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National Geochronological Database

Frequently anticipated questions:

• What does this data set describe?
  1. How should this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
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• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
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• How reliable are the data; what problems remain in the data set?
  1. How well have the observations been checked?
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• Who wrote the metadata?

What does this data set describe?

1. How should this data set be cited?

   Sloan, Jan, Henry, Christopher D., Hopkins, Melanie, Ludington, Stephen D., Zartman, Robert E., Bush, Charles A., and Abston, Carl, 2003, National Geochronological Database: Open-File Report 03-236, U.S. Geological Survey, Menlo Park, California.

   Online Links:

   • <http://mrdata.usgs.gov/geochron/>

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -179.119444

   East_Bounding_Coordinate: -67.021389

   North_Bounding_Coordinate: 71

   South_Bounding_Coordinate: 26.5625

3. What does it look like?

   <http://mrdata.usgs.gov/geochron/ofr-2003-236.png> (PNG)

   Sample locations in the conterminous United States, (768 x 512 pixels)

4. Does the data set describe conditions during a particular time period?

   Calendar_Date: 1995

   Currentness_Reference:

   Publication dates of the initial database (DDS-14) and the revision (OFR 2003-236).

5. What is the general form of this data set?

   Geospatial_Data_Presentation_Form: relational database

6. How does the data set represent geographic features?
   1. How are geographic features stored in the data set?

      This is a Point data set. It contains the following vector data types (SDTS terminology):

      • Entity point (18576)

   2. What coordinate system is used to represent geographic features?

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitude and longitude values are specified in decimal degrees.

      The horizontal datum used is North American Datum of 1927.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378206.4.
      The flattening of the ellipsoid used is 1/294.98.
      

7. How does the data set describe geographic features?

   main

   Sample locations and characteristics

   recno

   Record ID.

   Sample identifier, links site description with analytical results. Integer values. Int of width 5.

   Range of values
   Minimum:	1
   Maximum:	18669
   Resolution:	1

   longitude

   Geographic longitude.

   Geographic longitude in decimal degrees, NAD27. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 28 records have no value for longitude.

   Range of values
   Minimum:	-179.119444
   Maximum:	-67.021389

   latitude

   Geographic latitude.

   Geographic latitide in decimal degrees, NAD27. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 28 records have no value for latitude.

   Range of values
   Minimum:	26.5625
   Maximum:	71

   longdeg

   Longitude degrees.

   Degrees of longitude, NAD27. Integer values. Int of width 5.

   Value	Definition
   (no value)	Information not available for this record. 28 records have no value for longdeg.

   Range of values
   Minimum:	67
   Maximum:	179
   Resolution:	1

   longmin

   Longitude minutes.

   Minutes of longitude, NAD27. Integer values. Int of width 5.

   Value	Definition
   (no value)	Information not available for this record. 30 records have no value for longmin.

   Range of values
   Minimum:	0
   Maximum:	59
   Resolution:	1

   longsec

   Longitude seconds.

   Seconds of longitude, NAD27. Integer values. Int of width 5.

   Value	Definition
   (no value)	Information not available for this record. 30 records have no value for longsec.

   Range of values
   Minimum:	0
   Maximum:	60
   Resolution:	1

   west

   Longitude hemisphere.

   Hemisphere of longitude, E or W. Textual values of no more than 1 characters.

   Value	Definition
   (no value)	Information not available for this record. 29 records have no value for west.

   latdeg

   Latitude degrees.

   Degrees of latitude, NAD27. Integer values. Int of width 5.

   Value	Definition
   (no value)	Information not available for this record. 28 records have no value for latdeg.

   Range of values
   Minimum:	25
   Maximum:	71
   Resolution:	1

   latmin

   Latitude minutes.

   Minutes of latitude, NAD27. Integer values. Int of width 5.

   Value	Definition
   (no value)	Information not available for this record. 31 records have no value for latmin.

   Range of values
   Minimum:	0
   Maximum:	60
   Resolution:	1

   latsec

   Latitude seconds.

   Seconds of latitude, NAD27. Integer values. Int of width 5.

   Value	Definition
   (no value)	Information not available for this record. 30 records have no value for latsec.

   Range of values
   Minimum:	0
   Maximum:	60
   Resolution:	1

   north

   Latitude hemisphere.

   Hemisphere of latitude, N or S. Textual values of no more than 1 characters.

   Value	Definition
   (no value)	Information not available for this record. 29 records have no value for north.

   country

   Country.

