Inca Minerals Limited (ASX: ICG) has announced a highly positive update regarding the results of geophysical 3D modelling at Riqueza in Peru.
Inca reported that 3D magnetic bodies were identified below surface geophysical targets at Cunayhuasi, Cuncayoc West, Cuncayoc East, and Huasijaja in the greater Alteration Ridge area.
The company noted that these magnetic bodies possibly relate to late-stage intrusions associated with the adjacent volcanic dome. ICG said that the occurrence of late-stage intrusive bodies associated with a volcanic dome is consistent with the internal architecture of epithermal and/or porphyry systems.
The magnetic 3d modeling had utilised data from the South32-funded geophysical survey conducted in 2018.
The Riqueza is a Zn-Ag-Pb-Au-Cu focused project located in Peru, South America. The project area comprises nine mining concessions; Nueva Santa Rita, Antacocha I, Antacocha II, Rita Maria, Maihuasi, Uchpanga, Uchpanga II, Uchpanga III, and Picuy.
The project was reported to have nearly two dozen porphyry and porphyryskarns targets. The six main Riqueza prospect areas include Humaspunco, Pinta, Uchpanga, Colina Roja, Pampa Corral, and Alternation Ridge.
Magnetic 3D modeling
The company had completed the magnetic total magnetic intensity (TMI) grid data of the Riqueza Project geophysical survey of four areas. This was then analysed to produce new 3D inversions models using the Geosoft magnetic vector inversion (MVI) code.
The company reported that the magnetic modelling was carried out by independent service provider Resource Potentials and said that the modelling is not constrained by known magnetic measurements and the smooth, cloud-like magnetic bodies may vary in size and amplitude in relation to depth from surface.
Four priority targets
The company reported that the specific area subject of 3D modelling covers four high priority geophysical targets in the greater Alteration Ridge Area including the Cunayhuasi priority-1 (P-1) target, the Cuncayoc East P-1 target, the Cuncayoc West priority-2 (P-2) target, all of which are located within the new Cuncayoc Copper Prospect area, and the Huasijaja P-2 target.
Magnetic bodies identified
Inca said that several important magnetic bodies have been identified extending below these surface geophysical targets.
The company said that the largest magnetic body identified occurs below the Huasijaja target, which is approximately 1,000m long, 400m wide and the 500m thickness and occurs close to the surface.
Inca said that the 3D model of the Cuncayoc Copper 3D Area1 shows a number of NE-SW orientated magnetic bodies arranged en echelon along the NW-SE trend.
The company noted that the four magnetic bodies are associated with and extend at depth below the Cunayhuasi P-1 target, the combined Cuncayoc West P-2/East P-1 target, and the Huasijaja P-2 target.
Inca said that the 3D models of the Cunayhuasi P-1 target area2 and Cuncayoc West P-2 and Cuncayoc East P-1 area3 show the occurrence of magnetic bodies below each of the surface geophysical targets.
Possible epithermal and/or porphyry systems
The company reported that the NE-SW orientation of the magnetic bodies along a NW-SE trend is consistent with the structural regime and geological development of the project area.
Inca said that the newly identified magnetic bodies have a shape and configuration like that of late-stage intrusions and that these are possibly related to the rhyolite dome.
The company also reported that the occurrence of an early-stage rhyolite dome and array of later stage intrusions is entirely consistent with the geological development and internal architecture of epithermal and porphyry systems.
Other exploration programs at Riqueza
Inca said that two other programs are currently ongoing, grid soil sampling and WorldView3 satellite imagery.
Grid soil sampling
The company said that until now, approximately 700 grid soil samples have been collected, representing ±60% of the program. Approximately 300 samples have been submitted for geochemical analysis. The projected completion of the program is 20-25 days.
WorldView3 satellite imagery
Inca reported that the WorldView3 satellite imagery program is currently nearing completion. The company said that near-infrared images are being examined for, inter alia, sulphide and hydrothermal clay distribution.
The company reported that the clarity and precision of the reflectance and Digital Elevation Model (DEM) data is such that very detailed interpretations of the entire project can now be completed. This work will greatly assist in target generation.
Updates and next steps
The company said that it plans to generate multi-layer targets for further exploration based on the information from the recent 3D modelling, completion of the geochemical data from the grid soil program, and interpretation of the WorldView3 satellite imagery, in combination with the original geophysical data and other data (including known mineralisation).
The company announced that the next steps at Riqueza include completion of the grid soil program (sampling and assays); interpretation of the subsequent geochemical data; completion of the WorldView3 imagery interpretation; continued detailed mapping of the greater Yanacolipa geophysical target area in the NE part of the project area (considered incomplete); and target generation based on all layers of data.
Inca noted that this would be based on South32-funded exploration completed to date and as per scheduled exploration.
Inca’s Managing Director Ross Brown said: “In the context of intrusive activity, structures created during tensional movement are the most prospective for porphyry emplacement.
The NE-SW orientation of the recently modelled magnetic bodies is therefore highly encouraging.
It is felt that the newly identified magnetic bodies have a shape and configuration like that of late-stage intrusions and that these are possibly related to the rhyolite dome.
The occurrence of an early-stage rhyolite dome and array of later stage intrusions is entirely consistent with the geological development and internal architecture of epithermal and porphyry systems. “