A common Holocene attracting state for the elemental composition of allochthonous lake sediments across the Tibetan Plateau


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Bernhard.Diekmann [ at ] awi.de

Abstract

Sedimentary archives on the Tibetan Plateau are a reliable source of information on palaeoenvironmental change in central Asia. Reconstructing environmental changes offers the opportunity to gain information on the dynamics of major circulation systems of the Earth´s atmosphere which influence the climatic conditions in central Asia. However, supra-regional comparisons of proxy records inferred from sedimentary archives reveal individual responses of single archives to superimposed environmental change throughout the Holocene (Wischnewski et al., 2011). This observation gave rise to an ongoing debate whether the individual response of sedimentary archives results from high age uncertainties resulting from radiocarbon based dating techniques (earlier proposed by Mischke and Zhang, 2010) or from a non-linear response of sedimentary systems to superimposed environmental change (Wischnewski et al., 2011). Here we present new insights into the dynamics of allogenic sediment supply to lake systems under changing environmental conditions. To reconstruct sediment dynamics across the Tibetan Plateau, we analyzed the elemental composition via non-destructive X-Ray Fluorescence measurements of lacustrine sediment cores retrieved from three lake systems situated on the southern and northern Tibetan Plateau. By applying a factor analysis on the bulk elemental composition of lacustrine sediments we found a common factor as expressed by similar loadings of the elements Ti, Rb, Fe and Zr. Their link to heavy mineral compounds suggests an allogenic origin and hence a coupling of factor scores to sediment routing systems within each catchment. To test a non-linear response of individual sedimentary systems to environmental change we reconstructed phase spaces from time series data in form of factor scores via a time-lag embedding method. A phase space is an abstract space which maps the entire temporal succession of evolutionary states (called trajectory) in a multidimensional Euclidean space. This so-called phase space reconstruction offers the opportunity to identify and characterize the underlying dynamics by analyzing the geometry of trajectories within the reconstructed space. The results suggest that all lake systems share a similar long-term trend in the dynamics of detrital input. Thereby, lake trajectories tend to converge towards a common attracting state in the Late Holocene. After reaching the basin of attraction, all trajectories remain in a cyclic orbit around the attracting state with a frequency spectrum similar to major variations in solar irradiance and the North Atlantic overturning circulation. These results shed new light on the comparability of low dimensional proxy-data and the environmental signal processing of complex sedimentary systems.



Item Type
Conference (Poster)
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Not peer-reviewed
Publication Status
Published
Event Details
Working Group on Sediment Generation, Third Meeting (WGSG-3), 04 Jul 2016 - 06 Jul 2016, Leuven, Belgium.
Eprint ID
44779
Cite as
Ramisch, A. , Lockot, G. , Hartmann, K. , Stauch, G. , Lehmkuhl, F. , Haberzettl, T. and Diekmann, B. (2016): A common Holocene attracting state for the elemental composition of allochthonous lake sediments across the Tibetan Plateau , Working Group on Sediment Generation, Third Meeting (WGSG-3), Leuven, Belgium, 4 July 2016 - 6 July 2016 .


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