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LASL: San Juan Mountains Study Area
Geochemical samples were collected during May-July 1976 as part of the Los Alamos Scientific Laboratory (LASL) San Juan Mountains NURE Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) study. This rectangular study area encompassed parts of the Cortez, Durango, Moab, and Montrose quadrangles. A total of 1,982 sediment and 1,706 water samples were collected from 1,995 sites and analyzed for uranium. These data were published in the San Juan Mountains NURE HSSR study GJBX-22(77) report. The Cortez quadrangle part of the San Juan Mountains study was the area between 37°N to 38°N latitude and 108°W to 108°22'30"W longitude and contained 347 sediment and 265 water samples.

LASL: Cortez Quadrangle
The remainder of the Cortez quadrangle was sampled during August-September 1977 (108°22'30"W to 109°W longitude) and May-September 1978 (west of 109°W longitude). These samples were also analyzed for uranium content. At a later date, most of these samples and the San Juan Mountains study samples were reanalyzed by multielement methods for up to 43 additional elements. The data from all Cortez quadrangle samples collected and analyzed were released in the Cortez Quadrangle NURE HSSR study GJBX-77(79) report. In this quadrangle report the original San Juan Mountains study samples were given new ID numbers and in some records, errors were apparently corrected.

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

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

Sediment Samples

• LA1: Los Alamos Delayed-Neutron Counting Analysis of sediments for U.
• LA2: Los Alamos Energy Dispersive X-Ray Fluorescence Analysis of sediments for Ag, Bi, Cd, Cu, Nb, Ni, Pb, Sn, and W.
• LA4: Los Alamos Arc-Source Emission Spectrography Analysis of sediments for Be and Li.
• LA5: Los Alamos Neutron Activation Analysis of sediments for Al, Au, Ba, Ca, Ce, Cl, Co, Cr, Cs, Dy, Eu, Fe, Hf, K, La, Lu, Mg, Mn, Na, Rb, Sb, Sc, Sm, Sr, Ta, Tb, Th, Ti, V, Yb, and Zn.

Water Samples

• LA6-DN: Los Alamos Delayed-Neutron Counting Analysis of waters for U.
• LA6-FL: Los Alamos Fluorometry Analysis of waters for U.
• LA7: Los Alamos Plasma-Source Emission Spectrography Analysis of waters for Ca, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Ti, and Zn.

Discussion of the Reformatting Process for Cortez Quadrangle

The Cortez quadrangle sediment and water data consist of reformatted records from the Cortez Quadrangle NURE HSSR study GJBX-77(79) report combined with records from the Cortez portion of the San Juan Mountains NURE HSSR study GJBX-22(77) report. The following problems were found and addressed during the comparison and reformatting stages for the Cortez quadrangle data:

