# Gulf of Alaska Alkenone paleotemperatures, d18Oseawater reconstructions, benthic oxygen isotopes and benthic faunal data for the past 18,000 years #----------------------------------------------------------------------- # World Data Service for Paleoclimatology, Boulder # and # NOAA Paleoclimatology Program #----------------------------------------------------------------------- # NOTE: Please cite original publication, online resource and date accessed when using this data. # If there is no publication information, please cite Investigator, title, online resource and date accessed. # # Description/Documentation lines begin with # # Data lines have no # # # Online_Resource: https://www.ncdc.noaa.gov/paleo/study/21950 # Online_Resource: http://www1.ncdc.noaa.gov/pub/data/paleo/paleocean/by_contributor/praetorius2015/praetorius2015-87jc.txt # # Archive: Paleoceanography # # Parameter_Keywords: oxygen isotopes, reconstruction, biomarkers, age control, population abundance #--------------------------------------- # Contribution_Date # Date: 2017-04-19 #--------------------------------------- # Title # Study_Name: Gulf of Alaska Alkenone paleotemperatures, d18Oseawater reconstructions, benthic oxygen isotopes and benthic faunal data for the past 18,000 years #--------------------------------------- # Investigators # Investigators: Praetorius, Summer; Mix, Alan; Davies-Walczak, Maureen; Wolhowe, Matthew; Addison, Jason; Prahl, Fredrick #--------------------------------------- # Description and Notes # Description: Alkenone paleotemperatures, d18Oseawater reconstructions, and benthic faunal data in this worksheet are from jumbo piston core EW0408-85JC in the Gulf of Alaska. The age model for this core is previously published in Davies-Walczak et al., 2014 (DOI: 10.1016/j.epsl.2014.04.004). Additional benthic oxygen isotope data is provided from cores EW0408-87JC and EW0408-26JC in the Gulf of Alaska, along with the radiocarbon chronology for EW0408-87JC. Source reference for EW0408-26JC age model- Praetorius, S.K. and A.C., Science, 2014 (DOI: 10.1126/science.1252000). Please cite original reference when using this data and consult original publication for details on radiocarbon chronology. # Provided Keywords: ocean hypoxia, deglacial, oxygen minimum zone, alkenone paleotemperature #--------------------------------------- # Publication # Authors: Praetorius, S.K., A.C. Mix, M.H. Davies, M.D. Wolhowe, J.A. Addison, and F.G. Prahl # Published_Date_or_Year: 2015 # Published_Title: North Pacific deglacial hypoxic events linked to abrupt ocean warming # Journal_Name: Nature # Volume: 527 # Edition: # Issue: # Pages: 362-366 # Report Number: # DOI: 10.1038/nature15753 # Online_Resource: http://www.nature.com/nature/journal/v527/n7578/full/nature15753.html # Full_Citation: # Abstract: Marine sediments from the North Pacific document two episodes of expansion and strengthening of the subsurface oxygen minimum zone (OMZ) accompanied by seafloor hypoxia during the last deglacial transition. The mechanisms driving this hypoxia remain under debate. We present a new high-resolution alkenone palaeotemperature reconstruction from the Gulf of Alaska that reveals two abrupt warming events of 4–5 degrees Celsius at the onset of the Bølling and Holocene intervals that coincide with sudden shifts to hypoxia at intermediate depths. The presence of diatomaceous laminations and hypoxia-tolerant benthic foraminiferal species, peaks in redox-sensitive trace metals, and enhanced 15N/14N ratio of organic matter, collectively suggest association with high export production. A decrease in 18O/16O values of benthic foraminifera accompanying the most severe deoxygenation event indicates subsurface warming of up to about 2 degrees Celsius. We infer that abrupt warming triggered expansion of the North Pacific OMZ through reduced oxygen solubility and increased marine productivity via physiological effects; following initiation of hypoxia, remobilization of iron from hypoxic sediments could have provided a positive feedback on ocean deoxygenation through increased nutrient