SYNCHROTRON INFRARED MICROSPECTROMETRY APPLIED TO PETROGRAPHY IN MICROMETER-SCALE RANGE - FLUID CHEMICAL-ANALYSIS AND MAPPING

The potentiality of synchrotron infrared microspectrometry was investi gated for in situ analysis of fluid inclusions and volatiles of partic ular geological interest. Thanks to the intrinsic high brightness of t he synchrotron infrared source, areas as small as a few mu m(2) can be probed, providing a high-contrast analysis of small inclusions in geo logical materials. We have identified organic components in such small volumes in their liquid and gaseous phase, thus allowing a deeper ana lysis of oil-water inclusions entrapped in diagenetic cements. Such de tailed analysis opens up new perspectives in petroleum reservoir evolu tion studies. The high signal-to-noise ratio of spectra obtained in sm all volume allows a fast and accurate chemical mapping of the inclusio n components, Drastic refraction effects preclude, at the present stat e, a quantitative analysis of either the volume or the thickness of th e individual inclusions, Traces of volatiles such as CO2 and H2O are e asily detected in the vitreous and gaseous part of the glass melt flui d inclusions. We have also profiled the hydroxyl concentration near a wail, and calculated the hydrogen diffusion coefficient in anhydrous m inerals such as diopside.