1. During the NURE sample collection phase, LASL sites and samples were initially assigned a 6-digit integer Identification Number (LASLID) starting with 000001. After 1977, most LASL sites were reassigned a new 1-letter+5-digit Identification Number starting with A00001. All LASL samples and the early LASL reports use the 6-digit integer LASLID. Most of the later reports only use the 1-letter+5-digit LASLID. Although both sets of numbers were usually assigned sequentially, they do not correspond one to one with each other: 100001 does not equal C00001, etc. Whenever possible, the 1-letter+5-digit LASL Identification Number was saved in the LASLID field. When the corresponding 6-digit site number could be determined from sample number translation key lists or other sources, this Identification Number was saved in the SITE field.
2. The correlation of the two LASL Identification Numbers for samples in the Cortez quadrangle was first solved by comparing records from the San Juan Mountains NURE HSSR study GJBX-22(77) report with those from the Cortez Quadrangle NURE HSSR study GJBX-77(79) report. Later a LASL Identification Number translation key was found for the Cortez quadrangle sediment samples and the values were confirmed. Additional 1-letter+5-digit LASL Identification Number values were found in the translation key for the 1,370 sediment samples collected in the quadrangle after the San Juan Mountains NURE HSSR study. The 1-letter+5-digit LASL Identification Number was saved in the LASLID field and the corresponding 6-digit site number was manually added to the SITE field. Therefore, the LASLID field contains the Identification Number found in the Cortez Quadrangle NURE HSSR study GJBX-77(79) report. The SITE field contains the corresponding LASL Identification Number used to label the original field maps, field notes, and sample containers and reported in the San Juan Mountains NURE HSSR study GJBX-22(77) report.
3. Corresponding records for 347 sediment samples were found in both the San Juan Mountains NURE HSSR study GJBX-22(77) and Cortez Quadrangle NURE HSSR study GJBX-77(79) reports. Each set of corresponding records were compared and combined into a single composite record.
4. When combining corresponding sediment records from the San Juan Mountains NURE HSSR study GJBX-22(77) and Cortez Quadrangle NURE HSSR study GJBX-77(79) reports, some differences between corresponding records were found in the sample collectors comments(COMMENTS), conductivity measurement(COND), scintillometer reading(SCIN), pH measurement(PH), stream channel character(STRCHANL), sample date(SAMPDAT), sample hour(SAMPHR), sample type(SAMPTYP), rock type(ROCKTYP), vegetation type(VEGTYPE), weather(WEATHER), water temperature(WTRTEMP), local relief(RELIEF), or possible contamination(CONTAMC) fields. These differences appear to be due to corrections added to the later Moab Quadrangle NURE HSSR study GJBX-146(79) report. Therefore when differences were found, the value from the Cortez Quadrangle NURE HSSR study GJBX-77(79) report was retained in the field and the differing value from the San Juan Mountains NURE HSSR study GJBX-22(77) report was added as a comment to the REFORMAT field. These changes were also noted in the REFORMAT comment fields.
5. When combining corresponding sediment records from the San Juan Mountains NURE HSSR study GJBX-22(77) and Cortez Quadrangle NURE HSSR study GJBX-77(79) reports, differences in latitude(LAT) and longitude(LONG) coordinates were found for 323 sediment samples. These differences appear to be due to corrections added to the later Cortez Quadrangle NURE HSSR study GJBX-77(79) report. Therefore when differences were found, the value from the Cortez Quadrangle NURE HSSR study GJBX-77(79) report was retained in the field and the differing value from the San Juan Mountains NURE HSSR study GJBX-22(77) report was added as a comment to the COORDPRB field.
6. One dry stream-sediment sample record contained a value for the well pump type(WELLPUMP). This parameter was not normally recorded for stream-sediment sample records. The value was removed from the record and added as a comment to the REFORMAT field.
7. Two stream-sediment samples have a latitude of exactly 37°N, the dividing line between the Cortez quadrangle and the Shiprock quadrangle. These coordinate values were not changed but a comment was added to the COORDPRB field for each record.

Water Records

1. The correlation of the two LASL Identification Numbers for samples in the Cortez quadrangle was first solved by comparing records from the San Juan Mountains NURE HSSR study GJBX-22(77) report with those from the Cortez Quadrangle NURE HSSR study GJBX-77(79) report. Later a LASL Identification Number translation key was found for the Cortez quadrangle water samples and the values were confirmed. Additional 1-letter+5-digit LASL Identification Number values were found in the translation key for the 1,370 sediment samples collected in the quadrangle after the San Juan Mountains NURE HSSR study. The 1-letter+5-digit LASL Identification Number was saved in the LASLID field and the corresponding 6-digit site number was manually added to the SITE field. Therefore, the LASLID field contains the Identification Number found in the Cortez Quadrangle NURE HSSR study GJBX-77(79) report. The SITE field contains the corresponding LASL Identification Number used to label the original field maps, field notes, and sample containers and reported in the San Juan Mountains NURE HSSR study GJBX-22(77) report.
2. Corresponding records for 265 water samples were found in both the San Juan Mountains NURE HSSR study GJBX-22(77) and Cortez Quadrangle NURE HSSR study GJBX-77(79) reports. Each set of corresponding records were compared and combined into a single composite record.
3. When combining corresponding water records from the San Juan Mountains NURE HSSR study GJBX-22(77) and Cortez Quadrangle NURE HSSR study GJBX-77(79) reports, some differences between corresponding records were found in the sample collectors comments(COMMENTS), conductivity measurement(COND), scintillometer reading(SCIN), pH measurement(PH), stream channel character(STRCHANL), sample date(SAMPDAT), sample hour(SAMPHR), sediment type(SEDTYPE), sediment color(SEDCOLR), or vegetation type(VEGTYPE) fields. These differences appear to be due to corrections added to the later Moab Quadrangle NURE HSSR study GJBX-146(79) report. Therefore when differences were found, the value from the Cortez Quadrangle NURE HSSR study GJBX-77(79) report was retained in the field and the differing value from the San Juan Mountains NURE HSSR study GJBX-22(77) report was added as a comment to the REFORMAT field. These changes were also noted in the REFORMAT comment fields.
4. When combining corresponding water records from the San Juan Mountains NURE HSSR study GJBX-22(77) and Cortez Quadrangle NURE HSSR study GJBX-77(79) reports, differences in latitude(LAT) and longitude(LONG) coordinates were found for 252 sediment samples. These differences appear to be due to corrections added to the later Cortez Quadrangle NURE HSSR study GJBX-77(79) report. Therefore when differences were found, the value from the Cortez Quadrangle NURE HSSR study GJBX-77(79) report was retained in the field and the differing value from the San Juan Mountains NURE HSSR study GJBX-22(77) report was added as a comment to the COORDPRB field.
5. One stream-water sample has a latitude of exactly 37°N, the dividing line between the Cortez quadrangle and the Shiprock quadrangle. This coordinate value was not changed but a comment was added to the COORDPRB 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).

