100%-owned, 212-hectare concession package, with an additional 49 hectares pending to be added to the Company’s portfolio. The AntaKori Project lies within the Yanacocha-Hualgayoc mining district in the Department of Cajamarca, northern Peru.
The AntaKori Project is located some 800 km to the north of Lima, in the Yanacocha-Hualgayoc mining district in the prolifically mineralized region of central Cajamarca, northern Peru. This district was one of the earliest mining areas developed by the Spanish in Peru. Production estimates from 1771 to 1951 totalled 167 million ounces of silver with significant gold and base metals from relatively small vein and manto-type deposits (Velasquez, 1980). More recently, bulk tonnage low grade gold and copper deposits have become the leading gold producers in Peru. This has been a result of the discovery of Yanacocha, Cerro Corona and Tantahuatay deposits, which all lie within 35 km of the AntaKori Project, as well as other major deposits like Sipan, Pierina, Alto Chicama, Antamina and future mines like La Granja, Conga, Galeno and Michiquillay. Within the Hualgayoc district there are several mining operations of both open pit and underground. Most important currently are the Cerro Corona porphyry Cu-Au-Mo mine of Gold Fields, producing at 19,000 T/day, and the Tantahuatay epithermal Au-Ag mine of Buenaventura and Southern Peru Copper.
As a result of the long history of mining in the area, the stratigraphy of the Hualgayoc area is well documented. AntaKori lies near the boundary of two geological terrains: (a) Tertiary aged volcanic and intrusive rocks and (b) Cretaceous aged sediment rocks. In general, the surface geology of the property can be divided into three elongate belts. To the west, the rocks consist of andesite to dacite flows and tuffs with interbedded layers of sediment belonging to the Tantahuatay volcanic center. The middle portion of the property is covered by younger glacial moraine and colluvium deposits. To the east is dominated by the San Miguel diorite.
The AntaKori property is located at the northern end of the Hualgayoc district, on the northeastern side of the Tertiary Tantahuatay volcanic center. The age of the Tertiary Calipuy formation andesitic flows and tuffs at Tantahuatay and AntaKori ranges from 12.6 -13.2 Ma. The Tertiary volcanic rocks are underlain by a t hick pile of shallow marine, fossilferous limestones of the Chulec formation that are interbedded with minor calcareous shales and siltstones. The Chulec Formation in turn is underlain by the Inca Formation shales, siltstones and minor sandstones. The bottom of the section exposed by drilling is the Lower Cretaceous age (125 -113 Ma.) Farrat Formation, which consists of quartzites, siltstones and intercalated shales.
The Cretaceous aged sedimentary rocks on the property were intruded in the Miocene by a medium- to coarse-grained diorite porphyry stock called the Cerro San Miguel porphyry. It may have generated metasomatic skarn, marble, quartzites, and hornfels formation in the sedimentary rocks. This diorite porphyry is relatively unaltered in outcrop and poorly mineralized outside of small veinlets that cut it. Younger diorite and quartz diorite intrusions have been documented along with medium-grained biotite-feldspar-quartz dacite domes and associated rhyolite/dacite volcanic rocks that form the next phase of igneous activity. The final phase of igneous activity consists of andesitic dykes, which intrude the dacite domes and cut the epithermal mineralization.The Cerro Corona quartz diorite porphyry located 7 km away is dated at 14.4 Ma and the Sinchao rhyodacite flows have been dated at 9.5 Ma. The rhyodacites at AntaKori are mineralized, hence their age date gives an upper date for a least one of the stages of mineralization found at the AntaKori property.
There is a strong, NW-trending system of fractures associated with the Hualgayoc Fault System, which is controlling the emplacement of a number of world class Cu-Au ore deposits such as AntaKori, Tantahuatay, Cerro Corona, Yanacocha, Conga, Galeno and Michiquillay. The structural features that are relevant to the AntaKori property are reflections of the general structural fabric of the Hualgayoc district and of the region. Several stages of faulting have affected the region over a long time period. The large, northwest trending Sinchao normal fault has been active throughout the formation of the district geology since the mid Tertiary. This is also true for the northeast and due east trending structures found at the adjoining Tantahuatay volcanic center as they run onto the AntaKori property. The easterly orientated structures are probably tension generated with veins, hydrothermal breccia dikes, or late igneous dikes filling them. The majority of the drill core of the AntaKori property is moderately to intensely-fractured and is evidence of the complicated structural history present.
Mineralization in the AntaKori property consists of several types; (a) epithermal high-sulphidation mineralization associated with structures within the Tertiary volcanic rocks, (b) retrograde and prograde skarns and associated massive sulphide bodies developed within the Cretaceous aged sedimentary rocks and older intrusive rocks, and (c) porphyry style mineralization and associated hydrothermal breccias.
Early History: The Sinchao district has been mined for copper since pre-Colombian times.
1920: The Sinchao district was evaluated in the 1920’s by Asarco (Norperu). Geologists of Northern Peru Mining and Smelting Corporation studied the Tantahuatay and Sinchao areas and suggested the possible existence of copper porphyry deposits in the area (Castro, 1996). Previous small scale mining was done in the Sinchao mining concessions, mainly within the massive sulphide replacement type lenses in the southern portion of the property. In the first half of the 1900’s there were several small underground mines, including the Volare, Maria Eugenia, Cleopatra, Tres Mosqueteros, Incognita, Sinchao, Rita Margot and Inquisicion mines.
