The research is aimed at using high resolution and microsampling techniques for isotopic studies of two types of ore deposits with which the PIs have extensive experience - MVT-type deposits of the North Pennine orefield and the Cornubian base metal province. Emphasis will be placed on developing the analytical technology to use isotopic methods as a means of under- standing the scale, timing, and causes of hydrothermal fluid circulation in the continental lithosphere and the role of fluids in effecting mass transfer and intracrustal differentiation. Integration of (a) multi-isotopic (Nd, Sr, Pb, O, H, N, Ar, S, C) studies of individual minerals, (b) Sm-Nd dating of key minerals, (c) Ar-Ar dating of small, fine grained minerals, and (d) Ar-Ar and Rb-Sr dating of fluid inclusions. The goal is to determine source reservoirs of hydrothermal fluids and their interactions with crustal rocks and their role in mineralization. The strength of the proposal lies in the integration of so many different isotopic systems, which to date has been limited by lack of technological developments. The Michigan lab is well equipped for most of the proposed work.