The North Junction zone of the Galore Creek deposit is located at the headwaters of Galore Creek, a northerly flowing tributary of the Scud River, some 85 kilometres south-southwest of Telegraph Creek.
At least twelve alkalic porphyry copper-gold deposits are known to occur within the Galore Creek syenite complex. This complex comprises a series of Late Triassic to Early Jurassic orthoclase-porphyry syenitic bodies which have intruded coeval Upper Triassic Stuhini Group volcanic rocks and related sediments. Faults which offset and segment the intrusive rocks and a sub-horizontal fracture cleavage are the two main structural elements in the syenite complex. The complex is roughly 5 by 2.5 kilometres in area.
The deposits are hosted primarily by highly altered potassium- enriched volcanic rocks and pipe-like breccias adjacent to syenite dikes and stocks. Typically, the deposits are manto-shaped and have a north to northeast trend related to the syenite contacts and zones of structural weakness.
The syenite complex is made up of four intrusive phases that are most closely associated with the copper deposits. Six other phases are recognized but are peripheral to the Central zone deposit. The copper-bearing rocks near the syenite intrusion are extensively metasomatized, recrystallized and locally brecciated. These may include pyroclastic and intrusive breccia, trachyte, phonolite, lithic tuff, crystal tuff, pyroxene basalt, pyroxene andesite and minor sediments. These rocks have been converted to skarns and fenitic porphyroids so that original rock types are unclear. The term "hornfels" was frequently applied to these meta-volcanic rocks in the early stages of exploration.
Alteration and mineralization are contemporaneous and spatially overlap. The hydrothermal system was extensive and the resultant alteration led to the formation of large gossans. Potassic alteration consisting of potassium feldspar, titanium biotite and magnetite have converted the syenites and volcanic rocks to pink, white and orange rocks composed mostly of orthoclase. Alteration of pyroxene, hornblende and biotite to assemblages of chlorite and calcite plus/minus albite and epidote characterizes the propylitic zone, best developed in the syenitic rocks. Calc-silicate alteration consisting of abundant garnet, diopside, epidote, albite and anhydrite is an unusual feature of the complex. Garnet replaces up to 50 per cent of the metavolcanic rocks and infills breccias near the northern end of the Central zone breccia pipe but is generally absent from the other deposits. However unusual this metasomatic overprint is, the distribution of sulphides, precious metal and magnetite is considered consistent with the expected zoning pattern for alkalic porphyry deposits.
Barr (CIM Bulletin July 1966) describes the North Junction deposit as follows: "The North Junction deposit outcrops in the northwest part of the Complex, approximately 1.6 kilometres distant from, and 300 metres higher in elevation than the uppermost exposures of the Central Zone. The deposit is localized along the contact between two porphyritic units of the Complex, and, like the Central Zone, trends slightly east of north and dips steeply to 60 degrees northwest. Sulphide mineralization includes chalcopyrite, bornite and pyrite, which occur principally as disseminated replacements associated with hydrothermal biotite and potash feldspar alteration. The metavolcanics, which host the mineralization of this deposit, also contain abundant anhydrite, commonly 10 per cent or greater. It occurs as veins or as a replacement mineral. Near surface it has been converted to gypsum."
Work conducted since discovery in 1955 outlined a significant copper-gold-silver mineralized zone in the Central Zone and identified several satellite mineralized zones, most importantly the Southwest, North Junction and Junction Zones.
No work was done between 1968 and 1972. In 1972, Hudson Bay became operator and in 1972 and 1973 an additional 25,352 metres of diamond drilling was completed in 111 holes. This work concentrated on the mineralization in the Central and North Junction Zones.
In 1990, a total of 219 pre-1990 drill core pulps and/or core samples were analyzed for gold by Mingold Resources. This work was undertaken because past operators had never properly evaluated the gold content of various zones on the property. The holes selected for gold assaying are located in three separate zones on the property: North Junction, Saddle and Southwest Zone.
In 1991, diamond drilling by Kennecott Canada Inc of three holes was successful in determining the limited north strike potential of the North Junction Zone. This volcanic hosted copper-gold zone had been tested by drilling in the 1960s and early 1970s. This work delineated a mineralized zone which strikes N20E and dips northwest at angles between 20 and 60. The zone has been traced for a length of 300 meters and a down dip thickness of 250 meters and has an average width of 60 metres. Drillholes GC400, 402 and 403 were designed to test the northern strike extension of the North Junction Zone. GC403, the last hole designed to test for the northern extension of the North Junction Zone, intersected a thick sequence of host volcanics comprising intermediate composition lapilli and ash tuffs. A 57 metre intercept from 187 metres to 244 metres averaged 0.51 percent copper and 0.253 gram per tonne gold (Assessment Report 21900).
In 2007, the Little Creek prospect was generated from geophysical and drill core data. The location has similar geophysical properties as Southwest and West Fork zones and it is on a low resistivity trend with the North Junction zone. Only one hole was drilled to test and GC07-0774 intersected small 3 to 4 grams per tonne gold intervals and a Southwest-like breccia (Assessment Report 29742).
In 2008, Galore Creek Mining Corporation (GCMC) completed nine diamond drill holes totalling 2,049.58 metres. The main objectives of the drill program were to obtain ABA (Acid Base Accounting) data in the Central, Southwest, North Junction and Junction pits, to confirm legacy grades in the Junction pit, and to collect metallurgical data in the Central pit.
The North Junction zone contains a 1992 mineral resource of 7,700,000 tonnes grading 1.50 per cent copper at a cut-off of 0.40 per cent copper (CIM Special Volume 46, page 642). Specific information on reserves and resource for various zones is not published and may be part of the overall reserves published in 2011. Refer to the Central Zone deposit (104G 090) for further details of the Galore Creek deposits. Further details of a common work history and 2011 reserves and resources are given.
AMEC reports five zones as being modelled toward its 2011 Mineral Resource Estimate: the Central Zone (including the Bountiful deposit), Southwest Zone, Junction/North Junction Zone, Southwest Zone, and West Fork Zone. The Junction and North Junction zone have historically been separate and are treated as such for MINFILE.
Refer to the Central Zone deposit (104G 090) for further details of the Galore Creek deposits. Further details of a common work history and 2011 reserves and resources are given. Details of work history on specific zones (including the North Junction zone) are not readily available or easily broken out from the overall Galore property body of work.
