Mineral Resources On-Line Spatial Data
Mineral Resources > Online Spatial Data > National Geochronological Database
Tables and fields explained here are available only as part of the comprehensive download package geochron-csv.zip or in the full geodatabase geochron-gdb.zip
| Field | Description |
|---|---|
| recno | Sample identifier, a value of main:recno |
| karrecno | Sequence number, for this sample, of this analysis |
| karage | Age estimate in millions of years |
| karerr | Uncertainty of the age estimate attributable to the analytical method, in millions of years |
| karmin | Rock or mineral analyzed |
| karanaltype | Specific type of analytic method used |
| karlabno | Identifier for this analysis assigned by the laboratory |
| kardeccon | Radioactive decay constants used in calculations |
| k2opct | Potash concentration as weight percent of the sample |
| 40arrad | Concentration of radiogenic 40Ar |
| pctradar | Percent of argon that is radiogenic |
| sampsuit | Group identifier of related samples |
| addref | Additional bibliographic reference information for this analysis |
| karcomm | Comments on the age estimate, typically provides context for the age |
| karsampcom | Comments on the sample analyzed |
| karanalcom | Comments on the analytic method used |
| karothrcom | Other comments pertinent to this analysis |
| (table) | Potassium-Argon and Argon-Argon radiometric age results, observations, and parameters |
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://mrdata.usgs.gov/geochron/dd-list.php?tblname=K_Ar
Page Contact Information: pschweitzer@usgs.gov
Page Last modified: 17:34 on 28-Feb-2012
