Barksdale Resources Corp. to acquire an option to purchase 100% of San Javier from Tusk Exploration Ltd (private).
Total consideration of ~C$5.5 million consisting of:
• 4M BRO shares and C$50,000 in cash at closing (complete);
• 2M BRO shares and C$100,000 in cash on first anniversary;
• 3M BRO shares and C$150,000 in cash at sooner of PFS or three years;
• 4M BRO shares and C$200,000 in cash at sooner of securing construction financing or six years;
• Sliding scale NSR (1% below US$3.50 copper; 2% above).
Update: As announced Sept 16, 2020, certain title issues have led Barksdale and Tusk to defer 35% of the consideration from the first two option payments. If the title defects are corrected before the third anniversary,Barksdale shall pay the deferred consideration within 30 days. If Tusk fails to correct the issues before the third anniversary,the deferred consideration will be canceled, and the remaining option payments will be reduced by 35%.
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Summary:
San Javier exhibits many characteristics common to Iron Oxide Copper Gold (IOCG) deposits.
The oldest lithologic package in the region is composed of sedimentary rocks in an Ordovician through a Permian platform and a deep-water marine sequence comprised of limestone, shale, and sandstone. This sequence was affected by several tectonic events that resulted in low-angle overthrusting of basin sedimentary facies rocks over shallow water, platform sedimentary rocks. This deep-water carbonate rock package is referred to as the San Antonio Formation, outcropping less than 2 km north of the project area.
On top of these rocks was the deposition of the Barranca Group rocks during the Late Triassic, with mixed facies of marine and marshy environments depositing conglomerates, quartz sandstone, carbonaceous shale, and minor coal beds. The Barranca Group comprises the Late Triassic Arrayanes Formation (sandstone-siltstone), the Late Triassic Santa Clara Formation (carbonaceous shale, coal beds), and the indeterminate age Coyotes Formation (conglomerate).
The Cerro Verde, La Trinidad, and Mesa Grade prospects do appear to be members of the IOCG (iron oxidecopper-gold) class of deposits. Brief review of available data suggests that the Cerro Verde area may be part of a larger IOCG district that extends to the Yaqui River to the northeast and includes copper and gold deposits and prospects of the San Antonio district including Luz del Cobre, though these have traditionally been thought of as porphyry related.
Copper-gold mineralization occurs within hematitized intermediate to felsic extrusive, probably subaerial, volcanic rocks of the early Tertiary Tarahumara Volcanic unit. These volcanic rocks overlie terrestrial to lacustrine sediments of the Barranca Group. The sediments appear to consist of siltstones and sandstones with coal layers that grade upwards into coarse conglomerates immediately below the Tarahumara volcanic rocks. It is unclear from drill core and map patterns whether the Tarahumara volcanic rocks rest unconformably or conformably on the Barranca sedimentary rocks. In some instances, it appears the contact may be occupied by a low-angle structure (thrust or extensional normal fault). Mineralization appears to be both structurally and lithologically controlled. The Cerro Verde deposit, as currently understood, contains a major resource of low-grade (~0.35-0.4% Cu) copper oxide mineralization.
The prospects observed at San Javier (Cerro Verde, La Trinidad, and Mesa Grande) all appear to have similar characteristics. All display moderate to intense hydrolytic alteration (carbonate-sericite) with associated hematite mineralization. There is little evidence of earlier sodic or potassic alteration, though P. Henley notes the presence of “adularia” in a number of samples and whole rock analyses show enhanced K2O values suggesting that a precursor potassic alteration event may be present. Little to no evidence was seen of magnetite mineralization.
The alteration suite and the lack of magnetite suggest that these prospects represent very high levels of an IOCG system. The absence of discrete magnetic anomalies in the area of Constellation’s properties suggests that these prospects may be structurally detached from the lower portions of the hydrothermal systems that would be expected to have large areas of sodic alteration.
Supergene Mineralization
Supergene alteration is pervasive within the Cerro Verde area. Importantly, the low primary sulphide concentration and overall low pyrite content impeded more thorough leaching and enrichment. On the southern part of Cerro Verde, surface oxidation averages approximately 150 m in thickness and ranges up to 200 m thick at the summit. North from the summit, oxidation is locally greater than 50 m in thickness. In several areas, oxidation has been intersected in drill holes along structures exceeding these depths.
The main effect of oxidation is observed as the decomposition of specularite into goethite or bright-red fine-grained hematite. Secondary clays are scarce due to the original low sulphide content of the rocks involved. Chalcopyrite and pyrite have been oxidized, with copper redeposited as malachite and tenorite, and minor amounts of chrysocolla, brochantite, and tennantite. Commonly, there is a thin zone of mixing with some copper enrichment above the sulphide zone, where varying amounts of chalcocite, covellite, and native copper are deposited. These mixed zones are mostly discontinuous, generally 10 to 20 m in thickness, rarely up to 50 m thick, and non-existent in some areas.
By plotting elements on drill hole sections and comparing the different element abundances to the classified geometallurgical units defined from logging shows a clear depletion of manganese, calcium, magnesium, and zinc in the oxide zone. It is interpreted that the calcium depletion can be related to the leaching of siderite. Elements enriched in the oxide zone include barium, potassium, and strontium, although neither the mechanism nor the minerals involved are known.
The San Javier project comprises four groups of properties: Cerro Verde, San Carlos, Cobre Nuevo Norte, and Cobre Nuevo Sur. Most of the historic drilling focused on the Cerro Verde area, but the San Carlos group of claims, which includes the La Trinidad and Mesa Grande areas, also had some drilling, with mineralized intercepts over mineable widths. The Cobre Nuevo Norte and Cobre Nuevo Sur groups of claims have not been explored yet.