TY  - JOUR
A1  - Opitz, Stephan
A1  - Ramisch, Arne
A1  - Mischke, Steffen
A1  - Diekmann, Bernhard
T1  - Holocene lake stages and thermokarst dynamics in a discontinuous permafrost affected region, north-eastern Tibetan Plateau
JF  - Journal of Asian earth sciences
N2  - Sediments of a thermokarst system on the north-eastern Tibetan Plateau were studied to infer changes in the lacustrine depositional environment related to climatic changes since the early Holocene. The thermokarst pond with a length of 360 m is situated in a 14.5 x 6 km tectonically unaffected intermontane basin, which is underlain by discontinuous permafrost.
 A lake sediment core and bankside lacustrine onshore deposits were analysed. Additionally, fossil lake sediments were investigated, which document a former lake-level high stand. The sediments are mainly composed of marls with variable amounts of silt carbonate micrite, and organic matter.
 On the basis of sedimentological (grain size data), geochemical (XRF), mineralogical (XRD) and micropaleontological data (ostracods and chironomide assemblages) a reconstruction of a paleolake environment was achieved.
 Lacustrine sediments with endogenic carbonate precipitation suggest a lacustrine environment since at least 19.0 cal ka BP. However, because of relocation and reworking processes in the lake, the sediments did not provide distinct information about the ultimate formation of the lake. The high amount of endogenic carbonate suggests prolonged still-water conditions at about 9.3 cal ka BP. Ostracod shells and chironomid head capsules in fossil lake sediments indicate at least one former lake-level high stand, which were developed between the early and middle Holocene. From the late Holocene the area was possibly characterized by a lake-level decline, documented by a hiatus between lacustrine sediments and a reworked loess or loess-like horizon. After the lake-level decline and the following warming period, the area was affected by thermally-induced subsidence and a re-flooding of the basin because of thawing permafrost.
KW  - Palaeoenvironmental reconstruction
KW  - Palaeolimnology
KW  - Lake level
KW  - XRD
Y1  - 2013
U6  - https://doi.org/10.1016/j.jseaes.2013.08.006
SN  - 1367-9120
SN  - 1878-5786
VL  - 76
IS  - 17
SP  - 85
EP  - 94
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Herzschuh, Ulrike
A1  - Pestryakova, Luidmila Agafyevna
A1  - Savelieva, Larissa A.
A1  - Heinecke, Liv
A1  - Böhmer, Thomas
A1  - Biskaborn, Boris K.
A1  - Andreev, Andrei
A1  - Ramisch, Arne
A1  - Shinneman, Avery L. C.
A1  - Birks, H. John B.
T1  - Siberian larch forests and the ion content of thaw lakes form a geochemically functional entity
JF  - Nature Communications
N2  - Siberian larch forests growing on shallow permafrost soils have not, until now, been considered to be controlling the abiotic and biotic characteristics of the vast number of thaw-lake ecosystems. Here we show, using four independent data sets (a modern data set from 201 lakes from the tundra to taiga, and three lake-core records), that lake-water geochemistry in Yakutia is highly correlated with vegetation. Alkalinity increases with catchment forest density. We postulate that in this arid area, higher evapotranspiration in larch forests compared with that in the tundra vegetation leads to local salt accumulation in soils. Solutes are transported to nearby thaw lakes during rain events and snow melt, but are not fully transported into rivers, because there is no continuous groundwater flow within permafrost soils. This implies that potentially large shifts in the chemical characteristics of aquatic ecosystems to known warming are absent because of the slow response of catchment forests to climate change.
Y1  - 2013
U6  - https://doi.org/10.1038/ncomms3408
SN  - 2041-1723
VL  - 4
PB  - Nature Publ. Group
CY  - London
ER  -