utilization and carbon export. Such a biogeochemical amplification process implies high sensitivity of OMZ expansion to warming. #--------------------------------------- # Publication # Authors: Davies, M.H., A.C. Mix, J.S. Stoner, J.A. Addison, J. Jaeger, B. Finney, and J. Wiest # Published_Date_or_Year: 2011 # Published_Title: The deglacial transition on the southeastern Alaska Margin: Meltwater input, sea level rise, marine productivity, and sedimentary anoxia # Journal_Name: Paleoceanography # Volume: 26 # Edition: # Issue: # Pages: # Report Number: PA2223 # DOI: 10.1029/2010PA002051. # Online_Resource: # Full_Citation: # Abstract: Oxygen isotope data from planktonic and benthic foraminifera, on a high-resolution age model (44 14C dates spanning 17,400 years), document deglacial environmental change on the southeast Alaska margin (59°33.32'N, 144°9.21'W, 682 m water depth). Surface freshening (i.e., d18O reduction of 0.8‰) began at 16,650 ± 170 cal years B.P. during an interval of ice proximal sedimentation, likely due to freshwater input from melting glaciers. A sharp transition to laminated hemipelagic sediments constrains retreat of regional outlet glaciers onto land circa 14,790 ± 380 cal years B.P. Abrupt warming and/or freshening of the surface ocean (i.e., additional d18O reduction of 0.9‰) coincides with the Bølling Interstade of northern Europe and Greenland. Cooling and/or higher salinities returned during the Allerød interval, coincident with the Antarctic Cold Reversal, and continue until 11,740 ± 200 cal years B.P., when onset of warming coincides with the end of the Younger Dryas. An abrupt 1‰ reduction in benthic d18O at 14,250 ± 290 cal years B.P. likely reflects a decrease in bottom water salinity driven by deep mixing of glacial meltwater, a regional megaflood event, or brine formation associated with sea ice. Two laminated opal-rich intervals record discrete episodes of high productivity during the last deglaciation. These events, precisely dated here at 14,790 ± 380 to 12,990 ± 190 cal years B.P. and 11,160 ± 130 to 10,750 ± 220 cal years B.P., likely correlate to similar features observed elsewhere on the margins of the North Pacific and are coeval with episodes of rapid sea level rise. Remobilization of iron from newly inundated continental shelves may have helped to fuel these episodes of elevated primary productivity and sedimentary anoxia. #--------------------------------------- # Funding_Agency # Funding_Agency_Name: # Grant: #--------------------------------------- # Site Information # Site_Name: EW0408-87JC # Location: Gulf of Alaska # Country: # Northernmost_Latitude: 58.77 # Southernmost_Latitude: 58.77 # Easternmost_Longitude: -144.5 # Westernmost_Longitude: -144.5 # Elevation: -3680 #--------------------------------------- # Data_Collection # Collection_Name: EW0408-87JC d18O Praetorius15 # First_Year: 17770 # Last_Year: 760 # Time_Unit: cal yr BP # Core_Length: 14.5 # Notes: #--------------------------------------- # Chronology_Information # Chronology: # # Core marine sediment core # Depth midpoint midpoint depth in core # Planktonic 14C age calibrated radiocarbon age mixed planktonic foraminifera # 14C uncertainty radiocarbon age uncertainty NaN one standard deviation yr marine sediment # Calibrated age calibrated radiocarbon age NaN NaN cal yr BP marine sediment Calibrated using Marine13 Accelerator mass spectrometry N # Calibrated age ±2s age uncertainty NaN two standard deviation yr marine sediment NaN NaN N # # Core Depth midpoint (cm) Planktonic 14C age (yr BP_ 14C uncertainty (yr) Calibrated age (cal yr BP) Calibrated age ±2s NaN NaN NaN # EW0408-87JC 39 1640 15 760 110 NaN NaN NaN # EW0408-87JC 208.5 8520 20 8530 140 NaN NaN NaN # EW0408-87JC 245 10715 20 11330 160 NaN NaN NaN # EW0408-87JC 250 10740 40 11380 240 NaN NaN NaN # EW0408-87JC 255 10975 30 11700 300 NaN NaN NaN # EW0408-87JC 267 11090 25 11990 280 NaN NaN NaN # EW0408-87JC 281 11695 30 12740 130 NaN NaN NaN # EW0408-87JC 301 12460 40 13470 160 NaN NaN NaN # EW0408-87JC 329 13170 40 14370 320 NaN NaN NaN # EW0408-87JC 341 13330 45 