   Country of site (US). Textual values of no more than 2 characters.

   state

   State or province.

   State two letter postal abbreviation. Textual values of no more than 2 characters.

   county

   County.

   County name, occasionally more than one name is given. Textual values of no more than 35 characters.

   Value	Definition
   (no value)	Information not available for this record. 628 records have no value for county.

   quadscale

   Quadrangle map scale.

   Map quadrangle scale. Textual values of no more than 9 characters.

   Value	Definition
   (no value)	Information not available for this record. 63 records have no value for quadscale.

   quadname

   Quadrangle map name.

   Map quadrangle name. Textual values of no more than 69 characters.

   Value	Definition
   (no value)	Information not available for this record. 117 records have no value for quadname.

   sampsour

   Source of sample.

   General type of material sampled or geographic feature from which the sample was taken. Textual values of no more than 38 characters.

   Value	Definition
   (no value)	Information not available for this record. 371 records have no value for sampsour.

   rockname

   Rock name.

   Lithologic terms describing the sample. Textual values of no more than 35 characters.

   Value	Definition
   (no value)	Information not available for this record. 3 records have no value for rockname.

   descrip

   Description.

   Further description of the sampled material, often includes a geologic unit or structural element within the unit. Textual values of no more than 257 characters.

   Value	Definition
   (no value)	Information not available for this record. 2385 records have no value for descrip.

   labs

   Laboratories.

   Organizations whose laboratories provided the analyses. Textual values of no more than 107 characters.

   Value	Definition
   (no value)	Information not available for this record. 729 records have no value for labs.

   compiled

   Compiler name.

   Name of the person who compiled the data. Textual values of no more than 17 characters.

   datecomp

   Date compiled.

   Date record information was compiled, as year and month formatted as YYYY MM. Textual values of no more than 6 characters.

   locprec

   Precision of location.

   Comments on the precision of the location given. Textual values of no more than 65 characters.

   loccomm

   Location comment.

   General comments on the location given. Textual values of no more than 255 characters.

   Value	Definition
   (no value)	Information not available for this record. 2773 records have no value for loccomm.

   ref

   Reference.

   Primary bibliographic reference in which the dates were published. Textual values of no more than 469 characters.

   Value	Definition
   (no value)	Information not available for this record. 2 records have no value for ref.

   ref2

   Reference addition.

   Additional text of the bibliographic reference. Textual values of no more than 237 characters.

   Value	Definition
   (no value)	Information not available for this record. 17856 records have no value for ref2.

   FT

   Fission track dating results, observations, and parameters

   recno

   Record ID.

   Sample identifier, a value of main:recno. Integer values. Int of width 5.

   Range of values
   Minimum:	1
   Maximum:	18669
   Resolution:	1

   ftrecno

   Analysis ID.

   Sequence number, for this sample, of this analysis. Integer values. Int of width 5.

   Range of values
   Minimum:	1
   Maximum:	5
   Resolution:	1

   ftage

   Calculated age.

   Age estimate in millions of years. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 21 records have no value for ftage.

   Range of values
   Minimum:	0.02
   Maximum:	2346

   fterr

   Age uncertainty.

   Uncertainty of the age estimate attributable to the analytical method, in millions of years. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 189 records have no value for fterr.

   Range of values
   Minimum:	0.04
   Maximum:	1000

   ftmin

   Rock or mineral analyzed.

   Rock or mineral analyzed. Textual values of no more than 12 characters.

   Value	Definition
   (no value)	Information not available for this record. 11 records have no value for ftmin.

   ftlabno

   Lab sample ID.

   Identifier for this analysis assigned by the laboratory. Textual values of no more than 27 characters.

   Value	Definition
   (no value)	Information not available for this record. 9 records have no value for ftlabno.

   ftdeccon

   Decay constants.

   Radioactive decay constants used in calculations. Textual values of no more than 9 characters.

   Value	Definition
   (no value)	Information not available for this record. 547 records have no value for ftdeccon.

   trackdens

   Track density.

   Track density (count per square cm). Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 372 records have no value for trackdens.

   Range of values
   Minimum:	0
   Maximum:	1123

   fosstrack

   Fossil tracks counted.

   Fossil track density (count per square cm). Integer values. Int of width 5.

   Value	Definition
   (no value)	Information not available for this record. 435 records have no value for fosstrack.

   Range of values
   Minimum:	1
   Maximum:	4152
   Resolution:	1

   indudens

   Induced track density.

   Induced track density (count per square cm). Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 372 records have no value for indudens.

