USAP-DC

{"dp_type": "Dataset", "free_text": "Depth-Age"}

[{"awards": "1443336 Osterberg, Erich", "bounds_geometry": ["POINT(-180 -90)"], "date_created": "Thu, 29 Aug 2019 00:00:00 GMT", "description": "The South Pole Ice Core (SPICEcore) was drilled in 2014-2016 to provide a detailed multi-proxy archive of paleoclimate conditions in East Antarctica during the Holocene and late Pleistocene. Interpretation of these records requires an accurate depth-age relationship. Here, we present the SP19 timescale for the age of the ice of SPICEcore. SP19 is synchronized to the WD2014 chronology from the West Antarctic Ice Sheet Divide (WAIS Divide) ice core using stratigraphic matching of 251 volcanic events. These events indicate an age of 54,302 +/- 519 years BP (before the year 1950) at the bottom of SPICEcore. Annual layers identified in sodium and magnesium ions to 11,341 BP were used to interpolate between stratigraphic volcanic tie points, yielding an annually-resolved chronology through the Holocene. Estimated timescale uncertainty during the Holocene is less than 18 years relative to WD2014, with the exception of the interval between 1800 to 3100 BP when uncertainty estimates reach +/- 25 years due to widely spaced volcanic tie points. Prior to the Holocene, uncertainties remain within 124 years relative to WD2014. Results show an average Holocene accumulation rate of 7.4 cm/yr (water equivalent). The time variability of accumulation rate is consistent with expectations for steady-state ice flow through the modern spatial pattern of accumulation rate. Time variations in nitrate concentration, nitrate seasonal amplitude, and \u03b415N of N2 in turn are as expected for the accumulation-rate variations. The highly variable yet well-constrained Holocene accumulation history at the site can help improve scientific understanding of deposition-sensitive climate proxies such as \u03b415N of N2 and photolyzed chemical compounds.", "east": -180.0, "geometry": ["POINT(-180 -90)"], "keywords": "Antarctica; Calcium (ca); Chemistry:ice; Chemistry:Ice; Depth; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciochemistry; Glaciology; Ice; Ice Core; Ice Core Chemistry; Ice Core Data; Ice Core Records; Ice Core Stratigraphy; Nitrate; Nitrogen Isotopes; Paleoclimate; Snow/ice; Snow/Ice; South Pole; SPICEcore", "locations": "South Pole; Antarctica", "north": -90.0, "nsf_funding_programs": "Antarctic Glaciology", "persons": "Winski, Dominic A.; Fudge, T. J.; Dunbar, Nelia; Buizert, Christo; Bay, Ryan; Souney, Joseph Jr.; Sigl, Michael; McConnell, Joseph; Fegyveresi, John; Cole-Dai, Jihong; Thundercloud, Zayta; Cox, Thomas S.; Kreutz, Karl; Epifanio, Jenna; Ortman, Nikolas; Brook, Edward J.; Beaudette, Ross; Sowers, Todd A.; Steig, Eric J.; Morris, Valerie; Kahle, Emma; Ferris, David G.; Aydin, Murat; Nicewonger, Melinda R.; Casey, Kimberly A.; Alley, Richard; Waddington, Edwin D.; Osterberg, Erich; Severinghaus, Jeffrey P.; Jones, Tyler R.; Iverson, Nels", "project_titles": "Collaborative Research: South Pole Ice Core Chronology and Climate Records using Chemical and Microparticle Measurements", "projects": [{"proj_uid": "p0010051", "repository": "USAP-DC", "title": "Collaborative Research: South Pole Ice Core Chronology and Climate Records using Chemical and Microparticle Measurements"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "SPICEcore", "south": -90.0, "title": "The South Pole Ice Core (SPICEcore) chronology and supporting data", "uid": "601206", "west": -180.0}, {"awards": "0538427 McConnell, Joseph", "bounds_geometry": ["POINT(-112.1115 -79.481)"], "date_created": "Tue, 28 Mar 2017 00:00:00 GMT", "description": "A state-of-the-art continuous ice core analytical system was used to analyze samples from 0 to ~130 m depth of the recently