TY  - THES
A1  - Sorrel, Philippe
T1  - The Aral Sea : a palaeoclimate archive
T1  - Der Aralsee : ein Paläoklimaarchiv
N2  - The intracontinental endorheic Aral Sea, remote from oceanic influences, represents an excellent sedimentary archive in Central Asia that can be used for high-resolution palaeoclimate studies. We performed palynological, microfacies and geochemical analyses on sediment cores retrieved from Chernyshov Bay, in the NW part of the modern Large Aral Sea. The most complete sedimentary sequence, whose total length is 11 m, covers approximately the past 2000 years of the late Holocene. High-resolution palynological analyses, conducted on both dinoflagellate cysts assemblages and pollen grains, evidenced prominent environmental change in the Aral Sea and in the catchment area. The diversity and the distribution of dinoflagellate cysts within the assemblages characterized the sequence of salinity and lake-level changes during the past 2000 years. Due to the strong dependence of the Aral Sea hydrology to inputs from its tributaries, the lake levels are ultimately linked to fluctuations in meltwater discharges during spring. As the amplitude of glacial meltwater inputs is largely controlled by temperature variations in the Tien Shan and Pamir Mountains during the melting season, salinity and lake-level changes of the Aral Sea reflect temperature fluctuations in the high catchment area during the past 2000 years. Dinoflagellate cyst assemblages document lake lowstands and hypersaline conditions during ca. 0–425 AD, 920–1230 AD, 1500 AD, 1600–1650 AD, 1800 AD and since the 1960s, whereas oligosaline conditions and higher lake levels prevailed during the intervening periods. Besides, reworked dinoflagellate cysts from Palaeogene and Neogene deposits happened to be a valuable proxy for extreme sheet-wash events, when precipitation is enhanced over the Aral Sea Basin as during 1230–1450 AD. We propose that the recorded environmental changes are related primarily to climate, but may have been possibly amplified during extreme conditions by human-controlled irrigation activities or military conflicts. Additionally, salinity levels and variations in solar activity show striking similarities over the past millennium, as during 1000–1300 AD, 1450–1550 and 1600–1700 AD when low lake levels match well with an increase in solar activity thus suggesting that an increase in the net radiative forcing reinforced past Aral Sea’s regressions. On the other hand, we used pollen analyses to quantify changes in moisture conditions in the Aral Sea Basin. High-resolution reconstruction of precipitation (mean annual) and temperature (mean annual, coldest versus warmest month) parameters are performed using the “probability mutual climatic spheres” method, providing the sequence of climate change for the past 2000 years in western Central Asia. Cold and arid conditions prevailed during ca. 0–400 AD, 900–1150 AD and 1500–1650 AD with the extension of xeric vegetation dominated by steppe elements. Conversely, warmer and less arid conditions occurred during ca. 400–900 AD and 1150–1450 AD, where steppe vegetation was enriched in plants requiring moister conditions. Change in the precipitation pattern over the Aral Sea Basin is shown to be predominantly controlled by the Eastern Mediterranean (EM) cyclonic system, which provides humidity to the Middle East and western Central Asia during winter and early spring. As the EM is significantly regulated by pressure modulations of the North Atlantic Oscillation (NAO) when the system is in a negative phase, a relationship between humidity over western Central Asia and the NAO is proposed. Besides, laminated sediments record shifts in sedimentary processes during the late Holocene that reflect pronounced changes in taphonomic dynamics. In Central Asia, the frequency of dust storms occurring during spring when the continent is heating up is mostly controlled by the intensity and the position of the Siberian High (SH) Pressure System. Using titanium (Ti) content in laminated sediments as a proxy for aeolian detrital inputs, changes in wind dynamics over Central Asia is documented for the past 1500 years, offering the longest reconstruction of SH variability to date. Based on high Ti content, stronger wind dynamics are reported from 450–700 AD, 1210–1265 AD, 1350–1750 AD and 1800–1975 AD, reporting a stronger SH during spring. In contrast, lower Ti content from 1750–1800 AD and 1980–1985 AD reflect a diminished influence of the SH and a reduced atmospheric circulation. During 1180–1210 AD and 1265–1310 AD, considerably weakened atmospheric circulation is evidenced. As a whole, though climate dynamics controlled environmental changes and ultimately modulated changes in the western Central Asia’s climate system, it is likely that changes in solar activity also had an impact by influencing to some extent the Aral Sea’s hydrology balance and also regional temperature patterns in the past. <hr> The appendix of the thesis is provided via the HTML document as ZIP download.
N2  - Der Aralsee ist ein intrakontinental gelegenes endorheisches Gewässer fernab von ozeanischen Einflüssen, welches ein exzellentes sedimentäres Archiv für hochauflösende Paläoklimastudien in Zentralasien darstellt. In der vorliegenden Studie wurden umfangreiche palynologische, mikrofazielle und geochemische Analysen anhand von mehreren Bohrkernen aus der Chernyshov-Bucht im NW des heutigen Großen Aralsees durchgeführt. Die vollständigste der erbohrten Sequenzen weist dabei eine Länge von 11 m auf und beinhaltet näherungsweise die letzten 2000 Jahre des Holozän. Die hochauflösenden palynologischen Analysen der Studie, welche sowohl die Untersuchung von Dinoflagellatenzysten als auch Pollen beinhaltet, zeugen von einschneidenden Umweltveränderungen im Aralsee und seinem Einzugsgebiet. Die Untersuchung von Diversität und räumlicher Verbreitung der fossilen Dinoflagellatenzysten vermittelt dabei ein genaues Bild von den Salinitäts- und Seespiegeländerungen der letzten 2000 Jahre. Aufgrund der weitgehenden Abhängigkeit der hydrologischen Verhältnisse des Aralsees von der Wasserführung seinen tributären Flüsse, hängt sein Seespiegel unmittelbar von den Schmelzwasserzuflüssen im Frühjahr ab. Da der Schmelzwasserzufluss seinerseits mit den Temperaturveränderungen im Tien Shan und Pamir während der Schneeschmelze