   Range of values
   Minimum:	0.0072
   Maximum:	1479

   indutrack

   Induced tracks.

   Induced tracks counted. Integer values. Int of width 5.

   Value	Definition
   (no value)	Information not available for this record. 437 records have no value for indutrack.

   Range of values
   Minimum:	1
   Maximum:	10073
   Resolution:	1

   ratiotrack

   Ratio of total to induced tracks.

   Ratio of spontaneous to induced tracks. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 1277 records have no value for ratiotrack.

   Range of values
   Minimum:	0.0083
   Maximum:	20.874

   neutflux

   Neutron flux density.

   Thermal neutron flux used in irradiation (neutrons per square cm). Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 293 records have no value for neutflux.

   Range of values
   Minimum:	0.122
   Maximum:	8.8

   ft_u_ppm

   Uranium concentration.

   Total uranium concentration in the sample, in parts per million by weight. Textual values of no more than 8 characters.

   Value	Definition
   (no value)	Information not available for this record. 986 records have no value for ft_u_ppm.

   addref

   Bibliographic references.

   Additional bibliographic reference information for this analysis. Textual values of no more than 29 characters.

   Value	Definition
   (no value)	Information not available for this record. 1391 records have no value for addref.

   ftagecom

   Age comments.

   Comments on the age estimate, typically provides context for the age. Textual values of no more than 134 characters.

   Value	Definition
   (no value)	Information not available for this record. 404 records have no value for ftagecom.

   ftsampcom

   Sample comments.

   Comments on the sample analyzed. Textual values of no more than 75 characters.

   Value	Definition
   (no value)	Information not available for this record. 963 records have no value for ftsampcom.

   ftanalcom

   Analytical comments.

   Comments on the analytic method used. Textual values of no more than 134 characters.

   Value	Definition
   (no value)	Information not available for this record. 1140 records have no value for ftanalcom.

   ftothcom

   Other comments.

   Other comments pertinent to this analysis. Textual values of no more than 255 characters.

   Value	Definition
   (no value)	Information not available for this record. 811 records have no value for ftothcom.

   K_Ar

   Potassium-Argon and Argon-Argon radiometric age results, observations, and parameters

   recno

   Record ID.

   Sample identifier, a value of main:recno. Integer values. Int of width 5.

   Range of values
   Minimum:	1
   Maximum:	18669
   Resolution:	1

   karrecno

   Analysis ID.

   Sequence number, for this sample, of this analysis. Integer values. Int of width 5.

   Range of values
   Minimum:	1
   Maximum:	6
   Resolution:	1

   karage

   Calculated age.

   Age estimate in millions of years. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 70 records have no value for karage.

   Range of values
   Minimum:	-0.09
   Maximum:	6882.45

   karerr

   Age uncertainty.

   Uncertainty of the age estimate attributable to the analytical method, in millions of years. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 1752 records have no value for karerr.

   Range of values
   Minimum:	0
   Maximum:	940

   karmin

   Rock or mineral analyzed.

   Rock or mineral analyzed. Textual values of no more than 47 characters.

   Value	Definition
   (no value)	Information not available for this record. 127 records have no value for karmin.

   karanaltype

   Type of analysis.

   Specific type of analytic method used. Textual values of no more than 46 characters.

   Value	Definition
   (no value)	Information not available for this record. 83 records have no value for karanaltype.

   karlabno

   Lab sample ID.

   Identifier for this analysis assigned by the laboratory. Textual values of no more than 34 characters.

   Value	Definition
   (no value)	Information not available for this record. 10 records have no value for karlabno.

   kardeccon

   Decay constants.

   Radioactive decay constants used in calculations. Textual values of no more than 36 characters.

   Value	Definition
   (no value)	Information not available for this record. 5 records have no value for kardeccon.

   k2opct

   K2O concentration.

   Potash concentration as weight percent of the sample. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 2562 records have no value for k2opct.

   Range of values
   Minimum:	0
   Maximum:	23233

   40arrad

   Radiogenic argon-40 concentration.

   Concentration of radiogenic 40Ar. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 2622 records have no value for 40arrad.

   Range of values
   Minimum:	-0.0063
   Maximum:	2453

   pctradar

   Percent radiogenic argon.

   Percent of argon that is radiogenic. Integer values. Int of width 8.

   Value	Definition
   (no value)	Information not available for this record. 2194 records have no value for pctradar.

   Range of values
   Minimum:	0
   Maximum:	86868787
   Resolution:	1

   sampsuit

   Sample suite number.

