Sam Ford Fjord early Holocene Laurentide Glacier retreat data ----------------------------------------------------------------------- World Data Center for Paleoclimatology, Boulder and NOAA Paleoclimatology Program ----------------------------------------------------------------------- NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!! NAME OF DATA SET: - Sam Ford Fjord early Holocene Laurentide Glacier retreat data LAST UPDATE: 09/2010 (Original receipt by WDC Paleo) CONTRIBUTOR: Briner, J.P., A.C. Bini, and R.S. Anderson IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2010-095 WDC PALEO CONTRIBUTION SERIES CITATION:2010-095 Briner Jason P., et al. 2010. Study Title - Sam Ford Fjord early Holocene Laurentide Glacier retreat data IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2010-095. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCE: Briner, J.P., Bini, A.C., Anderson, R.S., 2009. Rapid early Holocene retreat of a Laurentide outlet glacier through an Arctic fjord. Nature Geoscience 2 (7), 496-499, doi:10.1038/ngeo556 ABSTRACT: Ice-sheet behaviour is disproportionately controlled by the dynamics of outlet glaciers that terminate in the ocean. However, outlet-glacier dynamics—particularly over timescales longer than the observational record—are not well understood, leading to uncertainties in our models of ice-sheet response to climate change. Here we use 10Be exposure ages and radiocarbon dating from the Sam Ford Fjord in the Canadian Arctic to reconstruct the retreat chronology of an outlet glacier of the Laurentide ice sheet, following the last glacial termination. We find that Sam Ford Fjord, which has a similar morphology to the troughs holding many outlet glaciers of the Greenland ice sheet, was rapidly deglaciated about 9,500 years ago, with retreat rates ranging from 5 to 58 m yr-1. The highest rates occurred in the deepest part of the fjord (900 m), whereas regions beyond the fjord mouth and up-valley of the head of the fjord experienced the lowest rates of retreat. We conclude that in such a fjord setting, there is a strong bathymetric control on the retreat of marine outlet glaciers: once the terminus of the outlet glacier retreated into deeper waters, increasing calving rates and basal sliding speeds caused the glacier to rapidly thin and retreat, stabilizing only when it reached the shallow inland head of the fjord. GEOGRAPHIC REGION: Sam Ford Fjord, Canadian Arctic PERIOD OF RECORD: 9,500 years ago FUNDING SOURCES: USA and NSF grant EAR-0644966 DESCRIPTION: 10Be exposure ages and radiocarbon dating from the Sam Ford Fjord in the Canadian Arctic reconstructing the retreat chrology of the Laurentide ice sheet of an outlet glacier, following the last glacial termination. Table 1 - 10Be surface exposure ages from Sam Ford Fjord Table 2 - Radiocarbon ages of marine bivalves from Sam Ford Fjord Lat 70.08°N - 70.97°N Lon 70.29°W - 71.45°W Elevation (m.a.s.l) 33-112 DATA: Table 1. 10Be surface exposure ages from Sam Ford Fjord Sample Sample type Lat.(N) Long.(W) Elevation(*a)(m a.s.l.) Distance from fjordhead (km) Sample Thickness(cm) Shielding Correction 10Be(*b)(105 atoms g-1) 10Be age(*c)(ka) CR03-81 quartz vein 70.97° 70.29° 33 110 3 1 0.48±0.03 10.3 ± 0.5 SF07-22 quartz vein 70.75° 70.47° 40 90.4 1 1 0.49±0.01 11.5 ± 0.2 SF07-21 quartz vein 70.72° 70.61° 40 85.4 2 0.979 0.40±0.01 9.5 ± 0.2 SF07-01 quartz vein 70.63° 71.01° 74 70.3 2 0.941 0.42±0.07 10.0 ± 1.6 SF07-02 quartz vein 70.63° 71.01° 45 70.3 2 0.941 0.40±0.07 10.0 ± 1.6 SF07-01/02(*d) quartz vein 70.63° 71.01° 59 70.3 2 0.941 0.40±0.01 9.7 ± 0.2 Average age (± 1 SD) 9.9 ± 0.2 SF07-17 quartz vein 70.35° 71.18° 76 38.7 2 0.965 0.40±0.08 9.6 ± 0.3 SF07-16 quartz vein 70.31° 71.23° 79 33.9 2 0.982 