BUTLER Zn-Cu-Ag VMS PROPERTY
The Butler property consists of 77 claims located 30km west of Eagle’s Nest. Exploration on the property began in 2004 following the VMS discoveries at McFaulds Lake in 2002. MacDonald Mines worked on the property and identified 5 Zn-Cu deposits between 2004 and 2013. In 2016, Noront acquired a 75% interest in the property from MacDonald Mines. The property covers a folded sequence of interlayered intrusive and volcanic rocks within which four significant Zn-Cu rich VMS occurrences (Butler 1 through 4) have been discovered, along with low-grade Ni-Cu-PGE and vanadium mineralization within peridotite and ferrogabbro sills.
The Butler property covers over 12km of strike length of highly prospective VMS terrain where favorable geology, widespread alteration and structure coincide. It is our belief that the property possesses strong potential for the discovery of a significant VMS deposit.
Deposit Geology & Mineralization
The Butler property is situated within the Butler Assemblage (ca. 2828Ma) which contains the oldest known geological units in the ROF. Regionally, the property overlies a doubly folded synform with prominent western and eastern limbs (figure 1) cored by a younger tonalite body of the same age as the footwall tonalite at Eagle’s Nest. The northern margin of the synform terminates against the Webequie Fault where both fold limbs have been dragged into this regional dextral shear zone.
All four of the significant VMS occurrences occur along the western and northern limb of the Butler property (figure 2) where volcanic units dip sub-vertically and young to the east and south, respectively.
Here the stratigraphy is floored locally by ultramafic flows (the only recorded komatiite in the ROF) and laterally extensive stacked ferrogabbro sills injected into a mafic to felsic volcanic sequence which progresses upwards into interlayered felsic to intermediate tuffs with lesser basaltic units.
Zn-Cu rich VMS mineralization is associated with these upper felsic tuffaceous units where strong hydrothermal alteration assemblages of biotite+/-anthophyllite-cordierite-chlorite-garnet is documented in footwall lithologies to the inferred hydrothermal vents.
Of the four Butler VMS occurrences, Butler 3 and 4 have the thickest intersections of Zn-Cu mineralization and will be the initial focus of future VMS exploration on the property.
Table 1 below highlights some of the better intersections through the four occurrences.
|Occurrence||DDH||From (m)||To (m)||Width (m)||Zn (%)||Cu (%)||Ag (g/t)|
|Butler 3||and including||205.5||220.0||16.0||2.2||1.0||9.6|
The geology of the eastern limb is similar in some respects but much more mafic dominated, lacking the extent of felsic volcanism. From west to east, the geology is dominated by mafic volcanic and meta-sedimentary units, locally with low-grade VMS mineralization, intruded by gabbro and ferrogabbro sills. To the east a panel of interlayered ultramafic and gabbroic sills intrude the volcanic sequence and locally contain wide intercepts of low grade Ni-Cu-PGE mineralization associated with peridotite bodies. Ferrogabbro and gabbro sills dominate the eastern margin of the eastern limb and locally contain magmatic V-Ti mineralization associated with cumulate ilmenite-magnetite layering. Regional facing directions have yet to be determined for the eastern limb and may have a significant impact on the interpreted structural model.
Should the eastern limb young to the west, the Butler assemblage may be interpreted as a synform with repeated stratigraphy on both fold limbs. Alternatively, if the eastern limb is shown to face eastward, a thrust model may be invoked whereby older Butler assemblage rocks in the eastern limb may have been thrust overtop younger (possibly Muketei age?) VMS stratigraphy of the western limb. Age dating of the Butler Assemblage has constrained only the eastern limb at circa 2828Ma. No age determinations have yet been made of the western limb.