4. OZCHEM - ufarrell/sgp_phase2 GitHub Wiki
Details of the Geoscience Australia OZCHEM National Whole Rock Geochemistry Dataset available here: https://pid.geoscience.gov.au/dataset/ga/32986.
OZCHEM data are available through the Geoscience Australia Exploring for the Future portal: https://portal.ga.gov.au/persona/eftf.
Inorganic Geochemistry data was downloaded from the portal in early 2021 (final download May 2021), with the guidance of Dr. David Champion.
OZCHEM includes 5813 samples with 262417 results from 3317 sites in Australia.
Geography
Lithology
40% coarser-grained siliciclastics (sandstone, arenite, greywacke, quartzite), 30% fine-grained siliciclastics (shale, siltstone, mudstone),16% carbonate (limestone, dolomite, grainstone).
Age
The figure below is based on interpreted age in Ma, and does not represent all samples - see Completeness and Data Collection/Processing below for more details.
Data
Geochemical data was entered in batches based on OZCHEM methods. Data include major, minor, trace and rare-earth elemental data, as well as some carbon isotopic data. Analytical methods (e.g. ICP:MS, XRF, AAS) are included for most data, but no experimental methods (e.g. details of acid digestion). Summary of batches (count samples, results and analyte lists) here.
Categories are based on those used on our search website (http://sgp-search.io/).
Completeness
Data Collection/Processing
Sedimentary samples were targeted. Samples were screened to remove igneous and metamorphic/altered samples based primarily on units, lithology, lithology description and qualifiers. For a full list of sample types deleted, see here and for the included lithologies and matched SGP terms see here.
There is some minor overlap between OZCHEM sites and existing SGP or USGS-CMIBS sites. Some have identical or near-identical names (particularly for drill cores, e.g., BMR Illowga Creek 6, DD91DC1, Erldunda 1, Ooraminna 1, Wallera 1/Wallara-1). Others are considered likely matches based on geographic comparison, with some of these also sharing similar names or attributes. Nevertheless, all sites from OZCHEM were added independently. This was partly due to the difficulties in making direct matches, and partly to preserve the OZCHEM site interpretations/metadata.
Interpreted Age
Interpreted ages are from the Australian Stratigraphic Units Database (https://www.ga.gov.au/data-pubs/datastandards/stratigraphic-units), spreadsheet provided by Dr. David Champion in 2021.
Ages were entered for 3575 samples where top (min_age), and base (max_age) age was available, with interpreted age as the mid-point. Interpreted age notes include details of how top and base ages were determined, and comments from the ASUD - for example, for samples from the Chilling Sandstone: "Age from Geoscience Australia database. Top age determined by: inferred, intrusive relationship. Base age determined by: inferred, underlying unit. Notes: See also Chilling Creek Formation of Wingate Group. Included in Finniss River Group by NTGS 1989 (89/26582). Removed from Finniss Group by NTGS (2005). Included in Finniss River Group again 2008. Conformably overlies Burrell Creek Formation, intruded by Ti-Tree Granophyre. Maximum depositional age: 1861+/-4Ma. Around 6500m thick. Hosts the Muldiva field Sn pegmatite deposit."
2238 samples remain without interpreted ages - units lacked a numerical age, or had partial information only. These will be filled in by SGP team members, where possible, in the next Phase.
Data entry - OZCHEM vs. SGP
An effort was made to match OZCHEM columns to SGP columns (see table below), but in some cases compromises were required e.g. concatenating data into one SGP column. Where information was particularly important (e.g. stratigraphical names, lithology names) the data was cleaned so that it could be matched to the existing dictionaries, although verbatim was also included.
Note that at the time of our download the Exploring for the Future portal was relatively new - most column types remain the same, but some additional metadata are now available which are not in the table below. Column descriptions are based on the metadata available here: https://portal.ga.gov.au/metadata/fe99610c-d703-4bbf-a2a1-546094d63e2, see also original documentation for OZCHEM: https://pid.geoscience.gov.au/dataset/ga/32986.
Note that full sample details from OZCHEM can be accessed using the IGSN (International Generic Sample Number). Persistent identifiers take the following format (where AUXXXXXX is the IGSN): https://pid.geoscience.gov.au/sample/AU1679316.
