# 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-age-85jc.txt # # Archive: Paleoceanography # # Parameter_Keywords: oxygen isotopes, alkenone paleotemperature, 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. Not all alkenone and isotope samples were taken from precisely the same depth intervals. Some isotope samples were measured on 2cm interval samples, whereas alkenone measurements were conducted on 1cm samples. Therefore, some of the d18O sw calculations are based on alkenone temperature and d18O pairs that have minor offsets in the midpoint depth range. Nearly all of these pairs are within a decade of one another in the age model. 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. Sediment concentrations (K37's mg/g) are not reported for a small number of samples for which analysis of the recovery standard was compromised (indicated with NAN). # Provided Keywords: ocean hypoxia, deglacial, oxygen minimum zone #--------------------------------------- # 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: National Science Foundation # Grant: AGS-0602395, OCE-1204204 #--------------------------------------- # Site Information # Site_Name: EW0408-85JC # Location: Gulf of Alaska # Country: # Northernmost_Latitude: 59.555 # Southernmost_Latitude: 59.555 # Easternmost_Longitude: -144.1535 # Westernmost_Longitude: -144.1535 # Elevation: -682 #--------------------------------------- # Data_Collection # Collection_Name: EW0408-85JC age model Praetorius15 # First_Year: 17370 # Last_Year: 1410 # Time_Unit: cal yr BP # Core_Length: 11.2 # Notes: Depths listed are depth in core (as opposed to depth below sea floor reported in Davies et al., 2011). Age model: Davies-Walczak et al., 2014. #--------------------------------------- # Chronology_Information # Chronology: #--------------------------------------- # 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,,,,,paleoceanography,,,C ## depth_m depth,,,m,,,midpoint depth in core,,N ## age_calyrBP calibrated radiocarbon age,planktonic foraminifera ,,cal yr BP,,,,Accelerator mass spectrometry,N ## age_calyrBP_1s calibrated radiocarbon age,,one standard deviation,yr,,,,,N #------------------------ # Data # Data lines follow (have no #) # Data line format - tab-delimited text, variable short name as header # Missing Value: NAN corename depth_m age_calyrBP age_calyrBP_1s EW0408-85JC 0.26 1410 105 EW0408-85JC 0.72 1930 120 EW0408-85JC 1.04 2820 120 EW0408-85JC 1.54 3400 120 EW0408-85JC 2.06 3880 125 EW0408-85JC 2.54 4680 145 EW0408-85JC 3.04 5400 130 EW0408-85JC 3.54 6370 100 EW0408-85JC 4.05 7940 95 EW0408-85JC 4.55 8620 135 EW0408-85JC 5.05 9220 145 EW0408-85JC 5.55 9950 130 EW0408-85JC 5.75 10320 85 EW0408-85JC 5.9 10660 85 EW0408-85JC 6.04 10950 85 EW0408-85JC 6.09 11150 75 EW0408-85JC 6.2 11510 115 EW0408-85JC 6.3 11900 115 EW0408-85JC 6.4 12290 105 EW0408-85JC 6.445 12650 75 EW0408-85JC 6.495 13450 105 EW0408-85JC 6.54 13800 75 EW0408-85JC 6.6 14060 80 EW0408-85JC 6.7 14330 105 EW0408-85JC 6.75 14570 115 EW0408-85JC 6.8 14820 110 EW0408-85JC 6.845 15070 95 EW0408-85JC 6.9 15460 120 EW0408-85JC 7.04 16130 125 EW0408-85JC 7.26 16600 125 EW0408-85JC 7.54 17010 150 EW0408-85JC 8.04 17090 70 EW0408-85JC 8.54 17130 65 EW0408-85JC 9.04 17170 60 EW0408-85JC 9.53 17210 60 EW0408-85JC 10.03 17260 60 EW0408-85JC 10.53 17310 70 EW0408-85JC 11.03 17370 80