NEW GOLD OCCURRENCES IN THE CLARENCE STREAM AREA OF SOUTHWESTERN NEW BRUNSWICK : ANOMALY “A” - DISTAL DEPOSITS OF AN INTRUSION-RELATED GOLD SYSTEM?

Significant gold occurrences located in proximity to Devonian granitoid intrusions have been discovered in the Clarence Stream area of southwestern New Brunswick. The newly discovered zones at Anomaly “A” are hosted by polydeformed Ordovician turbidites of the St. Croix Terrane, within the Northern Appalachian Gander Zone. The gold-bearing mineralized zones occur within shallowly to locally moderately dipping, brittle, shear zones and are defined by stockwork, massive, and multiply brecciated quartz-sulphide veins enveloped by altered wallrock. Gold occurs mostly in veins but also in altered wallrock and is associated mainly with arsenopyrite, pyrrhotite, pyrite, stibnite and other antimony-bearing sulphides. Stratigraphic top reversals and fold crests that have been observed in many drill core sections are interpreted to be the result of fault-related folds and polyphased folding. These mineralized shear zones may be associated with regional structures occurring in the vicinity of Anomaly A.

The gold mineralization is accompanied by discrete, visible, alteration of the originally grey coloured argillite and greywackes. The outer/weaker, greenish grey, alteration and the proximal/intense, buff-coloured alteration are distinguished mainly by the relative intensity of both dissolution of quartz and replacement of original dark grey detrital opaque minerals by white to buff leucoxene (?). In addition, the outer and proximal zones characteristically contain chlorite and sulphides, respectively. Wallrock alteration is characterized by immobility of Ti and Al, removal of Si, Na, Ca, Sr and possibly Fe and Mg and addition of S, As, Sb, and Au. Even the visibly unaltered samples contain As and Sb in excess of 100 times world averages indicating more extensive alteration than macroscopically discernable.

The interpreted vein paragenesis includes 1) early veins syn- and post- D1; 2) cross-cutting, multiphase, vuggy quartz-sulphide gold-bearing veins associated to late D2 high strain zones; and 3) late veinlets containing base metal sulphides and fluorite which are widespread and cross-cut gold veins. These late veins constrain the upper time limit of gold mineralization to Late Devonian based on their association with nearby plutons of that age.