Abstract
Abstract. To reconstruct palaeoclimate and palaeoenvironmental conditions in the northeast Siberian Arctic, we studied late Quaternary permafrost at the Oyogos Yar coast (Dmitry Laptev Strait). New infrared-stimulated luminescence ages for distinctive floodplain deposits of the Kuchchugui Suite (112.5 ± 9.6 kyr) and thermokarst-lake deposits of the Krest Yuryakh Suite (102.4 ± 9.7 kyr), respectively, provide new substantial geochronological data and shed light on the landscape history of the Dmitry Laptev Strait region during Marine Isotope Stage (MIS) 5. Ground-ice stable-isotope data are presented together with cryolithological information for eight cryostratigraphic units and are complemented by data from nearby Bol'shoy Lyakhovsky Island. Our combined record of ice-wedge stable isotopes as a proxy for past winter climate conditions covers about 200 000 years and is supplemented by stable isotopes of pore and segregated ice which reflect annual climate conditions overprinted by freezing processes. Our ice-wedge stable-isotope data indicate substantial variations in northeast Siberian Arctic winter climate conditions during the late Quaternary, in particular between glacial and interglacial times but also over the last millennia to centuries. Stable isotope values of ice complex ice wedges indicate cold to very cold winter temperatures about 200 kyr ago (MIS7), very cold winter conditions about 100 kyr ago (MIS5), very cold to moderate winter conditions between about 60 and 30 kyr ago, and extremely cold winter temperatures during the Last Glacial Maximum (MIS2). Much warmer winter conditions are reflected by extensive thermokarst development during MIS5c and by Holocene ice-wedge stable isotopes. Modern ice-wedge stable isotopes are most enriched and testify to the recent winter warming in the Arctic. Hence, ice-wedge-based reconstructions of changes in winter climate conditions add substantial information to those derived from paleoecological proxies stored in permafrost and allow a distinction between seasonal trends of past climate dynamics. Future progress in ice-wedge dating and an improved temporal resolution of ice-wedge-derived climate information may help to fully explore the palaeoclimatic potential of ice wedges.
Highlights
The wide tundra areas of the northeast Siberian Arctic lowlands are characterized by deep permafrost that results from cold continental climate conditions in west Beringia during the late Pliocene and Pleistocene when this region remained non-glaciated (Schirrmeister et al, 2013)
To address the issue of temporal and spatial representativity of ground-ice stable-isotope records, we present in this paper new data from different late Quaternary stratigraphic and chronological units at the Oyogos Yar Coast of the Dmitry Laptev Strait
We focus on our extensive studies of cryostratigraphy and, in particular, ground-ice stable isotopes
Summary
The wide tundra areas of the northeast Siberian Arctic lowlands are characterized by deep permafrost that results from cold continental climate conditions in west Beringia during the late Pliocene and Pleistocene when this region remained non-glaciated (Schirrmeister et al, 2013). Ice complex (IC) deposits formed in polygonal tundra environments with syngenetic ice-wedge growth during different periods of the late Quaternary in non-glaciated Beringia (Tumskoy, 2012; Schirrmeister et al, 2013). Snowmelt is the main source of the water that enters the frost crack, quickly refreezes there due to the negative ground temperatures, and forms a vertical ice vein. The periodic repetition of frost cracking and ice-vein formation results in ice-wedge growth in width and, if synchronous to sedimentation at the surface (syngenetic ice wedges), in height
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