FLUID INCLUSION INVESTIGATION OF SHAWANGUNK MINERAL DEPOSITS

Critical metals are needed for modern technologies and alternative energies in particular, while finding new mineral resources of them is difficult. An alternative to completely new mines is to re-examine historical mining districts. Many sites have large tailings piles or significant amounts of unmined parts of the deposit that are abundant with minerals that were not sought after at the time of operation for these sites such as rare earth element-enriched iron mine tailings in the Adirondacks (e.g., Taylor et al., 2019). Another potential location to re-examine is the Shawangunk lead-zinc district, New York. The formation of these deposits has not been examined since Wilbur et al. (1990) and before that was not investigated in great detail or with modern analyses. These deposits could contain Ga, Ge, In, and Ag and do not fit neatly into typical ore deposit models. It is commonly described as a Mississippi Valley Type deposit despite being sandstone/quartzite-hosted, with little to no evidence of the carbonates that are characteristic of those deposits. Examining the character of the fluid that created this deposit would be beneficial towards having a better understanding of the type of system it is and potentially open up exploration opportunities in other similar systems that have previously been ignored. The fluid inclusion study conducted by Wilbur et al. (1990) was flawed due to their lack of using an fluid inclusion assemblage (FIA) model, where fluid inclusions are placed into petrographically identified assemblages and distinguished as either primary, secondary, or pseudo-secondary. Their results were thus combining multiple fluid events. This project will focus on using an FIA approach to better constrain the fluid geochemistry and pressure/temperature conditions of formation. Samples of quartz, sphalerite, and galena were collected from a number of tailings piles, exploratory pits, and defined mines within the Shawangunks. The number of sites permit differentiation in the fluid geochemistry between the lead-dominated, zinc-dominated, and ore-poor (i.e. quartz-dominated) sites. Analyzing these samples will allow us to draw conclusions for mineral growth based on primary and secondary FIA, and therefore allow us to understand and draw a conclusion as to the origin of the ore system in the Shawangunks.