The Joanna JD mineral prospect is located 1.6 kilometres south-southeast of Mount Gordonia at the headwaters of a west-flowing tributary of Bell Creek. The prospect is 290 kilometres north of Smithers. It lies within the Omineca-Cassiar mountains in the north-central portion of the Toodoggone gold camp.

The Joanna JD prospect is situated within a Mesozoic volcanic arc assemblage which lies along the eastern margin of the Intermontane Belt, a northwest-trending belt of Paleozoic to Tertiary sediments, volcanics and intrusions bounded to the east by the Omineca Belt and to the west and southwest by the Sustut and Bowser basins.

Permian Asitka Group crystalline limestones are the oldest rocks exposed in the region. They are commonly in thrust contact with Upper Triassic Takla Group andesite flows and pyroclastic rocks. These Takla rocks have been intruded by plutons and other bodies of the mainly granodiorite to quartz monzonite Early Jurassic Black Lake Suite and are in turn unconformably overlain by or faulted against Lower Jurassic calcalkaline volcanics of the Toodoggone Formation, Hazelton Group.

The dominant structures in the area are steeply dipping faults which define a prominent regional northwest structural fabric trending 140 to 170 degrees. In turn, high angle, northeast-striking faults (approximately 060 degrees) appear to truncate and displace northwest-striking faults. Collectively these faults form a boundary for variably rotated and tilted blocks underlain by monoclinal strata.

The oldest rocks observed at the Joanna JD prospect are light to dark green porphyritic or massive andesitic flows and pyroclastics of the Takla Group (Assessment Report 20671). These have been summarized as basaltic and andesitic flows and breccia, with minor limestone and argillite (Bulletin 86). Toodoggone volcanics are exposed on the southwest and west ridges of Mount Gordonia, immediately to the north and west.

Propylitic alteration is widespread throughout the area surrounding the Joanna JD prospect, predominantly affecting andesitic flows and tuffs. These zones are characterized by chlorite alteration of plagioclase, biotite and hornblende phenocrysts, accompanied by a strong increase in epidote and/or carbonate, pyrite and magnetite in the groundmass (Assessment Report 20671).

The Joanna JD prospect consists of a northwest-trending fault enveloped by a zone of intensely propylitically altered andesitic volcanics and hosting a mineralized quartz vein. The zone forms a bright orange-yellow gossan varying in thickness from 1 to 6 metres and has a surface exposure of 15 to 20 metres, appearing to pinch-out at higher elevations. No sulphides other than pyrite were observed.

In 1986, a grab sample (TA-86-0002) of quartz and malachite assayed 0.79 gram per tonne gold, 5.9 grams per tonne silver and 0.777 per cent copper (Assessment Report 15338).

In 1988, two chip samples (18451 and 18452) of quartz veining with minor pyrite and malachite, located near the top of the hill to the south, yielded 0.19 and 0.16 gram per tonne gold with 0.043 and 0.088 per cent copper over 0.50 and 1.00 metre, respectively (Assessment Report 18536).

Several samples were taken from this zone in 1990 with the following assay results. Sample JD-032, a 50-centimetre chip sample including 15 centimetres of quartz vein, analysed 7.22 grams per tonne gold, 2.9 grams per tonne silver and 0.1501 per cent copper (Assessment Report 20671). Sample JD-033, a chip sample over 1.0 metre, analysed 1.49 grams per tonne gold, 1.6 grams per tonne silver and 0.2431 per cent copper (Assessment Report 20671).

Also at this time, other mineralized samples included: grab sample JD-026 of andesite with quartz veinlets hosting chalcopyrite and pyrite, located approximately 100 metres to the north, which assayed 1.035 per cent copper over 0.15 metre; grab sample JD-030 of oxidized quartz veining with trace pyrite, located approximately 200 metres to the south east, which assayed 0.745 gram per tonne gold with 3.4 grams per tonne silver over 0.20 metre and grab sample JD-37 of gossanous and propylitic-altered andesite with quartz veinlets hosting disseminated chalcopyrite and pyrite, located approximately 200 metres to the southwest, which assayed 0.105 gram per tonne gold, 20.2 grams per tonne silver, 1.349 per cent copper, 0.069 per cent cadmium and greater than 2.00 per cent zinc over 0.70 metres (Assessment Report 20671).

Work History

The area has been explored on conjunction with the Joanna West (MINFILE 094E 175) occurrence and a completed exploration history for the Joanna property can be found there.