   Group identifier of related samples. Integer values. Int of width 5.

   Value	Definition
   (no value)	Information not available for this record. 14168 records have no value for sampsuit.

   Range of values
   Minimum:	7
   Maximum:	641
   Resolution:	1

   addref

   Bibliographic references.

   Additional bibliographic reference information for this analysis. Textual values of no more than 51 characters.

   Value	Definition
   (no value)	Information not available for this record. 1391 records have no value for addref.

   karcomm

   Age comments.

   Comments on the age estimate, typically provides context for the age. Textual values of no more than 90 characters.

   Value	Definition
   (no value)	Information not available for this record. 2806 records have no value for karcomm.

   karsampcom

   Sample comments.

   Comments on the sample analyzed. Textual values of no more than 162 characters.

   Value	Definition
   (no value)	Information not available for this record. 11619 records have no value for karsampcom.

   karanalcom

   Analytical comments.

   Comments on the analytic method used. Textual values of no more than 255 characters.

   Value	Definition
   (no value)	Information not available for this record. 7491 records have no value for karanalcom.

   karothrcom

   Other comments.

   Other comments pertinent to this analysis. Textual values of no more than 373 characters.

   Value	Definition
   (no value)	Information not available for this record. 10041 records have no value for karothrcom.

   Rb_Sr

   Rubidium-Strontium radiometric dating results, observations, and parameters

   recno

   Record ID.

   Sample identifier, a value of main:recno. Integer values. Int of width 5.

   Range of values
   Minimum:	1
   Maximum:	18669
   Resolution:	1

   rbsrrecno

   Analysis ID.

   Sequence number, for this sample, of this analysis. Integer values. Int of width 5.

   Range of values
   Minimum:	1
   Maximum:	24
   Resolution:	1

   rbsrage

   Calculated age.

   Age estimate in millions of years. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 991 records have no value for rbsrage.

   Range of values
   Minimum:	0.71
   Maximum:	7394.61

   rbsrerr

   Age uncertainty.

   Uncertainty of the age estimate attributable to the analytical method, in millions of years. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 2299 records have no value for rbsrerr.

   Range of values
   Minimum:	0.1
   Maximum:	560

   87_86init

   Initial 87Sr/86Sr.

   Initial ratio of 87Sr to 86Sr in the sampled material. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 1688 records have no value for 87_86init.

   Range of values
   Minimum:	0.1037
   Maximum:	124.2

   rbsrmin

   Rock or mineral analyzed.

   Rock or mineral analyzed. Textual values of no more than 46 characters.

   Value	Definition
   (no value)	Information not available for this record. 26 records have no value for rbsrmin.

   rbsranltyp

   Type of analysis.

   Specific type of analytic method used. Textual values of no more than 49 characters.

   Value	Definition
   (no value)	Information not available for this record. 923 records have no value for rbsranltyp.

   rbsrlabno

   Analysis ID.

   Identifier for this analysis assigned by the laboratory. Textual values of no more than 23 characters.

   Value	Definition
   (no value)	Information not available for this record. 5 records have no value for rbsrlabno.

   rbsrdeccon

   Decay constants.

   Radioactive decay constants used in calculations. Textual values of no more than 21 characters.

   Value	Definition
   (no value)	Information not available for this record. 35 records have no value for rbsrdeccon.

   rb_ppm

   Rubidium concentration.

   Rubidium concentration in parts per million by weight. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 444 records have no value for rb_ppm.

   Range of values
   Minimum:	0
   Maximum:	164165

   sr_ppm

   Strontium concentration.

   Strontium concentration in parts per million by weight. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 1093 records have no value for sr_ppm.

   Range of values
   Minimum:	0.1
   Maximum:	21210

   87srrad

   Radiogenic 87Sr.

   Radiogenic 87Sr. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 6420 records have no value for 87srrad.

   Range of values
   Minimum:	0.01
   Maximum:	176

   87rb_86sr

   Ratio 87Rb/86Sr.

   Ratio of 87Rb to 86Sr counted by mass spectrometry. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 1265 records have no value for 87rb_86sr.

   Range of values
   Minimum:	0
   Maximum:	62166

   87sr_86sr

   Ratio 87Sr/86Sr.

   Ratio of 87Sr to 86Sr counted by mass spectrometry. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 689 records have no value for 87sr_86sr.

   Range of values
   Minimum:	0.043
   Maximum:	70758

   norm

   Normal?.

