TY  - JOUR
A1  - Rach, Oliver
A1  - Engels, S.
A1  - Kahmen, A.
A1  - Brauer, Achim
A1  - Martin-Puertas, C.
A1  - van Geel, B.
A1  - Sachse, Dirk
T1  - Hydrological and ecological changes in western Europe between 3200 and 2000 years BP derived from lipid biomarker delta D values in lake Meerfelder Maar sediments
JF  - Quaternary science reviews : the international multidisciplinary research and review journal
N2  - One of the most significant Late Holocene climate shifts occurred around 2800 years ago, when cooler and wetter climate conditions established in western Europe. This shift coincided with an abrupt change in regional atmospheric circulation between 2760 and 2560 cal years BP, which has been linked to a grand solar minimum with the same duration (the Homeric Minimum). We investigated the temporal sequence of hydroclimatic and vegetation changes across this interval of climatic change (Homeric climate oscillation) by using lipid biomarker stable hydrogen isotope ratios (ED values) and pollen assemblages from the annually-laminated sediment record from lake Meerfelder Maar (Germany). Over the investigated interval (3200-2000 varve years BP), terrestrial lipid biomarker ED showed a gradual trend to more negative values, consistent with the western Europe long-term climate trend of the Late Holocene. At ca. 2640 varve years BP we identified a strong increase in aquatic plants and algal remains, indicating a rapid change in the aquatic ecosystem superimposed on this long-term trend. Interestingly, this aquatic ecosystem change was accompanied by large changes in ED values of aquatic lipid biomarkers, such as nC(21) and nC(23) (by between 22 and 30%(0)). As these variations cannot solely be explained by hydroclimate changes, we suggest that these changes in the Wag value were influenced by changes in n-alkane source organisms. Our results illustrate that if ubiquitous aquatic lipid biomarkers are derived from a limited pool of organisms, changes in lake ecology can be a driving factor for variations on sedimentary lipid MN values, which then could be easily misinterpreted in terms of hydro climatic changes. (C) 2017 Elsevier Ltd. All rights reserved.
KW  - Holocene
KW  - Climate dynamics
KW  - Paleoclimatology
KW  - Western Europe
KW  - Continental biomarkers
KW  - Organic geochemistry
KW  - Stable isotopes
KW  - Vegetation dynamics
Y1  - 2017
U6  - https://doi.org/10.1016/j.quascirev.2017.07.019
SN  - 0277-3791
VL  - 172
SP  - 44
EP  - 54
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Anoop, A.
A1  - Prasad, S.
A1  - Basavaiah, Nathani
A1  - Brauer, Achim
A1  - Shahzad, F.
A1  - Deenadayalan, K.
T1  - Tectonic versus climate influence on landscape evolution: A case study from the upper Spiti valley, NW Himalaya
JF  - Geomorphology : an international journal on pure and applied geomorphology
N2  - We have undertaken structural, geomorphological, and morphometric analyses to investigate the role of tectonism and climate in the landscape evolution in the upper Spiti valley, NW Himalayas. Geomorphometric analyses coupled with field investigations reveal active tectonic deformation in the Spiti region. The calculated geomorphic indices (steepness, concavity and Hack) demonstrate uplift/subsidence along the Kaurik-Chango fault, whereas transverse topographic index (T-index) reveals basin tilting associated with active faulting near Hansa and Lingti valley. Investigation of well-dated Mane palaeolake sediments also provides evidence of regional tectonic instability. Four episodes (ca. 7.8, 7.4, 6.5 and 6.1 cal ka) of neotectonic activity have been identified during the period of the lake's existence. We have also compiled data on the regional climate variability and compared it with the age of the Mane palaeo-landslide. Our results indicate that the landslide occurred towards the end of the early Holocene intensified monsoon phase and is located near an active fault. Our data on regional tectonic instability and the coincidences of modern and palaeo-landslides with zones of active deformation suggest that tectonism is an important factor governing landscape stability in the Spiti region.
KW  - Geomorphic indices
KW  - Holocene
KW  - Palaeo-lake sediments
KW  - Palaeo-landslides
KW  - Monsoon
Y1  - 2012
U6  - https://doi.org/10.1016/j.geomorph.2011.10.028
SN  - 0169-555X
VL  - 145
IS  - 4
SP  - 32
EP  - 44
PB  - Elsevier
CY  - Amsterdam
ER  -