OFR 97-492: Walker Lake Quadrangle NURE HSSR Study
 |
| About USGS / Science Topics / Maps, Products & Publications / Education / Publication: FAQ |
|
>> Pubs Warehouse > OF 97-492 > State Coverage > Walker Lake Quadrangle
This page is currently being rewritten to the Version 1.41 format.
[See History of NURE HSSR Program for a summary of the entire program.]
The Lawrence Livermore Laboratory (LLL) conducted a NURE pilot study of the Walker River Basin area which covers parts of the Reno and Walker Lake quadrangles. For the study, a total of 19 rock, 245 sediment, and 196 water samples were collected (18 rock, 231 sediment, and 189 water samples were from within the Walker Lake quadrangle). These samples were analyzed by neutron activation at LLL and the data were released in the Walker River Basin Study GJBX-40(76) preliminary report.
From March - June, 1979, a total of 793 sediment and 74 water locations were sampled in the Walker Lake quadrangle as part of the Savannah River Laboratory (SRL) Walker Lake Quadrangle NURE Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) study. At each sediment location, 2 sediment fractions were collected, the S1 fraction (<100 mesh) and the S0 fraction (>100 mesh and <18 mesh). The second fraction was presumably collected to avoid wind blown dust contamination. All of these samples were analyzed by SRL for uranium and other elements (16 additional elements in sediments and 9 in waters) and the analytical data were released in the Walker Lake NURE HSSR quadrangle GJBX-107(80) report. The samples were then sent to other laboratories including Oak Ridge Gaseous Diffusion Plant for "supplemental analyses" (23 elements in sediments and 31 elements in waters). SRL did not release the supplemental analytical data as a separate report.
In 1982, SRL released a summary report and data files for 50 quadrangles in the Western United States. This report, GJBX-132(82), contains both the SRL analytical data and the supplemental analytical data for the SRL samples from the Walker Lake quadrangle but the concentration values often differ from those reported in the GJBX-107(80) quadrangle report. The introduction section of the GJBX-132(82) summary report states:
"The data in the present report may not be identical to those reported previously. This is due to the use of different "scrub" procedures for the preparation of the data for release. The differences should be minor."
However, during the reformatting process it was found that many of the analytical values in the Western United States summary report GJBX-132(82) appear to be double the corresponding values in the quadrangle report GJBX-107(80). Other differences between the two files are discussed below.
SRL analyses of light hydrocarbons (methane, ethane, propane, and butane) in ground waters were released in the GJBX-131(82) summary report for 44 western quadrangles and 3 eastern quadrangles within the United States. This report includes data for 37 of the Walker Lake quadrangle ground water samples.
Data for gold analyses of sediments by SRL neutron activation were released in the GJBX-135(82) summary report. The introduction of that report states:
"This report contains previously unreported neutron-activation analyses of gold in sediment samples determined at SRL. These data were not included in the standard SRL NURE data reports because the gold spectrum was not measured in the original analytical procedure and the report format was designed without the gold analyses being included. Gold analyses became available as the analytical procedure was refined, but the report format was not modified to incorporate these data."
Only those sediment samples that had detectable concentrations of gold by neutron activation analysis were given in the GJBX-135(82) report. Sediment samples with concentrations below detection limits were not reported and can only be ascertained by identifying which samples were actually analyzed by neutron activation at SRL.
From July through October of 1979, 702 sediment and 15 water samples were collected by Oak Ridge Gaseous Diffusion Plant (ORGDP) personnel in the Walker Lake quadrangle as part of the Sonora Pass Detailed Geochemical Survey. At 21 locations within the study, radiometric readings of rock samples were also recorded. The samples were analyzed for multiple elements by ORGDP and the data were reported in the Sonora Pass Detailed Study GJBX-184(80) report.
