@article{ZhangCaoYuanetal.2022, author = {Zhang, Di and Cao, Kai and Yuan, Xiaoping and Wang, Guocan and van der Beek, Peter}, title = {Late Oligocene-early Miocene origin of the First Bend of the Yangtze River explained by thrusting-induced river reorganization}, series = {Geomorphology}, volume = {411}, journal = {Geomorphology}, publisher = {Elsevier Science}, address = {Amsterdam [u.a.]}, issn = {0169-555X}, doi = {10.1016/j.geomorph.2022.108303}, pages = {13}, year = {2022}, abstract = {The origin of the First Bend of the Yangtze River is key to understanding the birth of the modern Yangtze River. Despite considerable efforts, the timing and mechanism of formation of the First Bend remain highly debated. Inverse river-profile modeling of three tributaries (Chongjiang, Lima, and Gudu) of the Jinsha River, integrated with regional tectonic and geomorphic interpretations, allows the onset of incision at the First Bend to be constrained to 28-20 Ma. The spatio-temporal coincidence of initial river incision and activity of Yulong Thrust Belt in southeastern Tibet highlights thrusting to be fundamental in reshaping the pre-existing stream network at the First Bend. These results enable us to reinterpret a change in sedimentary environment from a braided river to a swamp-like lake in the Jianchuan Basin south of the First Bend, recording the destruction of the hypothesized southwards-flowing paleo-Jinsha and Shuiluo Rivers at ~36-35 Ma by magmatism. During the late Oligoceneearly Miocene, the paleo-Shuiluo River was diverted to the north by focused rock uplift due to thrusting along the Yulong Thrust Belt, which also led to exhumation of the Jianchuan Basin. Diversion of the paleo-Shuiluo River can be explained by capture from a downstream river in the footwall of the Yulong Thrust Belt. Subsequent rapid headward erosion, that was caused by thrusting-induced drop of local base level, is recorded by upstream younging ages for the onset of incision and led to the formation of the First Bend. The combination of new ages for the onset of incision at 28-20 Ma at the First Bend and younger ages upstream indicates northwards expansion of the Jinsha River at a rate of 62 +/- 18 mm/yr. Our results suggest that the origin of the First Bend was likely triggered by thrusting at 28-20 Ma, after which the Yangtze River formed.}, language = {en} } @article{YuanJiaoDupontNivetetal.2022, author = {Yuan, Xiaoping P. and Jiao, Ruohong and Dupont-Nivet, Guillaume and Shen, Xiaoming}, title = {Southeastern Tibetan Plateau growth revealed by inverse analysis of landscape evolution model}, series = {Geophysical research letters}, volume = {49}, journal = {Geophysical research letters}, number = {10}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0094-8276}, doi = {10.1029/2021GL097623}, pages = {10}, year = {2022}, abstract = {The Cenozoic history of the Tibetan Plateau topography is critical for understanding the evolution of the Indian-Eurasian collision, climate, and biodiversity. However, the long-term growth and landscape evolution of the Tibetan Plateau remain ambiguous, it remains unclear if plateau uplift occurred soon after the India-Asia collision in the Paleogene (similar to 50-25 Ma) or later in the Neogene (similar to 20-5 Ma). Here, we reproduce the uplift history of the southeastern Tibetan Plateau using a 2D landscape evolution model, which simultaneously solves fluvial erosion and sediment transport processes in the drainage basins of the Three Rivers region (Yangtze, Mekong, and Salween Rivers). Our model was optimized through a formal inverse analysis with 20,000 forward simulations, which aims to reconcile the transient states of the present-day river profiles. The results, compared to existing paleoelevation and thermochronologic data, suggest initially low elevations (similar to 300-500 m) during the Paleogene, followed by a gradual southeastward propagation of topographic uplift of the plateau margin.}, language = {en} } @article{TianQinZhangetal.2022, author = {Tian, Fang and Qin, Wen and Zhang, Ran and Herzschuh, Ulrike and Ni, Jian and Zhang, Chengjun and Mischke, Steffen and Cao, Xianyong}, title = {Palynological evidence for the temporal stability of the plant community in the Yellow River Source Area over the last 7,400 years}, series = {Vegetation history and archaeobotany}, volume = {31}, journal = {Vegetation history and archaeobotany}, number = {6}, publisher = {Springer}, address = {New York}, issn = {0939-6314}, doi = {10.1007/s00334-022-00870-5}, pages = {549 -- 558}, year = {2022}, abstract = {The terrestrial ecosystem in the Yellow River Source Area (YRSA) is sensitive to climate change and human impacts, although past vegetation change and the degree of human disturbance are still largely unknown. A 170-cm-long sediment core covering the last 7,400 years was collected from Lake Xingxinghai (XXH) in the YRSA. Pollen, together with a series of other environmental proxies (including grain size, total organic carbon (TOC) and carbonate content), were analysed to explore past vegetation and environmental changes for the YRSA. Dominant and common pollen components-Cyperaceae, Poaceae, Artemisia, Chenopodiaceae and Asteraceae-are stable throughout the last 7,400 years. Slight vegetation change is inferred from an increasing trend of Cyperaceae and decreasing trend of Poaceae, suggesting that alpine steppe was replaced by alpine meadow at ca. 3.5 ka cal bp. The vegetation transformation indicates a generally wetter climate during the middle and late Holocene, which is supported by increased amounts of TOC and Pediastrum (representing high water-level) and is consistent with previous past climate records from the north-eastern Tibetan Plateau. Our results find no evidence of human impact on the regional vegetation surrounding XXH, hence we conclude the vegetation change likely reflects the regional climate signal.