   T or N or empty; meaning of this field is not clear. Textual values of no more than 1 characters.

   Value	Definition
   (no value)	Information not available for this record. 1058 records have no value for norm.

   sampsuit

   Sample suite number.

   Group identifier of related samples. Integer values. Int of width 5.

   Value	Definition
   (no value)	Information not available for this record. 14168 records have no value for sampsuit.

   Range of values
   Minimum:	7
   Maximum:	641
   Resolution:	1

   addref

   Bibliographic references.

   Additional bibliographic reference information for this analysis. Textual values of no more than 51 characters.

   Value	Definition
   (no value)	Information not available for this record. 1391 records have no value for addref.

   rbsragecom

   Age comments.

   Comments on the age estimate, typically provides context for the age. Textual values of no more than 87 characters.

   Value	Definition
   (no value)	Information not available for this record. 2721 records have no value for rbsragecom.

   rbsrsamcom

   Sample comments.

   Comments on the sample analyzed. Textual values of no more than 104 characters.

   Value	Definition
   (no value)	Information not available for this record. 6498 records have no value for rbsrsamcom.

   rbsranlcom

   Analytical comments.

   Comments on the analytic method used. Textual values of no more than 227 characters.

   Value	Definition
   (no value)	Information not available for this record. 1543 records have no value for rbsranlcom.

   rbsrothcom

   Other comments.

   Other comments pertinent to this analysis. Textual values of no more than 211 characters.

   Value	Definition
   (no value)	Information not available for this record. 4255 records have no value for rbsrothcom.

   Sm_Nd

   Samarium-Neodymium radiometric dating results, observations, and parameters

   recno

   Record ID.

   Sample identifier, a value of main:recno. Integer values. Int of width 5.

   Range of values
   Minimum:	1
   Maximum:	18669
   Resolution:	1

   smndrecno

   Analysis ID.

   Sequence number, for this sample, of this analysis. Integer values. Int of width 5.

   Range of values
   Minimum:	1
   Maximum:	3
   Resolution:	1

   smndage

   Calculated age.

   Age estimate in millions of years. Integer values. Int of width 5.

   Value	Definition
   (no value)	Information not available for this record. 1 records have no value for smndage.

   Range of values
   Minimum:	178
   Maximum:	575
   Resolution:	1

   smnderr

   Age uncertainty.

   Uncertainty of the age estimate attributable to the analytical method, in millions of years. Integer values. Int of width 5.

   Value	Definition
   (no value)	Information not available for this record. 2 records have no value for smnderr.

   Range of values
   Minimum:	21
   Maximum:	75
   Resolution:	1

   smndmin

   Rock or mineral analyzed.

   Rock or mineral analyzed. Textual values of no more than 21 characters.

   smndlabno

   Analysis ID.

   Identifier for this analysis assigned by the laboratory. Textual values of no more than 8 characters.

   smnddeccon

   Decay constants.

   Radioactive decay constants used in calculations. Real numbers stored in double precision.

   Range of values
   Minimum:	0.00000654
   Maximum:	0.00000654

   sm_ppm

   Samarium concentration.

   Samarium concentration in parts per million by weight. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 27 records have no value for sm_ppm.

   Range of values
   Minimum:	1.88
   Maximum:	14.81

   nd_ppm

   Neodymium concentration.

   Neodymium concentration in parts per million by weight. Real numbers stored in double precision.

   Range of values
   Minimum:	0.15
   Maximum:	50.46

   143smrad

   Ratio 147Sm/144Nd.

   Ratio of counts of 147Sm to 144Nd in the sample, measured by mass spectrometry. Real numbers stored in double precision.

   Range of values
   Minimum:	0.1074
   Maximum:	0.3809

   143ndrat

   Ratio 143Nd/144Nd.

   Ratio of counts of 143Nd to 144Nd in the sample, measured by mass spectrometry. Real numbers stored in double precision.

   Range of values
   Minimum:	0.51079
   Maximum:	0.513212

   smndagecom

   Age comments.

   Comments on the age estimate, typically provides context for the age. Textual values of no more than 40 characters.

   smndothcom

   Other comments.

   Other comments pertinent to this analysis. Textual values of no more than 80 characters.

   Value	Definition
   (no value)	Information not available for this record. 32 records have no value for smndothcom.

   U_Th_Pb

   Radiometric age estimates, observations, and parameters using techniques involving isotopes of uranium, thorium, and lead.

   recno

   Record ID.

   Sample identifier, a value of main:recno. Integer values. Int of width 5.

