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Abstract Over the last 3.3 million years, the Antarctic Ice Sheet (AIS) has undergone phases of ice sheet growth and decay, impacting sea level and climate globally. Presently, the largely marine‐terminating AIS loses mass primarily by iceberg calving and basal melt of ice shelves. Quantifying past rates and timing of AIS melt is vital to understanding future cryosphere and sea level changes. One proxy for past ice sheet instabilities is iceberg rafted debris (IRD) fluxes. However, traditional methods of IRD quantification are labor‐intensive. Here, we present a new method of identifying IRD grains in sediment core X‐ray images using a convolutional neural network machine learning algorithm. We present a 3.3‐million‐year record of AIS IRD melt events using sediment cores from International Ocean Discovery Program Sites U1536, U1537, and U1538 in the Southern Ocean's “Iceberg Alley.” We identify two increases in the IRD fluxes throughout this period, at ∼1.8 and 0.43 Ma. We propose that after 1.8 Ma, the AIS expanded and transitioned from a primarily terrestrial‐terminating to a primarily marine‐terminating ice sheet. Therefore, after 1.8 Ma, glacial terminations and AIS iceberg discharge are associated with variations in global ice volume, presumably through the mechanism of sea level and, therefore, grounding line change. The second AIS regime change occurs during the Mid‐Brunhes Event (∼0.43 Ma). After this time, there are heightened and continuous IRD fluxes at each glacial termination, indicating increased AIS size and instability after this time. 

Abstract. Biostratigraphy is frequently used to generate age models and is significant to understanding the rate and timing of Cenozoic climate change. Records from the Southern Ocean (SO) are particularly valuable in understanding the past behavior of the Antarctic Ice Sheet, whereby clues to this behavior can be gained from the presence and composition of preserved microfossils. Diatoms, a nearly ubiquitous group of microalgae that make cell walls out of opal, preserve well in Southern Ocean sediments and have been used extensively in Southern Ocean biostratigraphy. Here, we present an updated diatom biostratigraphy of the Southern Ocean extending 3.3 Myr from sediments recovered during International Ocean Discovery Program (IODP) Expedition 382 “Iceberg Alley” Site U1537. Furthermore, we compare a tuned age model to a paleomagnetic-based age model to provide two independent estimates of ages of these datums with quantified uncertainty. The high sedimentation rate found at Site U1537 allows detailed age assessment, allowing the generation of more finely tuned age models in Southern Ocean sediments. 

{"Abstract":["Supplementary tables in support of "Antarctic response to orbital forcing during the intensification of extensive bipolar glaciation (1.75-3.30 Ma) from relative paleomagnetic intensity (RPI) stratigraphy of the Dove Basin, Scotia Sea, in Iceberg Alley.""]} 

Data files for rock magnetic data collected on discrete samples at the Institute for Rock Magnetism, University of Minnesota on a Quantum Designs Magnetic Properties System 3 (MPMS3) and Lakeshore Model 8600 Vibrating Sample Magnetometer (VSM). Data include Field Cooled (FC), Zero Field Cooled (ZFC), and Low Temperature Cycling of Room Temperature Saturation Isothermal Remanent Magnetization (LTC-RTSIRM) curves measured on the MPMS and Hysteresis Loops, Direct Current Demagnetization Curves, and Hysteresis Loops collected on the VSM. 

Computed Tomography (CT) Data Collected on IODP Site U1537 u-channel samples using the Oregon State University College of Veterinary Medicine Toshiba Aquillon 64 Slice Medical CT Scanner in collaboration with the Oregon State University Marine and Geology Repository.  U-channels were measured in batches of 8 with derived CT data selecting only a portion of these original files for each u-channel.  All data are archived in DICOM format and have been processed using SedCT Matlab Tools (Reilly et al., 2017; 10.1002/2017GC006884).   Files Include: U1537 U-Channel CT DICOM Files (Original).zip Data in DICOM format from original scans measured in batches of 8.  Includes excel spreadsheet with identifying information for which sections were measured in each scan. U1537A U-Channel CT DICOM Files (Split).zip Data in DICOM format, segmented so each u-channel is a sperate file.  Folder system organized by section with two subfolders included for scans that needed to be run in two scans (nominally sections longer than 1 m).  Includes U1537A sections: 24H-2A, 24H-3A, 24H-4A, 25H-3A, 25H-4A, 25H-5A, 25H-6A, 26H-2A, 26H-3A, 26H-4A, 26H-5A, 26H-6A, 26H-7A, 26H-8A, 27F-3A, 2F-4A. U1537D U-Channel CT DICOM Files (Split).zip Data in DICOM format, segmented so each u-channel is a sperate file.  Folder system organized by section with two subfolders included for scans that needed to be run in two scans (nominally sections longer than 1 m).  Includes U1537D sections: 24H-1W, 24H-2W, 24H-3W, 24H-4W, 24H-5W, 24H-6W, 25H-1W, 25H-2W, 25H-3W, 25H-4W, 25H-5W, 25H-6W, 25H-7W, 26H-5W, 26H-6W, 26H-7W, 27H-2W, 27H-3W, 27H-4W, 27H-5W,  27H-6W, 27H-W, 28F-1W, 28F-2W, 28F-3W, 29F-1W, 29F-2W, 29F-3W, 29F-4W, 30F-1W, 30F-2W, 30F-3W, 30F-4W, 31F-1W, 31F-2W, 31F-3W, 31F-4W. U1537A SedCT Output.zip CT#s, unscaled TIFF files, and PNG files scaled to 200-1400 HU for U1537A u-channels generated using SedCT Matlab Tools. U1537D SedCT Output.zip CT#s, unscaled TIFF files, and PNG files scaled to 200-1400 HU for U1537D u-channels generated using SedCT Matlab Tools. CTnumbers.zip CT# data organized for each core into excel spreadsheets. 