}, language = {en} } @article{JiaAnslanChenetal.2022, author = {Jia, Weihan and Anslan, Sten and Chen, Fahu and Cao, Xianyong and Dong, Hailiang and Dulias, Katharina and Gu, Zhengquan and Heinecke, Liv and Jiang, Hongchen and Kruse, Stefan and Kang, Wengang and Li, Kai and Liu, Sisi and Liu, Xingqi and Liu, Ying and Ni, Jian and Schwalb, Antje and Stoof-Leichsenring, Kathleen R. and Shen, Wei and Tian, Fang and Wang, Jing and Wang, Yongbo and Wang, Yucheng and Xu, Hai and Yang, Xiaoyan and Zhang, Dongju and Herzschuh, Ulrike}, title = {Sedimentary ancient DNA reveals past ecosystem and biodiversity changes on the Tibetan Plateau: overview and prospects}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {293}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2022.107703}, pages = {14}, year = {2022}, abstract = {Alpine ecosystems on the Tibetan Plateau are being threatened by ongoing climate warming and intensified human activities. Ecological time-series obtained from sedimentary ancient DNA (sedaDNA) are essential for understanding past ecosystem and biodiversity dynamics on the Tibetan Plateau and their responses to climate change at a high taxonomic resolution. Hitherto only few but promising studies have been published on this topic. The potential and limitations of using sedaDNA on the Tibetan Plateau are not fully understood. Here, we (i) provide updated knowledge of and a brief introduction to the suitable archives, region-specific taphonomy, state-of-the-art methodologies, and research questions of sedaDNA on the Tibetan Plateau; (ii) review published and ongoing sedaDNA studies from the Tibetan Plateau; and (iii) give some recommendations for future sedaDNA study designs. Based on the current knowledge of taphonomy, we infer that deep glacial lakes with freshwater and high clay sediment input, such as those from the southern and southeastern Tibetan Plateau, may have a high potential for sedaDNA studies. Metabarcoding (for microorganisms and plants), metagenomics (for ecosystems), and hybridization capture (for prehistoric humans) are three primary sedaDNA approaches which have been successfully applied on the Tibetan Plateau, but their power is still limited by several technical issues, such as PCR bias and incompleteness of taxonomic reference databases. Setting up high-quality and open-access regional taxonomic reference databases for the Tibetan Plateau should be given priority in the future. To conclude, the archival, taphonomic, and methodological conditions of the Tibetan Plateau are favorable for performing sedaDNA studies. More research should be encouraged to address questions about long-term ecological dynamics at ecosystem scale and to bring the paleoecology of the Tibetan Plateau into a new era.}, language = {en} } @article{HuangJacksonDekkersetal.2019, author = {Huang, Wentao and Jackson, Michael J. and Dekkers, Mark J. and Zhang, Yang and Zhang, Bo and Guo, Zhaojie and Dupont-Nivet, Guillaume}, title = {Challenges in isolating primary remanent magnetization from Tethyan carbonate rocks on the Tibetan Plateau: Insight from remagnetized Upper Triassic limestones in the eastern Qiangtang block}, series = {Earth \& planetary science letters}, volume = {523}, journal = {Earth \& planetary science letters}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0012-821X}, doi = {10.1016/j.epsl.2019.06.035}, pages = {15}, year = {2019}, abstract = {Carbonate rocks, widely used for paleomagnetically quantifying the drift history of the Gondwana derived continental blocks of the Tibetan Plateau and evolution of the Paleo/Meso/Neo-Tethys Oceans, are prone to pervasive remagnetization. Identifying remagnetization is difficult because it is commonly undetectable through the classic paleomagnetic field tests. Here we apply comprehensive paleomagnetic, rock magnetic, and petrographic studies to upper Triassic limestones in the eastern Qiangtang block. Our results reveal that detrital/biogenic magnetite, which may carry the primary natural remanent magnetization (NRM), is rarely preserved in these rocks. In contrast, authigenic magnetite and hematite pseudomorphs after pyrite, and monoclinic pyrrhotite record three episodes of remagnetization. The earliest remagnetization was induced by oxidation of early diagenetic pyrite to magnetite, probably related to the collision between the northeastern Tibetan Plateau and the Qiangtang block after closure of the Paleo-Tethys Ocean in the Late Triassic. The second remagnetization, residing in hematite and minor goethite, which is the further subsurface oxidation product of pyrite/magnetite, is possibly related to the development of the localized Cenozoic basins soon after India-Asia collision in the Paleocene. The youngest remagnetization is a combination of thermoviscous and chemical remanent magnetization carried by authigenic magnetite and pyrrhotite, respectively. Our analyses suggest that a high supply of organic carbon during carbonate deposition, prevailing sulfate reducing conditions during early diagenesis, and widespread orogenic fluid migration related to crustal shortening during later diagenesis, have altered the primary remanence of the shallow-water Tethyan carbonate rocks of the Tibetan Plateau. We emphasize that all paleomagnetic results from these rocks must be carefully examined for remagnetization before being used for paleogeographic reconstructions. Future paleomagnetic investigations of the carbonate rocks in orogenic belts should be accompanied by thorough rock magnetic and petrographic studies to determine the origin of the NRM. (C) 2019 Elsevier B.V. All rights reserved.