14650 400 NaN NaN NaN # EW0408-87JC 381 13830 30 15510 230 NaN NaN NaN # EW0408-87JC 420.5 14290 40 16160 230 NaN NaN NaN # EW0408-87JC 460 14560 70 16570 310 NaN NaN NaN # EW0408-87JC 492 14840 70 16950 330 NaN NaN NaN # EW0408-87JC 540 14930 60 17120 300 NaN NaN NaN # EW0408-87JC 920 15060 45 17300 220 NaN NaN NaN # EW0408-87JC 1002 15020 50 17250 240 NaN NaN NaN # EW0408-87JC 1449 15445 40 17770 190 NaN NaN NaN # #--------------------------------------- # Variables # Data variables follow that are preceded by "##" in columns one and two. # Variables list, one per line, shortname-tab-longname components (9 components: what, material, error, units, seasonality, archive, detail, method, C or N for Character or Numeric data) ## corename core name,marine sediment,,,,paleoceanography,,,C ## depth-mid depth ,,,m,,,midpoint depth in core,,N ## age_calkaBP age,,,cal ka BP,,,,,N ## d18Ocib delta 18O,Cibicidoides,,per mil VPDB,,paleoceanography,,Accelerator mass spectrometry,N ## d18Ocib+0.64 delta 18O,Cibicidoides,,per mil VPDB,,paleoceanography,corrected to Uvigerina peregrina d18O equivalent by adding 0.64,,N ## d18Ocib+0.64-slc delta 18O,Cibicidoides,,per mil VPDB,,paleoceanography,corrected to Uvigerina peregrina d18O equivalent by adding 0.64; Sealevel corrected based on the reconstruction of Waelbroeck et al., 2002,, #------------------------ # Data # Data lines follow (have no #) # Data line format - tab-delimited text, variable short name as header # Missing Value: Depth EW0408-87JC 0.61 1.76849558 2.96 3.6 3.6 EW0408-87JC 1.83 7.36 3.09 3.73 3.67 EW0408-87JC 2.03 8.28 3.26 3.90 3.80 EW0408-87JC 2.08 8.48 3.23 3.87 3.75 EW0408-87JC 2.14 8.91 3.07 3.71 3.57 EW0408-87JC 2.34 10.45 3.50 4.14 3.83 EW0408-87JC 2.36 10.60 3.42 4.06 3.73 EW0408-87JC 2.40 10.91 3.40 4.04 3.68 EW0408-87JC 2.42 11.06 3.55 4.19 3.81 EW0408-87JC 2.44 11.21 3.42 4.06 3.66 EW0408-87JC 2.45 11.29 3.36 4.00 3.59 EW0408-87JC 2.48 11.36 3.38 4.02 3.59 EW0408-87JC 2.50 11.38 3.37 4.01 3.57 EW0408-87JC 2.53 11.54 3.41 4.05 3.59 EW0408-87JC 2.54 11.60 3.56 4.20 3.73 EW0408-87JC 2.56 11.71 3.52 4.16 3.67 EW0408-87JC 2.62 11.86 3.41 4.05 3.56 EW0408-87JC 2.63 11.88 3.26 3.90 3.41 EW0408-87JC 2.64 11.91 3.74 4.38 3.88 EW0408-87JC 2.66 11.95 3.69 4.33 3.83 EW0408-87JC 2.68 12.02 3.83 4.47 3.96 EW0408-87JC 2.70 12.12 3.77 4.41 3.89 EW0408-87JC 2.72 12.23 3.77 4.41 3.88 EW0408-87JC 2.75 12.39 3.76 4.40 3.85 EW0408-87JC 2.80 12.66 3.87 4.51 3.93 EW0408-87JC 2.81 12.74 3.74 4.38 3.79 EW0408-87JC 2.84 12.83 3.66 4.30 3.69 EW0408-87JC 2.92 13.12 3.91 4.55 3.90 EW0408-87JC 2.94 13.20 3.75 4.39 3.73 EW0408-87JC 2.95 13.23 3.86 4.50 3.84 EW0408-87JC 2.96 13.27 3.88 4.52 3.85 EW0408-87JC 2.97 13.31 3.74 4.38 3.71 EW0408-87JC 2.98 13.34 3.78 4.42 3.74 EW0408-87JC 3.00 13.42 3.95 4.59 3.90 EW0408-87JC 3.01 13.47 3.94 4.58 3.88 EW0408-87JC 3.08 13.68 3.78 4.42 3.70 EW0408-87JC 3.14 13.87 3.85 4.49 3.76 EW0408-87JC 3.16 13.94 4.01 4.65 3.91 EW0408-87JC 3.19 14.03 3.83 4.47 3.72 EW0408-87JC 3.20 14.06 3.83 4.47 3.72 EW0408-87JC 3.29 14.35 3.92 4.56 3.78 EW0408-87JC 3.36 14.52 3.45 4.09 3.29 EW0408-87JC 3.38 14.57 4.07 4.71 3.90 EW0408-87JC 3.39 14.59 4.08 4.72 3.90 EW0408-87JC 3.40 14.62 4.05 4.69 3.87 EW0408-87JC 3.41 14.65 4.20 4.84 4.01 EW0408-87JC 3.43 14.68 3.99 4.63 3.80 EW0408-87JC 3.45 14.73 4.06 4.70 3.87 EW0408-87JC 3.47 14.77 3.92 4.56 3.72 EW0408-87JC 3.49 14.81 4.15 4.79 3.95 EW0408-87JC 3.50 14.83 4.12 4.76 3.92 EW0408-87JC 3.55 14.94 4.19 4.83 3.98 EW0408-87JC 3.58 15.02 4.05 4.69 3.84 EW0408-87JC 3.61 15.07 4.04 4.68 3.82 EW0408-87JC 3.65 15.16 4.09 4.73 3.86 EW0408-87JC 3.70 15.26 4.28 4.92 4.05 EW0408-87JC 3.81 15.51 4.21 4.85 3.96 EW0408-87JC 3.85 15.57 4.19 4.83 3.93 EW0408-87JC 3.90 15.65 4.13 4.77 3.87 EW0408-87JC 3.99 15.81 4.17 4.81 3.89 EW0408-87JC 4.05 15.90 4.36 5.00 4.07 EW0408-87JC 4.11 16.00 4.22 4.86 3.92 EW0408-87JC 4.21 16.17 4.25 4.89 3.94 EW0408-87JC 4.41 16.37 4.42 5.06 4.10 EW0408-87JC 4.51 16.47 4.37 5.01 4.05 EW0408-87JC 4.61 16.58 4.43 5.07 4.11 EW0408-87JC 4.71 16.69 4.52 5.16 4.19 EW0408-87JC 4.93 16.95 4.41 5.05 4.08 EW0408-87JC 5.01 16.98 4.38 5.02 4.05