{"Abstract":["Rock magnetic data from IODP Exp. 382 Sites U1537 and U1538 to support Reilly et al. "A geochemical mechanism for >10 m offsets of magnetic reversals inferred from the comparison of two Scotia Sea drill sites"\nExcel Files:\n\nU1537_CubeSummary_Zenodo.xlsx : Summary of NRM, ARM, IRM, and magnetic susceptibility investigations on U1537 cube samples\nU1538_CubeSummary_Zenodo.xlsx : Summary of NRM, ARM, IRM, and magnetic susceptibility investigations on U1538 cube samples\nZip Files:\n\nFORC_Data.zip : First order reversal curve data files in MicroMag format for samples discussed in paper\nDCD_Data.zip : DC Demagnetization curve data files for samples discussed in paper\nHysteresis_Data.zip : Hysteresis Loops for samples discussed in paper\nMPMS_Data.zip : Data collected on Magnetics Property Measurement System 3, including Field Cooled/Zero Field Cooled Curves, Low Temperature Cycling of Room Temperature IRM, and AC Susceptibility\n \nNRM = Natural Remanent Magnetization; ARM = Anhysteretic Remanent Magnetization; IRM = Isothermal Remanent Magnetization"]} 

Paleomagnetic, rock magnetic, or geomagnetic data found in the MagIC data repository from a paper titled: A Geochemical Mechanism for >10 m Apparent Downward Offsets of Magnetic Reversals Inferred From Comparison of Two Scotia Sea Drill Sites 

Abstract The Southern Ocean paleoceanography provides key insights into how iron fertilization and oceanic productivity developed through Pleistocene ice-ages and their role in influencing the carbon cycle. We report a high-resolution record of dust deposition and ocean productivity for the Antarctic Zone, close to the main dust source, Patagonia. Our deep-ocean records cover the last 1.5 Ma, thus doubling that from Antarctic ice-cores. We find a 5 to 15-fold increase in dust deposition during glacials and a 2 to 5-fold increase in biogenic silica deposition, reflecting higher ocean productivity during interglacials. This antiphasing persisted throughout the last 25 glacial cycles. Dust deposition became more pronounced across the Mid-Pleistocene Transition (MPT) in the Southern Hemisphere, with an abrupt shift suggesting more severe glaciations since ~0.9 Ma. Productivity was intermediate pre-MPT, lowest during the MPT and highest since 0.4 Ma. Generally, glacials experienced extended sea-ice cover, reduced bottom-water export and Weddell Gyre dynamics, which helped lower atmospheric CO 2 levels. 

Abstract Antarctica is one of the most vulnerable regions to climate change on Earth and studying the past and present responses of this polar marine ecosystem to environmental change is a matter of urgency. Sedimentary ancient DNA ( sed aDNA) analysis can provide such insights into past ecosystem-wide changes. Here we present authenticated (through extensive contamination control and sed aDNA damage analysis) metagenomic marine eukaryote sed aDNA from the Scotia Sea region acquired during IODP Expedition 382. We also provide a marine eukaryote sed aDNA record of ~1 Mio. years and diatom and chlorophyte sed aDNA dating back to ~540 ka (using taxonomic marker genes SSU, LSU, psbO ). We find evidence of warm phases being associated with high relative diatom abundance, and a marked transition from diatoms comprising <10% of all eukaryotes prior to ~14.5 ka, to ~50% after this time, i.e., following Meltwater Pulse 1A, alongside a composition change from sea-ice to open-ocean species. Our study demonstrates that sed aDNA tools can be expanded to hundreds of thousands of years, opening the pathway to the study of ecosystem-wide marine shifts and paleo-productivity phases throughout multiple glacial-interglacial cycles.