The Ana Paula Project is controlled by Minera Aurea S.A. de C.V., which is a wholly owned subsidiary of Heliostar Metals Limited.
Heliostar owns all issued and outstanding shares of Aurea Mining Inc., which through its wholly owned subsidiary Minera Aurea indirectly holds the title and permit to mine the Ana Paula Gold Project.
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Summary:
The geologic units underlying the Ana Paula deposit are primarily sedimentary rocks composed of a thin bedded, interlayered package of limestone and calcareous mudstone and shale units with occasional fine-grained lapilli tuffs and carbonaceous limestone units that appear to correspond to the Acapetlahuaya formation which have been intruded by intermediate sills, dykes and stocks.
Mineralization
Low grade gold mineralization at Ana Paula extends 1,150 m roughly north south along strike. The width of mineralization is highly variable, between 100 m and 300 m wide with an average width of approximately 200 m. Mineralization extends down dip approximately 950 m to the west. The high-grade mineralization amenable to underground mining methods strikes 300 m east west, is approximately 150 m wide and extends down dip to the south 600 m. Gold mineralization is still open down dip.
Re-logging of historic and current drill holes has resulted in the differentiation of a suite of mineralized and barren veins and their cross-cutting relationships have enabled paragenetic sequence to be established. Lloyd (2023c) describes up to eight veining events, of which two or three are gold mineralizing events. While two of the veining events are related to gold deposition, the same mineralized fluids responsible for the mineralized veins also deposited gold as matrix fillings and clast replacements in the Polymictic Breccia and mineralized skarn style replacement bodies along feldspar porphyry and sediment contacts. Six veining events are described below.
V1: Quartz-pyrite veinlets are hosted in the sediments, typically 1 to 2 mm in width, and composed of variable amounts of silica and fine- grained pyrite.
V2: Sulfide micro-veinlets, the main gold mineralizing event at Ana Paula, are hosted in all rock types, but more abundant outside of the Polymictic Breccia in the feldspar porphyries. This generation of micro-veinlets occur as thin breccia veins 3 to 12 mm wide, as mossy patchy halos, as sheeted veins 2 to 5 mm wide, or more commonly as wispy discontinuous micro-veinlets only 1 mm in width or less.
V3: Quartz-pyrite±ankerite micro-veinlets are contemporaneous and very similar to V2 veinlets. This generation also occurs as medium-grained pyrite in veinlets or as patches, and appears to be responsible for a few distinct intervals that are gold rich but lack arsenic. It is this medium-grained pyrite that also often creates the massive sulfide mineralization in the sediments.
V4: White quartz and massive sulfide veining usually occurs as 1 to 3 mm wide white massive quartz veinlets with sections of massive sulfides, which is almost always comprised of pyrite. This generation of veinlets appear to be post-mineral.
V5: Grey quartz veinlets are usually 1 to 10 mm in width and may or not contain fine-grained pyrite or more rarely arsenopyrite. Overall, not very common and possibly a later re-mobilization of the early gold mineralization.
V6: Epithermal quartz veins which may be quartz, quartz-adularia, quartz-carbonates, or calcite often with calcite crystals growing into open space. Widths are variable between 1 mm and 10 cm and clearly cross-cut all other veinlets and host rocks.
In summary the four sites of gold deposition are:
1. Polymictic Breccia hosted mineralization with mainly sulfide (arsenopyrite and/or pyrrhotite or later replaced by pyrite) filling the matrix.
2. Exoskarn style pyrite replacement sediments along intrusive contacts.
3. Arsenopyrite micro-veinlets that fracture all rock types, but best developed in the feldspar porphyries.
4. Disseminated sulfides in the feldspar porphyries, likely a different manifestation of the V2 arsenopyrite microveinlets.
All four styles of mineralization have been developed by mineralizing fluids that exploited the contact zones between the feldspar porphyries and host thin-bedded sediments and deposited arsenopyrite, pyrrhotite and gold. Petrographic work suggests that pyrite has overprinted an earlier pyrrhotite phase of mineralization and this suggests that the mineralizing fluids have evolved with time. It is interpreted that this event represents a retrograde skarn event as seen at other deposits in the GGB (Jones, 2017).
Deposit Type
Gold mineralization at Ana Paula is largely hosted in a north - south trending corridor of intrusive rocks steeply dipping to the west, at the contacts with sedimentary rocks and hornfels, and within important breccia bodies. Gold deposition within the High Grade Panel (HGP) is located at the intersection of a diatreme breccia, which was emplaced along a roughly east – west trending fault, and the contact zones formed by feldspar porphyries intruding host sediments (Lloyd, 2023c). The best analogy for the Ana Paula deposit is the diorite hosted zone at Los Filos where gold mineralization travelled out from a proximal skarn setting, along intrusive / sediment contacts, and then deposited in the brittle body of the diorite intrusive (Jones, 2017). At Ana Paula, the distal brittle bodies are the feldspar porphyry dikes and sills. The breccia initially received gold in its porous matrix before becoming a brittle body late in the mineralizing event. Intrusions at Ana Paula have been dated at 66.0 – 66.7 Ma ± 0.7-1.8 Ma (Valencia et al, 2008), which may also date the earliest onset of mineralization (Lloyd, 2023c).
The QP considers the description of the deposit type as an intrusive related gold skarn is appropriate deposit for the Ana Paula Project and further exploration should follow that model.