Universal Copper Ltd. ("Universal Copper" or the "Company") (TSX Venture: UNV) (Frankfurt: 3TA2) has completed a comprehensive 3-Dimensional (“3D”) geological modelling initiative to establish the controls on the distribution of higher-grade mineralization at the Company’s flagship Poplar Copper Deposit (“Poplar”) which will be used to direct ongoing exploration drilling at Poplar in 2023. This is the first time a 3D geological model has been created for the Poplar deposit and it demonstrates the project has considerable exploration upside potential:
- Higher-grade copper-molybdenum-gold-silver mineralization is focused along porphyry intrusion contacts; these contact zones have not been the focus of historic exploration drilling.
- The deposit is open at depth, toward the north and toward the east
- Numerous higher-grade targets (porphyry intrusion contacts, step-outs, step-downs, and down-plunge target zones) are present both internal to and adjacent to the Poplar Resource suggesting there is excellent potential to increase the grade and tonnage of the resource.
- The Poplar deposit is one of the few remaining road accessible porphyry copper-molybdenum-gold-silver deposits in British Columbia with the potential for grade and resource expansion as well as the potential for discovery of additional new porphyry centers within the large land position.
Clive Massey, Universal Copper’s CEO, stated: “The newly recognized geological controls on copper-molybdenum-gold-silver mineralization are the result of a dedicated 8-month 3D geological modelling effort based on logging/relogging of drill core, lithogeochemistry, mineralization zonation, and newly acquired alteration data. This campaign has yielded a heighten understanding of the distribution of higher-grade mineralization at Poplar.” Mr. Massey added, “Furthermore, the work has established a predictive modeling framework which will be central to targeting exploration drill holes in 2023 where we will continue to add high-grade tonnes to the Poplar deposit.”
Recent high-grade intercepts include drill hole 22-PC-138 which cut 214.4 meters @ 0.500% CuEq* (0.401% copper, 0.15 g/t gold and 1.27 g/t silver) as well as drill hole 22-PC-137 that contained 0.535% CuEq* (0.353% copper, 0.14 g/t gold and 5.91 g/t silver) over the last 216 metres of the hole (see news releases from July 12, 2022, and May 31, 2022). These recent drill results indicate copper-molybdenum-gold-silver mineralization in new search spaces is extensive, continuous, and controlled by the host rock geology. Prior to this year, a 3D geological model had not previously been developed for the Poplar deposit. The new model will be used to target higher grade mineralization and to increase the size of the deposit through diamond drilling going forward (see below).
New 3D Geological Modeling of the Poplar Resource
Systematic geological modeling was done at the Poplar deposit to identify the controls on copper-molybdenum-gold-silver mineralization, establish the 3D mineral deposit geometry, and to evaluate the distribution and continuity of higher-grade mineralized shoots (Fig. 1). A first pass core re-logging initiative using historical drill core at Poplar demonstrated: 1) higher grade shoots and zones of the deposit are controlled by intrusive, volcanic, and sedimentary contacts, and 2) the overlap in the distribution of mineralization-distal (quartz-sericite-pyrite) and mineralization-proximal (K feldspar and biotite) alteration assemblages suggest the deposit is the product of two or more overlapping copper-molybdenum-gold-silver porphyry systems (telescoping). Based on this new understanding, the 3D modeling work was constrained by updated lithogeochemical characterization of rock types, modeling of rock type distribution, and by the zonation of alteration minerals and metals.
Lithogeochemical Rock Classification
Previous attempts to construct a 3D geological model for the Poplar deposit have been hindered by a lack of consistently defined key rock units. Universal Copper has utilized the historical multi-element geochemical drill core database at Poplar to generate a revised host rock classification scheme based on immobile elements (Ni-Th and Zr-Ti) which can be used to “fingerprint” rock types and generate an internally consistent rock classification scheme (Fig. 2).
Lithological modeling based on the 2022 core relogging work as well as newly defined lithogeochemical units was completed to characterize the Poplar deposit architecture and to constrain the controls on mineralization. The oldest rocks at Poplar consist of layered sedimentary and volcanic rocks that dip shallowly to moderately toward the east and are intruded by the C Porphyry (mineralized), followed by the X Porphyry (mineralized) and then by a series of sills, dikes, and other post mineral intrusions (Fig. 1). The X porphyry occurs as vertical bodies internal and marginal to the C porphyry. Comparing the orientation of the layered rocks (sedimentary and volcanic) to the orientation of the X Porphyry suggests the deposit may be tilted toward the east, imparting a steep westerly plunge to the magmatic-hydrothermal system. The newly recognized geometry for X Porphyry contacts is a first-order control on high-grade mineralization.
Alteration modeling at Poplar was conducted using 12 representative drill holes across the deposit where higher grade mineralization is present. A Terraspec was used to generate Short Wave Infrared (“SWIR”) data to quantify the alteration mineralogy at regular intervals down the drill holes. Mineralization-distal alteration zones (quartz-sericite and chlorite-epidote) overlap with mineralization-proximal alteration zones (potassium feldspar-biotite) suggesting the deposit may be a product of two or more overlapping porphyry-type mineralizing events (telescoping; Fig. 3). Telescoped porphyry deposits can have mineralized root zones, as well as multiply overprinted high-grade zones with elevated vein density.
The Universal Copper technical team has improved the understanding of the distribution of higher-grade mineralization at Poplar and is continuing to build out a predictive modeling framework. The new 3D geological framework will be directly applied toward upcoming drill campaigns, which are being designed to test the newly recognized search spaces both inside and adjacent to known mineralized volumes. Multiple high-priority target zones have been identified and the team anticipates further refinement of the exploration framework as new datasets come into focus from 2023 drilling.