in Verbindung steht, spiegeln die Paläo-Salinität und der Paläo-Seespiegel des Aralsees folglich die Temperaturveränderungen im hochgelegenen Einzugsgebiet des Aralsees wider. Die Untersuchung der fossilen Dinoflagellatenzysten belegt besonders niedrige Seestände und hypersaline Bedingungen während der Perioden 0–425 AD, 920–1230 AD, 1500 AD, 1600 AD, 1800 AD und seit 1960, wohingegen oligohaline Bedingungen und höhere Seestände zwischen diesen Phasen dokumentiert sind. Ferner stellen umgelagerte Dinoflagellatenzysten aus Paläogenen und Neogenen Ablagerungen wertvolle Proxies für den Beleg von extremen Flächenspülereignissen dar, wie sie beispielsweise 1230–1450 AD aufgetreten und durch sehr hohe Niederschläge dokumentiert sind. Anhand der in der Studie erarbeiteten Daten ist davon auszugehen, dass die am Aralsee nachgewiesenen Umweltveränderungen im Wesentlichen von klimatischen Änderungen induziert wurden, durch historischen Bewässerungsfeldbau oder militärischen Konflikten jedoch noch verstärkt werden konnten. Darüber hinaus zeigen die Seestandsveränderungen eine sehr hohe Korrelation mit der Sonnenaktivität im letzten Jahrtausend, wie etwa während den Perioden 1000–1300 AD, 1450–1550 und 1600–1700 AD. Komplementär zu der Untersuchung von Dinoflagellatenzysten liefert die Pollenanalyse wertvolle Klimadaten für das Becken des Aralsees. Verschiedene Temperatur- (Jahresmittel, kältester gegen wärmster Monat) und Niederschlagsparameter wurden mit Hilfe der Methode der „probability mutual climatic spheres“ quantitative ausgewertet, womit die Klimaentwicklung im westlichen Zentralasien der letzten 2000 Jahre nachvollzogen werden konnte. Kalte und aride Bedingungen wiesen demnach die durch trockenangepasste Vegetation und Steppenelementen geprägten Perioden 0–400 AD, 900–1150 AD und 1500–1650 AD auf. Andererseits traten warme und weniger aride Klimabedingungen in den durch niederschlagsbedürftigere Pflanzen gekennzeichneten Zeiträumen 400–900 AD and 1150–1450 AD in den Vordergrund. Die Studie zeigt für das Becken des Aralsees, dass die Veränderungen im Niederschlagsmuster hauptsächlich vom zyklonalen System des östlichen Mittelmeergebietes (EM) gesteuert werden, welches den nahen Osten und das westliche Zentralasien mit Feuchtigkeit im Winter und Frühjahr versorgt. Da seinerseits das EM maßgeblich von Luftdruckänderungen der Nordatlantischen Oszillation (NAO) während seiner negativen Phase reguliert wird, ist ein Zusammenhang zwischen der Feuchtigkeit im westlichen Zentralasien und dem NAO anzunehmen. Außerdem belegen die laminierten Sedimente Veränderungen in den Sedimentationsprozessen während des späten Holozän, sowie ausgeprägte Änderungen im taphonomischen Verhalten. In Zentralasien hängt die Häufigkeit der im Frühjahr auftretenden Staubstürme hauptsächlich von der Intensität und der Position des Sibirienhochs (SH) ab. Der Gehalt an Titanium (Ti) als Proxy für äolischen Eintrag in den laminierten Sedimenten erlaubt die Rekonstruktion von winddynamischen Veränderungen in Zentralasien in den letzten 1500 Jahren. Die Studie beinhaltet daher die bislang längste Analyse der Variabilität des SH. Hohe Titaniumwerte sprechen für eine stärkere Winddynamik während den Perioden 450–700 AD, 1210–1265 AD, 1350–1750 AD und 1800–1975 AD, und dokumentieren demzufolge eine stärker ausgeprägtes SH während des Frühjahrs. Umgekehrt belegen geringe Titaniumwerte für die Zeit von 1180–1210 AD, 1265–1310 AD, 1750–1800 AD und 1980–1985 AD einen reduzierten Einfluss des SH.
T2  - The Aral Sea : a palaeoclimate archive
KW  - Aralsee
KW  - spätes Holozän
KW  - Klimaveränderung
KW  - Seestandsänderung
KW  - Dinoflagellatenzyste
KW  - Pollenanalyse
KW  - Winddynamik
KW  - Zentralasien
KW  - Mediterranes Tiefdrucksystem
KW  - Sibirienhoch
KW  - Vegetation
KW  - NAO
KW  - Aral Sea
KW  - late holocene
KW  - climatic change
KW  - lake-level change
KW  - Central Asia
Y1  - 2006
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-7807
ER  - 
TY  - JOUR
A1  - Mischke, Steffen
A1  - Zhang, Chengjun
T1  - Ostracod distribution in Ulungur Lake (Xinjiang, China) and a reassessed Holocene record
JF  - Ecological research
N2  - Ostracod shells in surface sediments from Ulungur Lake (Xinjiang, China) belong mainly to Limnocythere inopinata as the dominant species, and Candona neglecta and Darwinula stevensoni as accompanying, less abundant taxa. Shells of an additional nine species were recorded only sporadically. The three most abundant ostracods have wide tolerance ranges in terms of salinity, substrate and water depth. The similarly recorded bivalve Pisidium subtruncatum, and the gastropods Gyraulus chinensis and Radix auricularia belong to the most tolerant representatives of the genera. The bivalve and gastropods, in addition to the ostracod assemblage, reflect the fact that Ulungur Lake has experienced strong lake level and salinity variations due to water withdrawal in the catchment and the counteracting diversion of river waters to the lake in recent decades. The substrate in Ulungur Lake is typically fine-grained, apart from the delta region of the Ulungur River channel, which is marked by relatively coarse-grained detrital sediments barren of ostracod shells. This channel was created 40 years ago to divert water to Ulungur Lake and support its local fisheries and recreational facilities. A reassessed Holocene ostracod record from the lake shows that a significantly higher salinity and lower lake level existed in the early Holocene before 6.0 ka in response to the regional climate. In contrast, a higher lake level and lowest salinity is inferred for the late Holocene period between ca. 3.6 and 1.3 ka before present. Afterwards, the lake level declined and salinity increased in response to regional moisture reduction, although conditions similar to the early Holocene lake status were not re-established. Our surface-sediment-derived data provide a baseline for analysis of future environmental variations due to global climate change and regional water management.
KW  - Ostracoda
KW  - Water depth
KW  - Substrate
KW  - Holocene
KW  - Central Asia
Y1  - 2011
U6  - https://doi.org/10.1007/s11284-010-0768-1
SN  - 0912-3814
VL  - 26
IS  - 1
SP  - 133
EP  - 145
PB  - Springer
CY  - Tokyo
ER  - 
TY  - JOUR
A1  - Van der Meeren, T.
A1  - Mischke, Steffen
A1  - Sunjidmaa, N.
A1  - Herzschuh, Ulrike
A1  - Ito, E.
A1  - Martens, K.