| OZCHEM column name (2021) | Column description (Geoscience Australia Portal Metadata 2025) | SGP table_name.column_name(s) | Notes |
|---|---|---|---|
| FID | GA internal unique identifier for the geochemistry sample analysis result. | sample.original_num | See also sampleno, sampleid |
| eno | Unique number of the entity this sample or interval belongs to (eg, well, site, or section). | ||
| siteid | Name or identifier of the sampling feature. | site.section_name | |
| feature | Type of entity (eg, wells, regions, outcrops). | site.site_type | Three feature types only. Field site and section = outcrop. Borehole = core. |
| state | The State, Territory or other administrative region in which the well was drilled. | NOT IMPORTED | Same information as statename. |
| statename | Full name of the Australian state. | site.state_province | |
| country | The name of the country in which the sample occurs. | site.country | |
| locdesc | An optional text description of the field site location. (eg, 300 metres south of Andamooka homestead.). | site.site_desc | |
| hmapno | Number of the 1:100K map sheet. | NOT IMPORTED | |
| hmapname | Name of the 1:100K map sheet. | NOT IMPORTED | |
| qmapid | Number of the 1:250K map sheet. | NOT IMPORTED | |
| qmapname | Name of the 1:250K map sheet. | NOT IMPORTED | |
| easting | The MGA94 easting of the point at which the borehole enters the solid Earth. | site.easting | |
| northing | The MGA94 northing of the point at which the borehole enters the solid Earth. | site.northing | |
| utm_zone | UTM zone of the MGA94 easting and northing coordinates. | site.utm_zone | |
| latitude | The latitude of the point at which the borehole enters the solid Earth. | site.lat_original, site.lat_dec | |
| longitude | The longitude of the point at which the borehole enters the solid Earth. | site.long_original, site.long_dec | |
| datum | Datum of the latitude and longitude coordinates. | site.datum_dec | |
| original_datum | Decoded original datum or internal SRID. | site.datum_original | |
| accuracy | Limit of the accuracy of the location in metres. | site.uncertainty_m | The original OZCHEM column description is included in site.site_notes. |
| originator | Name of the person who acquired the sample. | NOT IMPORTED | |
| jobno_list | Aggregated list of unique identifiers for the analysis batch jobs. | analyte_determination.result_notes | Concatenated in result_notes along with jobbatchno_list and resultbatchno_list |
| jobbatchno_list | Aggregated list of the job batches from which this sample came from. | analyte_determination.result_notes | Concatenated in result_notes along with jobno_list and resultbatchno_list |
| resultbatchno_list | Aggregated list of all the job request numbers used in this analyses batch. | analyte_determination.result_notes | Concatenated in result_notes along with jobno_list and jobbatchno_list |
| sampleno | Sample number linking to borehole samples table. | sample.alternate_num | |
| sampleid | Identifying number or code assigned to the sample in the field or laboratory. | sample.alternate_num | |
| subsampleid | Optional text field used to identify subsamples eg this might identify the site for point analyses or categorize extract analyses. Rows with a null value in this column are considered to be whole-rock analyses. | NOT IMPORTED | all = 'WHOLE ROCK' |
| refid | Non-unique reference identifier for this job. For jobs sourced from LABSUBS this would normally be null as the NPM_JOB_REQUESTNO already identifies the row. | NOT IMPORTED | |
| slatitude | Sample latitude. | NOT IMPORTED | This seems to be the same as latitude |
| slongitude | Sample longitude. | NOT IMPORTED | This seems to be the same as longitude |
| access_code | Security code used for restricting access (C = confidential, A = GA internal only, O = open [ie public access]). | NOT IMPORTED | All = O |
| region | Name of the geographical region that corresponds broadly to a geological province at the Earth surface. | NOT IMPORTED | |
| province | Name of the geological province (eg, basin, craton, orogen) which contains the sample. | site.basin_id, site.craton_terrane_id | Matched to basin and craton/terrane names where possible. |
| stratno | Code to formal unit description in the Australian Stratigraphic Units Database. | SEE NOTES | |
| unitname | Name of the stratigraphic unit in which the sample occurs, either a unit name registered in the Australian Stratigraphic Units Database or an informal or company-reported unit name. | geol_context.strat_id, geol_context.verbatim_strat | Used to match to existing unit names, or to add new names to the dictionary (dic_strat), verbatim stored in verbatim_strat. |
| informal | Informal or company-reported stratigraphic unit name. | NOT IMPORTED | |
| lithgroup | Aggregated list of lithology group type names by order of the proportion of the sample comprised by this earth material. | sample.lith_notes | Concatenated in lith_notes along with qualifier. |
| qualifier | Lithology qualifier of the earth material description (eg, felsic, weathered, metamorphosed, porphyrytic). | sample.lith_notes | Concatenated in lith_notes along with description. |
| lithname | Name of rock or unconsolidated earth material. | sample.verbatim_lith | sample.lith_id was determined based on this name, the verbatim stored in sample.verbatim_lith |
| grouping | An optional field for a user-defined classification. Often used to classify suites of rocks from particular regions into classes. The values entered here are up to the users and have no global significance. | NOT IMPORTED | |
| description | A free text description of the earth material. | sample.lith_notes | Concatenated in lith_notes along with qualifier. |
| modeocc | Description of the mode of occurrence of the earth material, its morphology, or relationship to adjacent material. (eg, dyke, clast, matrix, phenocryst). By order of the proportion of the sample comprised by this earth material. | NOT IMPORTED | Mostly NULL. Used to filter data. |
| group_type | One of 'ROCK', 'SEISMIC TRAVERSE', 'REGOLITH (SURFACE)', 'SHIP' as applicable. | NOT IMPORTED | Used to filter data. |
| materialclass | Broad classification of the material that comprises the observed sample. (eg, rock, sediment, water, oil). | NOT IMPORTED | Used to filter data. |
| sample_type | Type or form of the sample (e.g., half core, outcrop specimen, drill chips, float specimen, unknown). | NOT IMPORTED | |
| analysis_datetime | The latest date of geochemistry analysis. | NOT IMPORTED | |
| technique_list | Aggregated list of analytical techniques (eg XRF, ICP-MS,Titration) used. | NOT IMPORTED | This is a list of techniques which is also in the columns related to each individual analyte |
| method_list | Aggregated list of methods used to analyse the sample. | NOT IMPORTED | This is a list of methods which is also in the columns related to each individual analyte |
| top_depth | Uppermost depth (in m) for borehole interval for drill hole samples. | sample.min_depth | |
| base_depth | Lowermost depth (in m) for borehole interval for drill hole samples. | sample.max_depth |