The Creede vein district is a world-class epithermal base metal sulfide deposit associated with a large Tertiary caldera cluster in Colorado. Because the sedimentary, diagenetic and hydrothermal history of the volcaniclastic sediments filling the Creede caldera moat is critical to understanding the cycling of fluids, sulfur and metals into the district vein mineralization, we propose a comprehensive investigation of fine-scale (<30 um) sulfur isotopic systematics in the moat sediments using the SHRIMP ion microprobe. Microbeam techniques of stable isotope analysis offer great insight into mineralizing processes, because minerals contain more information concerning their origins and subsequent modifications than can be obtained by conventional bulk isotopic sampling and analytical techniques. The principal investigators will apply their experience in resolving fine-scale sulfur isotopic variations in lacustrine and volcanic environments to the Creede moat sediments, in cooperation with bulk isotopic studies proposed by other Creede project scientists. In particular, they will focus on microscopic sulfur isotope variations that record critical sedimentary and diagenetic events, as well as any contribute towards an improved Creede model, and will advance our understanding of the timing and interplay of sedimentary, diagenetic and hydrothermal ore-forming processes in shallow crustal environments.
