Vitrinite

Abstract: Temperature is the most sensitive parameter in hydrocarbon generation. Thus, reconstruction of temperature history is essential when evaluating petroleum prospects. No measurable parameter can be directly converted to paleotemperature. Maturation indices such as vitrinite reflectance, Tmax from Rock-Eval pyrolysis, spore coloration, Thermal Alteration Index (TAI), or concentration of biological markers offer an indirect approach. All these indices are a function of the thermal history through rather complex kinetics, frequently influenced by the type of organic matter. Their significance and validity are reviewed. Besides the problems of identification (e.g., vitrinite) and interlaboratory calibration, it is important to simultaneously interpret kerogen type and maturation and to avoid difficult conversions from one index to another. Geodynamic models, where structural and thermal histories are connected, are another approach to temper ture reconstruction which could be calibrated against the present distribution of temperature and the present value of maturation indices. Kinetics of kerogen decomposition controls the amount and composition of hydrocarbons generated. An empirical time-temperature index (TTI), originally introduced by Lopatin, does not allow such a quantitative evaluation. Due to several limitations (no provision for different types of kerogen and different rates of reactions, poor calibration on vitrinite reflectance), it is of limited interest unless one has no access to a desk-top computer. Kinetic models, based on a specific calibration made on actual source rock samples, can simulate the evolution of all types of organic matter and can provide a quantitative evaluation of oil and gas generated. Examples from the Jurassic source rocks of the Paris basin, Monterey Formation of California, Green River shales of Utah, Paleozoic source eds of the Algerian Sahara, and Miocene rocks of the Mahakam Delta, Indonesia, illustrate various aspects of the discussion. Geological/geochemical models are the most efficient way to integrate geological, seismic, and geochemical data, and they should greatly help to reduce the risk in exploration.

Abstract: Within the new vitrinite classification (ICCP System 1994) the maceral group vitrinite is divided into three subgroups, telovitrinite, detrovitrinite and gelovitrinite, which are each further sub-divided into two macerals. The dominant parameter for these newly ordered and in part newly defined sub-groups is the degree of destruction (degradation), whereas the macerals can be further distinguished by their morphological characteristica and their degree of gelification. The new system is furthermore related more closely to the huminite classification system still in use and a future one to be published by the ICCP.

Abstract: 1 Introduction.- 2 The Conditions of Peat Formation.- 2.1 Peatland Ecology.- 2.1.1 Coastal Marshes and Swamps.- 2.1.1.1 The Marine Influence on Peat Accumulation.- 2.1.1.2 The Influence of Marine Transgressions and Regressions.- 2.1.2 Fresh-Water Peatlands.- 2.1.2.1 Upper Delta and Alluvial Plain Swamps, Marshes and Bogs.- 2.1.2.2 Limnic Environments.- 2.2 Peat Composition and Peat-Forming Plants.- 2.3 Climate and Peat Accretion.- 2.4 Evolutionary Trends in Peat and Coal Formation.- 3 The Coalification Process.- 3.1 Biochemical Coalification.- 3.1.1 The Vitrinitisation Path.