OFR 97-492: Marfa Quadrangle NURE HSSR Study

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National Geochemical Database—Reformatted Data from the National Uranium Resource Evaluation (NURE) Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) Program

By Steven M. Smith
Version 1.40 (2006)

Brief History and Description of Data

[See History of NURE HSSR Program for a summary of the entire program.]

ORGDP: Marfa Quadrangle
Totals of 219 stream-sediment and 182 ground water samples were collected from the Marfa quadrangle as part of the Oak Ridge Gaseous Diffusion Plant (ORGDP) Marfa Quadrangle NURE Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) study. Field sampling was conducted by ORGDP personnel, which began in March of 1979, and was completed between January and February of 1980. These samples were analyzed by the ORGDP for uranium and other elements. The analytical data were released as the Marfa Quadrangle NURE HSSR study GJBX-250(80) report.

ORGDP: Trans-Pecos Detailed Geochemical Survey
As part of the NURE program, detailed surveys were initiated to supply comprehensive geochemical data from specific target areas. The Trans-Pecos Detailed Study was designed to characterize the hydrogeochemistry, stream sediment geochemistry and radiometric patterns of known or potential uranium occurrences in southwest Texas. The Oak Ridge Gaseous Diffusion Plant (ORGDP) collected 1,434 stream sediment, 14 soil, 509 rock, and 595 ground water samples from 7 project areas within the Del Rio, Emory Peak, Fort Stockton, Marfa, Presidio, and Sonora quadrangles. These samples were analyzed by the ORGDP for uranium and other elements. During sample collection, radiometric readings for eU, eK, and eTh were obtained in the field at several locations. (Almost all of the rock and soil samples as well as a few stream sediment samples appear to be sites where only radiometric readings were taken.) In selected Survey Areas, ORGDP used portable field methods to determine concentrations of uranium, fluorine, sulfate, and total iron in water. In the interpretations and Detailed Study reports, ORGDP also included data from 541 stream sediment and 248 ground water samples collected during earlier Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) studies in the Emory Peak and Presidio quadrangles. The analytical data were released in seven parts as the Hydrogeochemical and Stream Sediment Detailed Geochemical Survey for Trans-Pecos, Texas report.

  1. Terrell Survey Area GJBX-29(80)-Part 1: 62 stream sediments and 4 ground waters plus 13 rocks or radiometric readings were collected during January of 1979 within the Del Rio, Emory Peak, Fort Stockton, and Sonora quadrangles. Additional data for 99 stream-sediment and 32 ground-water samples from the Emory Peak Quadrangle NURE HSSR study were included.
  2. Solitario Survey Area GJBX-29(80)-Part 2: 165 stream sediments, 1 soil, and 12 ground waters plus 57 rock or radiometric readings and 5 field analyses of water were collected during January of 1979 within the Emory Peak and Presidio quadrangles. Additional data for 355 stream-sediment and 115 ground-water samples from the Emory Peak quadrangle and Presidio quadrangle NURE HSSR studies were included.
  3. Sierra Vieja Survey Area GJBX-29(80)-Part 3: 246 stream sediments and 60 ground waters plus 64 rocks or radiometric readings and 30 field analyses of water were collected between February and March of 1979 within the Marfa quadrangle.
  4. Tascotal Survey Area GJBX-29(80)-Part 4: 533 stream sediments, 11 soils, and 451 ground waters plus 143 rocks or radiometric readings and 220 field analyses of water were collected between March and April of 1979 within the Emory Peak, Fort Stockton, Marfa, and Presidio quadrangles. Additional data for 87 stream-sediment and 101 ground-water samples from the Emory Peak quadrangle and Presidio quadrangle NURE HSSR studies were included.
  5. Chinati Mountains Survey Area GJBX-29(80)-Part 5: 122 stream sediments and 24 ground waters plus 78 rocks or radiometric readings were collected between January and February of 1980 within the Marfa and Presidio quadrangles.
  6. Stillwell Mountains Survey Area GJBX-29(80)-Part 6: 228 stream sediments, 2 soils, and 10 ground waters plus 142 rocks or radiometric readings were collected between January and February of 1980 within the Emory Peak quadrangle.
  7. Dryden Survey Area GJBX-29(80)-Part 7: 78 stream sediments and 34 ground waters plus 12 rocks or radiometric readings were collected during February of 1980 within the Del Rio, Emory Peak, Fort Stockton, and Sonora quadrangles.

Within the Marfa quadrangle, the Trans-Pecos Detailed Studies include:

Summary Tables

The following is a list of NURE sample types collected in the Marfa quadrangle.