0.40±0.07 9.1 ± 0.2 SF07-14 erratic cobble 70.28° 71.27° 112 30.8 5 0.997 0.40±0.06 9.6 ± 0.2 SF07-11 quartz vein 70.24° 71.31° 81 25.4 2 0.992 0.40±0.04 8.9 ± 0.9 SF07-12 quartz vein 70.24° 71.31° 105 25.4 2 0.992 0.43±0.05 9.5 ± 0.2 Average age (± 1 SD) 9.2 ± 0.5 SF07-03 quartz vein 70.21° 71.29° 73 22.7 2 1 0.45±0.01 10.1 ± 0.3 SF07-04 quartz vein 70.21° 71.29° 72 22.7 3 1 0.43±0.01 9.9 ± 0.2 Average age (± 1 SD) 10.0 ± 0.2 SF07-05 quartz vein 70.15° 71.38° 69 15.4 3 1 0.41±0.05 9.5 ± 1.2 SF07-06 quartz vein 70.15° 71.38° 70 15.4 3 1 0.42±0.03 9.5 ± 0.8 Average age (± 1 SD) 9.5 ± 0.8 SF07-08 quartz vein 70.08° 71.45° 87 8 3 0.997 0.35±0.04 7.9 ± 0.8 SF07-07 quartz vein 70.08° 71.45° 78 7 1 0.997 0.35±0.05 7.7 ± 1.1 Note: m a.s.l = above sea level *a Elevations used in age calculations were 10 m lowe than the sampled elevation. This adjusted elevation is the integrated sample elevation accounting for isostatic rebound.Because the rebound is not constrained in Sam Ford Fjord, the adjustement is based on the relative-sea-level ermergence curve at the head of Clyde Inlet (ref 9);the isostatic rebound should be similar between adjacent fjord heads because they are only 45 km apart and have similar deglaciation and emergence histories. *b Radionuclide concentrations reported here are not scaled for elevation, sample density, erosion rates, topographic shielding, lat./long., or sample thickness. Concentrations were scaled for these parameters according to refs 5 and 6 within the CRONUS online age calculator (ref 4). All 10Be/9Be ratios except for CR03-81 were normalized to a revised standard (07KNSTD3110) according to ref 3. CR03-81 was normalized to the former standard (KNSTD3770). The additional paramters needed to caclulate ages with the CRONUS online age calculator are erosion and density (0 and 2.65 for all samples, respectively) *c Calculated with locally-calibrated 10Be production rats of 4.33 atoms*g-1*yr-1 (ref 8). Reported uncertainties are the internal AMS uncertainties reported on the CRONUS online age calculator. *d SF07-01/02 is a composite sample with equivalent amounts of quartz from SF07-01 and SF07-02. Table 2. Radiocarbon ages of marine bivalves from Sam Ford Fjord Sample Sample type and association Lat.(N) Long.(W) Distance from fjordhead(km) "Elevation collected," elevation of marine limit (m a.s.l.) 14C age (14C yr BP ± 1 SD) Pre-correction(*a) Calibrated and (14C yr BP ± 1 SD) corrected age(*b) (cal. yr BP ± 1 SD) SF07-SH04 bivavle in delta 70.35° 71.19° 38.6 "31, 60(?)" 8770 ± 25 NA 9310 ± 50 I-1933 bivavle in delta 70.33° 71.18° 38 "19, 60(?)" 8210 ± 130 8620 ± 130 9130 ± 170 I-1553 bivavle in ice contact delta 70.21° 71.29° 22.5 "63, 64" 7500 ± 200 7910 ± 200 8210 ± 190 SF07-SH01 bivavle in ice-contact delta 70.21° 71.29° 22.4 "50, 64" 8000 ± 20 NA 8330 ± 30 GSC-630 reworked bivalve in moriane 70.19° 71.30° 20.4 "53, NA" 8000 ± 150 8410 ± 75 8830 ± 120 SF07-SH03 bivavle in ice-contact delta 70.07° 71.46° 5.6 "41, 58" 6640 ± 20 NA 7000 ± 50 GSC-633 reworked bivalves in push moraine 70.05° 71.48° 5.4 "50, NA" 6270 ± 150 6680 ± 75 7050 ± 90 I-1556 bivavle in ice-contact delta 70.02° 71.62° -2.5 "46, 66(?)" 6240 ± 140 6650 ± 140 7010 ± 160 Note: m a.s.l = above sea level; I-xxxx and GSC-xxx samples are from ref 11; SF07-SHxx samples are results from this study. *a 410 years were added to GSC and I ages because they were originally reported with an assumed ?13C of -25 per mil instead of 0 per mil. GSC errors are divided by two because they were originally reported at 2 standard deviation (2 SD). *b Radiocarbon ages calibrated with Calib 5.0.2 (ref 10); bivalves were corrected 540 yr (delta R = 140) for the reservoir offset calculated in Clyde Inlet (see Fig. 1; ref 9).