   Range of values
   Minimum:	1
   Maximum:	18669
   Resolution:	1

   upbrecno

   Analysis ID.

   Sequence number, for this sample, of this analysis. Integer values. Int of width 5.

   Value	Definition
   (no value)	Information not available for this record. 1 records have no value for upbrecno.

   Range of values
   Minimum:	1
   Maximum:	33
   Resolution:	1

   206_238age

   Age 206Pb/238U.

   Age estimate in millions of years using the 206Pb-238U method. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 575 records have no value for 206_238age.

   Range of values
   Minimum:	0.1
   Maximum:	16300

   err206_238

   Age uncertainty 206Pb/238U.

   Uncertainty of the age estimate by the 206Pb-238U method attributable to the analytical method, in millions of years. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 2194 records have no value for err206_238.

   Range of values
   Minimum:	0
   Maximum:	1285

   207_235age

   Age 207Pb/235U.

   Age estimate in millions of years using the 207Pb-235U method. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 611 records have no value for 207_235age.

   Range of values
   Minimum:	-26.6
   Maximum:	4460

   err207_235

   Age uncertainty 207Pb/235U.

   Uncertainty of the age estimate by the 207Pb-235U method attributable to the analytical method, in millions of years. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 2186 records have no value for err207_235.

   Range of values
   Minimum:	-350
   Maximum:	2127

   207_206age

   Age 207Pb/206Pb.

   Age estimate in millions of years using the 207Pb-206Pb method. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 12 records have no value for 207_206age.

   Range of values
   Minimum:	-50000
   Maximum:	4792.4

   err207_206

   Age uncertainty 207Pb/206Pb.

   Uncertainty of the age estimate by the 207Pb-206Pb method attributable to the analytical method, in millions of years. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 2058 records have no value for err207_206.

   Range of values
   Minimum:	1
   Maximum:	320

   208_232age

   Age 208Pb/232Th.

   Age estimate in millions of years using the 208Pb-232Th method. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 1994 records have no value for 208_232age.

   Range of values
   Minimum:	24.5
   Maximum:	13383

   err208_232

   Age uncertainty 208Pb/232Th.

   Uncertainty of the age estimate by the 208Pb-232Th method attributable to the analytical method, in millions of years. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 2421 records have no value for err208_232.

   Range of values
   Minimum:	1.8
   Maximum:	210

   uintcpt

   Upper intercept.

   Upper intercept of the Concordia diagram. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 1267 records have no value for uintcpt.

   Range of values
   Minimum:	14.9
   Maximum:	3900

   erruintcpt

   Upper intercept uncertainty.

   Uncertainty in the upper intercept. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 1458 records have no value for erruintcpt.

   Range of values
   Minimum:	1
   Maximum:	550

   lintcpt

   Lower intercept.

   Lower intercept of the Concordia diagram. Textual values of no more than 8 characters.

   Value	Definition
   (no value)	Information not available for this record. 2172 records have no value for lintcpt.

   errlintcpt

   Lower intercept uncertainty.

   Uncertainty in the lower intercept. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 2243 records have no value for errlintcpt.

   Range of values
   Minimum:	0.8
   Maximum:	900

   pbinitrat

   Initial lead isotopic composition.

   Initial ratios of lead isotopes in common lead, in sequence: 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb. Textual values of no more than 24 characters.

   Value	Definition
   (no value)	Information not available for this record. 1253 records have no value for pbinitrat.

   upbmin

   Rock or mineral analyzed.

   Rock or mineral analyzed. Textual values of no more than 52 characters.

   Value	Definition
   (no value)	Information not available for this record. 8 records have no value for upbmin.

   upblabno

   Analysis ID.

   Identifier for this analysis assigned by the laboratory. Textual values of no more than 26 characters.

   Value	Definition
   (no value)	Information not available for this record. 7 records have no value for upblabno.

   upbdeccon

   Decay constants.

   Radioactive decay constants used in calculations. Textual values of no more than 35 characters.

   Value	Definition
   (no value)	Information not available for this record. 5 records have no value for upbdeccon.

   u_ppm

   Uranium concentration.

   Uranium concentration in parts per million by weight. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 409 records have no value for u_ppm.

   Range of values
   Minimum:	0
   Maximum:	791000

   th_ppm

   Thorium concentration.

   Thorium concentration in parts per million by weight. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 1894 records have no value for th_ppm.

   Range of values
   Minimum:	0.1
   Maximum:	414000

   pb_ppm

   Lead concentration.