Summary of Marfa quadrangle sample types.
Sediment Sample Type Number of Samples Water Sample Type Number of Samples
Wet Streams 16 Wells 338
Dry Streams 653 Springs 22
Soils 10    
Rocks 141    
Total Sediments 820 Total Waters 360

These Marfa quadrangle samples were analyzed by one or more of the following methods:

Sediment (and Rock) Samples

Water Samples


Discussion of the Reformatting Process for Marfa Quadrangle

The Marfa quadrangle sediment and water data consist of reformatted records from the Marfa Quadrangle NURE HSSR study GJBX-250(80) report and reformatted records from the Trans-Pecos Detailed Study's Sierra Vieja Survey Area GJBX-29(80)-Part 3; Tascotal Survey Area GJBX-29(80)-Part 4; and Chinati Survey Area GJBX-29(80)-Part 5 reports. The following problems were found and addressed during the comparison and reformatting stages for the Marfa quadrangle data:

Sediment Records

  1. Fifty-two records for Sierra Vieja Survey Area sediment samples collected in the Marfa quadrangle were found in the digital data file but were not listed in the Trans-Pecos Detailed Study Sierra Vieja Survey Area GJBX-29(80)-Part 3 report. A comment in the REFORMAT field identifies these records.
  2. Eight records for Tascotal Survey Area sediment samples collected in the Marfa quadrangle were found in the digital data file but were not listed in the Trans-Pecos Detailed Study Tascotal Survey Area GJBX-29(80)-Part 4 report. A comment in the REFORMAT field identifies these records.
  3. Twelve records for Chinati Survey Area sediment samples collected in the Marfa quadrangle were found in the digital data file but were not listed in the Trans-Pecos Detailed Study Chinati Survey Area GJBX-29(80)-Part 5. A comment in the REFORMAT field identifies these records.
  4. Unlikely sample collection dates were found for six samples. These dates were removed from the SAMPDAT field. For each record, the original SAMPDAT value and the most likely correct value was added as a comment to the REFORMAT field.
  5. ORGDP usually assigned a MAPCODE value to each record to identify the 1:250,000-scale quadrangle in which the sample was collected. Within the Marfa quadrangle, 2 sediment records had MAPCODE values that did not correspond with the quadrangle identified from the latitude and longitude coordinates of the sample. It is assumed that the MAPCODE values were in error but this was not confirmed. A comment in the REFORMAT field identifies each of these records.
  6. Twenty-two sample records had incomplete or conflicting information about the sample type. Sample type codes for these samples were added to the SAMPTYP field based on information found in the field notes on microfiche that accompany the reports.
  7. Eighteen of the sediment samples collected in the Marfa quadrangle were not analyzed by any method. However, these sample records do include a scintillometer measurement of the local gamma-ray activity at that sample site. The measured value is recorded in SCIN field.
  8. Forty-eight stream-sediment samples in this quadrangle share the same latitude-longitude coordinates with another (24 distinct coordinate sites). It is unclear whether this represents sets of samples collected at the same twenty-four sites or single samples collected at separate sites so close together that the coordinate precision was insufficient to distinguish locations. Some sets appear to be samples possibly collected at the same site during different studies.
  9. Two stream-sediment samples originally had a latitude of exactly 30°N, the dividing line between the Marfa quadrangle and the Presidio quadrangle. The coordinates for these samples were changed slightly to values found in tables on microfiche within the Trans-Pecos Detailed Study Tascotal Survey Area GJBX-29(80)-Part 4 or the Trans-Pecos Detailed Study Chinati Survey Area GJBX-29(80)-Part 5 reports. This slight change places the samples clearly in the Marfa quadrangle.
  10. The latitude and longitude coordinates for 1 stream-sediment sample collected within the Marfa quadrangle were not found in the data during the reformatting process. The record for this sample cannot be retrieved on a geographical basis.

