Organic Metamorphism and Geothermal History

One The Thermal Diagenesis of Organic Matter and the Methods of Paleogeothermal Analysis.- 1. The Thermal Diagenesis of Organic Matter.- 1.1. Historical developments.- 1.2. General concepts: writings on organic metamorphism; the key-role of burial.- 1.2.1.Bostick's work.- 1.2.1.1. Thermal simulations.- 1.2.1.2.Burial metamorphism.- 1.2.2. Case studies of Canadian basins by Hacquebard..- 1.2.3.Examples taken from French works.- 1.2.3.1. Case studies of Saharan oil and gas deposits.- 1.2.3.2. Case of gas deposits in South Aquitaine (France).- 1.3. General concepts: the appearance of the geothermy-burial duality.- 1.3.1. The thermal effects of eruptive events and volcanism.- 1.3.1.1. The metamorphic belt encircling the Pier granite of the Narragansett basin (Rhode Island, U.S.A.).- 1.3.1.2. Formation of natural cokes in the contact-zone of a basaltic dyke in the Ruhr Carboniferous.- 1.3.1.3. The identification of deep magmas along the edge of the Variscan range: case study of the Erkelenz basic massif.- 1.3.2. Published evidence of paleogeothermal variations occurring during geological history.- 1.3.2.1. American basins.- 1.3.2.1.1. Damberger's research, 1974.- 1.3.2.1.2. Pusey's work (1973), North Texas.- 1.3.2.2. Studies of European basins.- 1.3.2.3. The Australian Cooper basin.- 1.4. General concepts: progress towards a geothermal history influenced by time and space, and related to the geological history of basins. Search for a link with tectonics.- 1.4.1. German works.- 1.4.1.1. The aulacogen.- 1.4.1.2. The orogenic foreland basin.- 1.4.1.3. The subduction-collision area.- 1.4.2. Other German studies: the Rhenish Schistose Massif.- 1.4.3. Study of Saharan basins.- 1.4.4. Australian basins: the general relationship between thermal events and the creation of the Australian continent.- 2. Methods and Means of Paleothermal Analysis.- 2.1. Theoretical basis of chemical kinetics applied to thermal evolution of organic matter.- 2.1.1. Principles behind the mathematical simulation of thermal alteration of organic matter.- 2.1.1.1. First order reaction.- 2.1.1.2. The role of temperature: the Arrhenius relationship.- 2.1.2. Applications.- 2.1.2.1. Karweil's graph (1956, 1975).- 2.1.2.2. Diagram of Hood et al. (1975).- 2.1.2.3. The Lopatin method (1971).- 2.1.2.4. Simulations by Tissot (1969) and Tissot & Espitalie (1975).- 2.1.2.5. The Diagen program.- 2.1.2.6. Conclusion.- 2.2. Elements of geothermy.- 2.2.1. General data.- 2.2.1.1. Some useful definitions units.- 2.2.1.2. Heat transfer by conduction.- 2.2.1.3. The concept of thermal potential.- 2.2.1.4. Applications.- 2.2.2. The geothermy of oceans and continents.- 2.2.3. The geothermal maps of some basins.- 2.2.3.1. Classification of geothermal maps and profiles.- 2.2.3.1.1. Comments.- 2.2.3.1.2. The North Sea.- 2.2.3.2. Conclusion: factors responsible for variations in the deep flows.- 2.3. Methods for reconstructing the thermal history of geological series.- 2.3.1. VRo vertical curves for wells.- 2.3.1.1. Recording the VRo curves.- 2.3.1.2. Interpretation of the VRo curves.- 2.3.1.2.1. Classification of the VRo curves.- 2.3.2. The statistical study of vertical VRo increase.- 2.3.2.1. Statistical analysis.- 2.3.2.2. Consequences.- 2.3.3. The reflectance of bitumens.