Durham E-Theses Late Quaternary ice sheet dynamics and palaeoceanography in the Ban Bay region CODLING, PETER How to cite: CODLING, PETER (2017) Late Quaternary ice sheet dynamics and palaeoceanography in the Ban Bay region, Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/12676/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk 2 Peter Codling “Late Quaternary ice sheet dynamics and palaeoceanography in the Baffin Bay region” There remains a lack of data surrounding the timings and dynamics of the initial retreat of the Greenland ice sheet (GIS) from its maximum extent at the end of the last glacial maximum (LGM), with poor chronostratigraphic constraint also present on the timings of major Baffin Bay detrital carbonate events (BBDC) during the last deglaciation. This study presents new high-resolution data from two cores extracted from the deep abyssal plain of central Baffin Bay. Two separate radiocarbon dates have been extracted using foraminifera which have been used in the development of an age-depth model; estimating the base of the longer gravity core ‘GC01’ to be approximately 22 ka in age. Samples adequate for radiocarbon dating are few and far between due to intense dissolution of biogenic carbonate in both cores. Measurements of elemental concentrations indicate that significant changes in sediment provenance occurred in central Baffin Bay over the last 22Ka. Substantial amounts of sediment influx from western Greenland occurred during the LGM until approximately 15.8 ka BP when the GIS began its initial stages of retreat as the marine area of Baffin Bay increased. Thereafter the use of sedimentological, geochemical and biological markers alongside radiocarbon dating has captured two separate periods of ice sheet instability associated with the BBDC 1 and BBDC 0 estimated to have occurred between 14.1-13.6 ka BP and 12.7-11.4 ka BP respectively. Further analysis of elemental concentrations attributes these two BBDC events to both be associated with large amounts of sediment influx from northern Baffin Bay i.e. the break-up of the Laurentide (LIS) and the Innuitian Ice Sheets (IIS). When plotted as a timeseries against GISP2 and NGRIP ice core records and regional records of marine palaeoenvironmental, change it is clear that BBDC 1 and BBDC 0 occur out-of-phase with Heinrich event 1 or Heinrich event 0. Instead, BBDC 1 appears to start during the later stages of the Bølling Interstadial and continue into the Allerød Interstadial, peaking during the Older Dryas Stadial. BBDC 0 is generally coeval with the Younger Dryas Stadial although likely ends before the start of Heinrich event 0 in the North Atlantic. Due to BBDC events occurring during both interstadials and stadials periods this would also suggest that the initial trigger for the start of BBDC events are not necessarily linked to temperatures changes on Greenland, supporting Jackson et al., 2017. Therefore, indicating that the LIS and IIS were likely decoupled from the North Atlantic climate mode during the last deglaciation. “Late Quaternary ice sheet dynamics and palaeoceanography in the Baffin Bay region” Peter Codling Thesis submitted for the degree of Master of Science Department of Geography Durham University December, 2017 Contents: Chapter 1: Introduction: ........................................................................................................... 1 1.1 Importance of Ice Sheet Research ...................................................................................... 1 1.2 Central Baffin Bay...................................................................................................................... 1 1.3 Thesis aims and objectives ........................................................................................................ 2 1.4 Study area and Core Selection: ................................................................................................. 3 Chapter Two: Review of previous research in Baffin Bay ........................................................... 5 Section 2.1 Present-day conditions in Baffin Bay: .......................................................................... 5 2.1.1 Introduction: History of Early Study in Baffin Bay: ............................................................ 5 2.1.2 Baffin Bay- Present-day Oceanographic Conditions: ......................................................... 5 2.1.4 Present-Day Ice flux through Baffin Bay: ........................................................................... 9 Section 2.2: Global drivers of climate change during the Quaternary: ........................................ 10 2.2.1 Introduction: The Quaternary: ......................................................................................... 10 2.2.2 Internal (Sub-Milankovitch) processes in Baffin Bay and the North Atlantic: ................. 10 2.2.4 Baffin Bay Detrital Carbonate Events (BBDC): ................................................................. 13 Section 2.3: Baffin Bay through the Quaternary: Ice Dynamics: .................................................. 14 2.3.1 Introduction: .................................................................................................................... 14 2.3.2 Ice Sheet inception and growth/decay in Baffin Bay: ...................................................... 14 Section 2.4 Oceanographic Changes in Baffin Bay:....................................................................... 20 2.4.1 Carbonate Dissolution Cycles: .......................................................................................... 20 2.4.2 Long-term Records of Sea-ice and Productivity Changes: ............................................... 22 2.4.3 Late Pleistocene and Holocene Productivity: .................................................................. 26 2.4.4 The Younger Dryas and the Holocene Transition: ........................................................... 26 2.4.5 The Early-Mid Holocene: .................................................................................................. 27 2.4.6 The Late Holocene - Recent Oceanographic Change in Baffin Bay: ................................. 28 Chapter 3: Methods: .............................................................................................................. 30 3.1 Introduction: ........................................................................................................................... 30 3.2 Core Sedimentology: ............................................................................................................... 30 3.3 Multi-core Scanner XRF, MSCL and core X-Rays: .................................................................... 30 3.4 Particle Size Analysis: .............................................................................................................. 31 3.5 Biological Analysis: Foraminifera ............................................................................................ 31 3.4.1 Sample Preparation: ........................................................................................................ 32 3.5.2 Sample Analysis: ............................................................................................................... 32 3.6 Geochemical Analysis: ............................................................................................................ 32 3.6.1 Biomarker Extractions: ..................................................................................................... 32 3.6.2 Osmium Isotope Analysis: ................................................................................................ 35 3.7 Radiocarbon Dating: ............................................................................................................... 36 3.8 Pb-210 Dating:......................................................................................................................... 36 Chapter 4: Results: ................................................................................................................. 38 4.1 Introduction: ........................................................................................................................... 38 4.2 Chronology: Description: ........................................................................................................ 38 4.3 Core Sedimentology: Descriptions: ......................................................................................... 40 4.3.1 GC01: Sedimentological Description:............................................................................... 40 4.3.2 BC06: Sedimentological Description: ............................................................................... 44 4.4 XRF geochemical and Physical properties: Descriptions: ......................................................