Lake A, Ellesmere Island Sedimentary Pellet Data ----------------------------------------------------------------------- World Data Center for Paleoclimatology, Boulder and NOAA Paleoclimatology Program ----------------------------------------------------------------------- NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!! NAME OF DATA SET: Lake A, Ellesmere Island Sedimentary Pellet Data LAST UPDATE: 11/2008 (Original receipt by WDC Paleo) CONTRIBUTOR: Jessica D. Tomkins, Queen's University IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2008-116 WDC PALEO CONTRIBUTION SERIES CITATION: Tomkins, J.D., et al. 2008. Lake A, Ellesmere Island Sedimentary Pellet Data. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2008-116. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCE: Tomkins, J.D., S.F. Lamoureux, D. Antoniades, and W.F. Vincent. 2008. Sedimentary pellets as an ice-cover proxy in a High Arctic ice-covered lake. Journal of Paleolimnology, Vol. 41, No. 1, pp. 225-242, January 2009. doi: 10.1007/s10933-008-9255-x ABSTRACT: Sediment aggregates ("sedimentary pellets") within the sedimentary record of Lake A (83°00'N, 75°30'W), Ellesmere Island, Canada, are used to construct a 1000 year proxy record of ice-cover extent and dynamics on this perennially ice-covered, High Arctic lake. These pellets are interpreted to form during fall or early winter when littoral sediment adheres to ice forming around the lake's periphery or during summer through the development of anchor ice. The sediment likely collects in ice interstices and is concentrated in the upper ice layers through summer surface ice melt and winter basal ice growth. The pellets remain frozen in the ice until a summer or series of summers with reduced ice cover allows for their deposition across the lake basin. Sedimentary pellet frequency within multiple sediment cores is used to develop a chronology of ice-cover fluctuations. This proxy ice-cover record is largely corroborated by a record of unusual sedimentation in Lake A involving iron-rich, dark-orange to red laminae overlying more diffuse laminae with a lighter hue. This sediment sequence is hypothesized to represent years with reduced ice cover through increased chemocline ventilation and iron deposition. During the past millennium, the most notable period of inferred reduced ice cover is ca. 1891 AD to present. Another period of ice cover mobility is suggested ca. 1582–1774 AD, while persistent ice cover is inferred during the 1800s and prior to 1582 AD. The proxy ice-cover record corresponds well with most regional meltseason proxy temperature and paleoecological records, especially during the 1800s and 1900s. GEOGRAPHIC REGION: Northern North America PERIOD OF RECORD: 989 YrBP - present FUNDING SOURCES: Natural Sciences and Engineering Research Council of Canada, ArcticNet (a Canadian Network of Centres of Excellence), the Canada Research Chair program, and the International Polar Year program. DESCRIPTION: This is a 989-year record of mean annual macroscopic (visible with the unaided eye) sedimentary pellet frequency between marker bed intervals (dated using an age-depth model based on a varve chronology), incorporating data from 11 sediment cores from Lake A, Ellesmere Island. Ellesmere Island, Nunavut, Canada Latitude 83°deg 0' N, Longitude 75°deg 30' W, 4m elevation. DATA: Tomkins et al. 2008 Lake A Sedimentary Pellet Data Column 1: Marker bed interval, bottom age (AD yr) Column 2: Marker bed interval, top age (AD yr) Column 3: Estimated cumulative dating error at the base of each marker bed interval (yr) Column 4: Mean annual frequency of sedimentary pellets (pellets/yr) AgeBot. AgeTop AgeErr. Pellets/yr 1891 2005 ± 37 0.19 1826 1890 ± 41 0.06 1775 1825 ± 48 0.04 1714 1774 ± 54 0.07 1582 1713 ± 64 0.11 1443 1581 ± 72 0.05 1368 1442 ± 81 0.04 1264 1367 ± 99 0.05 1210 1263 ± 120 0.05 1017 1209 ± 144 0.03