- 2.3.4. Plotting rank curves on horizontal or vertical planes.- 2.3.4.1. Principles used for interpretation.- 2.3.4.2. Examples.- 2.3.4.2.1. Vertical patterns.- 2.3.4.2.2. Horizontal patterns.- 2.3.5. Information obtained from the maturation/migration of hydrocarbons and natural coking.- 2.3.6. The Tgrad/Tiso method of Kantsler et al. (1978a, b).- 3. The Shallow Transmission of Deep Thermal Flows Examples of very conductive or non-conductive series.- 3.1. Series with high heat conducting lithologies.- 3.1.1. The effect of high heat conducting series on geothermy.- 3.1.2. Case study of the Congo: a non- or slightly migrated salt layer.- 3.1.2.1. Wells O, Y and N.- 3.1.2.2. The three remaining wells: V, U and R.- 3.1.3. Gabon: diapiric columns of Aptian salt.- 3.1.3.1. The effect of diapirs on present geothermy, factors to consider.- 3.1.3.2. The effect on the thermal evolution of OM, the various factors involved.- 3.1.4. Case study of the salt bearing basin of North West Germany.- 3.1.5. Case study of carbonate series: the Middle East.- 3.2. An example of a lithology with poor heat conductivity: the overpressured Akata formation in the Niger delta.- 3.2.1. Geological framework.- 3.2.1.1. The deltaic series.- 3.2.2. The general characteristics of OM dispersed in the series.- 3.2.3. The thermal evolution of OM.- 3.2.4. Present geothermy: its relation with the Akata.- 3.2.5. Interpretation: the role of the Akata formation in thermal conduction.- 3.2.6. Conclusions on the thermal barrier effect of undercompacted formations.- Two The Study of Organic Matter in Reflected Light and Fluorescence.- 4. The Optical Analysis of Sedimentary Organic Matter in Reflected Light and Fluorescence.- 4.1. Methods and means.- 4.2. Microscopical examination in reflected light.- 4.2.1. The measurement of reflectance.- 4.2.1.1. Plotting on diagrams.- 4.2.1.2. Statistical calculation.- 4.2.1.3. The case of anisotropic coals.- 4.2.2. Microhardness.- 4.2.3. Etching.- 4.3. Microscopical examination in the fluorescence mode.- 4.3.1. Principle.- 4.3.2. Equipment.- 4.3.3. The fading effect.- 4.3.4. Photometric measurements.- 4.3.4.1. Spectral fluorescence.- 4.3.4.2. Quantitative fluorescence.- 4.3.5. The 'global'index of fluorescence.- 5. Attempts at Classification of Organic Matter.- 5.1. The notion of 'rank'.- 5.2. The maceral concept.- 5.3. The maceral classification: the three groups of macerals.- 5.4. Other classifications.- 5.4.1. Soviet classifications.- 5.4.2. French classifications.- 6. The Main Groups of Organic Matter.- 6.1. The coaly primary macerals.- 6.1.1. The inertinite group.- 6.1.1.1. Fusinite.- 6.1.1.2. Semifusinite.- 6.1.1.3. Macrinite.- 6.1.1.4. Inertodetrinite.- 6.1.1.5. Sclerotinite.- 6.1.2. The vitrinite group.- 6.1.2.1. The properties of vitrinite.- 6.1.2.2. Classification of vitrinites.- 6.1.2.2.1. The huminite varieties.- 6.1.2.2.2. Vitrinite (s.s.) varieties.- 6.1.2.3. Vitrinite as a rank indicator.- 6.1.2.4. The fluorescent vitrinites.- 6.1.3. The exinite group.- 6.1.3.1. The'leaf'secretions.- 6.1.3.1.1. Cutinite.- 6.1.3.1.2. Fluorinite.- 6.1.3.1.3. Terpenite.- 6.1.3.2. Resinite.- 6.1.3.3. Suberinite.- 6.1.3.4. Sporinites.- 6.1.3.5. Algae and alginate.- 6.1.3.5.1. The unicellular algae.- 6.1.3.5.1.1. Tasmanaceae.- 6.1.3.5.1.2. Leiosphaerideae.- 6.1.3.5.1.3. Microfilamentous and/or Schizophyceae algae.