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Exploration History and Drilling
1999: Mansfield Minerals Inc. prospected the Rio Grande area collecting 210 surface rock samples which defined and delineated a zone of Cu-Au mineralization. A simplified sketch alteration map was generated showing the different alteration types and exploration targets in the 2 x 2 km area.
2000: Mansfield signed a joint venture agreement with Teck and the latter had the opportunity to earn a 55% interest and was the manager of the exploration project. In the following months Teck completed geological mapping at different scales and additional surface rock samples were collected which defined new mineralized zones. An orientation soil survey was completed, some hand trenches were dug and channel samples collected along their length; these assays returned encouraging results.
2001: Quantec Geoscience Argentina conducted ground magnetic and Induced Polarization (IP) geophysical surveys. A trenching program was undertaken in order to test the Cu-Au anomalies generated by the soil sampling and prospecting programs. A diamond drilling program consisting of 11 holes, totalling 3,220.6 m was completed. Additional work on the property was recommended; however, Teck terminated its exploration efforts in Argentina in early 2002, and returned the property to Mansfield.
2004-2005: In June 2004, Mansfield and Planet Ventures Inc. (predecessor of Antares) signed a joint venture agreement in which Antares became the operator of exploration on the property. Antares began actively exploring the property in October 2004 and completed the first phase of this work in May 2005.
2005-2008: Antares completed a gradient array ground IP survey, extensive surface trenching and sampling, an enhanced topographic survey, and numerous additional drill holes.
2009: The global economic crisis forced Antares to put the Rio Grande project on hold while it focused on its Haquira Cu-Mo-Au project in Peru.
2010: Antares was officially sold to First Quantum for C$650 MM. At the same time, Antares then spun out the Rio Grande project along with C$5 MM in cash into a new company called Regulus Resources Inc.
2011: Regulus completed an aggressive exploration program which included a Quantec Titan 24 geophysical survey (IP. DC and MT), 15,025 m of drilling in 20 diamond drill holes, the first metallurgical work on the property and the first 43-101 complaint resource on the Rio Grande project. Regulus announces the discovery of a new high-grade Au-Cu mineralized zone in the Southwest zone.
2012: Regulus and its JV partner company Pachamama Resources Inc. consolidated the Rio Grande project ownership through a plan arrangement which merged the two companies (retaining the name “Regulus”). The merged company raised C$27 MM and conducted a 24,970 m, 28 drill hole program which focused primarily on a new high-grade discovery in the southwest zone. Regulus also completed a single drill hole on the edge of a large Au soil anomaly in the Cerro Cori area, which is located 2 km east of Rio Grande.
2013-2014: Regulus conducts a follow-up 1,200 m, 4 drill hole campaign at Cerro Cori. During the second half of 2013, an extensive core re-logging campaign was initiated at Rio Grande, which included detailed geological descriptions for all 74,210 m drilled, extensive petrographic-staining work, integration of all geophysical information, development of an updated geological model, and definition of new drill targets.
2014 to 2018: Activities at Rio Grande were suspended from 2014 as Regulus focused on the AntaKori Cu-Au project in Peru. In 2018 the Rio Grande project was one of the assets spun out from Regulus into the new Argentina-focussed company Aldebaran.
2019-Present: No material work was performed on the Rio Grande project since the beginning of the year commencing July 1, 2020. The Rio Grande project is under review to evaluate potential synergies with the nearby Lindero Mine where Fortuna Silver entered into commercial production in Q1-2021.