Book contents
- Frontmatter
- Contents
- List of Contributors
- Preface
- The Proterozoic Biosphere
- PART I
- PART 2
- 14 Geographic and Geologic Data for PPRG Rock Samples
- 15 Flow Chart and Processing Procedures for Rock Samples
- 16 Procedures of Whole Rock and Kerogen Analysis
- 17 Abundances and Isotopic Compositions of Carbon and Sulfur Species in Whole Rock and Kerogen Samples
- 18 Procedures for Analysis of Extactable Organic Matter
- 19 Composition of Extractable Organic Matter
- 20 Modern Mat-Building Microbial Communities: Methods of Investigation and Supporting Data
- 21 Construction and Use of Geological, Geochemical, and Paleobiological Databases
- 22 Proterozoic and Selected Early Cambrian Microfossils and Microfossil-Like Objects
- 23 Described Taxa of Proterozoic and Selected Earliest Cambrian Carbonaceous Remains, Trace and Body Fossils
- 24 Atlas of Representative Proterozoic Microfossils
- 25 Informal Revised Classification of Proterozoic Microfossils
- 26 Models for Vendian-Cambrian Biotic Diversity and for Proterozoic Atmospheric and Ocean Chemistry
- 27 Glossary of Technical Terms
- References Cited
- Subject Index
- Index to Geologic Units
- Taxonomic Index
18 - Procedures for Analysis of Extactable Organic Matter
Published online by Cambridge University Press: 04 April 2011
- Frontmatter
- Contents
- List of Contributors
- Preface
- The Proterozoic Biosphere
- PART I
- PART 2
- 14 Geographic and Geologic Data for PPRG Rock Samples
- 15 Flow Chart and Processing Procedures for Rock Samples
- 16 Procedures of Whole Rock and Kerogen Analysis
- 17 Abundances and Isotopic Compositions of Carbon and Sulfur Species in Whole Rock and Kerogen Samples
- 18 Procedures for Analysis of Extactable Organic Matter
- 19 Composition of Extractable Organic Matter
- 20 Modern Mat-Building Microbial Communities: Methods of Investigation and Supporting Data
- 21 Construction and Use of Geological, Geochemical, and Paleobiological Databases
- 22 Proterozoic and Selected Early Cambrian Microfossils and Microfossil-Like Objects
- 23 Described Taxa of Proterozoic and Selected Earliest Cambrian Carbonaceous Remains, Trace and Body Fossils
- 24 Atlas of Representative Proterozoic Microfossils
- 25 Informal Revised Classification of Proterozoic Microfossils
- 26 Models for Vendian-Cambrian Biotic Diversity and for Proterozoic Atmospheric and Ocean Chemistry
- 27 Glossary of Technical Terms
- References Cited
- Subject Index
- Index to Geologic Units
- Taxonomic Index
Summary
As is discussed in Section 3.1.1, great care must be exercised to avoid contamination of extractable hydrocarbon samples by extraneous bitumens, particularly if the TOC (total organic carbon) content is low or if the amount of sample is small. In this study, sediment cores and outcrop samples were pre-rinsed with CH2C12 and dried to remove external contaminants. Where sample size permitted, external surfaces were removed by cutting with a diamond saw. Samples were then hammered to chips which were subsequently crushed to less than 200 mesh in a ring crusher. Rock powders were stored in clean glass containers. Lids were lined with pre-baked aluminium foil. All items used to handle the samples were scrupulously washed with hot water, and then distilled solvent, between each use.
TOC determination and Rock–Eval pyrolysis analysis were found to be particularly informative screening techniques. Samples with less than 0.2% TOC (i.e., <2mgC/g) were generally considered unsuitable for comprehensive hydrocarbon analysis because of the problems of contamination, although elemental and carbon isotopic analyses of their kerogens were parameters which could be reliably established at this low level of organic carbon. Samples with >0.2% TOC were usually assessed using Rock–Eval pyrolysis and the results interpreted using guidelines discussed by Espitalié et al. 1977. The relative proportions of bitumen (the Rock–Eval S1 peak in kg/tonne) and kerogen (S2 peak in kg/tonne), the pyrolysis temperature Tmax (°C), and the overall appearance of the pyrograms all provided useful information.
- Type
- Chapter
- Information
- The Proterozoic BiosphereA Multidisciplinary Study, pp. 799 - 810Publisher: Cambridge University PressPrint publication year: 1992