A list of geologic unit codes and explanations used for the Sonora Pass Detailed Study was obtained from Table 3 and Figure 3 of the GJBX-184(80) report and is reproduced here. These codes are found in the SGEOUNIT and PUNIT fields for each record in the NEW-FORMAT NURE data files.
| Code | Geologic Unit |
|---|---|
| QAL | Alluvium |
| QG | Glacial Deposits |
| QPBV | Olivine Basalt |
| TPV | Disaster Peak and Stanislaus Formation Undivided |
| TPVP | Disaster Peak Formation |
| TPVA | Stanislaus Formation |
| TMV | Relief Peak and Valley Springs Formations Undivided |
| TMVA | Relief Peak Formation |
| TMVP | Valley Springs Formation |
| TI | Intrusive Andesite |
| JGR | Granitic Rocks Undivided |
The following is a list of all sample types collected and reported for NURE studies in the Walker Lake quadrangle. The actual number of records in the NEW-FORMAT NURE data files may be greater because of the multiple records needed to preserve all the data.
| Sediment Sample Type | Number of Samples | Water Sample Type | Number of Samples |
|---|---|---|---|
| Wet Streams (SRL S1 fraction) | 5 | Streams | 121 |
| Wet Streams (SRL S0 fraction) | 5 | Wells | 65 |
| Wet Streams (other labs) | 485 | Springs | 81 |
| Dry Streams (SRL S1 fraction) | 174 | Lakes or Ponds | 11 |
| Dry Streams (SRL S0 fraction) | 174 | ||
| Dry Streams (other labs) | 447 | ||
| Soils (SRL S1 fraction) | 614 | ||
| Soils (SRL S0 fraction) | 614 | ||
| Spring Precipitates | 1 | ||
| Total Sediments | 2,519 | Total Waters | 278 |
These Walker Lake quadrangle samples were analyzed by one or more of the following methods:
Sediment Samples
Water Samples
Rock Samples
The data in the NEW-FORMAT NURE data files consist of records from all of the above reports. In order to reduce the number of records, a decision was made to use the data from the GJBX-132(82) western U.S. summary report rather than the GJBX-107(80) Walker Lake quadrangle report. The rationale for choosing this data set was that (1) it represents a later compilation of the data and (2) it should be more consistent across quadrangle boundaries because of the common "scrubbing procedure." Every record was checked against the "equivalent" record in the earlier GJBX-107(80) quadrangle report and any major differences were noted in the REFORMAT comment field. These different but unused quadrangle report records were combined and saved as extra files which may be accessed below.
For the sediment data file, the SRL analyses and the supplemental analyses were combined into a single record for each sample. Besides the S0 record, two records exist for each of the S1 samples in the Western Summary file for a total of 3 records per sample location. It could not be determined whether these two S1 records for each sample represent separate analyses or separate "scrubbed" versions of the same analysis. A comparison of the data values in these records usually showed significant variation for reported concentrations. One record was often very similar to the corresponding record found in the Walker Lake quadrangle GJBX-107(80) report but again some samples had significant differences. Hence, 3 different records exist for each S1 sample--the record reported in the quadrangle GJBX-107(80) report, and 2 records, each with differences, from the Western U.S. Summary GJBX-132(82) report. Both records from the Western U.S. Summary GJBX-132(82) report were saved in the NEW-FORMAT NURE sediment data file. Data from supplemental analyses was arbitrarily combined with the corresponding S1 record having the latest analytical date. Problems and differences between records were noted in the REFORMAT comment field. The "equivalent" record from the earlier quadrangle GJBX-107(80) report was saved in an extra file which may be accessed separately below.
An additional problem with the S0 fraction sediment record was noted during the reformatting process: none of the digital files contained the analytical data from the SRL uranium and neutron activation analyses for these samples. These data are recorded in the appendices of the published Walker Lake quadrangle GJBX-107(80) report and therefore could eventually be added to the NEW-NURE FORMAT data files.
In the water data file, the SRL analyses and supplemental analyses records could NOT be combined because of overlapping determinations for 5 elements. Each water sample may therefore have 2 separate records - one for the SRL analysis and one for the supplemental analysis. During the reformatting process, other problems were discovered between water results reported in the Western U.S. summary GJBX-132(82) report and the Walker Lake quadrangle GJBX-107(80) report.
These problems could not be satisfactorily resolved during the reformatting process. The unused water data from the quadrangle GJBX-107(80) report were saved as an extra data file which may be accessed separately below.
Hydrocarbon data from the GJBX-131(82) report were added to fields in the appropriate ground water records and this addition was noted for each record in the REFORMAT comment field.
