Fluid Inclusion Studies on the Ecton Hill Copper Deposits, North Staffordshire

R. Masheder and A. H. Rankin
Mining Geology Division, Department of Geology, Royal School of Mines, Imperial College, London SW7 2BP

Abstract: Thermometric and D-ICP analysis of fluid inclusions in calcite and fluorite show that the fluids responsible for extensive carbonate-hosted copper mineralization in the Ecton Hill area were low-temperature (< 100 °C), high-salinity (19.5 to 23 wt. % NaCl equivalents) brines strongly enriched in calcium (mean Ca:Na wt. ratio = 1.9). Compared with the fluids responsible for classical ‘Mississippi Valley type’ lead-zinc deposits elsewhere in the south Pennine orefield, the Ecton ore-fluids were of lower temperature and slightly more enriched in potassium. Despite these subtle differences, the data are consistent with a basinal brine model for ore genesis in this western part of the orefield similar to that envisaged for the remainder of the orefield. These Ca-Na-K-Cl, copper-bearing brines were most probably derived from the Cheshire basin located to the west of the Derbyshire Dome.

Keywords: fluid inclusions • Ecton Hill copper deposits • north Staffordshire

Mineralogical Magazine; September 1988 v. 52; no. 367; p. 473-482; DOI: 10.1180/minmag.1988.052.367.05
© 1988, The Mineralogical Society
Mineralogical Society (www.minersoc.org)