DATE	Thursday, 26 June 2003
MEETING TYPE	General Meeting
TIME	6.15pm
VENUE	Fritz-Loewe Lecture Theatre, School of Earth Sciences, Melbourne University, cnr Swanston and Elgin Streets
PRELIMINARIES	Drinks and nibbles at 5.30 pm in the Tea Room, 4th Floor ($2 per person)
TITLE	The timing and origin of lead-zinc mineralisation in Ireland.
SPEAKER	Chris Reed of The University of Melbourne
ABSTRACT	The Lower Carboniferous carbonate rocks of central and southern Ireland are host to a large number of base-metal deposits. The sulphide mineralisation is concentrated on the hanging walls of normal faults, at the base of the lowest non-argillaceous carbonate (the Waulsortian Limestone). While much of the mineralisation resembles Mississippi Valley-type mineralisation, many of the deposits are classified as Irish-type deposits. This is a problematic classification that requires an additional component of synsedimentary or near-surface mineralisation. This talk evaluates the validity of the Irish-type model by investigating the nature and timing of mineralisation at four localities within the Irish ore-field. Significantly, there is no evidence to support the near-surface component to the mineralisation and instead it is suggested that the Irish mineralisation is entirely epigenetic. The thermal maturation of the Irish ore-field and its implications for ore-stage temperatures is also discussed.