Underexplored Parcel in a World-Class Belt
The property has a set of geological characteristics that suggest high potential to discover a large-scale IOCG or porphyry copper deposit. This includes a strong argillic–silica hydrothermal alteration system over 15 square kilometres, numerous specular hematite-silica hydrothermal breccia structures, silica–pyrite altered monzonite porphyry bodies, a subparallel system of andesite porphyry dikes and several north-northwest to northeast trending fault zones that are parallel to the Atacama and Chivato crustal scale fault zones, which are important regional controls on copper mineralization.
A magnetic survey over the Margarita project shows a circular magnetic low surrounded by magnetic highs beneath the hydrothermal alteration system. The magnetic highs are associated with less altered, andesitic to rhyodacitic rock units that may correspond to dome structures, which are considered to be part of the mineralizing intrusive hydrothermal system that characterizes the property. The lower magnetic responses correspond to strongly altered units that include various porphyritic and breccia bodies as well as andesitic dykes and provide a clear large-scale 1.5 km by 1.5 km geophysical target within the property boundaries.
An IP survey at the Margarita project consisted of a total of 49-line km with lines spaced every 250 m. The results of the program have demonstrated two north-northwest trending chargeability anomalies that are approximately 3 km by 500 m in dimension at a threshold of 30 millivolts, which is consistent with the presence of sulphide minerals. Importantly, these chargeability anomalies spatially overlap with resistivity lows that are consistent with hydrothermal alteration and form the basis of geophysical targeting at the project.
Recent Exploration/Drill Targeting
Torq has identified three primary target areas across the project area based on the completion of 1:2000 scale geological mapping, soil (pXRF) and rock geochemical sampling programs, and ground-based induced polarization and magnetic geophysical surveys. Geologically, the property can be broadly defined by a large-scale intrusive complex that is interpreted to be directly associated with copper-gold mineralization and by an overlying volcanic sequence that is mineralized along discrete north-northwest structural trends
The southern Margarita – Cototuda target area is characterized by a large scale 1.5 kilometre (km) by 500 m copper in soils (pXRF) geochemical anomaly that is hosted within a largely dioritic to dacitic intrusive complex. Copper oxide mineralization is observed both within various intrusive phases as disseminated stockwork vein zones and concentrated along the north-northwest trending Margarita and Cototuda structural trends, where shallow historical drilling has reported copper oxide mineralization within 100 m of surface (historical drilling not compliant with National Instrument 43-101). Alteration associated with the broad zone of mineralization is characterized by strong sericitic-hematite alteration with lesser potassic alteration observed within the Cototuda area.
Rock sampling within the alteration zone from this area has identified copper oxide mineralization with values up to 1.68% copper and up to 0.99 g/t gold within silica-hematite breccia bodies that occur parallel to the strong north-northwest structural trends observed within the target area. Rock sampling highlights are presented below in Table 1. Finally, the southern target areas are characterized by chargeability highs indicating the presence of sulphide, resistivity lows indicating hydrothermal alteration and magnetic anomalies that may be related to magnetite-copper sulphide mineralization.
The northern target areas are situated along the extensions of the Margarita and Cototuda north-northwest trending structures and are defined by copper in soils (pXRF) geochemical anomalies. The Cototuda North anomaly is hosted entirely within the volcanic sequence that overlies the mineralized intrusive bodies observed in the southern target area. Torq’s technical team believes that there is strong potential to encounter mineralized intrusive bodies within this structural corridor based on the presence of chargeability highs, indicating the potential for sulphide mineralization, and resistivity lows, indicating the presence of hydrothermal alteration at shallow depths of approximately 150 – 300 m. The Margarita North anomaly is hosted at the sub-horizontal contact between the volcanic sequence and underlying rhyodacitic and diorite intrusions. Strong sericite-clay-tourmaline alteration has been observed at the base of the intrusive bodies, passing upward to silica-hematite-pyrite alteration located within the volcanic sequence. In addition, strong resistivity lows, indicating intense alteration, are situated at shallow depths of approximately 150 m.
Table 1: Margarita – Cototuda target area selective rock sampling highlights
|Sample ID||Cu (%)||Sample ID||Cu (%)||Sample ID||Au (g/t)||Sample ID||Au (g/t)|
Historical Copper Oxide Drilling
Out of the 39 drill holes with known assay results available that define the copper oxide mineralization, 13 are within the land package of the Margarita - Cototuda agreements, totaling approximately 1500 m. The historical drill holes are located in the southwestern corner of the property in a zone of strong hydrothermal alteration. Copper oxide mineralization with reported grades of 0.2 – 0.6% copper were encountered to 210 m vertical depth with drilled widths ranging between 30 – 120 m. Importantly, none of these drill holes encountered primary copper sulphide mineralization.