROLOGY
(Item 148 from file: 109)
NSA-17-003202
USE OF A PORTABLE WHOLE-BODY COUNTER TO MEASURE INTERNAL CONTAMINATION IN
A FALLOUT-EXPOSED POPULATION
Cohn, S.H.; Conard, R.A.; Gusmano, E.A.; Robertson, J.S.
Brookhaven National Lab.,
Publication Date: 1961
Upton, N.Y.
25 p.
Primary Report No.: BNL-5974
Journal Announcement: NSA17
Document Type: Report
Language: English
The Marshallese people of Rongelap Atoll, who were accidentally exposed
to fallout in 1954, were the subject of a large scale survey for evaluating
radionuclide body burdens in 1961. Experience is described in the use of a
portable whole-body gamma counter, with details on measurements made,
methods used, and automatic data-handling techniques developed for
9003b2b
10/5/148
213260