As exploration steadily moves into more complex geological terranes, geologists require a range of tools and methods. Comprehensive understanding of mineral systems, including regional geotectonic and metallogenic context, is key. System elements include mineralisation fluid sources/drivers (e.g., fertile granites, volcanic or metamorphic sources). Fluid pathways enable the migration of mineralisation fluids to near-surface depositional sites. Deposition controls can include favourable lithologies with chemical or rheological contrast or structural trap sites. These elements can be used to predict where mineralisation may be and help narrow the exploration search window.
The Khotgor Gold project is an early-stage exploration project that exemplifies how applying mineral system analysis can improve understanding of the mineral potential of a project and assist exploration targeting. The project lies in the Khovd Province approximately 1,400 km southwest of Ulaanbaatar, Mongolia, and hosted in the Trans-Altai Zone, Dulate Arc subzone, part of the Edrengiin metallogenic belt. This region is prospective for a range of island-arc-magmatic−related mineral systems, including volcanogenic Au-Cu, porphyry Cu-Mo (±Au, Ag) and granite-related Au-vein type systems. Several high-K calc-alkaline−related Au-Ag quartz vein targets have been identified in the project.
SRK undertook an independent technical review of the exploration results and identified target areas and recommendations for ongoing exploration. The review encompassed available datasets, including mapping, geophysics (aeromagnetics, induced polarity), satellite (ASTER, Landsat) and geochemistry (rock chips, soils). These were used to assess the project’s defined mineralisation and broader mineral potential, with porphyry-style mineralisation identified as an additional target. Geophysical and satellite interpretations were integrated with all geological datasets to refine the structural and lithologic architecture and alteration patterns potentially associated with mineralisation. Evaluation of the defined Au-Ag vein mineralisation was also undertaken to define the local controls to assist with exploration targeting.
For exploration targeting, a mineral system framework was developed for Au-Ag vein and porphyry mineral systems. These included fluid sources/drivers (arc-related calc-alkaline rocks from mapping and geophysical interpretations), fluid pathways (long strike length structures, interpreted structural dilational sites) and fluid trap sites (favourable lithologies or structural traps, phyllic or argillic alteration, soil/rock chip anomalies).
Targeting was conducted in ArcGIS, a popular geographic information system (GIS) software, applying a fuzzy logic method, integrating ranked mineral system inputs developed from exploration and interpretive inputs. Targets were defined from areas with a higher number of highly ranked overlapping elements. By applying integrated data analysis to develop the structural, lithological, alteration interpretations and mineral system framework, SRK was able to provide an improved understanding of the project for effective future exploration.
