Pacific - Atlantic Mollusc Migration: Pliocene Inter-Ocean Gateway Archives on Tjörnes, North Iceland (Topics in Geobiology, 52)

This volume sheds new light on the marine fauna and geological setting of the Tjörnes Sequence, North Iceland, which is a classic site for the Pliocene and Pleistocene stratigraphy of the North Atlantic region. Readers will discover descriptions of new data collected by the editors over a period of over three decades on marine faunal assemblages and sedimentology available for palaeoenvironmental reconstructions, as well as the tectonic and stratigraphical relationships on Tjörnes Peninsula. The book includes a comprehensive account of all the collections of marine fossil invertebrate macrofossils and foraminifera known to the editors from the Tjörnes Sequence. It is expected to elucidate sedimentological and faunal changes from relatively stable Pliocene conditions to highly variable and periodically harsh climatic conditions of recurring Quaternary glaciations. The distribution, recent or fossil, of various species is recorded and pertinent ecological and biological features are also discussed. The Tjörnes Sequence records the Neogene migration of Pacific species into the North Atlantic. Researchers in geology, climate science, environmental science and earth science will find this book particularly valuable. Foreword: The Paleoclimatic and Paleobiogeographic Significance of the Tjörnes Basin, Northern Iceland Acknowledgements Contents Chapter 1: A Brief Resumé of the Geology of Iceland 1.1 Introduction 1.2 Plate Tectonic Setting 1.3 Geological History 1.3.1 Accumulation of Volcanics and Sediments at a Terrestrial Divergent Plate Margin 1.3.2 Climatic Conditions in Iceland 1.3.3 Glaciation History of Iceland 1.3.4 Terrestrial Sedimentary Basins and Sequences 1.3.5 Sedimentary Basins Offshore References Chapter 2: The Marine Realm Around Iceland: A Review of Biological Research 2.1 The Marine Environment 2.2 The Marine Life Around Iceland: A Historical Review 2.2.1 Invertebrates: Early Studies 2.2.1.1 Foraminifera: Early Studies (Before c. 1990) 2.2.1.2 Mollusca: Early Studies (Before c. 1990) 2.2.1.3 Other Invertebrates: Early Studies (Before c. 1990) 2.2.2 Invertebrates: Modern Studies 2.2.2.1 Modern Studies: The BIOICE Project 2.2.2.2 Foraminifera: Modern Studies 2.2.2.3 Mollusca: Modern Studies 2.2.2.4 Other Invertebrates: Modern Studies 2.2.2.5 Invertebrate Communities Around Iceland 2.2.3 Vertebrates 2.2.4 Algae and Phytoplankton 2.2.5 Concluding Remarks References Chapter 3: The Evolution of the Tjörnes Sedimentary Basin in Relation to the Tjörnes Fracture Zone and the Geological Structure of Iceland 3.1 Introduction 3.2 The Tjörnes Fracture Zone 3.3 Sediments on the North Iceland Shelf 3.4 Geology of the Tjörnes Horst 3.5 The Tjörnes Sequence 3.5.1 The Barmur Group 3.5.2 The Höskuldsvík Group 3.5.3 The Breiðavík Group 3.6 Current Tectonic Activity of the Tjörnes Fracture Zone 3.7 The Tjörnes Sedimentary Basin – Discussion 3.8 Conclusions References Chapter 4: A Review of the Research History of the Tjörnes