The Middle and Late Holocene Geology and Landscape Evolution of the Lower Acheron River Valley, Epirus, Greece
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The Middle and Late Holocene Geology and Landscape Evolution of the Lower Acheron River Valley, Epirus, Greece A THESIS SUBMITTED TO THE FACULTY OF THE GRADUATE SCHOOL OF THE UNIVERSITY OF MINNESOTA BY Mark Richard Besonen IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE August 1997 © Mark Richard Besonen 1997 Table of Contents LIST OF FIGURES •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••.••••••••••••••••••••••••••••••••••• VIII PREFACE AND ACKNOWLEDGMENTS ••••••••••••••••••••.••.•••.•.••••••••••••••••••••••••••••••••••••••••••••••••••• X ABSTRACT •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• XII INTRODUCTION ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 1 PHYSIOGRAPHY, GEOLOGY, AND NEOTECTONICS OF EPIRUS AND THE LOWER ACHERON VALLEY ........................................................................................................ 5 Physiography: .. ................. .................. ..... ... ........ .............................. ......... .. .................. 5 Previous Geologic Work Concerning Epirus: ................................ .. ........... ..... ............. 6 Geology: ... ........................... ..................... .... ... .......................... ............. .. .... ................. 8 Neotectonics: ........................ .... .... ................................ ...... .. ........... .. .......................... 11 HOLOCENE RELATIVE SEA LEVEL IN THE EPIRUS REGION ••••••••••••••••••••••••••••••••••••••••••• 11 A SUMMARY OF THE DISCREPANCY CONCERNING THE SIZE OF THE GLYKYS LIMEN (MODERN PHANARI BAY) ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 13 Ancient References: ................................... ......................... ........................................ 13 Modern Work: ............................................................................................................. 15 A SUMMARY OF THE DISCREPANCY CONCERNING THE NATURE, GEOMETRY, AND EVOLUTION OF THE ACHEROUSIAN LAKE ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 16 Ancient References: .... ......................................................................... ......... .............. 16 Modern Work: .... ......... ..... ...... .......... .. ........ .... ..... .. ... ............................ ....................... 16 A SUMMARY OF THE DISCREPANCY CONCERNING THE COURSE OF THE ACHERON RIVER WITH RESPECT TO KASTRI DURING THE CLASSICAL PERIOD •••••••••••••••••••••• 19 Ancient References: .................................................................................................... 19 Modern Work: ............................................................................................................. 20 THE USE OF MICROFOSSIL ASSEMBLAGES AND OTHER SEDIMENTOLOGICAL PARAMETERS FOR PALEOENVIRONMENTAL AND PALEOGEOGRAPHIC RECONSTRUCTIONS .................................................................................................... 21 The Use of Ostracoda and Foraminifera in Marginal Marine Settings: ... .... ..... .......... 21 Information Sources for Ostracod Ecology: ................................................................ 22 Information Sources for Foraminiferal Ecology: ........................................................ 22 The Problem of Contamination of Microfossil Assemblages: ............. ............. .... ...... 23 Other Sedimentological Parameters: ............................................................. .............. 23 METHODS AND PROCEDURES ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 23 Field Coring Program: ........................ ;....... ................................................................. 23 IV Field Core Logging and Sampling: ...................... .... ... .. ..................... .................. ....... 26 Laboratory Analyses: .. ... .. ..................... ..... ................. ........................................... ...... 26 Analysis of Microfossil Assemblages: ............... ..... .................................................... 26 Qualitative Assessment of Paleosalinity Based on Microfossil Assemblages: ........... 27 Loss on Ignition Analysis: .............. ............. ... .... ..... ..................... ... ...... ............. ......... 27 Pipette Grain Size Analysis: ........................................ ..... ... .................................. .. .. .. 28 Rock Magnetic Analyses: ... .................................. ........ ......... ................ .......... .. .. .. ...... 28 Radiocarbon Analysis: ................................ ... ........... ..... .... .. ................................. .... .. 29 Use of Literary and Historical References and Early Maps: ....................................... 30 RESULTS OF MICROFOSSIL ASSEMBLAGE ANALYSIS AND RELATED ECOLOGY OF THE LOWER ACHERON v ALLEY························································································30 Identification of Ostracods and Foraminifera: ...... ...................................................... 30 Ecology of Ostracods and Foraminifera: ........... .......................................................... 30 Recognition of Microfossil Assemblages: ................................................... ............... 31 Shallow, Fresh Water Microfossil Assemblage: .. ..... .................................................. 31 Shallow, Nearshore Brackish to Marine Water Microfossil Assemblage: ............. ... .. 33 Minimal Mixing and Contamination Between Modern Microfossil Assemblages: .... 34 Presence of Reworked Microfossils from Bedrock Valley Walls: ...... .. ...................... 34 RESULTS-ENVIRONMENTS OF DEPOSITION IN THE LOWER ACHERON VALLEY AND THE CHARACTERISTICS AND CRITERIA USED TO RECOGNIZE THEIR SEDIMENTARY DEPOSITS ..................................................................................................................... 35 Modern Fluvial and Deltaic Nearshore Depositional Systems: ........................ .......... 35 River Channel: ........................................................... .. ................ .... .......................... .. 37 Subaerial Natural Levee: ... ..................................................................... .... ... ... ... ........ 37 Crevasse Splay: ................................... ..... ......................................... ............ .............. 38 Floodplain: ................ ........................ .. ..... ... .. ....... ....................................................... 38 Backswamp: ................................................... ............................................................. 38 Shallow Fresh Water Lake: ........................................ .... ............................................. 40 Fresh to Brackish Water Delta Top Marsh: ...... .. .. ... ............................ .. ................ ..... .41 Delta Front-Distributary Channel, Distributary Mouth Bar, and Subaqueous Levee: .......... .................... ........ .. .. .. ................................................................. .... ............ ........ 41 Lower Delta Front and Prodelta: ...................... ... ... .............. .. ..... ......................... ....... 42 lnterdistributary Bay: ................................. ........... .... ............................. ............... ....... 42 Accretionary Beach: ................................. .. .... ... ... ....................................................... 42 THE MIDDLE AND LATE HOLOCENE GEOMORPHIC EVOLUTION AND PALEOGEOGRAPHY OF THE GLYKYS LIMEN •••••••••••••••••••••••••••••••••••••••••••••••••.••••••••••. 44 Overall Regressive Nature of Stratigraphy: ................................................................. 44 Generalized Nature of Reconstructed Shorelines: ............................... .. .. .................... 48 Glykys Limen in 2100 BC: .................. .. ........................... .. .. .... ...... .... ....... .................. 48 Maximum Inland Extent of Glykys Limen: ................................................. ............... 48 Glykys Limen in 1750 BC: ... ........................ .. ............................. ............... ................. 49 v Glykys Limen Between 1750 BC and AD 1100: ............ .................................... ... ..... 49 Glykys Limen in AD 1100: ................................. ............................................. .. ......... 51 Glykys Limen Since AD 1100 Based on Early Maps: .. .... .............................. ............ 51 Probable Redeposition of Organic Material From Core NC-92-20: .................. .... ..... 55 Changing Rates of Shoreline Progradation and Importance of Accretionary Beach Ridges: ............................................... ... .......................................................... .. ........... 57 Acherousian Lake as a Sediment Trap and Moderator of Shoreline Progradation: .... 59 Other Factors Capable of Moderating Coastal Evolution: .......................................... 60 THE LATE HOLOCENE BIRTH AND EVOLUTION OF THE ACHEROUSIAN LAKE •••.•••••••••• 61 Initial Formation of the Acherousian Lake and Flu vial Plug Impoundment Mechanism: ........................................ ........................................................................