- 3.1.2 The Fusinitisation Path.- 3.1.3 Plant-Specific Coal Components.- 3.2 Physico-Chemical Coalification.- 3.2.1 The Concept of Coal Rank.- 3.2.1.1 Solubility in Alkali Hydroxides.- 3.2.1.2 Moisture Content and Specific Energy.- 3.2.1.3 Volatile Matter and Fixed Carbon.- 3.2.1.4 Elemental Carbon.- 3.2.1.5 Vitrinite Reflectance and Other Physical Rank Parameters.- 3.2.2 The Effects of Pressure, Temperature and Time.- 4 Coal Petrographic Entities.- 4.1 Macerals.- 4.1.1 The Huminite/Vitrinite Group.- 4.1.1.1 The Humotelinite/Telovitrinite Subgroup.- 4.1.1.2 The Humodetrinite/Detrovitrinite Subgroup.- 4.1.1.3 The Humocollinite/Gelovitrinite Subgroup.- 4.1.2 The Inertinite Group.- 4.1.2.1 The Telo-Inertinite Subgroup.- 4.1.2.2 The Detro-Inertinite Subgroup.- 4.1.2.3 The Gelo-Inertinite Subgroup.- 4.1.3 The Liptinite Group.- 4.1.3.1 Primary Liptinites.- 4.1.3.2 Secondary Liptinites.- 4.1.4 Maceral Analysis.- 4.2 Microlithotypes.- 4.2.1 Microlithotype Analyses.- 4.2.2 The Relationship Between Microlithotypes and Macerals.- 4.3 Lithotypes.- 4.3.1 Lithotype Analysis.- 4.3.2 The Relationship Between Lithotypes, Macerals and Microlithotypes.- 4.4 Minerals.- 4.4.1 Phytogenic Minerals.- 4.4.2 Adventitious Minerals.- 4.4.2.1 Silicate Minerals.- 4.4.2.2 Silica Minerals.- 4.4.2.3 Carbonate Minerals.- 4.4.2.4 Phosphate Minerals.- 4.4.2.5 Sulphide Minerals.- 4.4.3 Mineral Analysis.- 5 Coal Facies and Depositional Environment.- 5.1 Phyterals and Macerals in Palaeo-Environmental Analysis.- 5.1.1 Botanical Attributes of Macerals.- 5.1.1.1 The Topogenous Model of Densosporinite Formation.- 5.1.1.2 The Ombrogenous Model of Densosporinite Formation.- 5.1.1.3 Densosporinite as Part of a Sedimentary Sequence.- 5.1.2 Scalar Properties of Macerals.- 5.1.2.1 The Tissue Preservation Index.- 5.1.2.2 The Gelification Index.- 5.2 Microlithotypes as Tools in Palaeo-Environmental Analysis.- 5.2.1 Microlithotype Proportions and Bandwidth.- 5.2.2 Hacquebard's Double Triangle.- 5.3 Lithotypes as Palaeo-Environmental Indicators.- 5.3.1 Black Coal Lithotypes.- 5.3.2 Brown Coal Lithotypes.- 5.4 Optical Properties as Palaeo-Environmental Indicators.- 5.4.1 Vitrinite Fluorescence.- 5.4.2 Vitrinite Reflectance and Other Rank Parameters.- 5.5 Geochemical Palaeo-Environmental Signatures.- 5.5.1 Elements of Palaeo-Environmental Significance.- 5.5.1.1 Sulphur.- 5.5.1.2 Boron.- 5.5.1.3 Other Elements.- 5.5.2 Organic Geochemical Characteristics.- 5.5.2.1 Alkanes.- 5.5.2.2 Fatty Acids.- 5.5.2.3 Isoprenoids.- 5.5.2.4 Heterocyclic Compounds.- 5.5.2.5 Aromatic Compounds.- 5.5.2.6 Amino Acids.- 5.6 Epiclastic Minerals and Palaeo-Environments.- 5.7 Summary of Palaeo-Environmental Indicators.- 6 The Relationship Between Coal and Interseam Sediments.- 6.1 Some Characteristics and Properties of Interseam Sediments.- 6.1.1 Single Particles.- 6.1.1.1 Origin and Composition of Single Particles.- 6.1.1.2 Particle Size.- 6.1.1.3 Particle Shape and Roundness.- 6.1.2 Depositional Fabric.- 6.1.2.1 Classification of Fabric Elements.- 6.1.2.2 Types of Aggregation.- 6.1.2.3 Symmetry Relationships.- 6.1.3 Coal Measure Structures.- 6.1.3.1 Stratification.- 6.1.3.2 Bed Undulations.- 6.1.3.3 Cross-Stratification.- 6.1.3.4 Surface and Sole Markings.- 6.1.4 Coal Measure Lithosomes.- 6.1.4.1 Natural Gamma-Ray Log.- 6.1.4.2 Density (Gamma-Gamma) Log.- 6.1.4.3 Neutron-Neutron Log.- 6.1.4.4 Caliper Log.- 6.1.4.5 Sonic Properties.