OFR 97-492: North America and Africa Plutonic Rocks Special Study
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[See History of NURE HSSR Program for a summary of the entire program.]
The Savannah River Laboratory (SRL) in contract with the Department of Geology of the University of North Carolina conducted a special study to investigate the association of uranium deposits with granitic source or host rocks. Splits of granite samples with available petrographic, major element, and isotopic data were obtained from various collections. These collections included samples of plutons from Egypt, Libya, Rhodesia, and other African countries as well as North American plutons from the Albuquerque, Athens, Augusta, Aztec, Boston, Charlotte, Cheyenne, Florence, Greensboro, Norfolk, Raleigh, Raton, Roanoke, Santa Fe, Socorro, Spartanburg, Tularosa, and Winston-Salem 1:250,000-scale quadrangles. These plutonic rock samples were analyzed by neutron activation at SRL for the same suite of elements being determined in the HSSR samples. The hopes of the study were to discern relationships that would: (1) provide a measure of uranium favorability for granites; and (2) provide ways to relate HSSR stream sediment or soil geochemistry data to bedrock geochemistry in granitic terranes. The analytical results from 441 samples of 92 plutons were released in the North America and Africa Plutonic Rocks Special Study GJBX-221(82) report. (Note: The numbers above reflect what was found in the accompanying digital data files even though the report claims that "eighty-seven plutons were represented by 467 samples.) The plutonic rock samples were given a latitude-longitude coordinate location that identifies only the general location of the pluton, which may comprise more than one quadrangle.
The digital files that accompanied the North America and Africa Plutonic Rocks Special Study GJBX-221(82) report did not include latitude and longitude coordinates. These values were found in tables on microfiche accompanying the report and were added to the digital data. Several other data fields were also added from these tables on microfiche. The reformatted plutonic rock data were saved as two extra files. One file contains the pre-existing analytical and descriptive data supplied with each sample or compiled during the study from literature sources and the second file contains the analytical study results from the SRL Laboratory. (The North America and Africa Plutonic Rocks Special Study extra data format is explained below.)
The two reformatted data files from the North America and Africa Plutonic Rocks Special Study are available by request from Steven M. Smith (smsmith@usgs.gov).
Explanations are only included for fields unique to this study. For the explanation of common fields consult the On-Line Manual for USGS-Reformatted NURE HSSR Data Files. After each field name is a format code. A format code of (N) means that the field is formatted as an Numeric field and a format code of (A2) indicates that the field is formatted as a 2 digit alphanumeric character string.
A two digit character code found in the data that identifies the pluton from which the sample was collected.
A unique alphanumeric sample identifier.
The name and general location of the sampled pluton. Field and names added from Table C-7 in the North America and Africa Plutonic Rocks Special Study GJBX-221(82) report. N/A = Not available.
The size of the pluton in square kilometers. Field and data added from the Pluton Descriptions table on microfiche in the North America and Africa Plutonic Rocks Special Study GJBX-221(82) report. N/A = Not available.
The latitude value for the pluton (not the sample). Latitude values are positive north of the equator and negative when south of the equator. The latitude values were added from the Pluton Descriptions table on microfiche in the North America and Africa Plutonic Rocks Special Study GJBX-221(82) report. Latitude values were only given with two decimal places and are thus useful only to the nearest 30 seconds or approximately 1 kilometer.
The longitude value for the pluton (not the sample). Longitude values are positive east of the Greenwich Meridian and negative when west of the Greenwich Meridian. The longitude values were added from the Pluton Descriptions table on microfiche in the North America and Africa Plutonic Rocks Special Study GJBX-221(82) report. Longitude values were only given with two decimal places and are thus useful only to the nearest 30 seconds or approximately 1 kilometer.
The name or names of the U.S. 2-degree (1:250,000-scale) quadrangle(s) in which the pluton is apparently located. The quadrangle names were added based on the given latitude and longitude coordinates values. When the coordinates were not available, the most likely quadrangle name was added based on the information found in the COMMENTS field or in the NAME field. No quadrangle names were determined (N/D) for plutons in Africa.
The age of the pluton expressed as million years before present (MY BP). The +/- value refers to the recorded uncertainty in the age (MY). Field and data added from the Pluton Descriptions table on microfiche in the North America and Africa Plutonic Rocks Special Study GJBX-221(82) report.
The age determination method used to obtain the value given in the AGE field. RB/SR = Rubidium-Strontium radiometric method, K/AR = Potassium-Argon radiometric method, N/A = Not available. Field and data added from the Pluton Descriptions table on microfiche in the North America and Africa Plutonic Rocks Special Study GJBX-221(82) report.
The initial strontium isotope ratio. Field and data added from the Pluton Descriptions table on microfiche in the North America and Africa Plutonic Rocks Special Study GJBX-221(82) report.
Concentration of silicon dioxide in rock reported in percent. These data were not determined during the North America and Africa Plutonic Rocks Special Study but were supplied with the samples or gathered from literature.
Concentration of aluminum oxide in rock reported in percent. These data were not determined during the North America and Africa Plutonic Rocks Special Study but were supplied with the samples or gathered from literature.
Concentration of titanium oxide in rock reported in percent. These data were not determined during the North America and Africa Plutonic Rocks Special Study but were supplied with the samples or gathered from literature.
Concentration of iron oxide in rock reported in percent. These data were not determined during the North America and Africa Plutonic Rocks Special Study but were supplied with the samples or gathered from literature.
Concentration of magnesium oxide in rock reported in percent. These data were not determined during the North America and Africa Plutonic Rocks Special Study but were supplied with the samples or gathered from literature.
Concentration of manganese oxide in rock reported in percent. These data were not determined during the North America and Africa Plutonic Rocks Special Study but were supplied with the samples or gathered from literature.
Concentration of calcium oxide in rock reported in percent. These data were not determined during the North America and Africa Plutonic Rocks Special Study but were supplied with the samples or gathered from literature.
Concentration of sodium oxide in rock reported in percent. These data were not determined during the North America and Africa Plutonic Rocks Special Study but were supplied with the samples or gathered from literature.
Concentration of potassium oxide in rock reported in percent. These data were not determined during the North America and Africa Plutonic Rocks Special Study but were supplied with the samples or gathered from literature.
Concentration of phosphorus pentaoxide in rock reported in percent. These data were not determined during the North America and Africa Plutonic Rocks Special Study but were supplied with the samples or gathered from literature.
Loss on ignition. The percent of weight loss in the rock during drying in an oven. The loss is assumed to be water. These data were not determined during the North America and Africa Plutonic Rocks Special Study but were supplied with the samples or gathered from literature.
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Frequently Asked Questions Concerning NURE Data
Home Page: USGS National Geochemical Database - NURE HSSR data
Page written by Bryan G. Moravec and Steven M. Smith.
Contact: Steven M. Smith (smsmith@usgs.gov)
Version 1.41: February 23, 2006
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