A geochemical survey is a systematic program of sample collection and chemical analysis conducted over a defined geographic area to characterize the spatial distribution of elements and compounds in geological media, identify geochemical anomalies, and provide data for mineral exploration, environmental assessment, or resource evaluation. Geochemical surveys are conducted at multiple scales in bauxite, gold, iron ore, and diamond mining, ranging from continental-scale multi-element surveys to detailed prospect-scale sampling campaigns.
Regional reconnaissance geochemical surveys typically employ stream sediment sampling as the primary method, collecting samples at drainage catchment intervals of 1–10 km2 to identify large-scale anomalous zones meriting follow-up investigation. National geological surveys in many countries have conducted systematic multi-element stream sediment surveys providing baseline geochemical data for mineral potential assessment. These datasets are invaluable for identifying underexplored regions with geochemical characteristics consistent with known ore deposit styles.
In the gold sector, regional geochemical surveys in greenfields exploration areas use soil, stream sediment, and rock chip sample collection to generate anomaly maps that guide more detailed follow-up programs. Multi-element geochemical surveys integrating gold pathfinder elements (As, Sb, Hg, Bi, Te, Tl) alongside gold itself provide robust discrimination of mineralization-related anomalies from background scatter.
Detailed prospect-scale geochemical surveys in iron ore exploration use closely spaced sampling of BIF outcrops, laterite profiles, and regolith zones to characterize ore body geometry, grade distribution, and lithological contacts. Downhole geochemical surveys using RC or diamond drillhole samples provide three-dimensional elemental distribution data for resource modeling.
In bauxite exploration, grid-based laterite auger surveys generate multi-element datasets used to construct contoured maps of bauxite ore quality parameters (Al2O3, SiO2, Fe2O3, TiO2, moisture) that directly inform mine planning and plant design.
In diamond exploration, kimberlite indicator mineral (KIM) surveys over stream sediment catchments use heavy mineral concentration and indicator mineral chemistry to trace indicator mineral dispersion trains back to kimberlite source bodies. These are often complemented by till sampling surveys in glaciated terrains.
The design, execution, and reporting of geochemical surveys for public resource reporting must adhere to internationally recognized standards for sampling, QAQC, data management, and competent person review, as stipulated by codes such as JORC (Australasia), NI 43-101 (Canada), and SAMREC (South Africa).