Hildreth W. The Novarupta-Katmai eruption of 1912 - largest eruption of the twentieth century: centennial perspectives / W.Hildreth, J.Fierstein. - Reston: U.S. Geological Survey, 2012. - xiv, 259 p.: col. ill., col. maps, col. ports. - (U.S. Geological Survey professional paper; 1791). - Ref.: p. 233-244. - ISBN 978-1-4113-3380-2  Место хранения:   018 | Институт нефтегазовой геологии и геофизики им. А.А.Трофимука | Новосибирск | Библиотека

Оглавление / Contents

Foreword ...................................................... iii Abstract ........................................................ 1 Chapter 1 The 1912 Eruption and its Importance ................. 3 Overview of the Eruption ............................. 3 Volcanological Significance of the 1912 Eruption ..... 3 Chapter 2 The Context of the 1912 Eruption .................... 13 Geographic Setting .................................. 13 Cultural Setting: Katmai Before 1912 ................ 13 Cultural Setting: The World in 1912 ................. 14 Scientific Context of the Early Katmai Investigations ...................................... 15 Geologic Setting of the Katmai Volcano Cluster ...... 17 Chapter 3 1912 Eruption Narrative: What Was Actually Recorded in 1912 .................................... 19 Chronology of Observations in 1912 .................. 19 Environmental Impact of the Eruption ................ 22 Recovery of Flora and Fauna ......................... 22 Chapter 4 History of Investigations and Interpretations ....... 25 Chronology of Geologic Investigations at Katmai ..... 25 Principal Contributors to the Early Geologic Investigations at Katmai ............................ 42 Chapter 5 Products of the 1912 Eruption ....................... 45 Eruptive Episode 1 .................................. 48 Layer A ........................................... 49 All-Rhyolite Ignimbrite ........................... 51 Layer В ........................................... 56 Compositionally Heterogeneous (Main) Valley- Filling Ignimbrite (VFI) .......................... 57 Compositionally Heterogeneous High-Energy Proximal Ignimbrite (HEPI) ................................. 62 Time Constraints for Episode I .................... 66 Eruptive Episodes II and III ........................ 68 Layer С ........................................... 70 Layer D ........................................... 71 Layer E ........................................... 71 Layer F ........................................... 73 Layer G ........................................... 74 Layer H ........................................... 76 Proximal Pyroclastic Density Currents ............. 77 Proximal Fall Deposits: Contrasting Facies ........ 77 Eruptive Episode IV: Dacitic Phantom Dome and Block Bed ........................................... 78 Eruptive Episode V: Novarupta Rhyolite Dome ......... 80 Chapter 6 Volcanological Aspects of the Primary Eruption Products ............................................ 87 Volumes Erupted ..................................... 87 Coignimbrite Ash and Coplinian Ash .................. 87 Atmospheric and Climatic Effects .................... 88 Changes in Compositional Proportions During the Eruptive Sequence ................................... 91 Banded Pumice ....................................... 94 Contemporaneity of Falls and Flows .................. 96 Characteristics of the Eruption Columns ............. 97 Column Collapse and Emplacement of Pyroclastic Density Currents .................................. 98 Episode I Eruptive Sequence ....................... 98 Concurrent Deposition of HEPI and VFI ............ 102 Particle Concentration Gradient .................. 105 Densification of Flow Units ...................... 105 Episodes II and III: Small Density Currents from Column Margins ................................... 111 Physical Features of VTTS Ignimbrite Sheet ......... 112 Aspect Ratio ..................................... 112 Flow Units and Progressive Aggradation ........... 112 Remobilized Flow Units ........................... 113 Diffusely Plane Laminated Ignimbrite ............. 114 "High Sand Mark" ................................. 114 Valley Margin Runups ............................. 116 Induration and Welding ........................... 119 Degassing pipes .................................. 122 Emplacement Over and Against Ice ................. 123 Chapter 7 Vent Structure at Novarupta ........................ 129 Asymmetry of the Proximal Ejecta Ring: The Turtle ............................................. 132 Chapter 8 Caldera Collapse and Seismicity .................... 135 Seismicity Accompanying the 1912 Eruption .......... 135 Comparison with Other Seismically Recorded Caldera Collapses .................................. 139 Hydrothermal Explosion Breccia and Phreatically Ejected Mud Layers ................................. 141 Chapter 9 The Ten Thousand Smokes ............................ 143 Fumarolic Deposits ................................. 147 Fumaroles in Novarupta Basin ....................... 153 Chapter 10 Secondary Deposits ................................. 155 Syneruptive Runoff and Remobilization .............. 155 Syneruptive Landslides ............................. 157 Lakes Impounded .................................... 158 Phreatic Craters and Deposits ...................... 165 Chapter 11 Posteruptive Evolution of the Landscape ............ 167 Rapid Incision of Gorges ........................... 167 Alluvial Plains, Channels, and Veneers ............. 168 Aeolian Deposits ................................... 170 Behavior of Ash-Covered Glaciers ................... 171 Katmai Caldera Lake and Intracaldera Glacier Development ........................................ 173 Photographic Comparisons: Then and Now ............. 177 Chapter 12 The Katmai Volcano Cluster ......................... 179 Alagogshak Volcano ................................. 179 Mount Martin ....................................... 179 Mount Mageik ....................................... 181 Trident Volcano and its Domes ...................... 182 Southwest Trident (Eruption of 1953-74) ............ 184 Mount Katmai ....................................... 186 Snowy Mountain ..................................... 188 Mount Griggs ....................................... 188 Other Volcanoes Behind the Volcanic Front .......... 190 Present-day Magma Distribution? .................... 190 Typically Small Magma Batches ...................... 191 Chapter 13 1912 Magma Compositions and Preeruptive Storage .... 193 1912 Bulk Compositions ............................. 193 Major Elements .................................. 193 Trace Elements .................................. 196 Affinities to Nearby Volcanoes ..................... 196 Volatile Compositions .............................. 203 Mineralogy of 1912 Products ........................ 203 Isotope Ratios ..................................... 205 Experimental Petrology ............................. 210 Preeruptive Magma Storage and Syneruptive Transport .......................................... 211 Plausible Storage Sites of 1912 Magmas .......... 212 No Preeruptive Magma Storage Beneath Novarupta .. 213 Data Bearing Upon Models of the 1912 Plumbing System .......................................... 214 Origin of the Rhyolite Magma ....................... 216 Alternatives to a Zoned Reservoir? ................. 217 Two Chambers? ................................... 217 A New Magma Batch from Depth? ................... 218 Roof-Zone Remelting? ............................ 218 1912 Magma Storage Model ........................... 219 Chapter 14 Comparisons with Other Historic Eruptions .......... 221 Chapter 15 Retrospective: Evolution of Ideas about the 1912 Eruption ........................................... 225 Advances in Volcanology and Progress in Understanding the 1912 Eruption .................... 227 Acknowledgments ............................................... 231 References .................................................... 233 Appendix A Major-element chemical analyses of eruptive products, Novarupta 1912 .......................... 246 Appendix B Trace-element chemical analyses of eruptive products, Novarupta 1912 .......................... 252 Appendix C Trace-element analyses of 1912 eruptive products by Instrumental neutron activation analysis (INAA) ............................................ 258