APTA - West Limb Hypothesis25 Apr 2026 17:48
Unsure if I have posted this on LSE or only in Telegram, but since I’ve found some time over the weekend and the BB is quiet, I thought I would share again. (For information only — I’m not a geologist. These concepts and hypotheses just help give a high-level view of what we’re aiming for.)
APTA currently hosts several very high-grade pods centred around 200m below surface, surrounded by a lower-grade halo. Over the past year, Orosur has been reviewing the geological concepts and re-logging all the historical cores. This detailed work is helping build a much better understanding of the system, which is essential for defining the MRE. Note: Pepas only advanced to its maiden MRE once a revised and robust geological model was in place.
One of the key hypotheses for APTA is the “West Limb”.
This is a structural reinterpretation suggesting the known APTA mineralisation could “loop back” or extend westward and down-dip into a potential feeder zone or offset limb. Testing this could significantly expand the deposit footprint and materially upgrade the deposit size.
From a high-level view, picture an ‘r’ shape: the current known deposit sits at the nose/curve of the ‘r’. The West Limb concept involves following the mineralisation back up and then down the vertical leg of the ‘r’ - toward a potential feeder.
Understanding the mechanics of these gold deposits is important — not just for the MRE, but for pinpointing other areas where gold may still be undiscovered.
Orosur will also be testing a couple of other concepts, including:
- South-Eastern Extensions (deeper down-dip continuity), and
- Overall Structural / Emplacement Reinterpretation (broader controls on the system).
The West Limb idea was first discussed a few years ago (including by AGEOS on the LSE board) and gained traction after earlier drilling at APTA. However, it was MAP-096 that provided the strongest confirmation of anticlinal folding, making the Western Limb a realistic target worth drilling now.
It’s also worth noting that Buriticá Mine (located ~60km north of APTA in the same Mid-Cauca belt) started with similar high-grade, somewhat poddy-style zones. Through extensive drilling and geological reinterpretation by Continental Gold, it was successfully expanded into a multi-million-ounce Tier-1 asset.