A1  - Verschuren, Dirk
T1  - Subfossil ostracode assemblages from Mongolia quantifying response for paleolimnological applications
JF  - Ecological indicators : integrating monitoring, assessment and management
N2  - Ostracodes (Ostracoda, Crustacea) are aquatic micro-crustaceans with a significant representation in the fossil record. If the environmental influence on the species composition of their communities is robustly quantified, past changes in ostracode communities reflected in fossil assemblages can be used for paleo-environmental reconstruction. We analyzed ostracode assemblages in recently deposited surface sediments from 56 lakes in western and central Mongolia, and simultaneously recorded local water chemistry and solute concentration in order to elucidate the distribution of individual ostracode species in relation to these broad environmental gradients. Multivariate analysis indicated that the species variation in ostracode assemblages could be mainly attributed to variations in percent calcium (%Ca) relative to total cation content, mean annual precipitation, calcium concentration, alkalinity, percent bicarbonate relative to total anion content, and mean July temperature. This matches well with the results of a similar analysis on presence/absence data of living ostracodes in nearshore samples, even though some differences exist between the faunal composition of both datasets. The documented response of ostracode species to environmental variation tracks the typical solute evolutionary pathway for surface waters in this region, characterized by calcite precipitation and consequent depletion in dissolved calcium. Hence, the best quantitative inference model (WA-PLS model with R-jack(2) = 0.70, RMSEP = 0.40) for paleolimnological application was obtained for %Ca. Comparison between this model and a specific conductance (SC) inference model based on the same dataset, and based on ostracode datasets from different regions, indicated that the %Ca inference model suffers less than the SC inference model from a step-change in reconstructed values. The statistical power of different inference models based on Mongolian ostracodes are variously affected by the common dominance of a single euryhaline species (Limnocythere inopinata), limited faunal turnover in the freshwater portion of the salinity gradient, and the bimodal frequency distribution of SC among regional lakes. The latter probably represents true scarcity of lakes with intermediate salinity rather than a biased representation in our dataset. In a broader context of ostracode ecology, and with respect to regional paleolimnological applications, we highlight the potential of fossil Mongolian ostracode assemblages to trace past hydrological shifts associated with changes in groundwater inflow.
KW  - Ostracoda
KW  - Inference model
KW  - Central Asia
KW  - Paleo-ecology
KW  - Solute evolution
Y1  - 2012
U6  - https://doi.org/10.1016/j.ecolind.2011.07.004
SN  - 1470-160X
SN  - 1872-7034
VL  - 14
IS  - 1
SP  - 138
EP  - 151
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Taft, Linda
A1  - Mischke, Steffen
A1  - Wiechert, Uwe
A1  - Leipe, Christian
A1  - Rajabov, Ilhomjon
A1  - Riedel, Frank
T1  - Sclerochronological oxygen and carbon isotope ratios in Radix (Gastropoda) shells indicate changes of glacial meltwater flux and temperature since 4,200 cal yr BP at Lake Karakul, eastern Pamirs (Tajikistan)
JF  - Journal of paleolimnolog
N2  - We report delta O-18 and delta C-13 values of 21 fossil shells from the aquatic gastropod Radix from a sediment core taken in the eastern basin of Lake Karakul, Tajikistan (38.86-39.16A degrees N, 73.26-73.56A degrees E, 3,928 m above sea level) and covering the last 4,200 cal yr BP. The lake is surrounded by many palaeoshorelines evidencing former lake-level changes, most likely triggered by changes in meltwater flux. This hypothesis was tested by interpreting the isotope ratios of Radix shells together with delta O-18 values of Ostracoda and of authigenic aragonite. The mean delta O-18 values of Radix and Ostracoda fall along the same long-term trend indicating a change in the isotopic composition of precipitation, which contributed to the glaciers in the catchment as snow and finally as melt water to the lake. The sclerochronological delta O-18 and delta C-13 patterns in Radix shells provide seasonal weather information, which is discussed in context with previously proposed climatic changes during the last 4,200 cal yr BP. The period between similar to 4,200 and 3,000 cal yr BP was characterized by stepwise glacier advance in the catchment most likely due to a precipitation surplus. Subsequently the climate remained relatively cold but the lake level fluctuated, as indicated by ostracod shell isotope data. From similar to 1,800 cal yr BP the sclerochronological patterns provide evidence for increasing melt water flux and transport of allochthonous carbon into the lake, most likely due to an accelerated glacier retreat. The period around 1,500 cal yr BP was characterized by strong warming, increasing meltwater flux, glacier retreat and an increasing lake level. Warm conditions continued until similar to 500 cal yr I'P probably representing the end of the Medieval Warm Period. A short relatively cold (dry?) period and a lower lake level are assumed for similar to 350 cal yr BP, possibly an analogue to the Maunder Minimum cooling in the North Atlantic region. Our results show that the lake system is complex, and that changes were triggered by external forcing and feedbacks. The similarity of delta O-18 values in Radix and ostracod shells demonstrates that both archives provide complementary information.
KW  - Palaeolimnology
KW  - Stable isotopes
KW  - Gastropods
KW  - Sclerochronology
KW  - Late Holocene
KW  - Central Asia
Y1  - 2014
U6  - https://doi.org/10.1007/s10933-014-9776-4
SN  - 0921-2728
SN  - 1573-0417
VL  - 52
IS  - 1-2
SP  - 27
EP  - 41
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Lauterbach, Stefan
A1  - Witt, Roman
A1  - Plessen, Birgit
A1  - Dulski, Peter
A1  - Prasad, Sushma
A1  - Mingram, Jens
A1  - Gleixner, Gerd
A1  - Hettler-Riedel, Sabine
A1  - Stebich, Martina
A1  - Schnetger, Bernhard
A1  - Schwalb, Antje
A1  - Schwarz, Anja
T1  - Climatic imprint of the mid-latitude Westerlies in the Central Tian Shan of Kyrgyzstan and teleconnections to North Atlantic climate variability during the last 6000 years
JF  - The Holocene : an interdisciplinary journal focusing on recent environmental change
N2  - In general, a moderate drying trend is observed in mid-latitude arid Central Asia since the Mid-Holocene, attributed to the progressively weakening influence of the mid-latitude Westerlies on regional climate. However, as the spatio-temporal pattern of this development and the underlying climatic mechanisms are yet not fully understood, new high-resolution paleoclimate records from this region are needed. Within this study, a sediment core from Lake Son Kol (Central Kyrgyzstan) was investigated using sedimentological, (bio) geochemical, isotopic, and palynological analyses, aiming at reconstructing regional climate development during the last 6000 years. Biogeochemical data, mainly reflecting summer moisture conditions, indicate predominantly wet conditions until 4950 cal. yr BP, succeeded by a pronounced dry interval between 4950 and 3900 cal. yr BP. In the following, a return to wet conditions and a subsequent moderate drying trend until present times are observed. This is consistent with other regional paleoclimate records and likely reflects the gradual Late Holocene diminishment of the amount of summer moisture provided by the mid-latitude Westerlies. However, climate impact of the Westerlies was apparently not only restricted to the summer season but also significant during winter as indicated by recurrent episodes of enhanced allochthonous input through snowmelt, occurring before 6000 cal. yr BP and at 5100-4350, 3450-2850, and 1900-1500 cal. yr BP. The distinct similar to 1500year periodicity of these episodes of increased winter precipitation in Central Kyrgyzstan resembles similar cyclicities observed in paleoclimate records around the North Atlantic, likely indicating a hemispheric-scale climatic teleconnection and an impact of North Atlantic Oscillation (NAO) variability in Central Asia.