Sequence, North Iceland 4.1 Introduction 4.2 Early Reconnaissance 4.3 Early Placement of Tjörnes in the Regional Icelandic Stratigraphy 4.4 Pioneering Studies of Marine Macrofossils of the Tjörnes Sequence 4.5 Geological Mapping and Lithostratigraphy of the Tjörnes Sequence 4.6 Paleomagnetic Research on Tjörnes 4.7 Reexamination of the Tjörnes Sequence and Recent Studies of Marine Macrofossils in the Sequence 4.8 Palynological and Plant Remains Research of the Tjörnes Sequence 4.9 Studies of Marine Microfossils in the Tjörnes Sequence 4.10 The Tjörnes Fracture Zone (TFZ) and the Position of Tjörnes with Regard to Plate Tectonics 4.11 Discussion and State of Knowledge 4.12 Conclusions References Chapter 5: Lithostratigraphy of the Tjörnes Sequence in Barmur and Höskuldsvík on the West Coast of Tjörnes, North Iceland 5.1 Introduction 5.2 Re-examination of the Stratigraphy of the Tjörnes Beds (Barmur Group) 5.3 The Kaldakvísl Lava Group 5.4 The Barmur Group 5.4.1 Lithofacies Types of the Barmur Group 5.4.1.1 Diamictite Facies 5.4.1.2 Conglomerate Facies 5.4.1.3 Shelly Conglomerate Facies 5.4.1.4 Sandstone Facies 5.4.1.5 Siltstone Facies 5.4.1.6 Mudrock and Lignite Facies 5.4.2 The Héðinshöfði Formation: Kaldakvísl Group 5.4.3 The Eyvík Formation 5.4.4 The Kaldakvísl Locality 5.4.5 The Oddi Formation 5.4.5.1 The Tunguá Member 5.4.5.2 The Syðrihóll Member 5.4.6 The Lynghöfði Formation 5.4.6.1 The Kvíslarós Member 5.4.6.2 The Kvíslarkambur Member 5.4.7 The Grænhöfði Formation 5.4.7.1 The Klungur Member 5.4.7.2 The Tungugerðiskambar Member 5.4.7.3 The Hústorfa Member 5.4.8 The Tungugerði Formation 5.4.8.1 The Egilsgjóta Member 5.4.8.2 The Háibakki Member 5.4.8.3 The Skonsubakki Member 5.4.9 The Reká Formation 5.4.9.1 The Skonsur Member 5.4.9.2 The Rekárfoss Member 5.4.9.3 The Flekatá Member 5.4.10 The Hringver Formation 5.4.10.1 The Hvilft Member 5.4.10.2 The Skeifárbás Member 5.4.11 The Skeifá Formation 5.4.11.1 The Brunngil Member 5.4.11.2 The Ytri Svarthamar Member 5.4.12 The Tungugrænur Formation 5.4.12.1 The Votalág Member 5.4.12.2 The Grænur Member 5.4.13 The Tunga Formation 5.4.13.1 The Tungukambur Member 5.4.13.2 The Hallbjarnarstaðakambur Member 5.4.13.3 Outcrops Along the Hallbjarnarstaðaá River 5.4.13.4 The Kambsgjá Member 5.4.14 The Stórhöfði Formation 5.4.14.1 The Tófugjá Member 5.4.14.2 The Nöf Member 5.4.14.3 The Stapi Member 5.5 The Höskuldsvík Group. Definition, Boundaries, and Location 5.6 Discussion 5.7 Conclusions References Chapter 6: An Age Model for the Miocene to Pleistocene Tjörnes Sequence, North Iceland 6.1 Introduction 6.2 The Kaldakvísl Lava Group. Chronological Data from the Basement Lavas South of Tunguá and Kaldakvísl 6.3 The Barmur Group 6.3.1 Previous Age Models for the Traditional Tjörnes Beds 6.3.2 The Héðinshöfði Graben 6.3.3 The Eyvík Graben 6.3.4 The Kaldakvísl Locality and the Age of the Tapes Zone 6.3.5 Tectonic Fault Blocks at the Base of the Barmur Group: The Lynghöfði – Kaldakvísl – Grænhöfði Area 6.3.6 Sedimentary Sequence Between Egilsgjóta and Skeifá, Below the Skeifá Basalts 6.3.7 The Sequence of Strata