collected intermediate core WDC05Q from West Antarctica. Interpretation of these records and publication of findings is ongoing.", "east": -112.1115, "geometry": ["POINT(-112.1115 -79.481)"], "keywords": "Antarctica; Depth-Age-Model; Geochronology; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core Records; WAIS Divide; WAIS Divide Ice Core", "locations": "WAIS Divide; Antarctica", "north": -79.481, "nsf_funding_programs": null, "persons": "McConnell, Joseph", "project_titles": "Trace and Ultra-Trace Chemistry Measurements of the WAIS Divide Ice Core", "projects": [{"proj_uid": "p0000148", "repository": "USAP-DC", "title": "Trace and Ultra-Trace Chemistry Measurements of the WAIS Divide Ice Core"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "WAIS Divide Ice Core", "south": -79.481, "title": "WAIS Divide Ice-Core Chronology from Intermediate Core WDC05Q", "uid": "601013", "west": -112.1115}, {"awards": "0944197 Waddington, Edwin", "bounds_geometry": ["POINT(-112.1115 -79.481)"], "date_created": "Tue, 28 Mar 2017 00:00:00 GMT", "description": "The West Antarctic Ice Sheet Divide (WAIS Divide, WD) ice core is a newly drilled, high-accumulation deep ice core that provides Antarctic climate records of the past ~68 ka at unprecedented temporal resolution. The upper 2850 m (back to 31.2 ka BP) have been dated using annual-layer counting. Here we present a chronology for the deep part of the core (67.8-31.2 ka BP), which is based on stratigraphic matching to annual-layer-counted Greenland ice cores using globally well-mixed atmospheric methane. We calculate the WD gas age-ice age difference (Delta age) using a combination of firn densification modeling, ice-flow modeling, and a data set of d15N-N2, a proxy for past firn column thickness. The largest Delta age at WD occurs during the Last Glacial Maximum, and is 525 +/- 120 years. Internally consistent solutions can be found only when assuming little to no influence of impurity content on densification rates, contrary to a recently proposed hypothesis. We synchronize the WD chronology to a linearly scaled version of the layer-counted Greenland Ice Core Chronology (GICC05), which brings the age of Dansgaard-Oeschger (DO) events into agreement with the U/Th absolutely dated Hulu Cave speleothem record. The small Delta age at WD provides valuable opportunities to investigate the timing of atmospheric greenhouse gas variations relative to Antarctic climate, as well as the interhemispheric phasing of the \\\"bipolar seesaw\\\".\n\nWe present the WD2014 chronology for the upper part (0-2850 m; 31.2 ka BP) of the West Antarctic Ice Sheet (WAIS) Divide (WD) ice core. The chronology is based on counting of annual layers observed in the chemical, dust and electrical conductivity records. These layers are caused by seasonal changes in the source, transport, and deposition of aerosols. The measurements were interpreted manually and with the aid of two automated methods. We validated the chronology by comparing to two high-accuracy, absolutely dated chronologies. For the Holocene, the cosmogenic isotope records of 10Be from WAIS Divide and 14C for IntCal13 demonstrated that WD2014 was consistently accurate to better than 0.5% of the age. For the glacial period, comparisons to the Hulu Cave chronology demonstrated that WD2014 had an accuracy of better than 1% of the age at three abrupt climate change events between 27 and 31ka. WD2014 has consistently younger ages than Greenland ice core chronologies during most of the Holocene. For the Younger Dryas-Preboreal transition (11.595 ka; 24 years younger) and the Bolling-Allerod Warming (14.621 ka; 7 years younger), WD2014 ages are within the combined uncertainties of the timescales. Given its high accuracy, WD2014 can become a reference