Gold concentrations from the GJBX-135(82) report were added to the appropriate sediment records. A value of -0.01 (<0.01 ppm Au) was added to all other sediment samples determined to have been analyzed by SRL neutron activation. This value was chosen because 0.01 is the lowest reported gold concentration in the entire report.
Records from the Sonora Pass Detailed Study GJBX-184(80) report were reformatted and added to the NEW-FORMAT NURE data files.
Records from the Walker River Basin Pilot Study GJBX-40(76) were added to the NEW-FORMAT NURE sediment and water files. The LLL files also contained numerical estimates of the absolute error associated with each elemental concentration. These data were not included in the NEW-FORMAT NURE data files but were placed into additional data files which can be accessed below. The Absolute Error Extra Data Format is explained later in this document.
The LLL Walker River Basin Pilot Study data has analytical values for several elements which were not normally included in NURE HSSR studies. These data include values for Ho, Nd, and Ru in rock and sediment samples, and values for Cs, Ru, Sb, Sm, Ta, W, and Yb in water samples. These data are also available below as extra data files. See the Walker River Basin Extra Data Format later in this document.
Records for rock samples from the two special studies were combined into a single file and can be accessed below. Field formats are the same as those found in the On-Line Manual for New-Format NURE HSSR Data Files and the Walker River Basin Extra Data Format.
The NURE HSSR data are now available online in two databases: The sediment database (also includes data for soils and some rocks) at http://tin.er.usgs.gov/nure/sediment/ and the water database at http://tin.er.usgs.gov/nure/water/. From these two websites, NURE HSSR data can be selected, examined, summarized, and downloaded by political boundaries (State and County), by quadrangle (1:250,000-scale, 1:100,000-scale, and 1:63,360-scale for Alaska or 1:24,000-scale for the Lower 48 States), and by hydrologic unit (drainage region, subregion, river basin, or sub-basin). Selected data can be downloaded as a dBase file, a shapefile, an HTML table, or ASCII text (tab- or comma-delimited).
Walker Lake Quadrangle Sediment Data - 3,347 records
Walker Lake Quadrangle Water Data - 352 records
Walker Lake Quadrangle Rock Data - walklk_r.dbf.gz
Unused set of quadrangle sediment records - walklksx.dbf.gz
Unused set of quadrangle water records - walklkwx.dbf.gz
LLL Error Estimates Data for Walker River Basin Sediment Analyses - walkbnse.dbf.gz
LLL Error Estimates Data for Walker River Basin Water Analyses - walkbnwe.dbf.gz
LLL Walker River Basin Extra Element Sediment Data - walkbnsx.dbf.gz
LLL Walker River Basin Extra Element Water Data - walkbnwx.dbf.gz
SRL reported results for two fractions for all of the sediment samples. Samples with a suffix of "S0" on the SRLID consist of the fraction of sediment which passed a 18-mesh but did not pass a 100-mesh sieve. Samples with a suffix of "S1" on the SRLID consist of the fraction of sediment which passed a 100-mesh sieve. Sediment samples collected for the ORGDP Sonora Pass Detailed Study and the LLL Walker River Basin Pilot Study were also sieved at 100-mesh. Due to fractionation of some elements between discretely sized sediment particles, analytical data may not be directly comparable for sediment samples with different sieve fractions.
Many records contain analytical values with insignificant digits. Most data should only have 2 or 3 significant digits. Differences after the second or third digit should be ignored.
Latitude-longitude coordinates were reported in the original Sonora Pass Detailed Study data files, as decimal degrees, to only 3 decimal places. Therefore, the precision of these coordinates is limited to +/- 0.001 degrees or +/- 3.6 seconds. This translates to a minimum precision of +/- 364 feet (111 m) for latitude values and between +/- 300 feet (91 m) to +/- 280 feet (85 m) for longitude values (calculated at latitudes of 35° and 40°N, respectively.)
The LLL Walker River Basin data were reported without indicating element concentrations below the limits of detection. According to the Walker River Basin Study GJBX-40(76) preliminary report:
Those cases where there are no data listed indicate that the observed values are below the limit of detection. However, missing values should not be regarded as being less than the lowest value reported, because detection limits are dependent on irradiation of the samples, and irradiation conditions were different for various parts of the study.
