Fluid Inclusion Geothermometry in Sedimentary Systems: From Paleoclimate to Hydrothermal
Published:January 01, 2012
Robert H. Goldstein, 2012. "Fluid Inclusion Geothermometry in Sedimentary Systems: From Paleoclimate to Hydrothermal", Analyzing the Thermal History of Sedimentary Basins: Methods and Case Studies, Nicholas B. Harris, Kenneth E. Peters
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Fluid inclusion geothermometry is useful for establishing detailed thermal histories of sedimentary rocks that cannot be gleaned from other techniques. The fluid inclusion technique requires careful attention to petrography and evaluation of thermal reequilibration. The fluid inclusion assemblage approach (FIA) is most important in evaluating the extent to which fluid inclusions have been altered.
Fluid inclusion geothermometry can be accomplished in both low- and high-temperature sedimentary systems. At low temperature, it can be used in paleoclimate work by generating bubbles from metastable inclusions, using cooling and femtosecond laser techniques. At elevated paleotemperature, homogenization temperatures (Th) can be measured from inclusions composed of high-temperature aqueous liquid without dissolved gas, high-temperature aqueous liquid with dissolved gas, gas, and petroleum. Given consistent FIAs and an understanding of the pressure-volume-temperature (PVT) relations for the inclusions, fluid inclusion Th data can be pressure-corrected given certain constraints.
Inclusions can be used to evaluate the detailed spatial, temporal, tectonic, and fluid composition history of a system that cannot be determined in other ways. Fluid inclusions are used as a tool for determining the maximum temperature achieved in a sample, but this commonly would be an underutilization of the data generated. Unlike other techniques, fluid inclusions can link thermal history to fluid flow, as a means of evaluating whether heating was associated with normal burial conditions, hydrothermal systems, or cool fluids flowing into warmer rocks. Hydrothermal systems can be identified when geothermometry indicates: (1) repeated increases and decreases in temperature inconsistent with the burial and unroofing history; (2) paleotemperatures higher than what the most liberal burial history analysis will allow; (3) paleogeothermal gradients or pressure-temperature data inconsistent with normal burial; (4) evidence for locally increased temperature at the same depth within a region; and (5) geothermometric evidence that higher temperatures are focused in fracture, fault, or stratigraphic conduits for paleofluid flow.
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Analyzing the Thermal History of Sedimentary Basins: Methods and Case Studies
Thermal histories of sedimentary basins are critical sources of scientific and practical information. They provide us with windows into past and present tectonic processes and the configuration of the crust and mantle. Using records of present and past temperature distributions, we can identify and constrain interpretations of tectonic events, distinguish different basin types and interpret pathways of fluid flow. These insights can be used calibrate basin and petroleum system models and to interpret and predict the distribution of minerals and petroleum, diagenesis and reservoir quality, and the geomechanical properties of rock units. This volume summarizes the current state of the art for many modern approaches used to estimate paleotemperature. Many techniques are now available based on both organic and inorganic components in the rock. Even techniques that are now many years old, such as apatite fission track analysis, have und