KW  - Central Asia
KW  - climate
KW  - Holocene
KW  - lake sediments
KW  - mid-latitude Westerlies
KW  - NAO
Y1  - 2014
U6  - https://doi.org/10.1177/0959683614534741
SN  - 0959-6836
SN  - 1477-0911
VL  - 24
IS  - 8
SP  - 970
EP  - 984
PB  - Sage Publ.
CY  - London
ER  - 
TY  - JOUR
A1  - Schmidt, Birgit Angelika
A1  - Ziemann, Martin Andreas
A1  - Pentzien, Simone
A1  - Gabsch, Toralf
A1  - Koch, Werner
A1  - Krüger, Jörg
T1  - Technical analysis of a Central Asian wall painting detached from a Buddhist cave temple on the northern Silk Road
JF  - Studies in Conservation
N2  - A great number of Central Asian wall paintings, archeological materials, architectural fragments, and textiles, as well as painting fragments on silk and paper, make up the so called Turfan Collection at the Asian Art Museum in Berlin. The largest part of the collection comes from the Kucha region, a very important cultural center in the third to ninth centuries. Between 1902 and 1914, four German expeditions traveled along the northern Silk Road. During these expeditions, wall paintings were detached from their original settings in Buddhist cave complexes. This paper reports a technical study of a wall painting, existing in eight fragments, from the Buddhist cave no. 40 (Ritterhohle). Its original painted surface is soot blackened and largely illegible. Gruwedel, leader of the first and third expeditions, described the almost complete destruction of the rediscovered temple complex and evidence of fire damage. The aim of this case study is to identify the materials used for the wall paintings. Furthermore, soot deposits as well as materials from conservation interventions were of interest. Non-invasive analyses were preferred but a limited number of samples were taken to provide more precise information on the painting technique. By employing optical and scanning electron microscopy, energy dispersive X-ray spectroscopy, micro X-ray fluorescence spectroscopy, X-ray diffraction analysis, and Raman spectroscopy, a layer sequence of earthen render, a ground layer made of gypsum, and a paint layer containing a variety of inorganic pigments were identified.
KW  - Wall paintings
KW  - Central Asia
KW  - Silk Road
KW  - Pigments
KW  - Microscopy
KW  - EDX
KW  - XRF
KW  - Raman spectroscopy
Y1  - 2016
U6  - https://doi.org/10.1179/2047058414Y.0000000152
SN  - 0039-3630
SN  - 2047-0584
VL  - 61
SP  - 113
EP  - 122
PB  - Routledge, Taylor & Francis Group
CY  - Abingdon
ER  - 
TY  - JOUR
A1  - Bougeois, Laurie
A1  - de Rafelis, Marc
A1  - Reichart, Gert-Jan
A1  - de Nooijer, Lennart J.
A1  - Dupont-Nivet, Guillaume
T1  - Mg/Ca in fossil oyster shells as palaeotemperature proxy, an example from the Palaeogene of Central Asia
JF  - Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences
N2  - Fossil oyster shells are well-suited to provide palaeotemperature proxies from geologic to seasonal timescales due to their ubiquitous occurrence from Triassic to Quaternary sediments, the seasonal nature of their shell growth and their relative strong resistance to post-mortem alteration. However, the common use to translate calcitic oxygen isotopes into palaeotemperatures is challenged by uncertainties in accounting for past seawater delta O-18, especially in shallow coastal environment where oysters calcify. In principle, the Mg/Ca ratio in oyster shells can provide an alternative palaeothermometer. Several studies provided temperature calibrations for this potential proxy based on modem species, nevertheless their application to palaeo-studies remains hitherto unexplored. Here, we show that past temperature variability in seawater can be obtained from Mg/Ca analyses from selected fossil oyster species and specimens. High-resolution Mg/Ca profiles, combined with delta O-18, were obtained along 41 fossil oyster shells of seven different species from the Palaeogene Proto-Paratethys sea (Central Asia) found in similar as well as different depositional age and environments providing comparison. Suitable Mg/Ca profiles, defined by continuous cyclicity and reproducibility within one shell, are found to be consistent for specimens of the same species but differ systematically between species, implying a dominant species-specific effect on the Mg/Ca signal. Two species studied here (Ostrea (Turkostrea) strictiplicata and Sokolowia buhsii) provide an excellent proxy for palaeoclimate reconstruction from China to Europe in Palaeogene marine sediments. More generally, the protocol developed here can be applied to identify other fossil oyster species suitable for palaeoclimate reconstructions. (C) 2015 Elsevier B.V. All rights reserved.