- 6.1.3.5.2. The colonial algae.- 6.1.3.5.2.1. A special genus: the 'colonial algae' of the Niger delta.- 6.2. The structureless primary matters.- 6.2.1. The fluorescent groundmasses or organomineral associations.- 6.2.1.1. The sapropelic groundmasses.- 6.2.1.1.1. The lacustrine sapropelic groundmasses.- 6.2.1.1.1.1. Microscopical characteristics.- 6.2.1.1.1.2. Known examples.- 6.2.1.1.1.3. Geochemical and sedimentological characteristics.- 6.2.1.1.2. The marine sapropelic groundmasses.- 6.2.1.1.2.1. Microscopical criteria.- 6.2.1.1.2.2. General distribution.- 6.2.1.1.2.3. Geochemical and sedimentological criteria.- 6.2.1.2. The humic groundmasses.- 6.2.1.2.1. Microscopical characteristics.- 6.2.1.2.2. Deposits.- 6.2.1.2.3. Origin and geochemical properties.- 6.2.2. Bituminite.- 6.2.3. The diffuse OM in rocks: formation, conservation.- 6.3. The secondary macerals and the liquid or solid products of coalification.- 6.3.1. Oil and hydrocarbons.- 6.3.2. Exsudatinite.- 6.3.3. Micrinite.- 6.3.4. Bitumens.- 6.3.4.1. Criteria for distinguishing bitumens under the microscope.- 6.3.4.2. The microhardness of bitumens.- 6.3.4.3. Bitumen fluorescence.- 6.3.4.4. Bitumen reflectance.- 6.3.4.5. Distribution of bitumens.- 7. The Rank Evaluation of Dispersed Organic Matter.- 7.1. Optical methods.- 7.1.1. The vitrinite Ro in dispersed OM: difficulties and limitations.- 7.1.1.1. Scarcity of coaly fragments.- 7.1.1.2. True diagnosis of vitrinite.- 7.1.1.3. Causes of error.- 7.1.1.3.1. Cavings in drill cuttings.- 7.1.1.3.2. Alteration due to oxidation.- 7.1.1.3.3. Reworking of coals from older series.- 7.1.2. Bitumen Ro, a useful complement.- 7.1.3. Spectral fluorescence.- 7.1.3.1. Sporinites.- 7.1.3.2. Algae.- 7.1.3.3. Other fluorescent subjects.- 7.1.4. TAI: index of thermal alteration in TL.- 7.1.4.1. Historical.- 7.1.4.2. Development of the current method.- 7.2. Rank measurements by spectroscopical methods.- 7.2.1. ESR (Electron Spin Resonance).- 7.2.1.1. Principle.- 7.2.1.2. Technology and application.- 7.2.2. The spectroscopy of infrared absorption.- 7.2.2.1. Principle and technology.- 7.2.2.2. Application to diagenesis.- 8. The Alterations of Coal.- 8.1. The initial stages of coalification: humification and gelification.- 8.1.1. The principal precursor substances.- 8.1.2. Humification.- 8.1.2.1. The progress of humification with rank.- 8.1.3. Gelification.- 8.2. Coalification jumps.- 8.3. Coking.- 8.3.1. The coking process.- 8.3.2. The factors behind coking.- 8.3.2.1. Coal rank.- 8.3.2.2. Maceral composition.- 8.3.2.3. The rate of temperature rise.- 8.3.3. The petrology of cokes.- 8.3.4. Natural cokes, coal pyrolysis and coalification.- 8.3.5. Coking and graphitation.- 8.3.6. Natural regional phenomena.- 8.4. The oxidation of coals.- 8.4.1. The first studies.- 8.4.2. Alpern and Maume studies.- 8.4.3. The author's attempts.- 9. Organic Matter Transformation: Hydrocarbon Generation.- 9.1. Historical development.- 9.2. Control by geochemical and optical analyses.- 9.3. Hydrocarbon precursors.- 9.4. Modes of hydrocarbon expulsion.- 9.5. Generation of gas.- 9.5.1. The catagenetic gas.- 9.5.2. The biogenic, early gas.- Summary.- Three A Paleogeothermal Survey of a Sequence of Sedimentary Basins Through the Study of Organic Metamorphism in Boreholes.- 10. The Rhine Valley, Continental Tertiary Trough.