   Lead concentration in parts per million by weight. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 431 records have no value for pb_ppm.

   Range of values
   Minimum:	0.01
   Maximum:	170100

   204pb

   Isotopic concentration 204Pb.

   Concentration of 204Pb isotope in the sample. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 812 records have no value for 204pb.

   Range of values
   Minimum:	0
   Maximum:	83.62

   206pb

   Isotopic concentration 206Pb.

   Concentration of 206Pb isotope in the sample. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 786 records have no value for 206pb.

   Range of values
   Minimum:	1.228
   Maximum:	95.51

   207pb

   Isotopic concentration 207Pb.

   Concentration of 207Pb isotope in the sample. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 787 records have no value for 207pb.

   Range of values
   Minimum:	0.1455
   Maximum:	46.02

   208pb

   Isotopic concentration 208Pb.

   Concentration of 208Pb isotope in the sample. Real numbers stored in double precision.

   Value	Definition
   (no value)	Information not available for this record. 787 records have no value for 208pb.

   Range of values
   Minimum:	0.053
   Maximum:	1889

   sampsuit

   Sample suite number.

   Group identifier of related samples. Integer values. Int of width 5.

   Value	Definition
   (no value)	Information not available for this record. 14168 records have no value for sampsuit.

   Range of values
   Minimum:	7
   Maximum:	641
   Resolution:	1

   addref

   Bibliographic references.

   Additional bibliographic reference information for this analysis. Textual values of no more than 25 characters.

   Value	Definition
   (no value)	Information not available for this record. 1391 records have no value for addref.

   upbagecom

   Age comments.

   Comments on the age estimate, typically provides context for the age. Textual values of no more than 84 characters.

   Value	Definition
   (no value)	Information not available for this record. 1661 records have no value for upbagecom.

   upbsampcom

   Sample comments.

   Comments on the sample analyzed. Textual values of no more than 224 characters.

   Value	Definition
   (no value)	Information not available for this record. 699 records have no value for upbsampcom.

   upbanalcom

   Analytical comments.

   Comments on the analytic method used. Textual values of no more than 199 characters.

   Value	Definition
   (no value)	Information not available for this record. 1294 records have no value for upbanalcom.

   upbothrcom

   Other comments.

   Other comments pertinent to this analysis. Textual values of no more than 255 characters.

   Value	Definition
   (no value)	Information not available for this record. 757 records have no value for upbothrcom.

   datadxny

   Data dictionary, explaining tables and fields

   id

   Row ID.

   Row identifier within datadxny table. Integer values. Int of width 0.

   Range of values
   Minimum:	1
   Maximum:	149
   Resolution:	1

   tblorder

   Table order.

   Order in which this table should appear in some presentations. Integer values. Int of width 0.

   Range of values
   Minimum:	1
   Maximum:	7
   Resolution:	1

   tblname

   Table name.

   Name of the table. Textual values of no more than 20 characters.

   number

   Field order.

   Order in which this field occurs in the RDBMS. Integer values. Int of width 0.

   Value	Definition
   (no value)	Information not available for this record. 7 records have no value for number.

   Range of values
   Minimum:	1
   Maximum:	31
   Resolution:	1

   label

   Field label.

   Label of the field in the RDBMS. Textual values of no more than 32 characters.

   Value	Definition
   (no value)	Information not available for this record. 7 records have no value for label.

   category

   Category.

   General category of information provided by the contents of the field. Textual values of no more than 50 characters.

   Value	Definition
   (no value)	Information not available for this record. 7 records have no value for category.

   short_desc

   Short description.

   Descriptive name of the field used in some presentations, not constrained by rules affecting the label. Textual values of no more than 40 characters.

   Value	Definition
   (no value)	Information not available for this record. 7 records have no value for short_desc.

   description

   Description.

   Longer description of the purpose and contents of the field. Textual values of no more than 4096 characters.

   link

   Link.

   URL providing more information about the field. Textual values of no more than 96 characters.

   Value	Definition
   (no value)	Information not available for this record. 149 records have no value for link.

   origin

   Origin.

   Abbreviation of an organization, data set, or other entity responsible for defining the field. Textual values of no more than 12 characters.

   Value	Definition
   (no value)	Information not available for this record. 149 records have no value for origin.

   sqltype

   SQL data type.

   Data type of the field as used in the RDBMS. Textual values of no more than 8 characters.

   Value	Definition
   (no value)	Information not available for this record. 7 records have no value for sqltype.

   dbftype

   DBF field type.