- 6.1.4.6 Resistivity Log.- 6.1.4.7 Spatial Attitude.- 6.1.4.8 Combination Tools.- 6.1.4.9 Data Management.- 6.2 Coal Seams and Their Floor Rocks.- 6.3 Coal Seams and Their Roof Rocks.- 6.3.1 Concordant Coal/Roof Couples.- 6.3.1.1 Abrupt Contacts Between Coal and Roof Rocks.- 6.3.1.2 Gradational Contacts Between Coal and Roof Rocks.- 6.3.2 Discordant Coal/Roof Couples.- 6.3.2.1 Coal/Roof Discordance Due to Unequal Loading..- 6.3.2.2 Coal/Roof Discordance Due to Erosion.- 6.4 Coal Seam Splitting.- 6.4.1 Seam Splitting Due to Differential Subsidence.- 6.4.2 Seam Splitting Due to Autosedimentational Causes.- 7 Coal-Producing Sedimentary Environments.- 7.1 The Braid Plain.- 7.1.1 The Gravelly Braid Plain.- 7.1.2 The Sandy Braid Plain.- 7.1.3 The Coals of the Braid Plain.- 7.2 The Alluvial Valley and Upper Delta Plain.- 7.2.1 The Point Bar.- 7.2.2 The Flood Plain.- 7.2.3 The Flood Basin.- 7.2.4 The Coals of the Alluvial Valley and Upper Delta Plain.- 7.3 The Lower Delta Plain.- 7.3.1 The Prodelta.- 7.3.2 The Delta Front.- 7.3.3 The Distributary Channel.- 7.3.4 The Interdistributary Bay.- 7.3.5 The Coals of the Lower Delta Plain.- 7.4 The Barrier Beach/Strand-Plain System.- 7.4.1 The Offshore Transition Zone.- 7.4.2 The Shoreface.- 7.4.3 The Foreshore.- 7.4.4 TheBackshore.- 7.4.5 The Tidal Inlet.- 7.4.6 The Backbarrier.- 7.4.7 Marine Transgression (Barrier Retrogradation).- 7.4.8 Marine Regression (Barrier Progradation).- 7.4.9 The Coals of the Backbarrier Strand-Plain System.- 7.5 The Estuary.- 7.5.1 Present and Past Estuarine Deposits.- 7.5.2 The Coals of the Estuarine System.- 8 Coal Formation and Sequence Stratigraphy.- 8.1 Basic Concepts of Sequence Stratigraphy.- 8.2 Sequence-Stratigraphic Time and Space Constraints on Coal Formation.- 8.3 The Influence of Sequence-Stratigraphic Settings on Coal Formation.- 8.3.1 Properties of Transgressive Coal Seams with a Marine Roof.- 8.3.1.1 Chemical Signatures of Transgressive Coals with a Marine Roof.- 8.3.1.2 Mineralogical Signatures of Transgressive Coals with a Marine Roof.- 8.3.1.3 Petrographic Signatures of Transgressive Coals with a Marine Roof.- 8.3.2 Properties of Transgressive Coal Seams Without a Marine Roof.- 8.3.3 Properties of Coal Seams Formed During Marine Regression.- 8.4 Sequence Stratigraphic Interpretation of Coal Seam Settings.- 9 Coal-Producing Tectonic Environments.- 9.1 Early Examples of a Tectonic Classification of Coalfields.- 9.2 Basin Formation as Part of Plate Tectonics.- 9.3 Coalfields Situated Near Convergent Plate Edges.- 9.3.1 Molasse Foredeeps Associated with Subduction Zone Continental Margins.- 9.3.1.1 The Sunda Arc.- 9.3.1.2 The Sydney Basin.- 9.3.1.3 The Rocky Mountains Foredeep.- 9.3.2 Molasse Foredeeps Associated with Continental Collision Margins.- 9.3.3 Coal-Bearing Intradeeps.- 9.3.4 Coal-Bearing Transtensional Lateral Basins.- 9.4 Coalfields Situated Near Divergent Plate Edges.- 9.4.1 The Kinematics of Continental Rifting.- 9.4.2 Coal Formation in Rift Valleys.- 9.4.3 Coal Formation in Nascent Continental Margin Settings.- 9.5 Coalfields on Midplate Continental Margins.- 9.5.1 Coalfields of Mobile Shelf Basins.- 9.5.2 Coalfields on Stable Shelf Margins.- 9.6 Coalfields of the Continental Interior.- 9.6.1 Epeirogenic Coal Basins.- 9.6.2 Coalfields Associated with Wrench Faults.- 9.6.3 Coal Formation in Non-Tectonic Basins.- 10 Concluding Remarks.- References.- Author Index.