Campbell – Research

The analysis of light stable isotopes (H, C, O, S) is a geochemical tool that has applications in many areas of geoscience. At New Mexico Tech, we have a stable isotope laboratory in which we can analyze most types of geologic samples. My main research interests involve using this lab to study the origins of metallic ore deposits, particularly looking at the source of water in the mineralizing solutions. When combined with microthermometry and geochemical analysis of fluid inclusions, stable isotope analysis is a powerful tool for understanding how ore deposits form. Some of my specific interests within the ore deposit field are tungsten deposits, gold deposits, and the evolution of magmatic ore fluids.

Most of our ore deposit studies also include some aspect of fluid inclusion analysis. A particularly exciting area is the study of fluid inclusions in opaque ore minerals. Most fluid inclusion studies examine inclusions in transparent gangue (non-ore) minerals because most ore minerals are opaque. In order to apply the information gained from the gangue minerals to ore minerals, one must assume that they were deposited at the same time. I have developed a technique to look directly at inclusions in some opaque minerals, using an infrared microscope. Past studies have dealt with wolframite and enargite, both minerals that are transparent to infrared radiation. Presently, we are working on inclusions in pyrite from a variety of ore deposits.

In conjunction with other faculty members in the department, there are many other stable isotope studies going on in our lab. They include looking at subareal erosional surfaces in carbonates, crustal contamination in volcanic rocks from the Valles Caldera, paleoclimatic interpretation from lacustrine carbonates and ostracods, and rates of meteoric recharge in desert soils. Increasingly we are involved in studies dealing with environmental issues such as paleohydrological characterization of nuclear waste disposal sites and hydrological tracing in waste dumps.