Raman Spectra Of Carbonaceous Material Research Articles

Thermal history of the 3.5–3.2 Ga Onverwacht and Fig Tree Groups, Barberton greenstone belt, South Africa, inferred by Raman microspectroscopy of carbonaceous material

Research Article| January 01, 2004 Thermal history of the 3.5–3.2 Ga Onverwacht and Fig Tree Groups, Barberton greenstone belt, South Africa, inferred by Raman microspectroscopy of carbonaceous material Michael M. Tice; Michael M. Tice 1Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305, USA Search for other works by this author on: GSW Google Scholar Benjamin C. Bostick; Benjamin C. Bostick 1Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305, USA Search for other works by this author on: GSW Google Scholar Donald R. Lowe Donald R. Lowe 1Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305, USA Search for other works by this author on: GSW Google Scholar Geology (2004) 32 (1): 37–40. https://doi.org/10.1130/G19915.1 Article history received: 09 Jun 2003 rev-recd: 09 Sep 2003 accepted: 11 Sep 2003 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Michael M. Tice, Benjamin C. Bostick, Donald R. Lowe; Thermal history of the 3.5–3.2 Ga Onverwacht and Fig Tree Groups, Barberton greenstone belt, South Africa, inferred by Raman microspectroscopy of carbonaceous material. Geology 2004;; 32 (1): 37–40. doi: https://doi.org/10.1130/G19915.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Raman spectra of carbonaceous material were collected in situ from samples of cherts of the Onverwacht and Fig Tree Groups in the central Barberton greenstone belt. The spectra feature two dominant peaks characteristic of disordered carbon: the D peak at ∼1310 cm−1 and the O peak at 1580–1600 cm−1. D peak positions and relative peak intensities and areas indicate that all samples have been altered to lower greenschist facies or above. No correlation was observed between maximum temperature and stratigraphic position or degree of hydrothermal alteration, implying that metamorphism in the central Barberton greenstone belt was regional and unaccompanied by the flow of large quantities of hydrothermal fluids. Samples from the Marble Bar Chert of the Pilbara block, Western Australia, have been heated to the same extent as samples from Barberton. This study demonstrates the use of Raman spectra of carbonaceous material as a sensitive geothermometer for low-temperature metamorphic facies. This application could also be used to establish the antiquity of putative microfossils from metamorphic terranes. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Raman spectra of carbonaceous material in metasediments: a new geothermometer

AbstractMetasedimentary rocks generally contain carbonaceous material (CM) deriving from the evolution of organic matter originally present in the host sedimentary rock. During metamorphic processes, this organic matter is progressively transformed into graphite s.s. and the degree of organisation of CM is known as a reliable indicator of metamorphic grade. In this study, the degree of organisation of CM was systematically characterised by Raman microspectroscopy across several Mesozoic and Cenozoic reference metamorphic belts. This degree of organisation, including within‐sample heterogeneity, was quantified by the relative area of the defect band (R2 ratio). The results from the Schistes Lustrés (Western Alps) and Sanbagawa (Japan) cross‐sections show that (1) even through simple visual inspection, changes in the CM Raman spectrum appear sensitive to variations of metamorphic grade, (2) there is an excellent agreement between the R2 values calculated for the two sections when considering samples with an equivalent metamorphic grade, and (3) the evolution of the R2 ratio with metamorphic grade is controlled by temperature (T). Along the Tinos cross‐section (Greece), which is characterised by a strong gradient of greenschist facies overprint on eclogite facies rocks, the R2 ratio is nearly constant. Consequently, the degree of organisation of CM is not affected by the retrogression and records peak metamorphic conditions. More generally, analysis of 54 samples representative of high‐temperature, low‐pressure to high‐pressure, low‐temperature metamorphic gradients shows that there is a linear correlation between the R2 ratio and the peak temperature [T(°C) = −445 R2 + 641], whatever the metamorphic gradient and, probably, the organic precursor. The Raman spectrum of CM can therefore be used as a geothermometer of the maximum temperature conditions reached during regional metamorphism. Temperature can be estimated to ± 50 °C in the range 330–650 °C. A few technical indications are given for optimal application.

Raman spectrum of carbonaceous material: a possible metamorphic grade indicator for low‐grade metamorphic rocks

Raman spectral analyses of carbonaceous material (CM) extracted from pelitic samples along two sections traversing the metamorphic belt of Taiwan were carried out in the present study. The results show similar spectral variations of CM with metamorphic grade as those documented in the literature. However, continuous sampling from zeolite facies through prehnite–pumpellyite facies to greenschist facies metamorphic rocks in the present study does reveal some interesting features on the Raman spectra of CM that were not noted before. Both the Raman D (disordered‐)/O (ordered‐) peak area (i.e. integrated intensity) ratio and the D/O peak width (i.e. full width at half maximum, FWHM) ratio of the CM decrease with progressive metamorphism, but the most prominent change in the D/O peak area ratio occurs in samples of lower greenschist facies metamorphic grade, while the most significant decrease in the D/O peak width ratio occurs in samples near the boundary of prehnite–pumpellyite facies and greenschist facies. This phenomenon is interpreted as a result of the decoupling of the changing rates of in‐plane crystallite size and degree of defects of CM with progressive metamorphism. It is postulated that the Raman spectrum of CM can serve as a metamorphic grade indicator to distinguish samples of prehnite–pumpellyite facies metamorphic grade from those of greenschist facies metamorphic grade.

Evaluation of graphitization by Raman scattering of carbonaceous material in the Paleozoic strata around the Hikami and the Kesengawa granites, Southern Kitakami Mountains, Northeast Japan.

Raman spectra of carbonaceous material in the Paleozoic strata around the Hikami and the Kesengawa granites in the Southern Kitakami Mountains have been investigated. Two spectral lines, one occurring near 1350cm-1, and another at about 1620cm-1, indicate the degree of graphitization in terms of the I1350/I1620 intensity ratio. The I1350/I1620 intensity ratio decreases with advancing coalification and graphitization, and becomes zero above about 190A in crystallite thickness Lc (002) determined by the X-ray diffraction techniques. X-ray parameters which indicate the degree of graphitization could not be obtained because of fluorides formation during chemical treatment for isolation of carbonaceous material. However, the I1350/I1620 value of the Raman spectra could determine the degree of graphitization even where other compounds coexist. The Raman spectra of graphites collected from along the western edge of the Kesengawa granite show a single line at 1620cm-1 rather than the 1580cm-1 line of the theoretical E2g2 mode in pristine graphite. The spectral line shift to higher frequency side suggests that these graphites might be graphite intercalation compounds. I1350/I1620 values of the Siluro-Devonian Formations around the Hikami granite are above 0.2. These data indicate that the Silurian stratum was not thermally affected by the Hikami granite. Laser Raman spectra of carbonaceous material in sedimentary and metamorphic rocks could be applied to evaluate the degree of graphitization, and to estimate thermal effects from granite plutons.