GEOCHEMICAL DATA FOR THE GREAT BASIN: A SUBSET OF THE USGS NEW NATIONAL GEOCHEMICAL DATABASE

Several legacy U.S. Geological Survey (USGS) hard copy and digital geochemical databases used between 1962 and 2002 have been digitally compiled and merged into the National Geochemical Database (NGDB). We have culled analytical data from the NGDB to create a subset for the Great Basin. The initial goal is to verify and publish these data so that they can be accessed and used by earth scientists. Displays of stream sediment or soil and rock data are being used to evaluate the geochemical expression of rock units, mineral belts, and significant ore deposits at various scales.

The Great Basin dataset contains analyses of rocks (94,380), stream sediments and soils (114,980), heavy mineral concentrate fractions of these sediments and soils, minerals (8,030), waters (3,080), organic materials (3,000), and leachates (260). Analytical records were derived from 4 principle sources. The first represents 730,000 records that were formerly in the USGS Rock Analysis Storage System (RASS), which was primarily used during regional mineral resource investigations between the 1960's and 1980's in support of resource assessment programs. The second, comprised of an additional 530,000 records collected during topical studies between the 1960's and 1995, were part of the “Pluto” database. The third is comprised of records generated since 1995. The fourth is an additional 195,000 analytical records that may be added but were never entered into either RASS or Pluto.

Re-processing of the Great Basin dataset was initiated in 2004 to correct errors in sample locations, add missing sample locations, and identify the sample media and analytical protocol of each record. This was done using original sample submittal forms, publications, field notebooks and base maps, and discussions with submitters and analysts. Fields were added to the original data to more fully describe the sample preparation methods used and sample media analyzed.