   Data type of the field when expressed in DBF. Textual values of no more than 1 characters.

   Value	Definition
   (no value)	Information not available for this record. 7 records have no value for dbftype.

   width

   DBF field width.

   Field width when expressed in DBF. Integer values. Int of width 0.

   Value	Definition
   (no value)	Information not available for this record. 7 records have no value for width.

   Range of values
   Minimum:	0
   Maximum:	4096
   Resolution:	1

   prec

   DBF field precision.

   Precision of the field (places to right of decimal) when expressed in DBF, only for numeric fields. Integer values. Int of width 0.

   Value	Definition
   (no value)	Information not available for this record. 76 records have no value for prec.

   Range of values
   Minimum:	0
   Maximum:	6
   Resolution:	1

   units

   Units.

   Units of measure of the field values. Textual values of no more than 64 characters.

   Value	Definition
   (no value)	Information not available for this record. 149 records have no value for units.

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • Sloan, Jan
   • Henry, Christopher D.
   • Hopkins, Melanie
   • Ludington, Stephen D.
   • Zartman, Robert E.
   • Bush, Charles A.
   • Abston, Carl

2. Who also contributed to the data set?

3. To whom should users address questions about the data?

Why was the data set created?

This database is a minor revision of DDS-14, with some corrections.

How was the data set created?

1. From what previous works were the data drawn?

   DDS-14 (source 1 of 1)

   Zartman, Robert E., Bush, Charles A., and Abston, C. C., 1995, National geochronological and natural radioelement data bases: Data Series 14, U.S. Geological Survey, Denver, Colorado.

   Type_of_Source_Media: digital files on CD-ROM

   Source_Contribution:

   Original database used by compilers of OFR-2003-236; corrections to some of the data are described at <http://geopubs.wr.usgs.gov/open-file/of03-236/>

2. How were the data generated, processed, and modified?

   Date: 21-Dec-2011 (process 1 of 1)

   Copied information from OFR 2003-236, added documentation, reformatted, and in some cases eliminated duplication, eliminated explicit uninformative values (for example "Unk" in many fields). Created specialized interfaces and report formats as well as web services and download packages.

   Person who carried out this activity:
   

   Peter N Schweitzer
   USGS ER GD
   Geologist
   12201 Sunrise Valley Drive
   Reston, VA 20192-0002
   USA
   

   703-648-6533 (voice)
   703-648-6252 (FAX)
   pschweitzer@usgs.gov
   

3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

1. How well have the observations been checked?

2. How accurate are the geographic locations?

3. How accurate are the heights or depths?

4. Where are the gaps in the data? What is missing?

5. How consistent are the relationships among the observations, including topology?

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: none

Use_Constraints: none

1. Who distributes the data set? (Distributor 1 of 1)
   Peter N Schweitzer
   USGS ER GD
   Geologist
   12201 Sunrise Valley Drive
   Reston, VA 20192-0002
   USA
   

   703-648-6533 (voice)
   703-648-6252 (FAX)
   pschweitzer@usgs.gov
   

2. What's the catalog number I need to order this data set?

   USGS Open-File Report 2003-236

3. What legal disclaimers am I supposed to read?

   This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey (USGS) editorial standards or with the North American Stratigraphic Code. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

4. How can I download or order the data?
   • Availability in digital form:

     Data format:	Sample characteristics and geologic age information in format WMS (version 1.1.1)
     Network links:	<http://mrdata.usgs.gov/services/geochron?request=GetCapabilities&service=WMS&version=1.1.1>

     Data format:	Sample characteristics and geologic age analyses in format WFS (version 1.0.0)
     Network links:	<http://mrdata.usgs.gov/services/geochron?request=GetCapabilities&service=WFS&version=1.0.0>

     Data format:	Sample characteristics and geologic age information in format Shapefile (version 1.0)
     Network links:	<http://mrdata.usgs.gov/geochron/geochron.zip>

     Data format:	Sample characteristics and geologic age information in format Comma-delimited text
     Network links:	<http://mrdata.usgs.gov/geochron/geochron-csv.zip>

   • Cost to order the data: none

Who wrote the metadata?

Dates:

Last modified: 21-Dec-2011

Metadata author:

Schweitzer, Peter, N
Eastern Mineral Resources Team
12201 Sunrise Valley Drive Mail Stop 954
Reston, VA 20192
USA

703-648-6533 (voice)
pschweitzer@usgs.gov