Keywords:
Impact craters -- Barents Sea.
;
Submarine geology.
;
Cratering.
;
Impact.
;
Electronic books.
Description / Table of Contents:
This book describes the Mjølnir impact event in the context of the geological and geophysical history of the Barents Sea region, and goes on to present elaborative numerical models of its formation and associated tsunami generation.
Type of Medium:
Online Resource
Pages:
1 online resource (324 pages)
Edition:
1st ed.
ISBN:
9783540882602
Series Statement:
Impact Studies
URL:
https://ebookcentral.proquest.com/lib/geomar/detail.action?docID=645596
Language:
English
Note:
Intro -- Preface -- Acknowledgements -- Contents -- Contributors -- 1 Introduction -- 1.1 Background -- 1.2 Barents Sea Geology -- 1.3 Mjlnir Impact at Volgian/Ryazanian Boundary -- 1.4 The Investigation History of Mjlnir -- 1.5 The Search for Oil and Gas in the Barents Sea -- 1.6 Future Mjlnir Studies -- 1.7 Etymology -- 2 Geological Framework -- 2.1 Plate Tectonic Evolution of the Arctic -- 2.2 Mesozoic Stratigraphy and Depositional Environments of the Arctic -- 2.2.1 Geological and Palaeogeographical Setting -- 2.2.1.1 Cretaceous Palaeogeographic Setting -- 2.2.1.2 The Barents Sea in Time and Space -- 2.2.2 Svalbard -- 2.2.3 Barents Sea -- 2.2.4 Greenland -- 2.2.5 Siberia -- 2.2.6 Late Jurassic and Early Cretaceous Depositional Configuration -- 3 Impact Structure and Morphology -- 3.1 Seismic Reflection Database -- 3.2 Shallow Structure -- 3.2.1 Main Features -- 3.2.2 Detailed Seismic Correlation to Nearby Shallow Boreholes -- 3.2.2.1 Borehole 7430/10-U-01 -- 3.2.2.2 Borehole 7329/03-U-01 -- 3.2.2.3 Impact Timing as Revealed from Seismic Correlation -- 3.2.3 Impact-Induced Deformation -- 3.2.4 Near-Field Erosional Features -- 3.2.4.1 Resurge Gullies -- 3.2.4.2 Crater Rim -- 3.3 Deep Structure -- 3.3.1 Impact-Induced Disturbance -- 3.3.1.1 Seismic Reflectivity Patterns -- 3.3.1.2 Shape and Dimensions -- 4 Impact Geophysics and Modelling -- 4.1 Features Related to the Cratering Process -- 4.1.1 Excavated Crater and Breccia -- 4.1.2 Impact Melts -- 4.1.3 Gravitational Collapse -- 4.1.4 Structural Uplift -- 4.2 Impact into a Marine Sedimentary Basin -- 4.3 Impact Crater Modelling -- 4.3.1 Potential Field Data -- 4.3.2 Marine Gravity Anomalies and Modelling -- 4.3.3 Marine Magnetic Anomalies and Modelling -- 4.3.4 Traveltime/Velocity Anomalies and Modelling -- 4.4 Modelled Porosity Anomalies -- 4.4.1 Density-Derived Porosity Anomaly.
