The Importance of Copper Breccias for Mineral Exploration

• David Kelley, the CEO of Chakana Copper discusses‍ the significance of breccias in copper mining.
• Breccias in copper ore systems are prolific globally, with a large portion of the world's copper coming from porphyry systems.
• Iron oxide copper (IOC) deposits are complex and two types exist: magmatic related ones and basinal fluid derived systems.
• Breccias, which originate from Italian meaning 'breach', form due to pressure changes and play a significant role in global copper production, especially in porphyry environments and IOC environments.
• Successful copper exploration depends on understanding various factors like alteration mineralogy, intrusive centers, and lithocap environments, with breccias being vital in several ore systems beyond just copper.

Introduction

Copper remains one of the most important base metals in the global economy, with demand projected to increase significantly in the coming years due to decarbonization and electrification trends. While most of the world's copper production comes from large porphyry deposits, an often overlooked and highly prospective target are breccia pipes associated with porphyry and IOCG (iron oxide-copper-gold) deposits.

Interview with David Kelley, CEO of Chakana Copper

What are Breccia Pipes?

As David Kelley, CEO of Chakana Copper, explains, breccia pipes get their name from the Italian word for "breach", referring to a violent fracturing event where high-pressure hydrothermal fluids break through the surrounding confining rock. This sudden release of pressure carries fragments of wall rock upwards, depositing them along with mineralization to form a vertical pipe-like breccia body.

Breccia pipes form above intrusions when magmatic-hydrothermal fluids overwhelm the strength of the overlying rocks, causing hydraulic fracturing. They act as conduits, focusing fluid flow from an underlying magmatic source upward towards the surface. This makes them highly prospective targets for finding high-grade mineralization.

The breccia fragments or clasts within pipes provide clues to their source and can be derived from wall rock, intrusions, or exotic lithologies carried up from depth. Strong tourmaline development within the breccia matrix is a common feature of many pipes. When well-developed, tourmaline breccia pipes can host exceptionally high copper grades, over 5% Cu.

While breccia pipes form vertically above porphyry and IOCG systems, they do not always reach the paleosurface. Their narrow pipe-like shape means they have a relatively small surface expression compared to the much larger causative intrusions at depth. This makes them challenging to initially detect and fully delineate. However, once recognized, breccia pipes provide important vectors that can guide exploration towards buried mineralization.

Major Discoveries Linked to Breccia Pipes

Some of the world's largest copper and IOCG deposits have been discovered by following up on breccia pipe targets. The immense 1.2 billion tonne Los Sulfatos deposit in Chile, containing 1.46% copper, was discovered by drilling a 2 km deep tourmaline breccia pipe. This demonstrates the incredible size and grade potential of underlying systems linked to breccia pipes.

The Olympic Dam IOCG deposit in Australia, the world's largest uranium resource, was originally discovered through a hematite breccia pipe anomaly at surface. Further examples of major discoveries guided by breccia pipes include the Candelaria and Manto Verde copper mines in Chile, Ernest Henry in Australia, and the Aitu Gold Mine in China.

A common exploration strategy is to thoroughly investigate the area surrounding known breccia pipes, as the causative porphyry systems often have multiple apophyses producing discrete breccia bodies. For example, the Filo del Sol project in Argentina contains over 20 breccia targets, highlighting the camp-scale potential. While initially subtle at surface, breccia pipes provide critical mineralization vectors that have led to many of the world's largest copper and IOCG deposits once followed up by systematic drilling.

Exploration Techniques

A suite of exploration techniques can help identify and delineate breccia pipe targets:

• Heavy mineral sampling - The dense tourmaline fragments that are characteristic of many breccia pipes concentrate in heavy mineral concentrates, providing an early-stage anomaly indicator.
• Lithological mapping - Careful mapping can delineate breccia outcrops and float trains downslope. Verifying breccia textures and clast composition under the microscope is important.
• Alteration mapping - Pipes are often surrounded by halos of advanced argillic alteration minerals like alunite and dickite. These lithocaps represent the paleo-surface expression of the hydrothermal system.
• Geophysics - Magnetic, gravity, and 3D IP surveys can trace breccia pipes to depth and pinpoint associated intrusive centers. Magnetic lows may also indicate magnetite depletion from hydrothermal alteration.
• Geochemistry - Elevated copper, gold, and pathfinder elements in soils, rocks and alteration clays help delineate targets. Mobile metal ions in soils may form distal leakage anomalies.
• Drilling - Once targets are refined, drilling is essential to confirm breccia textures, grade and full geometry. Both shallow percussion drilling and deep diamond drilling are utilized.
• Vectoring - Additional breccia bodies are commonly found nearby, representing separate apophyses from the same underlying intrusion. Careful structural mapping helps trace structure and identify new targets.

A successful breccia exploration program integrates all of these techniques to systematically develop and prioritize drill targets. Application of this exploration model has consistently led to important mineral discoveries over time.

Case Study: Chakana's Soledad Project

Chakana Copper’s Soledad project in Ancash, Peru provides an excellent case study of how breccia pipe exploration can unlock major discovery potential.

The Soledad project has a total of 154 targets, 80 if them breccia and 74 non-breccia, identified through comprehensive mapping, sampling, ground magnetics, and 3D IP surveys. Ongoing drilling aims to test the full breccia extent, which may connect to a large causative porphyry system at depth. 28 of the targets have been drilled so far.

The advanced argillic alteration assemblage at Soledad, containing dickite, kaolinite and alunite, represents a well-developed lithocap formed by hot, acidic fluids interacting with the paleo-surface. This further signals the potential for a large underlying mineralized system.

Detailed petrographic studies of the breccia pipes show two distinct mineralization events – an early high sulfidation stage with copper-rich tourmaline fragments, followed by a later low sulfidation gold-silver-galena event. Mineralogical studies indicate the gold is hosted in pyrite and is extractable by leaching. Free visible gold also occurs in late-stage veins.

In addition to the breccia pipes, Soledad contains extensive anomalous surface mineralization. Multiple large alteration and geochemical anomalies have been defined across the project, reflecting substantial yet untested discovery potential beneath the extensive breccia pipes.

Soledad provides a text-book example of how breccia pipe exploration, when conducted methodically utilizing modern geoscience techniques, can unlock major new porphyry and IOCG discoveries. The project's breccia pipes clearly vector towards a significant causative intrusive system at depth. Thorough drill testing of the full breccia geometries combined with additional systematic exploration to detect new breccia targets may lead to a major new discovery for Chakana Copper.

Conclusion

In summary, breccia pipes are an important yet commonly overlooked exploration target that can lead to world-class copper, gold and molybdenum discoveries. When evaluating prospective copper exploration and development projects, the presence of breccia pipes is a highly favorable indicator of substantial mineral potential. Investors should be aware of this exploration concept when conducting project due diligence.

About Chakana Copper‍

Chakana Copper is a Canadian minerals exploration company advancing the high-grade copper-gold-silver Soledad discovery in Peru. The mineralization is hosted in breccia pipes, which are cylindrical masses of fragmented rock cemented together. An initial inferred resource estimate for 7 breccia pipes was announced in Q1 2022, totaling 6.73 million tonnes containing 191,000 ounces of gold, 11.7 million ounces of silver, and 130 million pounds of copper at a copper-equivalent grade of 1.81%. This is from only a small fraction of the explored property, with significant potential remaining.