Lake A, Ellesmere Island 1,000 Sedimentary Pellet Data Tomkins, J.D.; Lamoureux, S.F.; Antoniades, D.; Vincent, W.F. Tomkins, J.D. Lamoureux, S.F. Antoniades, D. Vincent, W.F. PAGES 2k Network PAGES Arctic 2k earth science/paleoclimate/paleolimnology (age,null,two standard deviations,year,null,paleolimnology,null,null,N,Estimated cumulative dating error at the base of each marker bed interval (yr)) earth science/paleoclimate/paleolimnology (age at sample end,null,null,year Common Era,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (mineral matter,sediment,null,count per year,null,paleolimnology,null,null,N,Mean annual frequency of sedimentary pellets (pellets/yr)) earth science/paleoclimate/paleolimnology (age at sample start,null,null,year Common Era,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (Lake A, Ellesmere Island>LATITUDE 83>LONGITUDE -75.5) Sediment aggregates ("sedimentary pellets") within the sedimentary record of Lake A (83deg00'N, 75deg30'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. STUDY NOTES: 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. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Tomkins, J.D. Investigator : Lamoureux, S.F. Investigator : Antoniades, D. Investigator : Vincent, W.F. 2008-11-01 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/6204 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/canada/ellesmere/lake-a2008.xls https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/canada/ellesmere/lake-a2008.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/canada/ellesmere/lake-a2008.xls https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/canada/ellesmere/lake-a2008.txt English https://www.ncdc.noaa.gov/paleo/study/6204 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/canada/ellesmere/lake-a2008.xls https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/canada/ellesmere/lake-a2008.txt Tomkins, J.D., S.F. Lamoureux, D. Antoniades, and W.F. Vincent2009Sedimentary pellets as an ice-cover proxy in a High Arctic ice-covered lakeJournal of Paleolimnology411225-24210.1007/s10933-008-9255-x START YEAR: 933 cal yr BP * END YEAR: -55 cal yr BP -75.5 83 -75.5 83