Water Records

  1. Thirty records for Sierra Vieja Survey Area water samples collected in the Marfa quadrangle were found in the digital data file but were not listed in the Trans-Pecos Detailed Study Sierra Vieja Survey Area GJBX-29(80)-Part 3 report. A comment in the REFORMAT field identifies these records.
  2. Fifty-two records for Tascotal Survey Area water samples collected in the Marfa quadrangle were found in the digital data file but were not listed in the Trans-Pecos Detailed Study Tascotal Survey Area GJBX-29(80)-Part 4 report. A comment in the REFORMAT field identifies these records.
  3. One Marfa quadrangle water record was found in the digital data file that was not listed in the Marfa Quadrangle NURE HSSR study GJBX-250(80) report. A comment in the REFORMAT field identifies this record.
  4. One water sample record contained values for the concentration of hafnium (HF_PPM) and lanthanum (La_PPM). Hafnium and lanthanum were not analyzed in water samples by any of the documented ORGDP methods. These values were removed from the record and added as a comment to the REFORMAT field.
  5. Within the Marfa quadrangle, 4 water records had MAPCODE values that did not correspond with the quadrangle identified from the latitude and longitude coordinates of the sample. It is assumed that the MAPCODE values were in error but this was not confirmed. A comment in the REFORMAT field identifies each of these records.
  6. 184 water samples in this quadrangle share the same latitude-longitude coordinates with one, two, or three other samples (83 distinct coordinate sites). Many of these appear to be pairs of water samples collected at the same site using different combinations of filtration and acidification. The different sample types can be distinguished using the SAMPTYP or WTRTREAT fields. For others, it is unclear whether this represents sets of samples collected at the same sites or single samples collected at separate sites so close together that the coordinate precision was insufficient to distinguish locations.
  7. Seven well-water samples from four sites originally had a latitude of exactly 30°N, the dividing line between the Marfa quadrangle and the Presidio quadrangle. The coordinates for these samples were changed slightly to values found in tables on microfiche within the Trans-Pecos Detailed Study Tascotal Survey Area GJBX-29(80)-Part 4 or the Marfa Quadrangle NURE HSSR study GJBX-250(80) reports. This slight change places the samples clearly in the Marfa quadrangle.
  8. Three well-water samples from two sites originally had a longitude of exactly 104°W, the dividing line between the Marfa quadrangle and the Fort Stockton quadrangle. The coordinates for these samples were changed slightly to values found in tables on microfiche within the Trans-Pecos Detailed Study Tascotal Survey Area GJBX-29(80)-Part 4 or the Marfa Quadrangle NURE HSSR study GJBX-250(80) reports. This slight change places the samples clearly in the Marfa quadrangle.

Rock Records

  1. When rock samples were collected, the site descriptive data commonly utilized the same field formats found for stream-sediment samples. When analyzed, the analytical methods were also the same methods used for stream-sediment or soil samples. Because of these similarities, rock sample data were reformatted with and are now reported in the sediment database.
  2. 141 Marfa quadrangle records were identified in the SAMPTYP field as rock sample data and 10 records were identified as a soil samples. A closer examination of these records reveals that for 37 rock and all 10 soil records, the sample data are actually Gamma Spectrometer field analyses for equivalent potassium (eK), equivalent uranium (eU), and equivalent thorium (eTh). It appears that these measurements were taken at the sample site and that no rock sample or soil sample was actually collected for laboratory analysis. The Gamma Spectrometer field data for these sample sites are listed in the REFORMAT comment field.
  3. 104 of the rock samples collected in the Marfa quadrangle were not analyzed by any method. However, these 101 of these sample records do include a scintillometer measurement of the local gamma-ray activity at that sample site. The measured value is recorded in SCIN field.

Download The Data

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 web sites, 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).

Marfa Quadrangle Sediment Data - 819 records
Marfa Quadrangle Water Data - 360 records


Notes for Data Users

Except for 78 water samples that were acidified in the field (SAMPTYP 08), most of the ORGDP water samples were reportedly collected in the field without any filtering or acidification. (See the SAMPTYP coding explanation in the On-Line Manual for USGS-Reformatted NURE HSSR Data Files for descriptions of different Sample Types). However, the samples were filtered later in the laboratory through a 0.45 micron membrane filter before analysis. Therefore, the samples were not true "untreated water" samples and the analytical data may not be directly comparable for other quadrangle water samples of the same SAMPTYP when collected by a different laboratory. Since this was the standard procedure for Oak Ridge, water data from other Oak Ridge quadrangles should be comparable.

Latitude-longitude coordinates were reported in the original 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 +/- 317 feet (97 m) to +/- 300 feet (91 m) for longitude values (calculated at latitudes of 30° and 35°N, respectively.)

One stream-sediment and three rock samples collected in the Marfa quadrangle were not analyzed by any method.


Other NURE Geochemical Data for the Marfa Quadrangle

Marfa Quadrangle NURE Summary
A summary evaluation of the Marfa quadrangle was prepared by the Bendix Field Engineering Corporation and the University of Texas at Austin, Bureau of Economic Geology [PGJ/F-001(82)]. Totals of 626 rock samples were collected and analyzed for uranium by fluorometry and for 29 additional elements. Results from these analyses infer that five environments are favorable for uranium deposition: The Upper Cretaceous San Carlos and El Picacho Formations are favorable for sandstone deposits; The Tertiary Buckshot Ignimbrite contains uranium mineralization at the Mammoth Mine; The Allen Intrusions are favorable for authigenic deposits; and basin fill in several bolsons show characteristics that suggest favorability but have not been fully evaluated. Data for this study were only found in tables on the microfiche accompanying the report.


Marfa Quadrangle NURE Bibliography


Links Within Open-File Report 97-492

Back to Texas NURE data
Frequently Asked Questions Concerning NURE HSSR 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 1.20: August 07, 2000
Version 1.30: September 11, 2001
Version 1.41: February 23, 2006

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URL: https://pubsdata.usgs.gov/pubs/of/1997/ofr-97-0492/quad/q_marfa.htm
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