chronology for the Southern Hemisphere, with synchronization to other chronologies feasible using high-quality proxies of volcanism, solar activity, atmospheric mineral dust, and atmospheric methane concentrations.", "east": -112.1115, "geometry": ["POINT(-112.1115 -79.481)"], "keywords": "Antarctica; Depth-Age-Model; Geochronology; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core Records; WAIS Divide; WAIS Divide Ice Core", "locations": "WAIS Divide; Antarctica", "north": -79.481, "nsf_funding_programs": null, "persons": "Fudge, T. J.", "project_titles": "Collaborative Research: Establishing the Chronology and Histories of Accumulation and Ice Dynamics for the WAIS Divide Core", "projects": [{"proj_uid": "p0000026", "repository": "USAP-DC", "title": "Collaborative Research: Establishing the Chronology and Histories of Accumulation and Ice Dynamics for the WAIS Divide Core"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "WAIS Divide Ice Core", "south": -79.481, "title": "WD2014: Timescale for WAIS Divide Core 2006 A (WDC-06A)", "uid": "601015", "west": -112.1115}, {"awards": "0538416 McConnell, Joseph", "bounds_geometry": ["POLYGON((-54.9 -73.7,-49.57 -73.7,-44.24 -73.7,-38.91 -73.7,-33.58 -73.7,-28.25 -73.7,-22.92 -73.7,-17.59 -73.7,-12.26 -73.7,-6.93 -73.7,-1.6 -73.7,-1.6 -74.61,-1.6 -75.52,-1.6 -76.43,-1.6 -77.34,-1.6 -78.25,-1.6 -79.16,-1.6 -80.07,-1.6 -80.98,-1.6 -81.89,-1.6 -82.8,-6.93 -82.8,-12.26 -82.8,-17.59 -82.8,-22.92 -82.8,-28.25 -82.8,-33.58 -82.8,-38.91 -82.8,-44.24 -82.8,-49.57 -82.8,-54.9 -82.8,-54.9 -81.89,-54.9 -80.98,-54.9 -80.07,-54.9 -79.16,-54.9 -78.25,-54.9 -77.34,-54.9 -76.43,-54.9 -75.52,-54.9 -74.61,-54.9 -73.7))"], "date_created": "Wed, 08 Aug 2012 00:00:00 GMT", "description": "This data set consists of sodium (Na) and magnesium (Mg) concentrations versus depth in seven ice cores that were obtained by the Norwegian-U.S. Scientific Traverse of East Antarctica during the International Polar Year (IPY) 2007-2009. Additional glaciochemical analyses and a final depth-age scale will be added as these data become available.\n\nData are available via FTP.", "east": -1.6, "geometry": ["POINT(-28.25 -78.25)"], "keywords": "Antarctica; Chemistry:ice; Chemistry:Ice; East Antarctica; Geochemistry; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core Records", "locations": "East Antarctica; Antarctica", "north": -73.7, "nsf_funding_programs": "Antarctic Glaciology", "persons": "McConnell, Joseph", "project_titles": "Collaborative Research: Norwegian-United States IPY Scientific Traverse: Climate Variability and Glaciology in East Antarctica", "projects": [{"proj_uid": "p0000095", "repository": "USAP-DC", "title": "Collaborative Research: Norwegian-United States IPY Scientific Traverse: Climate Variability and Glaciology in East Antarctica"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -82.8, "title": "Ice Core Chemistry from the Norwegian-U.S. Scientific Traverse of East Antarctica, IPY 2007-2009", "uid": "609520", "west": -54.9}, {"awards": "0087521 Waddington, Edwin", "bounds_geometry": ["POINT(-148.82 -81.66)"], "date_created": "Sun, 15 Apr 2012 00:00:00 GMT", "description": "Researchers gathered data on annual snow layers at Siple Dome, Antarctica, using borehole optical stratigraphy. This data set contains annual layer depths and firn optical brightness. The brightness log is a record of reflectivity of the firn, and peaks in brightness are interpreted to be fine-grained high-density winter snow, as part of the wind slab depth-hoar couplet. \n\nData are available via FTP in ASCII text (.txt) format", "east": -148.82, "geometry": ["POINT(-148.82 -81.66)"], "keywords": "Antarctica; Borehole Optical Stratigraphy; Geology/Geophysics - Other; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Siple