}, language = {en} } @misc{KorzeniowskaKorup2017, author = {Korzeniowska, Karolina and Korup, Oliver}, title = {Object-based detection of lakes prone to seasonal ice cover on the Tibetan Plateau}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1037}, issn = {1866-8372}, doi = {10.25932/publishup-47503}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-475037}, pages = {25}, year = {2017}, abstract = {The Tibetan Plateau, the world's largest orogenic plateau, hosts thousands of lakes that play prominent roles as water resources, environmental archives, and sources of natural hazards such as glacier lake outburst floods. Previous studies have reported that the size of lakes on the Tibetan Plateau has changed rapidly in recent years, possibly because of atmospheric warming. Tracking these changes systematically with remote sensing data is challenging given the different spectral signatures of water, the potential for confusing lakes with glaciers, and difficulties in classifying frozen or partly frozen lakes. Object-based image analysis (OBIA) offers new opportunities for automated classification in this context, and we have explored this method for mapping lakes from LANDSAT images and Shuttle Radar Topography Mission (SRTM) elevation data. We tested our algorithm for most of the Tibetan Plateau, where lakes in tectonic depressions or blocked by glaciers and sediments have different surface colours and seasonal ice cover in images obtained in 1995 and 2015. We combined a modified normalised difference water index (MNDWI) with OBIA and local topographic slope data in order to classify lakes with an area > 10 km(2). Our method derived 323 water bodies, with a total area of 31,258 km(2), or 2.6\% of the study area (in 2015). The same number of lakes had covered only 24,892 km(2) in 1995; lake area has increased by -26\% in the past two decades. The classification had estimated producer's and user's accuracies of 0.98, with a Cohen's kappa and F-score of 0.98, and may thus be a useful approximation for quantifying regional hydrological budgets. We have shown that our method is flexible and transferable to detecting lakes in diverse physical settings on several continents with similar success rates.}, language = {en} } @article{KorzeniowskaKorup2017, author = {Korzeniowska, Karolina and Korup, Oliver}, title = {Object-Based Detection of Lakes Prone to Seasonal Ice Cover on the Tibetan Plateau}, series = {Remote sensing}, volume = {9}, journal = {Remote sensing}, publisher = {MDPI}, address = {Basel}, issn = {2072-4292}, doi = {10.3390/rs9040339}, pages = {23}, year = {2017}, language = {en} } @article{CookHoviusWittmannOelzeetal.2017, author = {Cook, Kristen L. and Hovius, Niels and Wittmann-Oelze, Hella and Heimsath, Arjun M. and Lee, Yuan-Hsi}, title = {Causes of rapid uplift and exceptional topography of Gongga Shan on the eastern margin of the Tibetan Plateau}, series = {Earth \& planetary science letters}, volume = {481}, journal = {Earth \& planetary science letters}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0012-821X}, doi = {10.1016/j.epsl.2017.10.043}, pages = {328 -- 337}, year = {2017}, abstract = {Erosion and tectonic uplift are widely thought to be coupled through feedbacks involving orographic precipitation, relief development, and crustal weakening. In many orogenic systems, it can be difficult to distinguish whether true feedbacks exist, or whether observed features are a consequence of tectonic forcing. To help elucidate these interactions, we examine Gongga Shan, a 7556 m peak on the eastern margin of the Tibetan Plateau where cosmogenic Be-10 basin-wide erosion rates reach >5 mm/yr, defining a region of localized rapid erosion associated with a restraining bend in the left-lateral Xianshuihe Fault. Erosion rates are consistent with topography, thermochronometry, and geodetic data, suggesting a stable pattern of uplift and exhumation over at least the past 2-3 My. Transpression along the Xianshuihe Fault, orographically enhanced precipitation, thermally weakened crust, and substantial local relief all developed independently in the Gongga region and existed there prior to the uplift of Gongga Shan. However, only where all of these conditions are present do the observed topographic and erosional extremes exist, and their relative timing indicates that these conditions are not a consequence of rapid uplift. We conclude that their collocation at 3-4 Ma set into motion a series of feedbacks between erosion and uplift that has resulted in the exceptionally high topography and rapid erosion rates observed today.