KW  - Palaeoclimate
KW  - Oyster
KW  - Mg/Ca
KW  - Sclerochronology
KW  - Palaeogene
KW  - Central Asia
Y1  - 2016
U6  - https://doi.org/10.1016/j.palaeo.2015.09.052
SN  - 0031-0182
SN  - 1872-616X
VL  - 441
SP  - 611
EP  - 626
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - GEN
A1  - Lauterbach, Stefan
A1  - Witt, Roman
A1  - Plessen, Birgit
A1  - Dulski, Peter
A1  - Prasad, Sushma
A1  - Mingram, Jens
A1  - Gleixner, Gerd
A1  - Hettler-Riedel, Sabine
A1  - Stebich, Martina
A1  - Schnetger, Bernhard
A1  - Schwalb, Antje
A1  - Schwarz, Anja
T1  - Climatic imprint of the mid-latitude Westerlies in the Central Tian Shan of Kyrgyzstan and teleconnections to North Atlantic climate variability during the last 6000 years
N2  - In general, a moderate drying trend is observed in mid-latitude arid Central Asia since the Mid-Holocene, attributed to the progressively weakening influence of the mid-latitude Westerlies on regional climate. However, as the spatio-temporal pattern of this development and the underlying climatic mechanisms are yet not fully understood, new high-resolution paleoclimate records from this region are needed. Within this study, a sediment core from Lake Son Kol (Central Kyrgyzstan) was investigated using sedimentological, (bio) geochemical, isotopic, and palynological analyses, aiming at reconstructing regional climate development during the last 6000 years. Biogeochemical data, mainly reflecting summer moisture conditions, indicate predominantly wet conditions until 4950 cal. yr BP, succeeded by a pronounced dry interval between 4950 and 3900 cal. yr BP. In the following, a return to wet conditions and a subsequent moderate drying trend until present times are observed. This is consistent with other regional paleoclimate records and likely reflects the gradual Late Holocene diminishment of the amount of summer moisture provided by the mid-latitude Westerlies. However, climate impact of the Westerlies was apparently not only restricted to the summer season but also significant during winter as indicated by recurrent episodes of enhanced allochthonous input through snowmelt, occurring before 6000 cal. yr BP and at 5100-4350, 3450-2850, and 1900-1500 cal. yr BP. The distinct similar to 1500year periodicity of these episodes of increased winter precipitation in Central Kyrgyzstan resembles similar cyclicities observed in paleoclimate records around the North Atlantic, likely indicating a hemispheric-scale climatic teleconnection and an impact of North Atlantic Oscillation (NAO) variability in Central Asia.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 408 
KW  - Central Asia
KW  - climate
KW  - Holocene
KW  - lake sediments
KW  - mid-latitude Westerlies
KW  - NAO
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-404085
ER  - 
TY  - JOUR
A1  - Fitzsimmons, Kathryn E.
A1  - Sprafke, Tobias
A1  - Zielhofer, Christoph
A1  - Günter, Christina
A1  - Deom, Jean-Marc
A1  - Sala, Renato
A1  - Iovita, Radu
T1  - Loess accumulation in the Tian Shan piedmont
BT  - Implications for palaeoenvironmental change in arid Central Asia
JF  - Quaternary international : the journal of the International Union for Quaternary Research
N2  - Whilst correlations have been made between the loess of Europe and China, deposits in Central Asia have remained largely overlooked by scientific investigation. The nature of the relationship between loess accumulation and palaeoclimate at the core of the Eurasian loess belt is particularly poorly understood. Here we reconstruct palaeoenvironmental change in Central Asia over the last 40 ky based on data from the Remizovka loess profile, in the northern foothills of the Tian Shan in southern Kazakhstan. Our interpretations are based on synthesis of chronostratigraphic, colour and magnetic susceptibility data, supported by chronostratigraphies from two additional sites nearby, Maibulak and Valikhanova. All three sites record substantially increased loess accumulation during late MIS 3 into the global last glacial maximum (gLGM). At Remizovka, increased loess flux occurred in two pulses at c. 38-25 ka and 22-18 ka, with the intervening period involving incipient pedogenesis. At Maibulak, two loess pulses at c. 40-30 ka and c. 28-22 ka are separated by a weakly developed paleosol which may date to the same time as pedogenesis at Remizovka. There is additional possible periglacial influence at Maibulak from c. 40-33.5 ka. At Valikhanova, there is some age overlap between paleosol and loess samples, but overall loess accumulation appears to have increased at c. 42-35 ka, c. 30 ka and the gLGM, with pedogenesis occurring >40 ka and c. 32 ka. At all three sites, Holocene loess accumulation is minimal; this period is characterised by pedogenesis. The chronostratigraphic variability between our sites highlights a need to interrogate climate-driven models for loess formation in piedmont environments. We interpret our data in the context of regional palaeoenvironmental archives to indicate that loess accumulation increased coeval with MIS 3 glacial advance in the Tian Shan, which was facilitated by northward expansion of the Asian monsoon and associated increase in precipitation. We hypothesise that increased ice volume impeded teleconnections with the temperate zone westerlies to the north; these were compressed against the piedmont resulting in increased wind strength and facilitating increased loess flux. Peak loess accumulation during the gLGM occurred under colder, drier climatic conditions, with reduced but sustained glacial ice volume and persistent influence of the westerlies in the arid Central Asian piedmont loess belt. In the absence of more widespread, reliably dated palaeoenvironmental records from the region, our data become of critical importance for understanding past environmental conditions in Central Asia, relative to elsewhere in Eurasia and globally.
KW  - Loess
KW  - Central Asia
KW  - Tian Shan piedmont
KW  - Kazakhstan
KW  - Palaeoenvironmental reconstruction
KW  - luminescence dating
Y1  - 2018
U6  - https://doi.org/10.1016/j.quaint.2016.07.041
SN  - 1040-6182
SN  - 1873-4553
VL  - 469
SP  - 30
EP  - 43
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Meijer, Niels
A1  - Dupont-Nivet, Guillaume
A1  - Abels, Hemmo A.
A1  - Kaya, Mustafa Y.
A1  - Licht, Alexis
A1  - Xiao, Meimei
A1  - Zhang, Yang
A1  - Roperch, Pierrick
A1  - Poujol, Marc
A1  - Lai, Zhongping
A1  - Guo, Zhaojie
T1  - Central Asian moisture modulated by proto-Paratethys Sea incursions since the early Eocene
JF  - Earth and planetary science letters
N2  - The establishment and evolution of the Asian monsoons and arid interior have been linked to uplift of the Tibetan Plateau, retreat of the inland proto-Paratethys Sea and global cooling during the Cenozoic. However, the respective role of these driving mechanisms remains poorly constrained. This is partly due to a lack of continental records covering the key Eocene epoch marked by the onset of Tibetan Plateau uplift, proto-Paratethys Sea incursions and long-term global cooling. In this study, we reconstruct paleoenvironments in the Xining Basin, NE Tibet, to show a long-term drying of the Asian continental interior from the early Eocene to the Oligocene. Superimposed on this trend are three alternations between arid mudflat and wetter saline lake intervals, which are interpreted to reflect atmospheric moisture fluctuations in the basin. We date these fluctuations using magnetostratigraphy and the radiometric age of an intercalated tuff layer. The first saline lake interval is tentatively constrained to the late Paleocene-early Eocene. The other two are firmly dated between similar to 46 Ma (top magnetochron C21n) and similar to 41 Ma (base C18r) and between similar to 40 Ma (base C18n) and similar to 37 Ma (top C17n). Remarkably, these phases correlate in time with highstands of the proto-Paratethys Sea. This strongly suggests that these sea incursions enhanced westerly moisture supply as far inland as the Xining Basin. We conclude that the proto-Paratethys Sea constituted a key driver of Asian climate and should be considered in model and proxy interpretations. (C) 2019 Elsevier B.V. All rights reserved.
