Announcement • Sep 01
Lefroy Exploration Limited Provides Progress Report for the Two-Hole Diamond Drill Program Underway At the Burns Au-Cu Intrusion-Related Mineral System
Lefroy Exploration Limited provided a progress report for the two-hole diamond drill program underway at the Burns Au-Cu intrusion-related mineral system. Burns is within the Company's wholly owned Eastern Lefroy Gold Project, located 70km southeast of Kalgoorlie. The first hole, LEFD006, has been completed to a downhole depth of 1245.8m, with the second hole, LEFD007a, located 240m to the south now underway. Burns is a new and unique style of an intrusion-related, gold (Au)-copper (Cu)-molybdenum (Mo)-silver (Ag) mineral system, hosted by Archean age rocks in the Eastern Goldfields Province (EGP) of Western Australia. LEX is aiming to advance the understanding of the scale and genesis of the system through this deep drilling program. The gold, copper, silver (and lesser molybdenum) mineralisation, hosted by multiple, diorite-porphyry intrusives and high-magnesium basalt, are considered by the Company to be a new and unique style of gold-copper mineralisation near Kalgoorlie, located within a land holding dominated by LEX. The initial 570m of LEFD006 (Figure 1) intersected a wide downhole interval of predominantly high-Mg basalt (refer LEX ASX release 1 August 2022). The basalt is variably epidote-biotite-magnetite-altered with localised hydrothermal breccia intervals, gypsum veins and narrow cross-cutting porphyry intervals. Mineralisation within the basalt interval includes fracture-fill native copper (Figure 4), with vein and/or fracture-fill chalcopyrite, pyrite, chalcocite and molybdenite (refer LEX ASX release 1 August 2022). This interval of altered basalt has increased the lateral extent of the copper mineralised Western Basalt zone by approximately 250m to the west. The alteration assemblage supports a large hydrothermal alteration cell which is consistent with an intrusion related system. Within this basalt unit, a new 40m interval (400m-440m) containing multiple cross-cutting diorite intrusives (porphyry) was intersected (Figure 1). The interval contains predominantly potassic-altered hematite and biotite, with associated pyrite-chalcopyrite and trace molybdenite mineralisation. (Figure 5). The chalcopyrite is stringer or fracture fill (Figure 5) and is most abundant between 415-440m (refer Figure 4 Lex ASX release 1 August 2022). This intersection of diorite porphyry is separate to the main porphyry (that is deeper) and has created an additional target for follow up drilling (Figure 1). From 510m to 710m downhole, four texturally different and variably altered diorite porphyry units were intersected. Importantly this contains the Burns Alkalic Porphyry (BAP) unit, which is interpreted by the Company to be a control on gold and copper mineralisation. The porphyry units are now grouped to form the Central Porphyry (Figure 1). Below the Central Porphyry, from 710m to 905m, a broad zone of biotite-altered, calcite-veined, sheared basalt was intersected. This 195m downhole interval contains multiple, massive porphyry units that are variably pyrite altered (Table 2) and is termed the Deformation Zone (Figure 1). Both the sheared basalt and porphyry are crosscut by later pink calcite veins, some containing rare anhydrite (calcium sulphate) and chalcopyrite (copper sulphide). A new zone of sulphide-altered, fine-grained sediment (siltstone) and porphyry was intersected from 905m to 1034m. This 33m interval of siltstone is variably pyrite-pyrrhotite altered (Figure 6). Below 1034m, to the end of hole (EoH), is an interval of weakly altered, massive basalt, which includes one porphyry unit. This 211m downhole interval is termed the Eastern Basalt and marks the eastern limit of the Burns system. The completion of LEFD006 has established four broad geological domains, each with contrasting alteration and geology, which now demonstrate that the Burns system has a width of at least 600m, with the western limit yet to be defined. The hole has also established continuity to the multiple porphyry units, approximately 300m below the existing drilling on the baseline section (0N) and to 1000m vertically below surface. The system remains open at depth and along strike (Figure1). Multiple sample batches from the drillhole have been submitted to the laboratory for gold, copper, and multi-element analysis. The interval from 400m to 480m that had significant chalcopyrite content (Figure 5) has been prioritised for assay, with results expect in late September. Due thedelay at the laboratory in Perth, subsequent results are not expected until October and November. The second diamond hole, LEFD007a, is currently underway and is at 231.07m downhole. The hole has a planned depth of 500m and is designed to intersect the down-plunge extent of a modelled high-grade Au Cu zone defined by holes LEFR260 & 320 (refer to long section Figure 3). The collar position of this hole is located 240m south of the baseline (0N) section (Figures 2 & 3). Interrogation of Company drill data including gold, copper, silver, and molybdenum 3D metal models highlighted a large, northwest trending, gently southerly plunging mineralised (Au, Cu, Ag, ± Mo) shell. Included within this shell is a higher-grade, northerly trending Au-Cu component (Figure 3), which provided the model to design and plan LEFD007a. As of 29 August, LEFD007a had intersected a 177.2m interval of the Western Basalt, which is the same unit as seen in the upper part of LEFD006. The fresh basalt interval is variably epidote-chlorite altered, with localised gypsum and calcite veining. Within the altered basalt are two 30m downhole intervals (149.15m to 184m and 205.56m to 230.77m) containing blebs of native copper that often occur with gypsum veins with associated magnesite (refer figures 7, 8, and 9 and Table 3). From 207.24m to 231.07m the basalt is magnetite-altered, occurring as veinlets, blebs, or breccia matrix. The increasing magnetite content (Table 3) supports the Company's view that the contact of the main porphyry target-zone is in the near vicinity. The anticipated target depth of this contact is approximately 350-450m downhole that is expected to be intersected later this week. This new, wide downhole interval of altered basalt has increased the lateral extent of the copper- mineralised Western Basalt zone 240m to the south of the baseline section and is open along strike and down dip. The alteration assemblage continues to support and expand an interpreted large, zoned, hydrothermal-alteration system around the diorite intrusions. LEFD007a is expected to be completed in early September, with assay results anticipated in November, dependent on laboratory turnaround.