The usefulness of the laser Raman microprobe (LRM) in characterizing the state of structural order of geologically relevant carbonaceous materials (CM) ranging from kerogen and coals to granulite-facies graphite (in our samples, 4 Å < La < ∞) is demonstrated. The first part ofthis paper is an overview of the process of graphitization, two techniques used to characterize CM structurally (HRTEM and XRD analysis), and the theory of Raman spectroscopic analysis of CM. The first- and second-order Raman spectra of 37 CM samples are presented: 24 grain separates from various metamorphic terranes (chlorite zone to granulite facies), eight kerogen and coal separates, two thin sections containing graphite, and three artificial fluid-deposited CM. The results are evaluated and discussed in terms of (1) various quantitative spectral parameters such as the positions, widths, height ratios, and area ratios of Raman peaks resulting from ordered and disordered materials, and (2) estimates of the in-plane crystallite size, La, based on the existing calibration data from XRD (Tuinstra and Koenig, 1970a) and HRTEM (Beny-Bassez and Rouzaud, 1985). We conclude that LRM spectroscopy is very well suited to the characterization of CM of geological interest, because the spectra allow one to distinguish different stages of crystallite development (even for very poorly and very well crystallized CM) more accurately than do quantitative routine XRD data and because the Raman spectra are more representative of the bulk carbonaceous sample than are HRTEM data. Our Raman results suggest that the mechanism and developmental stages of graphitization are basically the same for all (artificial, as well as natural) heat-treated CM once some low threshold ofthree-dimensional ordering is reached. It appears, however, that fluid-deposited CM may develop differently than heat-treated CM. Specific information is provided on the thermal response of metapelite-hosted CM, and the geological implications of identifying disordered CM (“graphite“) in situ are discussed.

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