}, language = {en} } @article{LiLiuWangetal.2017, author = {Li, Kai and Liu, Xingqi and Wang, Yongbo and Herzschuh, Ulrike and Ni, Jian and Liao, Mengna and Xiao, Xiayun}, title = {Late Holocene vegetation and climate change on the southeastern Tibetan Plateau: Implications for the Indian Summer Monsoon and links to the Indian Ocean Dipole}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {177}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2017.10.020}, pages = {235 -- 245}, year = {2017}, abstract = {The Indian Summer Monsoon (ISM) is one of the most important climate systems, whose variability and driving mechanisms are of broad interest for academic and societal communities. Here, we present a well-dated high-resolution pollen analysis from a 4.82-m long sediment core taken from Basomtso, in the southeastern Tibetan Plateau (TP), which depicts the regional climate changes of the past millennium. Our results show that subalpine coniferous forest was dominant around Basomtso from ca. 867 to ca. 750 cal. yr BP, indicating a warm and semi-humid climate. The timberline in the study area significantly decreased from ca. 750 to ca.100 cal. yr BP, and a cold climate, corresponding to the Little Ice Age (LIA) prevailed. Since ca. 100 cal. yr BP, the vegetation type changed to forest-meadow with rising temperatures and moisture. Ordination analysis reveals that the migration of vegetation was dominated by regional temperatures and then by moisture. Further comparisons between the Basomtso pollen record and the regional temperature reconstructions underscore the relevance of the Basomtso record from the southeastern TP for regional and global climatologies. Our pollen based moisture reconstruction demonstrates the strong multicentennial-scale link to ISM variability, providing solid evidence for the increase of monsoonal strengths over the past four centuries. Spectral analysis indicates the potential influence of solar forcing. However, a closer relationship has been observed between multicentennial ISM variations and Indian Ocean sea surface temperature anomalies (SSTs), suggesting that the variations in monsoonal precipitation over the southeastern TP are probably driven by the Indian Ocean Dipole on the multicentennial scale. (C) 2017 Elsevier Ltd. All rights reserved.}, language = {en} } @misc{DallmeyerClaussenNietal.2017, author = {Dallmeyer, Anne and Claussen, Martin and Ni, Jian and Cao, Xianyong and Wang, Yongbo and Fischer, Nils and Pfeiffer, Madlene and Jin, Liya and Khon, Vyacheslav and Wagner, Sebastian and Haberkorn, Kerstin and Herzschuh, Ulrike}, title = {Biome changes in Asia since the mid-Holocene}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe}, number = {643}, issn = {1866-8372}, doi = {10.25932/publishup-41875}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-418755}, pages = {107 -- 134}, year = {2017}, abstract = {The large variety of atmospheric circulation systems affecting the eastern Asian climate is reflected by the complex Asian vegetation distribution. Particularly in the transition zones of these circulation systems, vegetation is supposed to be very sensitive to climate change. Since proxy records are scarce, hitherto a mechanistic understanding of the past spatio-temporal climate-vegetation relationship is lacking. To assess the Holocene vegetation change and to obtain an ensemble of potential mid-Holocene biome distributions for eastern Asia, we forced the diagnostic biome model BIOME4 with climate anomalies of different transient Holocene climate simulations performed in coupled atmosphere-ocean(-vegetation) models. The simulated biome changes are compared with pollen-based biome records for different key regions. In all simulations, substantial biome shifts during the last 6000 years are confined to the high northern latitudes and the monsoon-westerly wind transition zone, but the temporal evolution and amplitude of change strongly depend on the climate forcing. Large parts of the southern tundra are replaced by taiga during the mid-Holocene due to a warmer growing season and the boreal treeline in northern Asia is shifted northward by approx. 4 degrees in the ensemble mean, ranging from 1.5 to 6 degrees in the individual simulations, respectively. This simulated treeline shift is in agreement with pollen-based reconstructions from northern Siberia. The desert fraction in the transition zone is reduced by 21\% during the mid-Holocene compared to pre-industrial due to enhanced precipitation. The desert-steppe margin is shifted westward by 5 degrees (1-9 degrees in the individual simulations). The forest biomes are expanded north-westward by 2 degrees, ranging from 0 to 4 degrees in the single simulations. These results corroborate pollen-based reconstructions indicating an extended forest area in north-central China during the mid-Holocene. According to the model, the forest-to-non-forest and steppe-to-desert changes in the climate transition zones are spatially not uniform and not linear since the mid-Holocene.}, language = {en} } @misc{LichtDupontNivetPullenetal.2016, author = {Licht, Alexis and Dupont-Nivet, Guillaume and Pullen, Alex and Kapp, Paul and Abels, Hemmo A. and Lai, Zulong and Guo, ZhaoJie and Abell, Jordan and Giesler, Dominique}, title = {Resilience of the Asian atmospheric circulation shown by paleogene dust provenance}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1114}, issn = {1866-8372}, doi = {10.25932/publishup-43638}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-436381}, pages = {8}, year = {2016}, abstract = {The onset of modern central Asian atmospheric circulation is traditionally linked to the interplay of surface uplift of the Mongolian and Tibetan-Himalayan orogens, retreat of the Paratethys sea from central Asia and Cenozoic global cooling. Although the role of these players has not yet been unravelled, the vast dust deposits of central China support the presence of arid conditions and modern atmospheric pathways for the last 25 million years (Myr). Here, we present provenance data from older (42-33 Myr) dust deposits, at a time when the Tibetan Plateau was less developed, the Paratethys sea still present in central Asia and atmospheric pCO(2) much higher. Our results show that dust sources and near-surface atmospheric circulation have changed little since at least 42 Myr. Our findings indicate that the locus of central Asian high pressures and concurrent aridity is a resilient feature only modulated by mountain building, global cooling and sea retreat.