Cortez Quadrangle Sediment Data - 1,657 records
Cortez Quadrangle Water Data - 598 records

Notes for Data Users

None at this time.

Other NURE Geochemical Data for the Cortez Quadrangle

Cortez Quadrangle NURE Summary
A summary evaluation report was prepared for the Cortez quadrangle by the U.S. Geological Survey [PGJ/F-051(82)]. An additional 45 rock samples, 1,657 stream-sediment samples and 598 water samples were collected from the quadrangle. In addition to the collected samples, data from selected oil and gas test wells were used in the analysis that was released only as appendices on microfiche accompanying the summary report.

Geochemistry of Uranium & Thorium in Mineralized Shales and Sandstones
The Pennsylvania State University undertook a study of the geochemistry of uranium and thorium in shales and sandstones from the Catskill Formation in Pennsylvania and the Morrison and adjoining formations in the Uravan mineral belt of Colorado [GJBX-126(80)]. The objectives of this project were to investigate the following questions:

1. Are sandstone-type uranium deposits accompanied by regional uranium anomalies in the host sediments?
2. What are the relations of uranium to thorium and other major and trace elements in sedimentary rocks, and how can these relations be used to improve methods for identifying uranium anomalies?
3. Are the ground-water conduits through which U was transported to sandstone-type uranium ore bodies enriched or depleted in uranium?
4. Is the U and Th content of zircons and other resistant accessory minerals a useful guide to uranium provinces in sedimentary rocks?

A total of 371 rock samples were collected from 6 uranium occurrences within Pennsylvania (Harrisburg and Newark quadrangles) and 102 rock samples were collected from 7 uranium occurrences in the Uravan mineral belt of Colorado (Cortez and Moab quadrangles). The results of analyses for major element oxides plus Ba, Cr, La, Sr, Sm, Th, U, V, and equivalent U are recorded as appendices within the report.

Cortez Quadrangle NURE Bibliography

• Campbell, J.A., Franczyk, K.J., Lupe, R.D., and Peterson, F., 1982, National Uranium Resource Evaluation, Cortez quadrangle, Colorado and Utah: U.S. Geological Survey, U.S. Department of Energy, Grand Junction, Colo., PGJ/F-051(82), 65 p.
• Maxwell, J.C., 1977, Uranium hydrogeochemical and stream sediment reconnaissance in the San Juan Mountains, southwestern Colorado: Los Alamos Scientific Laboratory informal report LA-6651-MS, Los Alamos, N.M., U.S. Department of Energy, Grand Junction, Colo., GJBX-22(77), 104 p.
• Rose, A.W., Pirc, S., Tole, M.P., Bell, C.A., Keith, M.L., and Pilione, L.J., 1980, Regional and local anomalies of uranium and thorium in rocks near sandstone-type uranium deposits in Pennsylvania and Colorado: Pennsylvania State University, U.S. Department of Energy, Grand Junction, Colo., GJBX-126(80), 140 p.
• Warren, R.G., George, W.E., Apel, C.T., Minor, M.M., Steinhaus, D.W., Martell, C.J., Stein, S.L., and Cheadle, J., III, 1979, Uranium hydrogeochemical and stream sediment reconnaissance of the Cortez NTMS quadrangle, Colorado/Utah, including concentrations of forty-three additional elements: Los Alamos Scientific Laboratory informal report LA-7505-MS, Los Alamos, N.M., U.S. Department of Energy, Grand Junction, Colo., GJBX-77(79), 198 p.

Links Within Open-File Report 97-492

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Page written by 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 1.41: February 23, 2006

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U.S. Department of the Interior | U.S. Geological Survey URL: https://pubsdata.usgs.gov/pubs/of/1997/492/quad/q_cortez.htm Questions or Assistance: USGS Web Contact Page Last Modified: Wed Dec 7 16:25 EST 2016