OVERVIEW
In January 2018, Sonoro Metals (“Sonoro” or the “Company”), through its wholly-owned Mexican subsidiary, Minera Mar De Plata, SA de C.V., entered into the first of five option agreements to acquire a 100% interest in the Cerro Caliche Group of Concessions which contain eight historic gold mining sites and is located in the municipality of Cucurpe, in northern Sonora State, Mexico. Historical data, combined with results from Sonoro’s current exploration activities, totaling 23,000 meters of drilling, and more than 6,000 soil and rock samples, confirm the existence of a broadly mineralized low-sulphidation, epithermal vein system with continuing potential to develop a large tonnage resource suitable for open pit mining.
An NI 43-101 technical report estimated inferred mineral resource (at a 0.25 g/t gold equivalent cut-off grade) of 11.5M tonnes at an average grade of 0.495 g/t gold and 4.3 g/t silver that would be amenable to open pit extraction methods.” The purpose of the technical report is to support the Company’s planned HLPO. To advance the HLPO, the Company has entered into Memorandums of Understanding with three China-based EPC companies for the HLPO’s finance and development. Because there can be no assured date as to when COVID related restrictions will be lifted, Sonoro is also investigating an alternative plan to advance its proposed HLPO with Mexican technical expertise, with the intent of eliminating the impact of future COVID-19 related travel restrictions. Additional information on the alternative plan will be announced in due course.
Sonoro’s focus has been the property’s shallow bulk tonnage potential. Results from drilling and field work, outlined a shallow oxide gold exploration target of between 75,000,000 to 100,000,000 tonnes with grades potentially between 0.3 g/t to 0.5 g/t AuEq. An analysis of all of the results of exploration to date has identified the Cerro Caliche’s deeper high-grade gold potential. The results were released by Sonoro in its May 26th, 2020 Project Development Report. An analysis of higher grade chip samples taken by the Company, over an area of 4 kms by 3 kms, was done for the Report and found that they were mostly restricted to elevations between 1,100 masl to almost 1,700 masl; most of these samples ranged from 4 g/t to 25 g/t gold with a high of 95 g/t. The decision to initiate the 2020 Phase One exploration drilling, which targets Cerro Caliche’s potential to host zones containing high-grade gold mineralization is based on the content and conclusions of this report and subsequent work to define specific drill targets. The Company has identified a number of deeper high-grade gold targets which it plans to drill in this planned next phase of drilling, subject to the Company obtaining additional financing.
| Project Development Report Written by Mel Herdrick, P.Geo. & Jorge Diaz, MSc. and approved by Stephen Kenwood, P.Geo.. This report examines the vast historical data from the site including over 23,000 meters of drilling and volumes of notes regarding the rock textures in the context of regional geology to better understand the conceptual model of how the data is congruent with Low Sulfidation Epithermal Vein Systems, typical for gold mines in the region. |
Full Report  | Summary  | Visual
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LOCATION
The Cerro Caliche gold project is strategically situated between two world-class mining districts of the Sierra Madre Gold Belt and the Sonoro-Mojave Megashear. Located approximately 45 kilometers from the town of Magdelena de Kino in the mining district of Cucurpe, the property covers approximately 1,400 hectares and is surrounded by several gold-silver mining operations including the Alio Gold’s San Francisco mine, Premier Gold’s Mercedes mine, Goldgroup’s Cerro Prieto mine and Agnico Eagle’s recently-acquired Santa Gertrudis mine.
GEOLOGY
Mineralization types throughout the Cucurpe mining district include variants of epithermal low sulfidation veins and related mineralized dikes and associated volcanic domes. Local altered felsic dikes cut the mineralized meta-sedimentary rock units and may be associated with mineralization both in the dikes and meta-sedimentary rocks. The district has historically been regarded as vein dominated, but recently, open pit mining operations have been developed on disseminated and stockwork style gold mineralization.
Host rocks include Jurassic-Cretaceous meta-sedimentary rock units including argillite, shale, quartzite, limestone, quartz pebble conglomerate and andesite. Younger intrusive rock consisting of medium coarse-grained granodiorite-granite is present in the westerly parts of the concessions near the historic Cabeza Blanca mine. It is apparent that veining cuts and pervasively alters the intrusive stock. Rhyolite occurs in irregular bodies distributed in higher elevations in the northerly part of the concession, including the Rincn area, where it occurs as flows, sills, dikes and rhyolite domes. Part of the rhyolite is mineralized and appears to be related to epithermal gold mineralization throughout the property.