}, language = {en} } @phdthesis{Mey2016, author = {Mey, J{\"u}rgen}, title = {Intermontane valley fills}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-103158}, school = {Universit{\"a}t Potsdam}, pages = {xii, 111}, year = {2016}, abstract = {Sedimentary valley fills are a widespread characteristic of mountain belts around the world. They transiently store material over time spans ranging from thousands to millions of years and therefore play an important role in modulating the sediment flux from the orogen to the foreland and to oceanic depocenters. In most cases, their formation can be attributed to specific fluvial conditions, which are closely related to climatic and tectonic processes. Hence, valley-fill deposits constitute valuable archives that offer fundamental insight into landscape evolution, and their study may help to assess the impact of future climate change on sediment dynamics. In this thesis I analyzed intermontane valley-fill deposits to constrain different aspects of the climatic and tectonic history of mountain belts over multiple timescales. First, I developed a method to estimate the thickness distribution of valley fills using artificial neural networks (ANNs). Based on the assumption of geometrical similarity between exposed and buried parts of the landscape, this novel and highly automated technique allows reconstructing fill thickness and bedrock topography on the scale of catchments to entire mountain belts. Second, I used the new method for estimating the spatial distribution of post-glacial sediments that are stored in the entire European Alps. A comparison with data from exploratory drillings and from geophysical surveys revealed that the model reproduces the measurements with a root mean squared error (RMSE) of 70m and a coefficient of determination (R2) of 0.81. I used the derived sediment thickness estimates in combination with a model of the Last Glacial Maximum (LGM) icecap to infer the lithospheric response to deglaciation, erosion and deposition, and deduce their relative contribution to the present-day rock-uplift rate. For a range of different lithospheric and upper mantle-material properties, the results suggest that the long-wavelength uplift signal can be explained by glacial isostatic adjustment with a small erosional contribution and a substantial but localized tectonic component exceeding 50\% in parts of the Eastern Alps and in the Swiss Rh{\^o}ne Valley. Furthermore, this study reveals the particular importance of deconvolving the potential components of rock uplift when interpreting recent movements along active orogens and how this can be used to constrain physical properties of the Earth's interior. In a third study, I used the ANN approach to estimate the sediment thickness of alluviated reaches of the Yarlung Tsangpo River, upstream of the rapidly uplifting Namche Barwa massif. This allowed my colleagues and me to reconstruct the ancient river profile of the Yarlung Tsangpo, and to show that in the past, the river had already been deeply incised into the eastern margin of the Tibetan Plateau. Dating of basal sediments from drill cores that reached the paleo-river bed to 2-2.5 Ma are consistent with mineral cooling ages from the Namche Barwa massif, which indicate initiation of rapid uplift at ~4 Ma. Hence, formation of the Tsangpo gorge and aggradation of the voluminous valley fill was most probably a consequence of rapid uplift of the Namche Barwa massif and thus tectonic activity. The fourth and last study focuses on the interaction of fluvial and glacial processes at the southeastern edge of the Karakoram. Paleo-ice-extent indicators and remnants of a more than 400-m-thick fluvio-lacustrine valley fill point to blockage of the Shyok River, a main tributary of the upper Indus, by the Siachen Glacier, which is the largest glacier in the Karakoram Range. Field observations and 10Be exposure dating attest to a period of recurring lake formation and outburst flooding during the penultimate glaciation prior to ~110 ka. The interaction of Rivers and Glaciers all along the Karakorum is considered a key factor in landscape evolution and presumably promoted headward erosion of the Indus-Shyok drainage system into the western margin of the Tibetan Plateau. The results of this thesis highlight the strong influence of glaciation and tectonics on valley-fill formation and how this has affected the evolution of different mountain belts. In the Alps valley-fill deposition influenced the magnitude and pattern of rock uplift since ice retreat approximately 17,000 years ago. Conversely, the analyzed valley fills in the Himalaya are much older and reflect environmental conditions that prevailed at ~110 ka and ~2.5 Ma, respectively. Thus, the newly developed method has proven useful for inferring the role of sedimentary valley-fill deposits in landscape evolution on timescales ranging from 1,000 to 10,000,000 years.