KW  - Paleogene
KW  - magnetostratigraphy
KW  - Central Asia
KW  - Xining Basin
KW  - westerlies
KW  - Asian monsoon
Y1  - 2019
U6  - https://doi.org/10.1016/j.epsl.2018.12.031
SN  - 0012-821X
SN  - 1385-013X
VL  - 510
SP  - 73
EP  - 84
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Roud, Sophie
A1  - Wack, Michael Richard
A1  - Gilder, Stuart A.
A1  - Kudriavtseva, Anna
A1  - Sobel, Edward
T1  - Miocene to early pleistocene depositional history and tectonic evolution of the Issyk-Kul Basin, Central Tian Shan
JF  - Geochemistry, geophysics, geosystems : G 3 ; an electronic journal of the earth sciences
N2  - The Issyk-Kul Basin (Kyrgyzstan), situated in the central Tian Shan Mountains, hosts the largest and deepest mountain lake in Central Asia. Erosion of the surrounding Terskey and Kungey ranges led to the accumulation of up to 4 km of sediment in the adjacent depression. Creation of the basin from regional shortening and uplift likely initiated around the Oligocene-Miocene, yet precise age control is sparse. To better understand the timing of these processes, we obtained magnetostratigraphic age constraints on fossil-poor, fluvio-lacustrine sediments exposed south of Lake Issyk-Kul, that agree well with previous age constraints of the equivalent strata outside the Issyk-Kul Basin. Two 500-650 m thick sections comprised mainly of Chu Group sediments were dated at 6.3-2.8 Ma and 7.0-2.4 Ma (late Miocene to early Pleistocene). Together with reinterpreted magnetostratigraphic constraints from underlying strata, we find that syn-tectonic deposition commenced at similar to 22 Ma with average sedimentation rates <10 cm/ka. Sedimentation rates increased to 10-30 cm/ka at 7 Ma, concurrent with accelerated uplift in the Terskey Range to the south. A deformation event in one section (Kaji-Say) between 5 and 3 Ma together with concurrent shifts of depositional centers throughout the basin signal the onset of substantial uplift of the Kungey Range to the north at similar to 5 Ma. This uplift and deformation transformed the Issyk-Kul area into a closed basin that facilitated the formation of a deep lake. Lacustrine facies deposited around 3 Ma mark the existence of Lake Issyk-Kul by that time.
KW  - Central Asia
KW  - Lake Issyk‐ Kul
KW  - magnetostratigraphy
KW  - Neogene
KW  - Tian
KW  - Shan
Y1  - 2021
U6  - https://doi.org/10.1029/2020GC009556
SN  - 1525-2027
VL  - 22
IS  - 4
PB  - Wiley
CY  - Hoboken, NJ
ER  - 
TY  - THES
A1  - Kudriavtseva, Anna
T1  - Interactions between tectonics, climate, and surface processes in the Kyrgyz Tian Shan
N2  - During the Cenozoic, global cooling and uplift of the Tian Shan, Pamir, and Tibetan plateau modified atmospheric circulation and reduced moisture supply to Central Asia. These changes led to aridification in the region during the Neogene. Afterwards, Quaternary glaciations led to modification of the landscape and runoff. 
In the Issyk-Kul basin of the Kyrgyz Tian Shan, the sedimentary sequences reflect the development of the adjacent ranges and local climatic conditions. In this work, I reconstruct the late Miocene – early Pleistocene depositional environment, climate, and lake development in the Issyk-Kul basin using facies analyses and stable δ18O and δ13C isotopic records from sedimentary sections dated by magnetostratigraphy and 26Al/10Be isochron burial dating. Also, I present 10Be-derived millennial-scale modern and paleo-denudation rates from across the Kyrgyz Tian Shan and long-term exhumation rates calculated from published thermochronology data. This allows me to examine spatial and temporal changes in surface processes in the Kyrgyz Tian Shan.
In the Issyk-Kul basin, the style of fluvial deposition changed at ca. 7 Ma, and aridification in the basin commenced concurrently, as shown by magnetostratigraphy and the δ18O and δ13C data. Lake formation commenced on the southern side of the basin at ca. 5 Ma, followed by a ca. 2 Ma local depositional hiatus. 26Al/10Be isochron burial dating and paleocurrent analysis show that the Kungey range to the north of the basin grew eastward, leading to a change from fluvial-alluvial deposits to proximal alluvial fan conglomerates at 5-4 Ma in the easternmost part of the basin. This transition occurred at 2.6-2.8 Ma on the southern side of the basin, synchronously with the intensification of the Northern Hemisphere glaciation. The paleo-denudation rates from 2.7-2.0 Ma are as low as long-term exhumation rates, and only the millennial-scale denudation rates record an acceleration of denudation. 
This work concludes that the growth of the ranges to the north of the basin led to creation of the topographic barrier at ca. 7 Ma and a subsequent aridification in the Issyk-Kul basin. Increased subsidence and local tectonically-induced river system reorganization on the southern side of the basin enabled lake formation at ca. 5 Ma, while growth of the Kungey range blocked westward-draining rivers and led to sediment starvation and lake expansion. Denudational response of the Kyrgyz Tian Shan landscape is delayed due to aridity and only substantial cooling during the late Quaternary glacial cycles led to notable acceleration of denudation. Currently, increased glacier reduction and runoff controls a more rapid denudation of the northern slope of the Terskey range compared to other ranges of the Kyrgyz Tian Shan.
N2  - Während des Känozoikums veränderten die globale Abkühlung und die Hebung des Tian Shan, des Pamir und des tibetischen Plateaus die atmosphärische Zirkulation und verringerten die Feuchtigkeitszufuhr nach Zentralasien. Diese Veränderungen führten während des Neogens zur Aridifizierung der Region. Danach führten die Vergletscherungen des Quartärs zu einer Veränderung der Landschaft und des Abflusses.