- 10.1. General location.- 10.2. Geological context.- 10.2.1. The stratigraphic series.- 10.2.2. The development of the Tertiary layers and the tectonic evolution of the trough.- 10.2.3. The organic fades.- 10.3. The thermal evolution of the series.- 10.3.1. Alsace: organic diagenesis.- 10.3.2. The north, German area: organic diagenesis.- 10.3.3. Present-day geothermy.- 10.3.4. A comparison of geothermy and paleogeothermy.- 10.3.5. Reconstruction of the thermal history of the basin.- 11. The Congo Basin, Lower Cretaceous Trough, Forerunner of The South Atlantic Oceanic Opening.- 11.1. Originality and interest of the basin.- 11.2. Geological framework.- 11.2.1. The lithostratigraphic succession.- 11.2.1.1. The prerift series.- 11.2.1.2. The oceanic series.- 11.3. Development of the main sedimentary formations.- 11.3.1. The presalt series.- 11.3.2. The marine (oceanic) series.- 11.3.3. The organic fades.- 11.3.3.1. Presalt series.- 11.3.3.2. Postsalt series.- 11.4. Thermal evolution of the basin.- 11.4.1. Rank evaluation of OM.- 11.4.2. The diagenetic variations of the series.- 11.4.3. Present-day geothermy.- 11.4.4. Interpretation of the diagenetic variations: an attempt to reconstruct the thermal history of the basin.- 12. The Red Sea, Active Oceanic Rift.- 12.1. Geological framework.- 12.2. Present-day geothermy.- 12.3. Thermal evolution of the sedimentary series.- 12.3.1. A deep well A.- 12.3.2. Three wells B1, B2 and C.- 12.3.3. The Gulf of Suez.- 12.4. Conclusion.- 13. The Japanese Archipelago, Island Arc or Oceanic Convergent Zone.- 13.1. Introduction.- 13.2. Geological framework.- 13.3. Coal evolution and present geothermy.- 13.4. General survey of the metamorphism of island arcs and convergent Systems.- 13.4.1. Japan.- 13.4.2. General case: other old metamorphic belts.- 13.4.3. Case of the Mariana arc.- 13.5. Attempt at a historical reconstruction.- 14 Upper Bavaria, Foreland of the Alpine Collision.- 14.1. Geotectonic framework.- 14.2. Organic diagenesis and geothermy.- 14.2.1. The autochthonous molassic basin in the foreland and below the nappe.- 14.2.2. Nappe of subalpine molasse.- 14.2.3. The flysch and Helvetics nappe.- 14.3. Conclusion.- 15. The Rhenish Paleozoic Massifs, The Ardenne and the Rhenish Schistose Massif: Complex Orogens.- 15.1. The caledonian cycle.- 15.1.1. Geological history.- 15.1.2. Organic diagenesis.- 15.2. The variscan cycle.- 15.2.1. The successive steps of the Breton phase in the Devonian of the Rhenish Schistose Massif.- 15.2.2. Variscan orogenesis: its three successive phases.- 15.2.2.1. The German region.- 15.2.2.2. Relationships with the neighbouring zones.- 15.2.3. Coalification.- 15.2.4. Neighbouring regions: general review.- 15.2.4.1. The North-Pas de Calais basin, in France.- 15.2.4.2. In Belgium, the Campine and southern basins.- 16. The Mesozoic Aulacogen or Bramsche Massif.- 16.1. Geological framework of north-west germany.- 16.1.1. The Harz.- 16.1.2. The Bramsche Massif.- 16.2. Coalification in the bramsche massif.- 16.2.1. Historical.- 16.2.2. Data and comments.- 16.3. Conclusion.- 17. The Lacq Region, Thermal Cretaceous Dome in Front of the Pyrenean Range.- 17.1. General features.- 17.2. Geological framework.- 17.2.1. The stratigraphic series.- 17.2.1.1. The Triassic.- 17.2.1.2. The Jurassic.- 17.2.1.3. The Cretaceous.- 17.2.1.4. The Lower Tertiary.