@article{ChristMaerzKutscheraetal.2017,
  author    = {Christ, Nicolas and Maerz, Sven and Kutschera, Edgar and Kwiecien, Ola and Mutti, Maria},
  title     = {Palaeoenvironmental and diagenetic reconstruction of a closed-lacustrine carbonate system},
  series = {Sedimentology : the journal of the International Association of Sedimentologists},
  volume    = {65},
  journal   = {Sedimentology : the journal of the International Association of Sedimentologists},
  number    = {1},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0037-0746},
  doi       = {10.1111/sed.12401},
  pages     = {235 -- 262},
  year      = {2017},
  abstract  = {Chemostratigraphic studies on lacustrine sedimentary sequences provide essential insights on past cyclic climatic events, on their repetition and prediction through time. Diagenetic overprint of primary features often hinders the use of such studies for palaeoenvironmental reconstruction. Here the potential of integrated geochemical and petrographic methods is evaluated to record freshwater to saline oscillations within the ancient marginal lacustrine carbonates of the Miocene Ries Crater Lake (Germany). This area is critical because it represents the transition from shoreline to proximal domains of a hydrologically closed system, affected by recurrent emergent events, representing the boundaries of successive sedimentary cycles. Chemostratigraphy targets shifts related to subaerial exposure and/or climatic fluctuations. Methods combine facies changes with C-13-O-18 chemostratigraphy from matrix carbonates across five closely spaced, temporally equivalent stratigraphic sections. Isotope composition of ostracod shells, gastropods and cements is provided for comparison. Cathodoluminescence and back-scatter electron microscopy were performed to discriminate primary (syn-)depositional, from secondary diagenetic features. Meteoric diagenesis is expressed by substantial early dissolution and dark blue luminescent sparry cements carrying negative C-13 and O-18. Sedimentary cycles are not correlated by isotope chemostratigraphy. Both matrix C-13 and O-18 range from ca -75 to +40 parts per thousand and show clear positive covariance (R=097) whose nature differs from that of previous basin-oriented studies on the lake: negative values are here unconnected to original freshwater lacustrine conditions but reflect extensive meteoric diagenesis, while positive values probably represent primary saline lake water chemistry. Noisy geochemical curves relate to heterogeneities in (primary) porosity, resulting in selective carbonate diagenesis. This study exemplifies that ancient lacustrine carbonates, despite extensive meteoric weathering, are able to retain key information for both palaeoenvironmental reconstruction and the understanding of diagenetic processes in relation to those primary conditions. Also, it emphasizes the limitation of chemostratigraphy in fossil carbonates, and specifically in settings that are sensitive for the preservation of primary environmental signals, such as lake margins prone to meteoric diagenesis.},
  language  = {en}
}
@article{LenzGrosseJonesetal.2016,
  author    = {Lenz, Josefine and Grosse, Guido and Jones, Benjamin M. and Anthony, Katey M. Walter and Bobrov, Anatoly and Wulf, Sabine and Wetterich, Sebastian},
  title     = {Mid-Wisconsin to Holocene Permafrost and Landscape Dynamics based on a Drained Lake Basin Core from the Northern Seward Peninsula, Northwest Alaska},
  series = {Permafrost and Periglacial Processes},
  volume    = {27},
  journal   = {Permafrost and Periglacial Processes},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {1045-6740},
  doi       = {10.1002/ppp.1848},
  pages     = {56 -- 75},
  year      = {2016},
  abstract  = {Permafrost-related processes drive regional landscape dynamics in the Arctic terrestrial system. A better understanding of past periods indicative of permafrost degradation and aggradation is important for predicting the future response of Arctic landscapes to climate change. Here, we used a multi-proxy approach to analyse a4m long sediment core from a drained thermokarst lake basin on the northern Seward Peninsula in western Arctic Alaska (USA). Sedimentological, biogeochemical, geochronological, micropalaeontological (ostracoda, testate amoebae) and tephra analyses were used to determine the long-term environmental Early-Wisconsin to Holocene history preserved in our core for central Beringia. Yedoma accumulation dominated throughout the Early to Late-Wisconsin but was interrupted by wetland formation from 44.5 to 41.5ka BP. The latter was terminated by the deposition of 1m of volcanic tephra, most likely originating from the South Killeak Maar eruption at about 42ka BP. Yedoma deposition continued until 22.5ka BP and was followed by a depositional hiatus in the sediment core between 22.5 and 0.23ka BP. We interpret this hiatus as due to intense thermokarst activity in the areas surrounding the site, which served as a sediment source during the Late-Wisconsin to Holocene climate transition. The lake forming the modern basin on the upland initiated around 0.23ka BP and drained catastrophically in spring 2005. The present study emphasises that Arctic lake systems and periglacial landscapes are highly dynamic and that permafrost formation as well as degradation in central Beringia was controlled by regional to global climate patterns as well as by local disturbances. Copyright (c) 2015 John Wiley \& Sons, Ltd.},
  language  = {en}
}