THUNDERBIRD FAULT


The Thunderbird fault, located 14km northeast of Eagle’s Nest, cuts the 12km long x 3km wide layered Thunderbird intrusion (figure 1) where past drilling has identified wide intervals of Fe-Ti-V mineralization in cumulate magnetite-ilmenite layers. The intrusion comprises alternating layers of strongly magnetic oxide-gabbro with non-magnetic gabbro.

Figure 1: Geology (above) and 1VD magnetics (below) of the Thunderbird Fault.

Figure 1: Geology (above) and 1VD magnetics (below) of the Thunderbird Fault.

Based on the airborne magnetic signature the intrusion is interpreted to be a doubly plunging synform with fold closures on its northeast and southwest limbs. A distinct magnetic low (figure 1, 3) measuring 2.7km long x 100-600m wide cuts the intrusion roughly in half and is interpreted to be an extensional fault (the Thunderbird Faut) parallel to the axial plane of an open fold in the intrusion marked by a ~30⁰ change in the strike of oxide layering. The fault is speculated to reflect a zone of magnetite destruction via ascending hydrothermal fluids. Sub-parallel faults with sinistral offset are observed in the magnetic pattern 1.5km southwest of the main Thunderbird fault (figure 3).

Initial interest in the area for gold is the result of a narrow gold intersection 1km south of the Thunderbird fault where NOT-09-2G24 returned 6.75g/t Au over 40cm within oxide-gabbro. Mineralization consists of thin cross-cutting quartz-sulfide veinlets (figure 2) with both extensional and shear fabrics, which show textural evidence for sulfidation of primary magnetite in a process similar to many BIF-hosted gold deposits worldwide. Given the proximity of this intersection to the mag-destructive Thunderbird fault, in 2020 Noront decided to perform soil sampling over the fault to test for gold anomalism. The results, shown in figure 3, are highly encouraging with 84% of samples collected along the fault returning anomalous gold signatures, compared with only 21% of samples collected perpendicular to the fault.

Noront considers these results to be an excellent early indicator of gold fertility within the Thunderbird Fault and plans to follow-up these results with additional soil sampling, ground geophysics and drilling.

Figure 2: Above: Close-up of quartz-pyrite-pyrrhotite veinlets replacing magnetite layer in oxide gabbro (NOT-09-2G024, 345.6m depth). Below - view of extensional and shear quartz veinlets cutting oxide gabbro (NOT-09-2G024, 346.0m depth).

Figure 2: Above: Close-up of quartz-pyrite-pyrrhotite veinlets replacing magnetite layer in oxide gabbro (NOT-09-2G024, 345.6m depth). Below – view of extensional and shear quartz veinlets cutting oxide gabbro (NOT-09-2G024, 346.0m depth).


Figure 3: Results of 2020 soil sampling over the Thunderbird Fault zone.

Figure 3: Results of 2020 soil sampling over the Thunderbird Fault zone.

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