Along the Coastline from the Skeifá Valley up to Höskuldsvík 6.4 The Höskuldsvík Group 6.5 The Breiðavík Group 6.5.1 Quaternary Sequence from the Matuyama Chron 6.5.2 Matuyama-Brunhes Transition in the Tjörnes Sequence 6.6 A New Age Model for the Tjörnes Sequence. Discussion 6.7 Conclusions References Chapter 7: Systematic Overview of the Pliocene Molluscs and Barnacles of the Barmur Group on Tjörnes, North Iceland 7.1 Paleontology 7.2 Gastropoda Prosobranchia 7.3 Gastropoda Opisthobranchia 7.4 Bivalvia 7.5 Cephalopoda 7.6 Arthropoda 7.7 Correlation with Other Cainozoic Faunas 7.7.1 Other Icelandic Sites 7.7.2 North Sea Sites 7.7.3 Greenlandic Sites 7.7.4 North American Sites 7.7.5 Siberian and Russian Sites 7.8 Concluding Remarks References Chapter 8: Foraminifera in the Pliocene Barmur Group on Tjörnes, North Iceland 8.1 Introduction 8.2 Sampling and Methods 8.3 Foraminiferal Contents, a Paleocoenosis 8.4 Systematics 8.5 Environmental and Stratigraphical Summary 8.5.1 The Tapes Zone 8.5.2 The Mactra Zone 8.5.3 The Serripes Zone 8.5.4 Concluding Remarks on Stratigraphy and Immigration 8.6 Conclusions References Chapter 9: Reconstructing the Paleoenvironments of the Pliocene Barmur Group in the Tjörnes Basin, North Iceland 9.1 Introduction 9.2 Review of the Marine Barmur Group Fauna 9.2.1 Sedimentary Facies, Mollusc Assemblages, and Foraminifera of the Tapes Zone 9.2.2 Sedimentary Facies, Mollusc Assemblages, and Foraminifera of the Mactra Zone 9.2.3 Sedimentary Facies, Mollusc Assemblages, and Foraminifera of the Serripes Zone 9.3 The Coastal Section at the Skeifá Fall: An Example of Faunal and Sedimentological Variability During Regressions and Transgressions Inferred from the Pliocene Tjörnes Sequence 9.4 Discussion 9.5 Conclusions References Chapter 10: Lithostratigraphy of the Upper Part of the Tjörnes Sequence in Furuvík, Breiðavík, Öxarfjörður, and Central Tjörnes Mountains, North Iceland 10.1 Introduction 10.2 The Breiðavík Group 10.3 Sedimentological Characteristics of the Breiðavík Group 10.3.1 Research Methods 10.3.2 Lithofacies Types of the Breiðavík Group 10.3.3 Tillites: Subglacial Facies Associations 10.3.4 Kame Conglomerates: Supraglacial Associations 10.3.5 Outwash and Lacustrine Conglomerates and Mudrocks: Proglacial Associations 10.3.6 Marine Mudrocks and Sandstones: Glaciolacustrine and Glaciomarine Associations 10.3.7 Shoreline Bar and Lagoon Associations 10.3.8 Alluvial Conglomerates and Sandstones 10.3.9 Volcanic Tuffs and Lava Flows of the Breiðavík Group 10.4 Lithostratigraphy of the Breiðavík Group 10.4.1 The Furuvík Formation 10.4.1.1 The Furugerði Member 10.4.1.2 The Miðnef Member 10.4.2 The Hörgi Formation 10.4.3 The Þrengingar Formation 10.4.3.1 The Fossgil Member 10.4.3.2 The Svarthamar Member 10.4.4 The Máná Formation 10.4.4.1 The Stapavík Member 10.4.4.2 The Torfhóll Member 10.4.4.3 The Dimmidalur Member 10.4.4.4 The Búrfellsá Member 10.4.5 The Grasafjall Formation 10.4.5.1 The Miðlækur Member 10.4.5.2 The Skeiðsöxl Member 10.4.5.3 The Bangastaðir Member 10.4.6 The Húsavík Formation 10.4.7 Environmental Development