Multiple episodes of fluid flow in base-metal deposits from southwest Scotland and Northern Ireland

Cathodoluminesence zones allow correlation of mineralizing and brecciation events in sulphide-bearing quartz veins from strata-bound base-metal deposi ts in the Southern Uplands of southwest Scotland and Northern Ireland. Ore- bearing veins are typically associated with NNW-SSE to NW-SE and E-W to NE- SW trending fractures and brittle fault zones. Two main ages of stratabound base-metal mineralization have occurred in this region; a late Caledonian, high temperature phase and a younger low temperature, lower Carboniferous phase. Between three and six cathodoluminescence zones were identified in a number of deposits. The similarity in cathodoluminescence zones developed at different deposits reflects similar broad fluctuations in the chemistry of ore-bearing fluids, correlated over a region of 120 km. Multiple episode s of brecciation during quartz and sulphide deposition suggests that faulti ng was an active process during hydrothermal activity. Quartz from Caledoni an mineralization contains cathodoluminescence zones, which are texturally distinct in comparison with the quartz from subsequent lower Carboniferous mineralization. (C) 2000 Elsevier Science B.V. All rights reserved.