Dome; Siple Dome Ice Core; Snow/ice; Snow/Ice", "locations": "Siple Dome; Antarctica", "north": -81.66, "nsf_funding_programs": "Antarctic Glaciology", "persons": "Hawley, Robert L.; Waddington, Edwin D.; Alley, Richard; Taylor, Kendrick C.", "project_titles": "Borehole Fingerprinting: Vertical Strain, Firn Compaction, and Firn Depth-Age Scales", "projects": [{"proj_uid": "p0000173", "repository": "USAP-DC", "title": "Borehole Fingerprinting: Vertical Strain, Firn Compaction, and Firn Depth-Age Scales"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "Siple Dome Ice Core", "south": -81.66, "title": "Annual Layers at Siple Dome, Antarctica, from Borehole Optical Stratigraphy", "uid": "609515", "west": -148.82}, {"awards": "0739491 Sowers, Todd", "bounds_geometry": ["POLYGON((-180 90,-144 90,-108 90,-72 90,-36 90,0 90,36 90,72 90,108 90,144 90,180 90,180 72,180 54,180 36,180 18,180 0,180 -18,180 -36,180 -54,180 -72,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -72,-180 -54,-180 -36,-180 -18,-180 0,-180 18,-180 36,-180 54,-180 72,-180 90))"], "date_created": "Sat, 01 Jan 2011 00:00:00 GMT", "description": "This data set contains depth profiles for delta carbon-13 (\u0026#948;13C) and delta deuterium (\u0026#948;D) of methane (CH\u003csub\u003e4\u003c/sub\u003e) in South Pole firn air. The investigators obtained air samples from two boreholes during December 2008 and January 2009, and subsequently determined isotope ratios at 18 depths. The profiles represent a roughly 100-year history of the isotopic composition of CH\u003csub\u003e4\u003c/sub\u003e at South Pole Station (no depth-age model provided).\n\nData are available via FTP as an ASCII text file (.txt) and a Microsoft Excel file (.xlsx).", "east": 180.0, "geometry": ["POINT(0 -89.999)"], "keywords": "Antarctica; Atmosphere; Chemistry:fluid; Chemistry:Fluid; Geochemistry; Isotope; Paleoclimate; Snow/ice; Snow/Ice; South Pole", "locations": "South Pole; Antarctica", "north": 90.0, "nsf_funding_programs": "Antarctic Glaciology", "persons": "Sowers, Todd A.", "project_titles": "Collaborative Research: Methane Isotopes, Hydrocarbons, and other Trace Gases in South Pole Firn Air", "projects": [{"proj_uid": "p0000162", "repository": "USAP-DC", "title": "Collaborative Research: Methane Isotopes, Hydrocarbons, and other Trace Gases in South Pole Firn Air"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -90.0, "title": "Methane Isotopes in South Pole Firn Air, 2008", "uid": "609502", "west": -180.0}, {"awards": "XXXXXXX Palais, Julie", "bounds_geometry": null, "date_created": "Thu, 26 Aug 2004 00:00:00 GMT", "description": "This data set includes isotope and depth age data, and CO2 and CH4 data from the Dome C Antarctica ice core. This core is a 906 meter core that spans approximately 32,000 years. It was a thermally drilled core and was retrieved during the 1977-78 Antarctic field season as part of the International Antarctic Glaciological project.", "east": null, "geometry": null, "keywords": "Antarctica; Chemistry:ice; Chemistry:Ice; Depth-Age-Model; Dome C Ice Core; Geochemistry; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core Records; Paleoclimate", "locations": "Antarctica", "north": null, "nsf_funding_programs": "Antarctic Glaciology", "persons": "Lal, Devendra; Lorius, Claude", "project_titles": "Nuclear Studies of Accumulating and Ablation Ice Using Cosmogenic 14c", "projects": [{"proj_uid": "p0000152", "repository": "USAP-DC", "title": "Nuclear Studies of Accumulating and Ablation Ice Using Cosmogenic 14c"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "Dome C Ice Core", "south": null, "title": "Dome C Ice Core Chemistry and Depth and Age Scale Data", "uid": "609243", "west": null}]

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