Cryostratigraphy, sedimentology, and the late Quaternary evolution of the Zackenberg River delta, northeast Greenland

Abstract

Abstract. The Zackenberg River delta is located in northeast Greenland (74 • 30 N, 20 • 30 E) at the outlet of the Zackenberg fjord valley. The fjord-valley fill consists of a series of terraced deltaic deposits (ca. 2 km 2 ) formed during relative sea-level (RSL) fall. We investigated the deposits using sedimentological and cryostratigraphic techniques together with optically stimulated luminescence (OSL) dating. We identify four facies associations in sections (4 to 22 m in height) exposed along the modern Zackenberg River and coast. Facies associations relate to (I) overriding glaciers, (II) retreating glaciers and quiescent glaciomarine conditions, (III) delta progradation in a fjord valley, and (IV) fluvial activity and niveo-aeolian processes. Pore, layered, and suspended cryofacies are identified in two 20 m deep ice-bonded sediment cores. The cryofacies distribution, together with low overall ground-ice content, indicates that permafrost is predominately epigenetic in these deposits. Fourteen OSL ages constrain the deposition of the cored deposits to between approximately 13 and 11 ka, immediately following deglaciation. The timing of permafrost aggradation was closely related to delta progradation and began following the subaerial exposure of the delta plain (ca. 11 ka). Our results reveal information concerning the interplay between deglaciation, RSL change, sedimentation, permafrost aggradation, and the timing of these events. These findings have implications for the timing and mode of permafrost aggradation in other fjord valleys in northeast Greenland.

Stratigraphical signatures of glacier activity, marine processes and a possible tsunami in the Leirfjorden fjord‐valley system, north Norway

“…; Gilbert et al . ). Despite the model, interpretation of the often complex fjord‐valley deposits is challenging, and several local factors can lead to stratigraphical variability, e.g.…”

Late Quaternary sedimentation and permafrost development in a Svalbard fjord‐valley, Norwegian high Arctic

“…This interpretive scenario concurs with studies of the post‐glacial infilling of fjord‐valleys in Canada (Syvitski, ; Marchand et al ., ), Norway (Corner, ; Eilertsen et al ., , ) and Greenland (Hansen, ; Storms et al ., ; Gilbert et al ., ). Corner () postulated a model for the sedimentary infilling of fjord‐valleys with the following systems tracts: a deglacial transgressive systems tract (DTST) comprising sediment deposited by retrogradational stacking in front of a retreating glacier and during the early sea‐level highstand; a deglacial highstand systems tract (DHST) formed during the retreat of fjord glacier and characterized by marine sedimentation with a rapid progradation of fjord‐head glaciofluvial delta; and a post‐glacial forced‐regressive systems tract (PRST) formed after a significant reduction in meltwater discharge, with the sediment delivered primarily by the fjord‐head fluvio‐deltaic system and the sedimentation rate in the fjord considerably decreased.…”

“…Fjord‐valleys in high‐Arctic regions involve further the coeval formation of permafrost, which is widespread at high latitudes. There have been several studies of fjord‐valleys in permafrost regions (Hansen, , ; Storms et al ., ; Gilbert et al ., ), but few have analysed the dynamics and sedimentary signature of epigenetic ground‐ice development in the gradually emerged fjord‐fill deposits. This sedimentological issue is addressed in the present study on the basis of cryofacies, which – much like ichnofacies, pedogenic facies or diagenetic facies – represent the signature of a particular secondary agent superposed on primary sedimentary deposits.…”

UAV-based remote sensing of immediate changes in geomorphology following a glacial lake outburst flood at the Zackenberg river, northeast Greenland

“…The studied section of the Zackenberg river incises elevated late Weichselian and Holocene terraces and late Weichselian morainic deposits (Cable et al, 2018;Gilbert et al, 2017). There is continuous permafrost at the study area, with a thickness of 200-300 m in the Zackenberg valley bottom, and 300-500 m in the mountainous region (Christiansen et al, 2008).…”