A reconnaissance of five silver-bearing veins between Schreiber, Ontario and Marathon, Ontario indicate that the Pb-Zn-Ag veins in this area are genetically related. The three veins of this type that were studied (the Deadhorse Creek North, Deadhorse Creek South, and Morley High Grade veins) have very similar mineralogies with freibergite as the Ag-bearing phase. A general paragenetic sequence was noted, from early massive sphalerite ± pyrite to later massive galena + sphalerite ± chalcopyrite ± freibergite.
Fluid inclusion studies on these three veins indicate low to moderate temperatures of formation (approximately 160-355 degrees Celsius), low salinites, and some form of NaCl-KCl-MgCl2-H2O fluid compositions.
The veins are not, as previously suggested, related to intrusion of the Coldwell Alkaline Complex since one vein cuts the thermal aureole of the Complex and another is over 60 km away from it. The veins may, however, be rift related with much of the data presented here lending support to this hypothesis.
The other two veins studied are of indeterminate origin. They are not directly genetically to the Pb-Zn-Ag veins since they have much different mineralogies. The Mogatherium vein contains a complex Cu-Pb-Bi-Te-Ag-S ore mineral assemblage, while only pyrite was found in the Gold Range samples analyzed.
Fluid inclusion analysis yielded poor results for these veins and thus their mode of formation is still a point of conjecture. They may be related to the intrusion of the Terrace Bay Batholith, with which the veins are spatially associated.