}, language = {en} } @misc{MischkeZhangFan2015, author = {Mischke, Steffen and Zhang, Chengjun and Fan, Rong}, title = {Early to mid-Holocene lake high-stand sediments at Lake Donggi Cona, northeastern Tibetan Plateau, China -}, series = {Quaternary research : an interdisciplinary journal}, volume = {83}, journal = {Quaternary research : an interdisciplinary journal}, number = {1}, publisher = {Elsevier}, address = {San Diego}, issn = {0033-5894}, doi = {10.1016/j.yqres.2014.06.005}, pages = {256 -- 258}, year = {2015}, language = {en} } @article{WangZhangWuennemannetal.2015, author = {Wang, Rong and Zhang, Yongzhan and W{\"u}nnemann, Bernd and Biskaborn, Boris and Yin, He and Xia, Fei and Zhou, Lianfu and Diekmann, Bernhard}, title = {Linkages between Quaternary climate change and sedimentary processes in Hala Lake, northern Tibetan Plateau, China}, series = {Journal of Asian earth sciences}, volume = {107}, journal = {Journal of Asian earth sciences}, publisher = {Elsevier}, address = {Oxford}, issn = {1367-9120}, doi = {10.1016/j.jseaes.2015.04.008}, pages = {140 -- 150}, year = {2015}, abstract = {Profundal lake sediment cores are often interpreted in line with diverse and detailed sedimentological processes to infer paleoenvironmental conditions. The effects of frozen lake surfaces on terrigenous sediment deposition and how climate changes on the Tibetan Plateau are reflected in these lakes, however, is seldom discussed. A lake sediment core from Hala Lake (590 km(2)), northeastern Tibetan Plateau spanning the time interval from the Last Glacial Maximum to the present was investigated using high-resolution grain-size composition of lacustrine deposits. Seismic analysis along a north-south profile across the lake was used to infer the sedimentary setting within the lake basin. Periods of freezing and melting processes on the lake surface were identified by MODIS (MOD10A1) satellite data. End-member modeling of the grain size distribution allowed the discrimination between lacustrine, eolian and fluvial sediments. The dominant clay sedimentation (slack water type) during the global Last Glacial Maximum (LGM) reflects ice interceptions in long cold periods, in contrast to abundant eolian input during abrupt cold events. Therefore, fluvial and slack water sedimentation processes can indicate changes in the local paleoclimate during periods of the lake being frozen, when eolian input was minor. Inferred warm (i.e., similar to 22.7 and 19.5 cal. ka BP) and cold (i.e., similar to 11-9 and 3-1.5 cal. ka BP) spells have significant environmental impacts, not only in the regional realm, but they are also coherent with global-scale climate events. The eolian input generally follows the trend of the mid-latitude westerly wind dynamics in winter, contributing medium-sized sand to the lake center, deposited within the ice cover during icing and melting phases. Enhanced input was dominant during the Younger Dryas, Heinrich Event 1 and at around 8.2 ka, equivalent to the well-known events of the North Atlantic realm. (C) 2015 Elsevier Ltd. All rights reserved.}, language = {en} } @misc{AichnerFeakinsLeeetal.2015, author = {Aichner, Bernhard and Feakins, Sarah J. and Lee, J. E. and Herzschuh, Ulrike and Liu, X.}, title = {High-resolution leaf wax carbon and hydrogen isotopic record of the late Holocene paleoclimate in arid Central Asia}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {506}, issn = {1866-8372}, doi = {10.25932/publishup-40844}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-408442}, pages = {15}, year = {2015}, abstract = {Central Asia is located at the confluence of large-scale atmospheric circulation systems. It is thus likely to be highly susceptible to changes in the dynamics of those systems; however, little is still known about the regional paleoclimate history. Here we present carbon and hydrogen isotopic compositions of n-alkanoic acids from a late Holocene sediment core from Lake Karakuli (eastern Pamir, Xinjiang Province, China). Instrumental evidence and isotopeenabled climate model experiments with the Laboratoire de Meteorologie Dynamique Zoom model version 4 (LMDZ4) demonstrate that delta D values of precipitation in the region are influenced by both temperature and precipitation amount. We find that these parameters are inversely correlated on an annual scale, i.e., the climate has varied between relatively cool and wet and more warm and dry over the last 50 years. Since the isotopic signals of these changes are in the same direction and therefore additive, isotopes in precipitation are sensitive recorders of climatic changes in the region. Additionally, we infer that plants use year-round precipitation (including snowmelt), and thus leaf wax delta D values must also respond to shifts in the proportion of moisture derived from westerly storms during late winter and early spring. Downcore results give evidence for a gradual shift to cooler and wetter climates between 3.5 and 2.5 cal kyr BP, interrupted by a warm and dry episode between 3.0 and 2.7 kyr BP. Further cool and wet episodes occur between 1.9 and 1.5 and between 0.6 and 0.1 kyr BP, the latter coeval with the Little Ice Age. Warm and dry episodes from 2.5 to 1.9 and 1.5 to 0.6 kyr BP coincide with the Roman Warm Period and Medieval Climate Anomaly, respectively. Finally, we find a drying tend in recent decades. Regional comparisons lead us to infer that the strength and position of the westerlies, and wider northern hemispheric climate dynamics, control climatic shifts in arid Central Asia, leading to complex local responses. Our new archive from Lake Karakuli provides a detailed record of the local signatures of these climate transitions in the eastern Pamir.