These missing values may cause problems when the LLL Walker River Basin data are used in statistical summaries or contouring routines.
The LLL Walker River Basin sample locations were originally reported in Universal Transverse Mercator (UTM) units to the nearest 25 meters. For the NEW-NURE FORMAT data files, these coordinates were converted to decimal latitude and longitude values. Be aware that the converted 4 decimal place coordinate values falsely implies an accuracy to the nearest 11 meters latitude and 9 meters longitude at a latitude of 38°N. In reality, the accuracy of these locations cannot be better than original limitation of 25 meters.
A summary evaluation report was prepared for the Walker Lake quadrangle by the U.S. Geological Survey [PGJ/F-010(82)]. Additional samples of 999 rocks, 228 sediments, and 129 waters were collected in the quadrangle to aid in the interpretation of uranium anomalies. The rock samples were analyzed for uranium and thorium by neutron activation, and for 45 other elements by emission spectroscopy. The sediment samples were analyzed for uranium by extraction fluorometry and for 34 other elements by semi-quantitative emission spectrography. The water samples were analyzed for uranium by extraction fluorometry, and for sulfate, phosphate, and nitrate by ion chromatography. These data were released only as microfiche appendices accompanying the summary report.
Data for uranium and multielement neutron activation analyses were missing from the digital S0 fraction sediment records. These missing data are recorded in the appendices of the published Walker Lake quadrangle GJBX-107(80) report.
The California Division of Mines and Geology and the Bendix Field Engineering Corporation conducted additional an additional study on the Sonora Pass uranium district. "The principal tasks of this study were to determine the location and extent of favorable uranium host rocks and to compile existing geologic data relevant to the region." Nineteen core holes were drilled to define the extent of uranium-bearing buried fluvial channels and to identify other channels within the project area. Some of these drill cores were analyzed for U, Th, Co, K, Sr, and V. Partial results for these analyses are reported in tables within the Sonora Pass project GJBX-132(81) report.
Explanations are only included here for fields unique to these files. For the explanation of common fields consult the On-Line Manual for New-Format 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.
A statistical estimate of measurement uncertainty associated with quantifying the corresponding uranium concentration determined by Delayed-Neutron Counting Analysis. (expressed as a percentage of the uranium concentration found in field U_DN_PPM for sediment data or U_DN_PPB for water data in the NEW-NURE FORMAT data files).
(Where EL represents different element symbols.) A numerical estimate of the uncertainties associated with quantifying the corresponding elemental concentration determined by Neutron Activation Analysis. (expressed in the same concentration units as the element concentration found in the NEW-NURE FORMAT data files).
Explanations are only included here for fields unique to these files. For the explanation of common fields consult the On-Line Manual for New-Format 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.
Elemental concentration of cesium in waters, in parts per billion. Blank = Not detected.
Elemental concentration of holmium in sediments, in parts per million. Blank = Not detected.
Elemental concentration of neodymium in sediments, in parts per million. Blank = Not detected.
Elemental concentration of ruthenium in waters, in parts per billion. Blank = Not detected.
Elemental concentration of ruthenium in sediments, in parts per million. Blank = Not detected.
Elemental concentration of antimony in waters, in parts per billion. Blank = Not detected.
Elemental concentration of samarium in waters, in parts per billion. Blank = Not detected.
Elemental concentration of tantalum in waters, in parts per billion. Blank = Not detected.
Elemental concentration of tungsten in waters, in parts per billion. Blank = Not detected.
Elemental concentration of ytterbium in waters, in parts per billion. Blank = Not detected.
Back to Nevada NURE data
Back to California NURE data
Frequently Asked Questions Concerning NURE HSSR Data
Home Page: USGS National Geochemical Database - NURE HSSR data
Page written by Andrew W. Holt and Steven M. Smith
Contact: Steven M. Smith (smsmith@usgs.gov)
Version 1.10: July 29, 1999
Version 1.20: August 07, 2000
Version 1.30: September 11, 2001
Version 1.40: January 13, 2006
| AccessibilityFOIAPrivacyPolicies and Notices | |
 |
|
