OFR 97-492: Brownwood 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: Texas Wide-Spaced Uranium Geochemical Survey
Early in the NURE Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) program, personnel from the Oak Ridge Gaseous Diffusion Plant (ORGDP) sampled several areas with a wide-spaced sample coverage (Phase I sampling). Phase I samples were generally collected in stream basins averaging 250 square kilometers in area and from wells at about a 16 km spacing. The purpose of the Phase I sampling was to define uranium provinces that warranted additional sampling at a higher density (Phase II sampling). These samples were sent to the ORGDP and analyzed for uranium and other elements. For many 1:250,000-scale 2-degree quadrangles, Phase I samples were included with later Phase II samples and utilized in the individual HSSR basic data quadrangle reports. Some Phase I samples were never utilized in basic data quadrangle reporting. ORGDP issued the Hydrogeochemical and Stream Sediment Wide-Spaced Sample Basic Data Release for Texas GJBX-131(81) report for several of these Phase I samples. This report includes data for 261 stream sediment and 406 water samples collected during 1976-77 in the Abilene, Austin, Brownwood, Corpus Christi, Del Rio, Eagle Pass, Houston, Llano, San Angelo, Sonora, and Waco quadrangles. The Wide-Spaced Sample Basic Data Release for Texas GJBX-131(81) report only contains data tables for Phase I samples; no explanatory text accompanies this report. The Wide-Spaced Sample Basic Data Release for Texas GJBX-131(81) report includes data records for 105 stream-sediment and 114 water samples collected within the borders of the Brownwood quadrangle. ORGDP apparently did not collect any Phase II samples in the Brownwood quadrangle by the time that NURE funding ended in the early 1980's. Therefore no specific NURE HSSR study exists for this quadrangle.

Llano Texas Pilot Geochemical Survey
In 1976, a pilot geochemical survey was undertaken to sample a small but regionally and geologically representative area to prepare for a subsequent reconnaissance geochemical survey of the uranium in Central Texas. A total of 134 stream-sediment, 6 soil, 158 water, and 267 plant samples were collected between February and March of 1976 from parts of the Llano, Brownwood, and Austin quadrangles. Of these, 44 sediment, 1 soil, 44 water, and 98 plant samples were collected within the borders of the Brownwood quadrangle. These samples were analyzed by the ORGDP for uranium and other elements and the analytical data were released as the Llano, Texas Pilot Geochemical Survey GJBX-36(76) report.

Summary Tables
The following is a list of NURE sample types collected in the Brownwood quadrangle.

Summary of Brownwood quadrangle sample types.
Sediment Sample Type No. of Samples Water Sample Type No. of Samples Plant Sample Type No. of Samples
Dry Streams 114 Streams 55 Deciduous Tree (7 types) 83
Wet Streams 35 Wells 112 Conifer (2 types) 12
Soils 1 Springs 1 Bush (1 type) 2
        Moss (1 type) 1
Total Sediments 150 Total Waters 168 Total Plants 98

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

Sediment Samples

Water Samples

Plant Samples


Discussion of the Reformatting Process for Brownwood Quadrangle

The Brownwood quadrangle sediment and water data consist of reformatted records from the Texas Wide-Spaced Survey GJBX-131(81) report plus reformatted records from the Llano Area Pilot Geochemical Survey GJBX-36(76) report. The following problems were found and addressed during the comparison and reformatting stages for the Brownwood quadrangle data:

Sediment Records

  1. Twelve separate stream-sediment samples in this quadrangle have the same six latitude-longitude coordinates. It appears that this represents six replicate pairs of samples collected at the same or nearly the same sites.
  2. One sample that was missing coordinates was identified as a site replicate. The coordinates of the other replicate sample were added to this record and the change was recorded in the COORDPRB field.
  3. One stream-sediment sample originally had a latitude of exactly 31°N, the dividing line between the Brownwood quadrangle and the Llano quadrangle. The coordinates for this sample were changed slightly to values found in tables on microfiche within the Llano Area Pilot Geochemical Survey GJBX-36(76) report. This slight change places the sample clearly in the Brownwood quadrangle.

Water Records

  1. Twenty-one sample records contained an invalid value of 'G', 'P', or 'U' for the well depth confidence (WLDPTCNF). It appears that the column was miscoded with values from an adjacent field on the original field note sample sheet. The correct values were not found. These values were removed from the WLDPTCNF field and added as a comment to the REFORMAT field.
  2. One sample record contained an impossible value for pH (PH) of 72. Although the most likely source of this error is a missing decimal point, this could not be confirmed in published sources. This value was removed from the PH field and added as a comment to the REFORMAT field.
  3. Two separate well-water samples in this quadrangle have the same latitude-longitude coordinates. It appears that this represents a replicate pairs of samples collected at the same or nearly the same site.
  4. One stream-water sample originally had a latitude of exactly 31°N, the dividing line between the Brownwood quadrangle and the Llano quadrangle. The coordinates for this sample were changed slightly to values found in tables on microfiche within the Llano Area Pilot Geochemical Survey GJBX-36(76) report. This slight change places the sample clearly in the Brownwood quadrangle.

Plant Records

  1. The Llano Area Pilot Geochemical Survey GJBX-36(76) report includes data for 98 plant samples collected in the Brownwood quadrangle.
  2. At the time of this Open-File release (v. 1.41), the ORGDP plant data have not been completely reformatted and released for downloading. See the ORGDP Plant Data page for a more detailed description of the data format and plant data availability.

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).

Brownwood Quadrangle Sediment Data - 150 records
Brownwood Quadrangle Water Data - 168 records


Notes for Data Users

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.)


Other NURE Geochemical Data for the Brownwood Quadrangle

None found.


Brownwood 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_brownw.htm
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