24-MMP-A1 General Geology and Exploration · May 2018
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
EGBC National Exam — Mining and Mineral Processing Engineering, 09-MMP-A1 General Geology and Exploration, 2018-May. Closed book; only a Casio or Sharp approved calculator permitted. Questions 1–4 are compulsory; a candidate then completes ONE more question chosen from Questions 5, 6 or 7.
Reference texts: Guilbert & Park, The Geology of Ore Deposits (genetic classification, deposit-type descriptions throughout); Evans, Ore Geology and Industrial Minerals, 3rd ed. (deposit classification, structural controls on ore); Klein & Dutrow, Manual of Mineral Science, 23rd ed. (crystal systems, diagnostic physical properties, hand-specimen identification); Telford, Geldart & Sheriff, Applied Geophysics, 2nd ed. (gravity, magnetic, electrical, EM and seismic methods); Kearey, Brooks & Hill, An Introduction to Geophysical Exploration, 3rd ed. (survey design and method selection); Rose, Hawkes & Webb, Geochemistry in Mineral Exploration, 2nd ed. (sample-medium selection, dispersion patterns); Peters, Exploration and Mining Geology, 2nd ed. (drilling methods and sampling).
Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.
| Sample material | Usefulness in a geochemical survey |
|---|---|
| Soil | The most widely used medium: residual or locally transported soil overlying, or immediately downslope of, mineralisation accumulates anomalous metal concentrations through weathering and short-range (hydromorphic/mechanical) dispersion. Systematic grid soil sampling is relatively cheap and gives good spatial resolution for delineating an anomaly over subcropping or shallowly covered mineralisation. |
| Stream sediment | Fine-grained sediment from active drainages integrates the geochemical signature of an entire upstream catchment in a single sample, making it an extremely cost-effective REGIONAL reconnaissance tool: an anomalous drainage basin identified from one downstream sample can then be followed upstream (an "orientation survey") to close in on its bedrock source. |
| Rock (bedrock / outcrop chip geochemistry) | Direct sampling of exposed or subcropping bedrock is used to confirm and characterise an anomaly already identified by soil or stream-sediment work, to map alteration halos around a target, and to vector toward higher-grade zones using immobile trace-element ratios that survive weathering (lithogeochemistry). |
| Glacial till | In glaciated terrain such as most of the Canadian Shield, till (unsorted glacial debris) directly overlies bedrock and carries indicator minerals (e.g. kimberlite indicator minerals for diamond exploration, or sulphide/gossan fragments) transported a known distance down-ice from their bedrock source, allowing the source to be traced back up-ice along the known ice-flow direction. |
| Vegetation (biogeochemistry) | Deep-rooted plants (leaves, twigs, bark) take up trace metals from groundwater and soil through their root systems; sampling vegetation can reveal deeply buried mineralisation beneath thick transported overburden where conventional soil and stream-sediment methods see no surface expression at all. |
These five media form a natural progression from broad regional reconnaissance to precise target definition: stream sediment is used first to screen entire catchments cheaply; soil then narrows an anomalous catchment down to a specific hillside or grid cell; till (in glaciated ground) or vegetation (over deep cover) is brought in where the standard soil/sediment methods are blind to a buried or transported source; and rock geochemistry is finally used to confirm and characterise the mineralisation once a specific target has been located. Surface or groundwater sampling (hydrogeochemistry) is a further, complementary medium not detailed above, useful for tracing acid-rock-drainage plumes from oxidising sulphide bodies, though its results are more transient and season-dependent than the five media described here.