of the Upper Part of the Máná Formation, and the Grasafjall and Húsavík Formations 10.5 Stratigraphic Overview of the Breiðavík Group 10.6 Conclusions References Chapter 11: Systematic Overview of the Molluscs and Barnacles of the Quaternary Breiðavík Group North Iceland 11.1 Paleontology 11.2 Gastropoda 11.3 Bivalvia 11.4 Arthropoda 11.5 Review of the Breiðavík Fauna 11.6 Correlation with Pleistocene Faunas 11.6.1 Other Icelandic Sites 11.6.2 North Sea Sites 11.6.3 Greenlandic Sites 11.6.4 North American Sites 11.6.5 Siberian and Russian Sites 11.7 Concluding Remarks References Chapter 12: Foraminifera in the Early Pleistocene Part of the Breiðavík Group, North Iceland 12.1 Introduction 12.2 Sampling and Methods 12.3 Foraminiferal Content 12.4 Systematics 12.5 Environmental and Stratigraphical Summary 12.5.1 The Hörgi Formation (Unit 2) 12.5.2 The Þrengingar Formation (Units 8–12) 12.5.3 The Máná Formation (Unit 14) 12.5.4 Remarks on Stratigraphy and Immigration 12.6 Conclusions References Chapter 13: Reconstructing the Paleoenvironments of the Quaternary Tjörnes Basin, North Iceland 13.1 Introduction 13.2 Review of the Breiðavík Group Paleoenvironments 13.2.1 Sedimentary Facies and Mollusc Assemblages of the Furuvík Formation 13.2.2 Sedimentary Facies, Mollusc Assemblages, and Foraminifera of the Hörgi Formation 13.2.3 Sedimentary Facies, Mollusc Assemblages, and Foraminifera of the Þrengingar Formation 13.2.3.1 Sedimentary Facies and Mollusc Assemblages of the Fossgil Member 13.2.3.2 Sedimentary Facies, Mollusc Assemblages, and Foraminifera of the Svarthamar Member 13.2.4 Sedimentary Facies, Mollusc Assemblages, and Foraminifera of the Máná Formation 13.2.4.1 Sedimentary Facies and Mollusc Assemblages of the Stapavík Member 13.2.4.2 Sedimentary Facies, Mollusc Assemblages, and Foraminifera of the Torfhóll Member 13.2.4.3 Sedimentary and Volcanic Facies of the Dimmidalur and Búrfellsá Members 13.2.5 Sedimentary and Volcanic Facies of the Grasafjall Formation 13.2.6 Sedimentary and Volcanic Facies, and Mollusc Assemblages of the Húsavík Formation and Younger Deposits 13.3 The Svarthamar Member: An Early Pleistocene Glacial-Interglacial Cycle 13.3.1 Stratigraphy, Sedimentary Facies, Molluscs, and Foraminifera of the Svarthamar Member 13.3.2 The Svarthamar Glacial-Interglacial Cycle: A Synthesis 13.4 Discussion 13.5 Conclusions References Chapter 14: Migration of Pacific Marine Mollusc Fauna into the North Atlantic Across the Arctic Ocean in Pliocene and Early Pleistocene Time 14.1 Introduction 14.2 Late Cainozoic Changes of Gateways Between the Pacific and North Atlantic Oceans 14.2.1 The Opening of the Bering Strait 14.2.2 The Closing of the Central American Seaway 14.3 The Late Cainozoic Trans-Arctic Migration 14.3.1 Pacific Molluscs in the Tapes and Mactra Zones of the Barmur Group, Tjörnes Sequence 14.3.2 Pacific Molluscs Appearing in the Serripes Zone of the Barmur Group, Tjörnes Sequence 14.3.3 Pacific Molluscs Appearing in the Lower Pleistocene Part of the Breiðavík Group, Tjörnes Sequence 14.4 Summary 14.5 Conclusions References Index