The nearby Mercedes mine complex area is interpreted to be part of the same hydrothermal event as the Cerro Caliche hydrothermal event as both are associated with development of extensional structural regional events in Tertiary age around 30 Ma to 35 Ma. Regionally, low temperature gold-silver fluids moved upward from a broad underlying area of emplaced calc-alkaline magma stock, through steep extensional (open) structures that tapped and channeled the fluids that deposited precious metals in quartz vein deposition sites in the Sierra Madre’s epithermal mineralized districts. The “boiling phase” changes kinetics within 1,000 meters of the paleosurface (the surface as it existed during the Tertiary) and defines the zones of deposition for the precious and base metals within the veins.
EXPLORATION PROGRAM
Sonoro Metals’ exploration conducted in the project area has defined a near surface resource posted to SEDAR which is a maiden resource which both initiates the Company’s program to quantify large areas of mineralized material that could support a conceptual small scale Heap Leach Pilot Operation. Continuation of drilling is projected to extend the mineralization in structural zones along trend and near surface. This completed work, combined with the completion of a working mineralization model, has developed excellent targets for deeper (up 250 meters deeper) high grade gold veins.
The goal of future exploration at Cerro Caliche is to increase the size of the numerous precious metal mineralized zones by focusing on three different mineralization formats:
- Extension of known zones of gold mineralization along trend of the vein zones outlined with drilling to the northwest and to the southeast together with the new high grade gold targets below the 75-meter depth of previous drilling;
- Targeting of porous geologic units including volcanic basal units of rhyolite flows; and,
- Newer untested but surface defined gold mineralized zones where 16 zones remain to be tested.
Future phases of drilling totaling approximately 50,000 meters planned for 2020-21 are designed to test the exploration target of between 75,000,000 to 100,000,000 tonnes with grades potentially between 0.3 g/t to 0.5 g/t AuEqR, assuming AuEqR = (Au g/t × 0.72) + (Ag g/t × 0.01133 × 0.30). The potential tonnages and grades set forth in the analysis of geological potential are conceptual in nature, as there has been insufficient exploration to define a mineral resource and it is uncertain if further exploration will result in the target being delineated as a mineral resource. Potential estimates are separate from the inferred mineral resources stated above.
Drilling will target both infill in zones that were previously drilled as well as a large number of holes to test undrilled portions of the various mineralized trends along strike and at depth.
PHASE ONE TESTING HIGH-GRADE GOLD TARGETS
Phase One of the program (the “Drilling Plan”) will total 6,000 meters of core drilling to test 20 targets, of which the initial 11 holes have been identified in the Drilling Plan. Of the remaining nine holes, seven have been tentatively identified in the Drilling Plan and two are reserved depending on the results of prior holes. This initial core drilling program is the first segment of the proposed 50,000 meters of core and rotary drilling contemplated in the Company’s May 26, 2020 news release.
The main purpose of the 2020 Phase One drilling program is to test for the presence of deeper high-grade type gold mineralization as outlined in the PDR. The PDR, which delineated the potential for higher grade gold zones deeper in the epithermal system, was disseminated to the public by the Company on May 25th, 2020 and is available here.
As illustrated in the Drilling Plan, the proposed 6,000 meters of core drilling will target mineralized zones projected to support vein zone coalescences at elevations favorable for the deposition of high-grade gold, at a depth from surface averaging approximately 200 to 300 meters. Drilling will test the confluence of parallel striking gold bearing vein zones that, at surface, are expressed as gold enriched sheeted vein sets. It will also similarly test at depth, the area’s coalescing of gold enriched stockwork zones. An additional focus is on areas where the rock type changes from quartzite to Cretaceous andesite host rock.
PROJECTED POTENTIAL GOLD GRADES
The deep potential targeted by Sonoro will test for similarities to the neighboring Mercedes mine, 9 km to the southeast. The Mercedes mine operates mainly underground with mining supplying a 2,000 tonnes per day mill that has operated since 2011 (Premier Gold website). The Mercedes mine is located in the same mineralized epithermal district and related hydrothermal – igneous system that hosts the Cerro Caliche mineralized area. Average mine-mill grades at the Mercedes mine have ranged between 3 and 6 grams/tonne gold with up to 100 grams/tonne silver. While encouraging because Cerro Caliche shares similarities with the geology at the Mercedes mine site, there can be no assurance that high grade gold zones similar to those at Mercedes will be discovered at Cerro Caliche.