Overview of Completed Exploration Work Programs
Detailed Core Re-logging Program
All of the historical core, totaling ~115,000 m, has been relogged by Aldebaran geologists using a systematic set of logging criteria in order to have more consistent definition of the various rock types, alteration types, veining types and mineralization types. In addition to now having more consistent and reliable geological data across all the drill holes, we have also recognized new geological features that suggest the geological evolution of the Altar deposits is likely different from previous interpretations. This new geologic understanding will aid us in the development of the forthcoming updated resource estimate and the development of new exploration targets, both extensions of known high grade mineralization and new undrilled targets.
Surface Geological Mapping
The first-ever surface bedrock geological map has now been completed over a ~3,000-hectare area covering the Altar property. At a scale of 1:10,000, the mapping focussed on defining the major lithological units, the main faults, and structures, as well as the main alteration and mineralization types. This work has been rationalized with the sub-surface drill hole information and incorporated into the new geological model.
Hyperspectral & Structural Mapping
Satellite-borne high-resolution imagery and hyperspectral data were collected over the Altar project area in early 2020. Two sets of data were collected and analysed: (1) ASTER regional, 1:50,000 scale satellite data covering an area 60 x 60 km (3,600 km2) around the Altar project, and (2) WORLDVIEW3 high-resolution 1:10,000 scale satellite data covering an area 16 x 24 km (384 km2) immediately over the areas of known mineralization. The purpose of these data sets is to give us some regional and more detailed context of the structural setting and associated hydrothermal alteration related to the Altar cluster of mineralized porphyries. This information has been integrated into our new geological/structural model for the project.
Geophysics – Ground Magnetic Survey
The first-ever systematic ground magnetics survey has been completed over most of the Altar property; a total of 383.4 line-kilometres, on 100 m spaced lines, covering ~4,425 hectares. This detailed ground magnetics provides much needed information regarding structure and locations of potentially favourable magnetite-bearing potassically-altered porphyry intrusions.
Geological – Structural Modeling
All the data sets described previously have been integrated into a new robust geological/structural model that has changed our understanding of the mineralization in a significant way. The recognition of discrete fault-bounded structural blocks that have played a role in controlling mineralization, as well as potentially subsequently offsetting mineralization, is an important revelation. This new 3D model will become the backbone for the re-evaluation of the current resource and targeting for resource expansion and drill testing of newly identified areas.
Copper (Cu), Gold (Au) and Copper Equivalent (CuEq) Grade Shell Modeling
Using the new geological/structural model described above as a framework, grade shells at different cut-offs were modeled for copper, gold, and copper equivalent. The purpose of these grade shells is to better highlight the distribution and geometry of the higher-grade mineralized zones and will be used as guides for the upcoming resource re-evaluation. Special attention was given to modeling supergene secondary copper zones (amenable to heap leach technology) versus hypogene primary copper zones (amenable to milling and flotation technology).
Arsenic (As) Modeling
Historically, Altar has been viewed to have an “arsenic issue” however, based on detailed re-logging of the drill holes, several important observations can be made:
- Arsenic is associated with enargite (Cu3AsS4).
- Enargite occurs in centimeter-wide, sheeted veinlets with pyrite.
- The veinlets are sub-vertical and therefore sub-parallel to the core axis of the vertically drilled holes (the majority of the historical drill holes are vertical).
- These sheeted veinlets form narrow structural corridors which have been now modeled.
- These narrow sub-vertical veinlets, and hence arsenic, could be overestimated within the vertical drill holes.
- A significant amount of the highest arsenic grade occurs within the supergene copper region of Altar Central, which could be processed using heap-leach technology and would not make it to a potential copper concentrate.
- The current resource model used no geology or arsenic grade shells and was based solely on geostatistical modeling; so it may have overestimated arsenic and spread it throughout the deposit.
To better constrain the arsenic and consider the observations above, detailed wireframes/solids of arsenic >300 ppm were constructed to represent the structural corridors of sheeted veinlets. It is anticipated that these high-arsenic solids will more realistically show the distribution and geometry of arsenic and reduce the overall arsenic content of the resource in future modeling.
The scientific and technical data contained on this page has been reviewed and approved by Dr. Kevin B. Heather, B.Sc. (Hons), M.Sc, Ph.D, FAusIMM, Chief Geological Officer (CGO) and director of Aldebaran, who serves as the qualified person (QP) under the definitions of National Instrument 43-101.