Im Issyk-Kul-Becken des kirgisischen Tian Shan spiegeln die Sedimentabfolgen die Entwicklung der angrenzenden Gebirgszüge und die lokalen klimatischen Bedingungen wider. In dieser Arbeit rekonstruiere ich die spätmiozäne bis frühpleistozäne Ablagerungsumgebung, das Klima und die Entwicklung der Seen im Issyk-Kul-Becken anhand von Faziesanalysen und stabilen δ18O- und δ13C-Isotopenaufzeichnungen aus Sedimentabschnitten, die durch Magnetostratigraphie und 26Al/10Be-Isochron-Bestattungsdaten datiert wurden. Außerdem präsentiere ich 10Be-abgeleitete moderne und paläo-Denudationsraten aus dem kirgisischen Tian Shan und langfristige Exhumierungsraten, die aus veröffentlichten thermochronologischen Daten berechnet wurden. So kann ich räumliche und zeitliche Veränderungen der Oberflächenprozesse im kirgisischen Tian Shan untersuchen.
Im Issyk-Kul-Becken änderte sich der Stil der fluvialen Ablagerung bei ca. 7 Ma. Wie die Magnetostratigraphie und die δ18O- und δ13C-Daten zeigen, setzte gleichzeitig die Aridifizierung des Beckens ein. Die Bildung von Seen begann an der Südseite des Beckens bei ca. 5 Ma, gefolgt von einer lokalen Ablagerungspause von ca. 2 Ma. 26Al/10Be-Isochron-Vergrabungsdatierungen und Paläostromanalysen zeigen, dass das Kungey-Gebirge im Norden des Beckens nach Osten wuchs, was zu einem Übergang von fluvial-alluvialen Ablagerungen zu proximalen alluvialen Fächerkonglomeraten bei 5-4 Ma im östlichsten Teil des Beckens führte. Dieser Übergang vollzog sich um 2,6-2,8 Ma auf der Südseite des Beckens, zeitgleich mit der Intensivierung der Vergletscherung der nördlichen Hemisphäre. Die Paläo-Denudationsraten von 2,7-2,0 Ma sind so niedrig wie die langfristigen Exhumierungsraten, und nur die Denudationsraten auf der Jahrtausendskala zeigen eine Beschleunigung der Denudation.
Diese Arbeit kommt zu dem Schluss, dass das Wachstum der Gebirgsketten im Norden des Beckens zur Entstehung der topografischen Barriere bei ca. 7 Ma und einer anschließenden Aridifizierung im Issyk-Kul-Becken führte. Eine verstärkte Absenkung und eine lokale tektonisch bedingte Umstrukturierung des Flusssystems auf der Südseite des Beckens ermöglichte die Bildung von Seen bei ca. 5 Ma, während das Wachstum des Kungey-Gebirges die nach Westen abfließenden Flüsse blockierte und zu einer Verknappung der Sedimente und einer Ausdehnung der Seen führte. Die Denudationsreaktion der kirgisischen Tian Shan-Landschaft verzögerte sich aufgrund der Trockenheit, und erst die erhebliche Abkühlung während der Gletscherzyklen des späten Quartärs führte zu einer merklichen Beschleunigung der Denudation. Gegenwärtig wird die Denudation des Nordhangs des Terskey-Gebirges im Vergleich zu anderen Gebirgszügen der kirgisischen Tian Shan durch den verstärkten Gletscherrückgang und den Abfluss beschleunigt.
KW  - Central Asia
KW  - δ18O and δ13C stable isotopes
KW  - 26Al/10Be cosmogenic radionuclides
KW  - magnetostratigraphy
KW  - Cenozoic aridification
KW  - denudation rates
KW  - Tian Shan
KW  - Zentralasien
KW  - δ18O and δ13C stabile Isotope
KW  - 26Al/10Be kosmogene Radionuklide
KW  - Magnetostratigraphie
KW  - Känozoische Aridifizierung
KW  - Denudationsraten
KW  - Tian Shan
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-603728
ER  - 
TY  - THES
A1  - Rembe, Johannes
T1  - Hercynian to Eocimmerian evolution of the North Pamir in Central Asia
T1  - Herzynische bis früh-kimmerische Entwicklung des Nordpamirs in Zentralasien
N2  - The North Pamir, part of the India-Asia collision zone, essentially formed during the late Paleozoic to late Triassic–early Jurassic. Coeval to the subduction of the Turkestan ocean—during the Carboniferous Hercynian orogeny in the Tien Shan—a portion of the Paleo-Tethys ocean subducted northward and lead to the formation and obduction of a volcanic arc. This Carboniferous North Pamir arc is of Andean style in the western Darvaz segment and trends towards an intraoceanic arc in the eastern, Oytag segment. A suite of arc-volcanic rocks and intercalated, marine sediments together with intruded voluminous plagiogranites (trondhjemite and tonalite) and granodiorites was uplifted and eroded during the Permian, as demonstrated by widespread sedimentary unconformities. Today it constitutes a major portion of the North Pamir.
In this work, the first comprehensive Uranium-Lead (U-Pb) laser-ablation inductively-coupled-plasma mass-spectrometry (LA-ICP-MS) radiometric age data are presented along with geochemical data from the volcanic and plutonic rocks of the North Pamir volcanic arc. Zircon U-Pb data indicate a major intrusive phase between 340 and 320 Ma. The magmatic rocks show an arc-signature, with more primitive signatures in the Oytag segment compared to the Darvaz segment. Volcanic rocks in the Chinese North Pamir were indirectly dated by determining the age of ocean floor alteration. We investigate calcite filled vesicles and show that oxidative sea water and the basaltic host rock are major trace element sources. The age of ocean floor alteration, within a range of 25 Ma, constrains the extrusion age of the volcanic rocks. In the Chinese Pamir, arc-volcanic basalts have been dated to the Visean-Serpukhovian boundary. This relates the North Pamir volcanic arc to coeval units in the Tien Shan. Our findings further question the idea of a continuous Tarim-Tajik continent in the Paleozoic.
From the Permian (Guadalupian) on, a progressive sea-retreat led to continental conditions in the northeastern Pamir. Large parts of Central Asia were affected by transcurrent tectonics, while subduction of the Paleo-Tethys went on south of the accreted North Pamir arc, likely forming an accretionary wedge, representing an early stage of the later Karakul-Mazar tectonic unit. Graben systems dissected the Permian carbonate platforms, that formed on top of the uplifted Carboniferous arc in the central and western North Pamir. A continental graben formed in the eastern North Pamir. Zircon U-Pb dating suggest initiation of volcanic activity at ~260 Ma. Extensional tectonics prevailed throughout the Triassic, forming the Hindukush-North Pamir rift system. New geochemistry and zircon U-Pb data tie volcanic rocks, found in the Chinese Pamir, to coeval arc-related plutonic rocks found within the Karakul-Mazar arc-accretionary complex. The sedimentary environment in the continental North Pamir rift evolved from an alluvial plain, lake dominated environment in the Guadalupian to a coarser-clastic, alluvial, braided river dominated in the Triassic. Volcanic activity terminated in the early Jurassic. We conducted Potassium-Argon (K-Ar) fine-fraction dating on the Shala Tala thrust fault, a major structure juxtaposing Paleozoic marine units of lower greenschist to amphibolite facies conditions against continental Permian deposits. Fault slip under epizonal conditions is dated to 204.8 ± 3.7 Ma (2σ), implying Rhaetian nappe emplacement. This pinpoints the Central–North Pamir collision, since the Shala Tala thrust was a back-thrust at that time.