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4.4.2 Velocity-Derived Porosity Anomaly -- 4.4.3 Postimpact Deformation-Derived Porosity Anomaly -- 4.4.4 Porosity Anomaly and Pore Space Volume -- 4.4.5 Porosity Anomaly and Hydrocarbon Potential -- 4.5 Potential Non-impact Origin -- 4.5.1 Clay Diapir -- 4.5.2 Salt Diapir -- 4.5.3 Igneous Feature -- 4.6 Alternative Interpretation of Mjlnir Crater Dimensions Based on Regional Gravity and Aero-magnetic Profiles and Modelling -- 4.6.1 The Mjølnir Aero-magnetic Anomaly -- 4.6.2 The Mjølnir Regional Free-Air Gravity Anomaly -- 4.6.3 Alternative Interpretation of Mjølnir Crater Dimensions -- 4.7 Impact-Induced Changes in Physical Properties -- 4.8 Mjlnir as an Oblique Impact Event -- 4.8.1 Elongated Crater Diameter -- 4.8.2 Seismic Disturbance Asymmetry -- 4.8.3 Peak-Ring Character -- 4.8.4 Offsets in Brecciation and Structural Uplift -- 4.8.5 Impact Direction and Angle -- 4.8.6 Mjølnir Impact Obliquity Constrains Models for Near-Field Perturbations -- 4.8.6.1 Nature and Distribution of Proximal Ejecta -- 4.8.6.2 Tsunami-Wave Distribution -- 5 Impact Cratering and Post-impact Sedimentation -- 5.1 Introduction -- 5.2 The Mjlnir Crater Core (7329/03-U-01) -- 5.2.1 The Ragnarok Formation -- 5.2.2 Ragnarok Formation, Unit I -- 5.2.3 Ragnarok Formation, Unit II -- 5.2.4 Hekkingen Formation -- 5.2.5 Klippfisk Formation -- 5.2.6 Spectral Gamma Results -- 5.2.7 Paleontology of the Ragnarok Formation -- 5.2.8 Paleontology of the Hekkingen Formation -- 5.2.9 Magnetic Properties and Densities of the Mjølnir Crater Core (7329/03-U-01) -- 5.3 The Mjlnir Impact Event in a Sequence Stratigraphical Framework -- 5.4 The Evidence for Impact Crater Formation -- 5.4.1 The Crater: Its Structure and Shape -- 5.4.2 Fracturing and Conglomerates -- 5.4.3 Mineralogical Evidence of Impact Cratering -- 5.4.4 Geochemistry -- 5.4.5 Paleontological Evidence of Impact Cratering.
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6 Ejecta Geology -- 6.1 The Identification of Ejecta Beds -- 6.1.1 Introduction -- 6.1.2 The Ragnarok Formation and Sindre Bed -- 6.1.3 The Discoveries of Large Amounts of Soot in Mjølnir Related Sediments -- 6.2 The Stratigraphical Distribution of the Ejecta Beds -- 6.2.1 Borehole 7430/10-U-01 -- 6.2.2 Borehole 7018/05-U-01 -- 6.2.3 Janusfjellet, Central Spitsbergen -- 6.2.4 Nordvik Peninsula, North-Western Siberia -- 6.2.5 The Mjølnir Ejecta as a Regional Stratigraphic Marker -- 7 The Impact Dynamics -- 7.1 Introduction -- 7.2 Numerical Model -- 7.3 Cratering Process -- 7.4 Ejecta Formation and Distribution -- 7.5 Resurge Flow and Tsunami Generation -- 7.6 Conclusions -- 8 Structural Analysis of Deformed Central Peak Sediments -- 8.1 Structural Position of the Mjlnir Impact Crater -- 8.2 Structural Geological Analysis -- 8.2.1 Type A Structures: Early Extensional Micro-faults and Fissures -- 8.2.2 Type B-Structures: Fragmentation of Semi-consolidated or Consolidated Beds -- 8.2.3 Type C-Structures: Liquefaction and Shearing -- 8.2.4 Type D-Structures: Folds, Rotated Strata and Shear Bands -- 8.2.5 Type E-Structures: Intensely Sheared Sequences -- 8.2.6 Type F-Structures: Late Brittle Fractures and Microfaults -- 8.3 Deformation History of the Ragnarok Formation -- 9 Postimpact Deformation Due to Sediment Loading: The Mjlnir Paradigm -- 9.1 Postimpact Burial -- 9.2 Mjlnir Crater -- 9.2.1 Postimpact Infilling -- 9.2.2 Faulting and Differential Vertical Movements -- 9.3 Other Craters: Chesapeake Bay, Chicxulub, Bosumtwi, and Montagnais -- 9.4 Original Crater Relief Reconstruction -- 9.4.1 Mjølnir -- 9.4.2 Chicxulub -- 9.4.3 Bosumtwi -- 9.4.4 Chesapeake Bay -- 9.5 Correction of Crater Morphological and Structural Parameters -- 9.5.1 Parameters Prone to Postimpact Burial Modification -- 9.5.2 Postimpact Modification Correction Factor.
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10 The Mjlnir Tsunami -- 10.1 Introduction -- 10.2 Tsunami Models -- 10.3 Tsunami Generation -- 10.3.1 Near Field Evolution -- 10.3.2 Far Field Propagation -- 10.3.2.1 Estimates of Far-Field Behaviour -- 10.3.2.2 Computations of Far-Field Behaviour -- 10.4 Discussion -- References -- Index -- Index.
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