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Global Geochemical Database for Critical Metals in Black Shales

November 13, 2017

The Global Geochemical Database for Critical Metals in Black Shales (CMIBS) contains new geochemical data compilations for fine-grained sedimentary rocks in which each geologic material sample has one 'best value' determination for each analyzed species, greatly improving speed and efficiency of use (Granitto and others, 2013). The CMIBS was created and designed to compile and integrate geochemical data from seven continents in order to facilitate petrologic studies, mineral resource assessments and mineral exploration, definition of geochemical baseline values and statistics, environmental impact assessments, paleobiological studies and paleoenvironmental trends through Earth history. and studies in human health and environmental geochemistry. The primary goal was to compile geochemical data for stratigraphic rock sequences containing dominantly fine-grained clastic rocks with appreciable organic carbon (>0.5 weight percent), collectively termed and referred to herein as 'black shale facies samples' but comprised of all fine-grained clastic rocks such as argillite, mudstone, claystone, and their low-medium grade metamorphic equivalents. In some cases, minor other lithologies within the stratigraphic sequences such as limestone,coal,or tuff layers are also included. The particular focus of the database was on black shale facies samples in regions and stratigraphic sequences known to contain high concentrations of 'critical metals' such as Ni, Mo, PGE, Se, U, and V. Therefore, this relational database serves as a data archive in support of present and future geologic and geochemical studies of critical metals in black shale facies samples, although a wide range of inorganic elements other than the above mentioned 'critical metals' are included. The database contains data tables in two different formats describing historical and new quantitative and qualitative geochemical analyses. The analytical results were determined by more than 130 laboratory and field analytical methods on 89,877 samples, of which 89,443 are rock, 170 are geologic material, 121 are sediment, 92 are soil and 2 are organic samples. The non-rock samples were included in the database because they were usually related to the black shale facies samples below them stratigraphically (in drill core, for example). Many of the samples are organic rich to the point that they are actually coal samples. More than 75 percent of the samples were collected by U.S. Geological Survey (USGS) personnel and analyzed in USGS laboratories or, under contracts, in commercial analytical laboratories. These data represent analyses of samples collected as part of various USGS programs and projects from 1961 through 2014. The CMIBS includes historical geochemical data originally archived in the USGS Rock Analysis Storage System (RASS) database, used from the mid-1960s through the late 1980s and the USGS PLUTO database used from the mid-1970s through the mid-1990s. All of these data are currently maintained in the USGS National Geochemical Database (NGDB). Retrievals from the NGDB were used to generate more than 3/4 of the CMIBS data set. Also included in the CMIBS are data from 11,084 samples of the Canadian Mining Industry Research Organization (CAMIRO) Project 08E04: Geochemistry of Shales as Vectors to Ore Deposits. This global black shale facies dataset was shared with the USGS for inclusion in the CMIBS. Bibliographic research for geochemical data of black shale facies yielded data from 11,697 additional samples published in numerous professional journals, theses and databases. The data of the CMIBS were checked for accuracy regarding sample location, sample media type, and analytical methods used.