No abstract

[1] The cathodoluminescence (CL) of quartz from ore, stockwork, veins, and interstitial fillings between lava pillows from the $2.7 Ga Noranda, Ben Nevis and Matagami volcanogenic massive sulfide (VMS) districts, Abitibi greenstone belt, has been investigated using the ''hot cathode'' technique (HC1-LM system) to assess the potential of these various sample types to host primary, seafloor VMS-related fluids trapped as inclusions in minerals with primary depositional morphologies. The CL responses indicate that the various quartz types are of hydrothermal origin, and are therefore a potential host for primary hydrothermal fluid inclusions. Most notable is a transient (t < 120 s) blue CL, characteristic of hydrothermal quartz, observed in most samples. CL characteristics are similar over $250 km indicating coherent, nonrandom behavior. Furthermore, in ore and stockwork material from the Matagami and Noranda districts respectively, CL reveals primary concentric growth zoned quartz that predates pulses of sulfide deposition-clear evidence that the quartz is undeformed and directly related to VMS mineralization. These growth zones are not apparent in transmitted light. In addition, ore and stockwork quartz commonly show a very unstable (t < 30 s) yellow CL coincident with microfractures and grain boundaries, defining areas affected by secondary hydrothermal activity. In ore from Matagami, local zones of nontransient brown CL may reflect strain zones associated with the deformation and recrystallization of the massive sulfide mound and indicate that such modifications can be recognized and are minor in the investigated cases. CL clearly reveals pseudo-hexagonal, apparently zoned structures in sulfidemineralized breccia pipe quartz from the Ben Nevis area. These structures and their host quartz, characterized by a very unstable (t < 20 s) bright yellow CL, are interpreted as recrystallized quartz that has undergone rapid growth from a strongly supersaturated solution and noncrystalline precursor. The CL also clearly reveals colloform/crustiform textures indicative of open-space filling; these textures are not visible optically.