- 17.2.2. Tectonic outlines of the Lacq region.- 17.2.3. General characteristics of the OM in the sedimentary series.- 17.2.3.1. Jurassic.- 17.2.3.2. Cretaceous.- 17.3. Thermal evolution.- 17.3.1. Present-day geothermy of the basin.- 17.3.2. Organic diagenesis of the series, Methodology.- 17.3.3. Organic diagenesis. Description of well sections.- 17.3.3.1. Wells located on the productive structures.- 17.3.3.1.1. The Lacq structure.- 17.3.3.1.2. The Meillon-St Faust structure.- 17.3.3.2. Wells located on the edges and in the Arzacq syncline.- 17.3.4. Interpretation of the diagenesis curves. Attempt at reconstructing the thermal history.- 17.3.4.1. Peculiarities of the Ro curves.- 17.3.4.2. Vertical location of the 'diagenetic front'.- 17.3.4.3. The thermal significance of this diagenetic front.- 17.3.4.4. Attempt at a reconstruction of the regional geothermal history.- 17.4. Evolution eastwards and below the pyrenean front: lannemezan wells.- 17.5. Conclusion.- Four Mineral Diagenesis: Comparison with Organic Diagenesis.- 18. Rock Metamorphism: The Role of Temperature and the 'Basement Effect' Concept.- 18.1. Review of elementary notions on rock metamorphism.- 18.2. The basement effect.- 19. Mineral Diagenesis or 'Premetamorphism'. Evolution of Clay Minerals.- 19.1. Clay and allied minerals.- 19.1.1. Brief description of clay and allied minerals.- 19.1.2. Genetic conditions and environment.- 19.1.3. Specificity of methods used to analyse clay minerals.- 19.2. Diagenetic transformations of phyllosilicates.- 19.2.1. Smectite disappearance.- 19.2.2. Kaolinite disappearance.- 19.2.3. The (irregular) mixed layers.- 19.2.4. Illite crystallinity.- 19.2.5. The Logic of clay Mineral Transformations.- 19.2.6. Characteristic minerals of the anchizone.- 20. Case Histories of Basin Diagenetic Surveys Using Clay Minerals In Comparison With Organic Evolution.- 20.1. The smectite tertiary series.- 20.1.1. The Gulf of Mexico.- 20.1.2. The Niger delta.- 20.1.3. The Upper Rhine Valley.- 20.2. The paleozoic sahara basins.- 20.2.1. The lllizi basin.- 20.2.2. The Ahnet-Mouydir basin.- 20.3. 'Black Earths' region of south-eastern France.- 20.3.1. Kaolinite distribution.- 20.3.2. Illite crystallinity.- 20.4. The Douala basin (Cameroons) and the Logbaba wells.- 20.4.1. Clay mineral survey.- 20.4.2. Organic diagenesis.- 20.5. Attempt at a synthesis: interpretation.- 20.5.1. Application to the Nagele 1 well.- 20.5.2. Second application: the Lacq region.- 20.5.3. Attempt at a graphic (and geodynamic) classification of these facts.- 20.6. Additional explanations.- 20.6.1. VRo equivalence to the smectite base.- 20.6.2. The thermal history of the Black Earths basin.- 20.7. Summary.- General Outlines.- 21. Main Results.- 21.1. The presence of paleogeothermal phases.- 21.2. Relationship between deep flows and the tectonic history.- 21.3. Tectonic-thermal classification of basins.- 21.3.1. Basins with a 'normal' or near normal geothermy.- 21.3.2. Hypothermal basins.- 21.3.3. Hyperthermal basins.- 21.3.3.1. The arc/back-arc areas, or internal zones of convergent systems.- 21.3.3.2. Divergent zones of the crust.- 21.4. Relationship between the tectonic activity and geothermy of the basins.- Conclusion.- References.- Abstracts.- General Index.- Geographical Index.- Index of Authors.- Glossary of Specialized Terms.