1953-1975: According to Castro (1996), copper mining at the Cleopatra zone started in 1953 and continued intermittently until 1960. Minera San Nicholas and other companies resumed small open-pit operations in 1962 and continued until 1974 when a drop in the price of copper caused the mine to close. From 1953 to 1974 the total production amounted to 132,169 tonnes at an average grade of 3.24 % copper and 82 g/t silver. At its peak production in 1973, the mine operated at a rate of 60 tonnes per day. The Inquisicion pit area, also called Mina Incognita, was also partially mined during the same time as Cleopatra. Two northeast-dipping structures in the centre of the Volare concession were mined by underground methods between 1969 and 1975. The Volare mine saw only limited production and the second of 2 veins contained mineralization grading 3.57% copper and 0.5 ounces per tonne silver (El Misti Gold Limited, 1998). Small scale mining was also performed at Mina Verdecita during the mid-1970.
In the early 1960’s Kennecott (Bear Creek Mining) and Cerro de Pasco Corp explored in the Sinchao district. The latter reportedly drilled two diamond drill holes in 1963. Kennecott then drilled two holes in 1970. Cerro de Pasco conducted regional exploration in 1963 and Ministerio de Fomento y Obras Publicas performed a large”scale regional soil sampling program over Cerro Tantahuatay (including the southwestern portion of Sinchao) in 1967, followed by Mincosa who performed a regional program and possibly a little mining.
1980-1998: Granges reportedly had a program at Sinchao in 1987. In 1991 Southern Peru Copper Corp started exploration on Sinchao due to work on the adjoining Tantahuatay volcanic complex with Buenaventura Mining (Coimolache Joint Venture). From 1996 to 1998 the property was explored by El Misti Gold (10 diamond drill holes and 22 reverse circulation holes). A geochemical grid on a 50m x 50m grid was done in 1996, with 354 samples, Au & 32 elements. In 1996 22 km of IP & resistivity geophysical surveys, and 23.3 km magnetics were completed. At a later date it El Misti Gold became Andean American Corp.
2006-2008: In 2006 Andean American Corp. passed ownership to a partially owned subsidiary, Sinchao Metals Corp. It had geophysics redone in 2006 by Arce Geophysics and conducted a surface mapping and sampling program. A total of 64 samples of massive sphalerite, galena and pyrite within the skarn mineralization returned average values of 14.27% zinc, 2.40% lead, 1.87 g/t gold, 85.04 g/t silver and 1.40% copper. A follow-up trenching program performed by Sinchao Metals collected 100 samples from 11 trenches and 76 soil samples. The trench samples returned average values of 0.61 g/t gold, 28.8 g/t silver and 0.38% copper, 0.57% lead and 0.52% zinc, with ranges of 0.10 to 14.48 g/t gold, 0.5 to 354 g/t silver, 0.008% to 2.23% copper, 0.0124% to 17.80% lead and 0.0055% to 2.37% zinc. The soil samples collected formed part of an orientation survey and returned average values of 0.15 g/t gold, 7.71 g/t silver and 0.24% copper, 0.11% lead and 0.21% zinc, with only a few isolated anomalous copper, lead and zinc values. Sinchao Metals executed a diamond drill program that totalled 9,502.11 metres in 38 drill holes. A total of 5,886 core samples were taken. Sinchao Metals actively explored the property until 2009.
2011: On February 7, 2011, Sinchao Metals announced that it had conducted a review of its properties earlier in 2011 and determined that title to the claims of four of the properties containing resources were not held by Sinchao. These properties, named Rita Margot, Maria Eugenia, Maria Eugenia 1 and Maria Eugenia 2, were reported to contain approximately 40% of the inferred resource previously disclosed by Sinchao. After a period where negotiations were held to recover the properties, on April 20, 2011, the company declared that it did not expect to be able to recover the properties and wrote down the project by $11,465,806 to management’s best estimate of its fair value as a result.
2012: Southern Legacy Minerals (SLM) acquired the AntaKori property in early 2012. SLM conducted a re-logging program of the existing diamond drill holes and completed a NI 43-101 compliant resource in July 2012, based on the pre-existing 70 drill holes. The initial NI 43-101 compliant inferred resource estimate for AntaKori, using cut-off grades of 0.2% Cu in-pit and 0.5% Cu underground, is 295 Mt @ 0.36 g/t Au, 10.2 g/t Ag, and 0.48 % Cu.
2014: In October 2014, Southern Legacy Minerals was amalgamated into Regulus Resources Inc.
Historically, a total of 70 drill holes totalling 17,950.81 meters have been completed on the AntaKori project between the 1960’s and 2008.
On July 3, 2012, Southern Legacy Minerals released the following NI 43-101 compliant resource estimate at the AntaKori Deposit. The resource estimate was completed by independent consultant, Scott E. Wilson, of Scott E. Wilson Consulting, and was based on 70 drill holes totaling 5,898 three-metre-length composites. The technical report is available here and on SEDAR (www.sedar.com).
|Resource Type||Tonnes (x1,000)||Grade Au g/t||KOz. Au||Grade Ag g/t||KOz. Ag||Grade Cu %||Cu Lbs (x1,000)||Grade Mo ppm||Mo Lbs (x1000)||Grade Pb %||Pb Lbs (x1,000)||Grade Zn %||Zn Lbs (x1,000)|