}, language = {en} } @article{MischkeLaiZhang2014, author = {Mischke, Steffen and Lai, Zhongping and Zhang, Chengjun}, title = {Re-assessment of the paleoclimate implications of the Shell Bar in the Qaidam Basin, China}, series = {Journal of paleolimnolog}, volume = {51}, journal = {Journal of paleolimnolog}, number = {2}, publisher = {Springer}, address = {Dordrecht}, issn = {0921-2728}, doi = {10.1007/s10933-012-9674-6}, pages = {179 -- 195}, year = {2014}, abstract = {The Shell Bar in the Qaidam Basin, China, is a prominent geological feature composed of millions of densely packed Corbicula shells. Since the mid 1980s, it has been regarded as evidence for existence of a large lake during Marine Isotope Stage (MIS) 3 in the presently hyper-arid Qaidam Basin. Early studies suggested the bivalve shells accumulated at the shore of a large lake, whereas more recent work led to the conclusion that the Shell Bar was formed within a deeper water body. Based on our re-assessment of sediments and fossils from the Shell Bar, investigation of exposed fluvio-lacustrine sections upstream of the Shell Bar and study of nearby modern streams, we infer that the Shell Bar represents a stream deposit. Corbicula is a typical stream-dweller around the world. Preservation of Corbicula shells of different sizes, as well as occurrence of many articulated shells, provide evidence against post-mortem transport and accumulation along a lake shore. Additionally, the SE-NW alignment of the Shell Bar is similar to modern intermittent stream beds in its vicinity and corresponds to the present-day slope towards the basin centre further NW, and furthermore, the predominantly sandy sediments also indicate that the Shell Bar was formed in a stream. Abundant ostracod shells in the Shell Bar sediments originated from stream-dwelling species that are abundant in modern streams in the vicinity of the Shell Bar, or in part from fluvio-lacustrine sediments exposed upstream of the Shell Bar, as a result of erosion and re-deposition. Deflation of alluvial fine-grained sediments in the Shell Bar region and protection of the stream deposits by the large and thick-walled Corbicula shells reversed the former channel relief and yielded the modern exposure, which is a prominent morphological feature. Occurrence of Corbicula shells in the Qaidam Basin indicates climate was apparently warmer than present during the formation of the Shell Bar because Corbicula does not live at similar or higher altitudes in the region today. Because the Shell Bar is no longer considered a deposit formed within a lake, its presence does not indicate paleoclimate conditions wetter than today.}, language = {en} } @article{WischnewskiHerzschuhRuehlandetal.2014, author = {Wischnewski, Juliane and Herzschuh, Ulrike and Ruehland, Kathleen M. and Braeuning, Achim and Mischke, Steffen and Smol, John P. and Wang, Lily}, title = {Recent ecological responses to climate variability and human impacts in the Nianbaoyeze Mountains (eastern Tibetan Plateau) inferred from pollen, diatom and tree-ring data}, series = {Journal of paleolimnolog}, volume = {51}, journal = {Journal of paleolimnolog}, number = {2}, publisher = {Springer}, address = {Dordrecht}, issn = {0921-2728}, doi = {10.1007/s10933-013-9747-1}, pages = {287 -- 302}, year = {2014}, abstract = {The Tibetan Plateau is a region that is highly sensitive to recent global warming, but the complexity and heterogeneity of its mountainous landscape can result in variable responses. In addition, the scarcity and brevity of regional instrumental and palaeoecological records still hamper our understanding of past and present patterns of environmental change. To investigate how the remote, high-alpine environments of the Nianbaoyeze Mountains, eastern Tibetan Plateau, are affected by climate change and human activity over the last similar to 600 years, we compared regional tree-ring studies with pollen and diatom remains archived in the dated sediments of Dongerwuka Lake (33.22A degrees N, 101.12A degrees E, 4,307 m a.s.l.). In agreement with previous studies from the eastern Tibetan Plateau, a strong coherence between our two juniper-based tree-ring chronologies from the Nianbaoyeze and the Anemaqin Mountains was observed, with pronounced cyclical variations in summer temperature reconstructions. A positive directional trend to warmer summer temperatures in the most recent decades, was, however, not observed in the tree-ring record. Likewise, our pollen and diatom spectra showed minimal change over the investigated time period. Although modest, the most notable change in the diatom relative abundances was a subtle decrease in the dominant planktonic Cyclotella ocellata and a concurrent increase in small, benthic fragilarioid taxa in the similar to 1820s, suggesting higher ecosystem variability. The pollen record subtly indicates three periods of increased cattle grazing activity (similar to 1400-1480 AD, similar to 1630-1760 AD, after 1850 AD), but shows generally no significant vegetation changes during past similar to 600 years. The minimal changes observed in the tree-ring, diatom and pollen records are consistent with the presence of localised cooling centres that are evident in instrumental and tree-ring data within the southeastern and eastern Tibetan Plateau. Given the minor changes in regional temperature records, our complacent palaeoecological profiles suggest that climatically induced ecological thresholds have not yet been crossed in the Nianbaoyeze Mountains region.