The Galore Creek region is mainly underlain by Upper Triassic volcanics and sediments of the Stuhini Group. This area is flanked to the west by Juro-Cretaceous quartz diorite to granodiorite of the Coast Plutonic Complex. Middle Triassic sediments with Permian sedimentary and metamorphic rocks are at the north and east limits of the area. Permian limestone is the dominant rock. North trending faults define boundaries between Upper and Middle Triassic rocks and between Paleozoic and Triassic rocks. Strata is folded into a linked series of anticlines and synclines with west or northwest trending axes. Younger folds with north-northwest trending axes transect the earlier formed structure. Syenite (orthoclase porphyry) intrusions of Juro-Triassic Age disrupt the stratigraphy and structural trends. These intrusions form a series of dikes, sheets and stocks. Eocene Age intrusions of quartz monzonite form stocks and are the youngest rocks in the area.
The area of interest is underlain mainly by dark green Stuhini Group volcanics consisting of andesitic tuffs with subordinate volcanic breccias and flows. Flows of dark green basalt, which grade to augite porphyry basalt, are interbedded with andesites. Minor sedimentary beds are also interbedded with the volcanics. They consist of calcareous argillites and conglomerates with some beds of pure limestone. Dikes and sills of medium to coarse-grained syenite porphyry cut area rocks. The intrusives, up to 6.1 metres wide, strike north and dip 50 to 90 degrees west. The dikes are considered to be related to the syenite porphyry stocks of Stikine Copper's porphyry copper deposit a few kilometres to the south.
Weak pyrite-epidote alteration occurs in the volcanics. Strong alteration consisting of feldspar-amphibole-garnet-epidote is often accompanied by chalcopyrite and sometimes magnetite. Calcareous beds may be involved with this process. Magnetite also occurs as a primary constituent of the volcanics. The syenite porphyry dikes are weakly to moderately altered to chlorite and pink potash feldspar. Weak to moderately disseminated chalcopyrite occurs where feldspathization is strongest. Traces of chalcopyrite are also found in the volcanics adjacent to mineralized dikes.
The best copper mineralization is associated with calc-silicate alteration in the volcanics. One 6 metre sample contained 0.23 per cent copper(Assessment Report 694). An 18 metre sample, which includes the 6 metre one, assayed 0.13 per cent copper.
Work History
The first recorded work on what is now the Grace claims was in 1964 when the area was staked as the “Stikine North Group” for the Scud Venture, an Asarco/Silver Standard joint venture. Geological mapping and a magnetometer survey were carried out that year (Assessment Report 592). An I.P. survey was carried out in 1965 and a single diamond drill hole was made but there are no logs available. The hole has been described as having intersected the Central Fault Zone and was weakly mineralized with pyrite and chalcopyrite. The IP survey outlined a 1 by 1.6 kilometre chargeability high flanking the Central Fault Zone and straddling the Grace 1 and Grace 2 claim boundary (Assessment Reports 688, 692). A rock chip sample taken from this area assayed 0.23 per cent Cu. over 6.1 metres. (Assessment Report 694).
The claims were allowed to lapse in the 1980s. Pioneer Metals Corporation staked the Grace 1 and 2 claims in 1987 and carried out ground programs from 1987 to 1993 concentrated on the Gale showing (Assessment Reports 18054 and 23050). A limited geological mapping and geochemical soil sampling program was performed in 1987 and 1991. An airborne magnetic and electromagnetic survey was flown in 1990 over the Grace claims totalling 163 kilometres (Assessment Report 20846) and some trenching and further soil sampling done in 1992. In 1993 there was a program of line cutting, geological sampling. The Gale showing was trenched with hand tools. Values of 0.19 per cent copper were obtained over a 6.0 metre chip sample. In 1997, 38 soil samples were taken on the Grace property by Pioneer. A remote sensing airphoto interpretation was done by Pioneer in 1999 Assessment Report 26071).
