gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1990.054.375.17 Near-Surface and Surficial Environments Characterization of Hydrocarbon Fluid Inclusions by Infra-Red and Fluorescence Microspectrometry Guilhaumou Nicole Laboratoire de Géologie de l'Ecole Normale Supérieure, URA 1316 du CNRS, 24 rue Lhomond, 75005 Paris, France Szydlowskii Nathalie Institut Français du Pétrole, BP 311, Rueil Malmaison Cedex, France Pradier Bernard Unité de Recherche en Pétrologie Organique, U.A. 724 du CNRS, Université d'Orléans, 45067 Orléans Cedex 2, France 6 1990 54 375 311 324 12 7 1989 5 12 1989 Copyright © 1990, The Mineralogical Society 1990 Abstract

Liquid-hydrocarbon-bearing fluid inclusions have often been described associated with petroleum occurrences and diagenetic sediments. Infra-red microspectrometry allows characterization of fluid inclusions greater than 20 µm by establishing the presence of aliphatic and aromatic hydrocarbons as well as associated H2O, CO2 and CH4. Semi-quantitative analyses have been made by focussing on gaseous and liquid phases separately. Some CH2/CH3 and CO2/CH4 ratios have been determined by this method.

Fluorescence microspectrometry permits precise measurements of the fluorescence emission spectrum of chromophore-bearing organic phases (essentially aromatic hydrocarbons) in fluid inclusions greater than 10 µm. Such a spectrum is a function of both the gross composition of the trapped oil and its thermal history.

Both of these methods lead to the in situ characterization of hydrocarbon fluid inclusions. They are useful in providing a quantifiable distinction between different oil generations trapped during mineral growth in diagenetic and epigenetic minerals.

 Keywords fluid inclusions hydrocarbon infra-red ultra-violet fluorescence microspectrometry