}, language = {en} } @article{HerzschuhBorkowskiScheweetal.2014, author = {Herzschuh, Ulrike and Borkowski, Janett and Schewe, Jacob and Mischke, Steffen and Tian, Fang}, title = {Moisture-advection feedback supports strong early-to-mid Holocene monsoon climate on the eastern Tibetan Plateau as inferred from a pollen-based reconstruction}, series = {Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences}, volume = {402}, journal = {Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0031-0182}, doi = {10.1016/j.palaeo.2014.02.022}, pages = {44 -- 54}, year = {2014}, abstract = {(Paleo-)climatologists are challenged to identify mechanisms that cause the observed abrupt Holocene monsoon events despite the fact that monsoonal circulation is assumed to be driven by gradual insolation changes. Here we provide proxy and model evidence to show that moisture-advection feedback can lead to a non-linear relationship between sea-surface and continental temperatures and monsoonal precipitation. A pollen record from Lake Ximencuo (Nianbaoyeze Mountains) indicates that vegetation from the eastern margin of the Tibetan Plateau was characterized by alpine deserts and glacial flora after the Last Glacial Maximum (LGM) (21-15.5 cal kyr BP), by alpine meadows during the Late Glacial (15.5-10.4 cal kyr BP) and second half of the Holocene (5.0 cal kyr BP to present) and by mixed forests during the first half of the Holocene (10.4-5.0 cal kyr BP). The application of pollen-based transfer functions yields an abrupt temperature increase at 10.4 cal kyr BP and a decrease at 5.0 cal kyr BP of about 3 degrees C. By applying endmember modeling to grain-size data from the same sediment core we infer that frequent fluvial events (probably originating from high-magnitude precipitation events) were more common in the early and mid Holocene. We assign the inferred exceptional strong monsoonal circulation to the initiation of moisture-advection feedback, a result supported by a simple model that reproduces this feedback pattern over the same time period. (C) 2014 Published by Elsevier B.V.}, language = {en} } @article{WangHerzschuhLiuetal.2014, author = {Wang, Yongbo and Herzschuh, Ulrike and Liu, Xingqi and Korup, Oliver and Diekmann, Bernhard}, title = {A high-resolution sedimentary archive from landslide-dammed Lake Mengda, north-eastern Tibetan Plateau}, series = {Journal of paleolimnolog}, volume = {51}, journal = {Journal of paleolimnolog}, number = {2}, publisher = {Springer}, address = {Dordrecht}, issn = {0921-2728}, doi = {10.1007/s10933-012-9666-6}, pages = {303 -- 312}, year = {2014}, abstract = {Lacustrine sediments have been widely used to investigate past climatic and environmental changes on millennial to seasonal time scales. Sedimentary archives of lakes in mountainous regions may also record non-climatic events such as earthquakes. We argue herein that a set of 64 annual laminae couplets reconciles a stratigraphically inconsistent accelerator mass spectrometry (AMS) C-14 chronology in a similar to 4-m-long sediment core from Lake Mengda, in the north-eastern Tibetan Plateau. The laminations suggest the lake was formed by a large landslide, triggered by the 1927 Gulang earthquake (M = 8.0). The lake sediment sequence can be separated into three units based on lithologic, sedimentary, and isotopic characteristics. Starting from the bottom of the sequence, these are: (1) unweathered, coarse, sandy valley-floor deposits or landslide debris that pre-date the lake, (2) landslide-induced, fine-grained soil or reworked landslide debris with a high organic content, and (3) lacustrine sediments with low organic content and laminations. These annual laminations provide a high-resolution record of anthropogenic and environmental changes during the twentieth century, recording enhanced sediment input associated with two phases of construction activities. The high mean sedimentation rates of up to 4.8 mm year(-1) underscore the potential for reconstructing such distinct sediment pulses in remote, forested, and seemingly undisturbed mountain catchments.}, language = {en} } @article{GaoZeilingerXuetal.2013, author = {Gao, Mingxing and Zeilinger, Gerold and Xu, Xiwei and Wang, Qingliang and Hao, Ming}, title = {DEM and GIS analysis of geomorphic indices for evaluating recent uplift of the northeastern margin of the Tibetan Plateau, China}, series = {Geomorphology : an international journal on pure and applied geomorphology}, volume = {190}, journal = {Geomorphology : an international journal on pure and applied geomorphology}, number = {20}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0169-555X}, doi = {10.1016/j.geomorph.2013.02.008}, pages = {61 -- 72}, year = {2013}, abstract = {The northeastern margin of the Tibetan Plateau is a tectonically active region consisting of a series of faults with bounded intermountain basins and is located in the transition zone between the Tibetan Plateau and the Loess Plateau. Active deformation that may affect the topography in this region can be quantified using geomorphic indices. Therefore, we applied geomorphic indices such as the hypsometric integral and the stream length gradient index to infer neo-tectonics in the northeastern margin of the Tibetan Plateau. Different time-scaled geodetic leveling data and river incision rates were also integrated into the investigation. The results show that the hypsometric integrals are not significantly affected by lithology but spatially correspond to the hanging walls of thrust faults. The hypsometric integrals are also positively correlated with the leveling data. Although the stream length gradient index is influenced by lithology, its most pronounced anomalies of the stream length gradient are associated with the thrust faults. Consequently, the uplift in the northeast margin of the Tibetan Plateau appeared to be concentrated along the hanging walls of the thrust faults.}, language = {en} }