If readers have taken heed of our recommendations for an appropriate mental framework for selecting inclusions for microthermometry (see Chapter 7), then the method for proper presentation of data will be straightforward. Those who have not collected data with respect to petrographically related assemblages of inclusions (FIAs) have chosen an inappropriate methodology in which they must assume that any variability in their data is due to the vagaries of nature. Such an assumption leads to a philosophy that maintains that it is both appropriate and sufficient to portray variability to a reader by lumping all data into a few encompassing histograms, and then to interpret the data from statistically determined means and modes. It is very understandable that such logic seems reasonable, but the fallacy is the assumption that any variability is “natural” and to be expected. Consider the numerous natural cases where inclusions along a single microfracture or a single growth zone yield very consistent microthermometric results, or the cases in which data from synthetically produced inclusions vary less than a few tenths of a degree! For these groups of inclusions trapped at a certain P-T-X condition, there is, in fact, little “natural” variability. So, in contrast to what a geoscientist might initially think, the more appropriate philosophical viewpoint should be that data are expected to be consistent, but only if the following criteria are met:
The data come from a single petrographically related population (FIA) of inclusions that samples a single event.
Figures & Tables
The past decade has revealed significant advantages to using fluid inclusions as a means of understanding the physical and chemical history of fluids in sedimentary basins, but it also has revealed important limitations which have required that a new approach must be employed to effectively use fluid inclusions. This book is divided into six sections: (1) what fluid inclusions are and what geologic history they are capable of recording; (2) basic phase equilibria that must be known to understand the behavior of pore fluids and fluid inclusions in nature; (3) the question of validity of using fluid inclusions as records of ancient diagenetic systems is dealt with in such a way that the questions commonly asked about the limitations of the technique are addressed; (4) hot to conduct a fluid inclusion study, a new petrographically based approach for conducting fluid inclusion research that is followed by methods that allow for the interpretation of compositions of pore fluids that existed in sedimentary rocks, and methods of geothermometry and geobarometry; (5) selected case histories that are designed specifically to give practice in evaluating fluid inclusion data from the diagenetic realm; and (6) a summary of the arsenal of analytical techniques that may be applied to fluid inclusions to develop additional constraints on fluid inclusion composition.