Practical Aspects of Geothermometry
Ascertaining thermal information from fluid inclusions is known as fluid inclusion geothermometry. In Chapter 6, crude petrographic methods for determining thermal conditions of entrapment and post-entrapment history are introduced. The appropriate procedures for collecting microthermometric data from inclusions are presented in Chapter 7, in which the approach of collecting data from fluid inclusion assemblages (FIAs) is stressed. In Chapter 3 the basic principles for understanding the significance of microthermometric data are covered, and in Chapter 4 some processes that can modify inclusions and affect the resulting microthermometric data are treated. Thus, at this point, it should be relatively clear to readers that there is a sound theoretical basis for interpreting microthermometric data as meaningful indicators of some aspects of the thermal history that a rock has experienced. In addition, readers should have developed an appreciation for the fact that there are natural processes that occur which may render the interpretation of Th data less straightforward than they might have originally thought! The purpose of this chapter is to present a systematic framework for interpreting fluid inclusion microthermometric Th data in order to obtain valid information regarding temperature of mineral precipitation, minimum temperature of mineral precipitation, or merely temperatures that a rock has experienced. The limitations of various procedures will be stressed throughout this presentation.
Correct utilization of fluid inclusions as geothermometers begins with observations of fluid inclusion assemblages (FIAs) — groups of fluid inclusions that come from the most finely discernible event of inclusion entrapment. The reason for making observations