N2  - Der Nordpamir, ein Teil der Kollisionszone zwischen Indien und Asien, bildete sich im Wesentlichen zwischen dem oberen Paläozoikum und der Trias–Jura Grenze. Zeitgleich mit der Subduktion des Turkestan-Ozeans—während der herzynischen Orogenese im heutigen Tien-Shan-Gebirge—subduzierte ein Teil der Paläotethys. Dies führte im Verlauf des Karbons zur Bildung und im Perm zur Obduktion eines Vulkan- bzw. Inselbogens. Dieser karbonische Vulkanbogen des Nordpamirs kann in einen westlichen Teil mit andinem Aufbau (Darvaz-Segment) und einen intraozeanischen östlichen Teil (Oytag-Segment) eingeteilt werden. Eine Abfolge aus Vulkaniten und zwischengeschalteten, marinen Sedimenten, zusammen mit in diese Folge intrudierten Plagiograniten (Trondhjemit und Tonalit) sowie Granodioriten, wurde während des Perms gehoben und erodiert. Dies wird durch weit verbreitete Sedimentationslücken im Nord Pamir belegt.
In dieser Arbeit werden erstmals umfassende Uran-Blei Isotopen (U-Pb) Altersdaten (basierend auf Laserablation mit induktiv gekoppeltem Plasma-Massenspektroskopie) und geochemische Daten der Vulkanite und Plutonite des karbonischen Vulkanbogens des Nordpamirs präsentiert. Die U-Pb Zirkonalter zeigen für die Plutonite eine Hauptintrusionsphase zwischen 340 Ma und 320 Ma. Sowohl die untersuchten Vulkanite als auch die Plutonite zeigen eine Inselbogensignatur. Dabei weisen die Magmatite des östlichen Oytag-Segmentes primitivere geochemische Eigenschaften als gleichalte Gesteine des Darvaz-Segmentes auf. Um das Alter der kaum datierten mafischen Vulkanite des Inselbogens genauer eingrenzen zu können, wurden während der Ozeanbodenmetamorphose gebildete Kalzite untersucht. Ausgehend von der Annahme, dass die in Hohlräumen der Basalte ausgebildeten Sekundärminerale in einem Zeitraum von etwa 25 Ma nach dem Austreten der Vulkanite entstehen, weisen diese auf ein viséisches bis serpukhovische Alter hin. Oxidatives Meerwasser und das basaltische Umgebungsgestein sind dabei Quellen der in den Kalziten eingebauten Spurenelemente. Die Untersuchungsergebnisse stellen eine geodynamische Beziehung des Vulkanbogens des Nordpamirs mit gleichalten Inselbogenkomplexen des Tien-Shan her. Des Weiteren stellen sie die Kontinuität kontinentaler Kruste zwischen Tarim und Karakum-Kraton im Paläozoikum in Frage.
Ab dem Perm setzte ein fortschreitender Rückzug des Meeres in der Region ein. Dies führte zu Erosion und kontinentalen Ablagerungsbedingungen im nordöstlichen Pamir spätestens ab dem Guadalupium (oberes Mittelperm). Das tektonische Regime Zentralasiens wurde im Perm durch Transversalverschiebungen und damit einhergehender Transpressions- und Transtensionstektonik bestimmt. Gleichzeitig dauerte die Subduktion der Paleotethys in Richtung Norden an. Dabei bildete sich schon im Perm ein Akkretionskeil—ein frühes Stadium des kimmerisch geprägten Karakul-Mazar Komplexes. Während des Perms zerschnitten Grabenstrukturen Teile der Karbonatplattform im zentralen und westlichen Nordpamir und formten ein kontinentales Grabensystem im nordöstlichen Pamir. Neue U-Pb Altersuntersuchungen an Zirkonen zeigen ein Einsetzen vulkanischer Aktivität vor etwa 260 Ma. Dehnungstektonik war auch während der Trias vorherrschend. Infolgedessen entwickelte sich das Hindukusch-Nordpamir-Rift-System. Zirkon U-Pb Altersdaten und Gesamtgesteinsgeochemie der triassischen Vulkanite der Riftbeckenablagerungen im Chinesischen Nordpamir stellen einen engen Zusammenhang zu zeitgleich intrudierenden, triassischen Plutoniten des Karakul-Mazar Akkretionskeils her. Das Ablagerungsmilieu des untersuchten Abschnitts des kontinentalen Beckens war im Guadalupium durch Schwemmebenen und Seen bestimmt. Es entwickelte sich zu einem von gröber-klastischen Schwemmfächern dominierten Ablagerungsraum während der Trias. Die vulkanische Aktivität endete während des Trias-Jura Übergangs.
Kalium-Argon (K-Ar) Altersdatierungen an Ton-Feinfraktionen einer großen Deckenüberschiebung (Shala-Tala-Überschiebung) belegen eine teilweise Schließung des nordöstlichen Hindukusch-Nordpamir-Riftbeckens in der ausgehenden Trias. Entlang der Shala-Tala-Überschiebung werden Paleozoische, marine Sedimentgesteine der unteren Grünschiefer- bis Amphibolitfazies gegen anchizonale, kontinentale Ablagerungen des Perms versetzt. Überschiebungsbewegungen unter epizonalen Bedingungen werden auf 204.8 ± 3.7 Ma (2σ) datiert. Dies gibt einen genauen Zeitmarker für die Kollision von Zentral und Nord Pamir, da sich ab diesem Zeitpunkt große Rücküberschiebungen bilden konnten.
KW  - geochronology
KW  - geochemistry
KW  - Pamir
KW  - Cimmerian orogeny
KW  - Hercynian orogeny
KW  - Central Asia
KW  - Zentralasien
KW  - kimmerische Orogenese
KW  - herzynische Orogenese
KW  - Pamir
KW  - Geochemie
KW  - Geochronologie
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-597510
ER  -