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Hai Cheng - One of the best experts on this subject based on the ideXlab platform.
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Black carbon traces of human activities in Stalagmites from Turkey
Journal of Archaeological Science, 2020Co-Authors: Koray Koç, Hai Cheng, R. Lawrence Edwards, Erdal Koşun, Ferdi Demirtaş, Dominik FleitmannAbstract:Abstract Speleothems are recognized as sensitive recorders of climatic fluctuations in the past and provide precisely dated and highly resolved environmental records. However, their potential as an archaeological archive is not fully acknowledged yet. Here we present several Stalagmites containing soot and charcoal layers from various caves in Turkey and provide evidence that these black carbon layers are directly related to human activity. The archaeological artefacts found in Tabak and Kocain caves in SW Turkey support the linkage between soot and charcoal layers existence and human activity in the caves. For this study, we focus on Stalagmites from Tabak and Kocain cave. To explore the age and nature of the soot and charcoal layers within Stalagmites Ta-9, Ta-10 and Ko-1, Uranium series dating, scanning electron microscope (SEM) and thin section analyses were performed. The episodic soot and charcoal deposition in Stalagmites Ta-9 and Ta-10 occurred between 7424 ± 225 yr BP and 6670 ± 218 yr BP while the soot and charcoal layers in Stalagmite Ko-1 formed between 2830 ± 189 yr BP and 470 ± 56 yr BP. In combination with the archaeological inventory in Tabak Cave, the soot and charcoal layers within Stalagmites Ta-9 and Ta-10 show that the cave was used repeatedly as a burial site during Chalcolithic period. In Kocain Cave was also used repeatedly between the Iron Age and Medieval Period, most likely for ritual activities and for providing animals with water from a small spring in the entrance to the cave. The soot and charcoal layers within Stalagmites from Turkey prove that speleothems are also important as archaeological archives.
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inter relationship and environmental significance of Stalagmite δ13c and δ18o records from zhenzhu cave north china over the last 130 ka
Earth and Planetary Science Letters, 2020Co-Authors: Hai Cheng, Zhiguo Rao, Shengrui Zhang, Xiaokang Liu, Zongli Wang, Lawrence R Edwards, Fahu ChenAbstract:Abstract There is a vigorous and ongoing debate about the interpretation of the Stalagmite δ 18 O record from east China as an indicator of East Asian summer monsoon (EASM) intensity. This is mainly because of the inconsistent spatial variation of precipitation amount in east China, but the generally consistent variation of precipitation δ 18 O, on various timescales. However, a direct comparison of a proxy record of precipitation amount with the δ 18 O record from the same Stalagmite has rarely been reported, especially in north China. Here, we present precisely-dated high-resolution Stalagmite δ 13 C and δ 18 O records for the past 130 ka (1 ka =1000 years) from Zhenzhu (ZZ) Cave in north China. On multi-millennial to orbital timescales, the δ 13 C and δ 18 O records exhibit a high degree of in-phase co-variation; however, there are differences in the trend and amplitude of change between various marine isotopic stages (MIS): specifically, MIS5e, MIS5c, MIS5a, MIS3 and MIS1. Modern monitoring results of two years from ZZ Cave, together with a comparison of the δ 13 C record from the cave with a pedogenic carbonate δ 13 C record from the western Chinese Loess Plateau (CLP), demonstrate that the δ 13 C record is a sensitive and reliable indicator of EASM rainfall amount. Considering that variations in both the amount and δ 18 O of precipitation can be modulated by the atmospheric circulation system, we conclude that the amplitude and trend of the Stalagmite δ 18 O variations from north China are not an absolute indicator of EASM intensity, but rather an indicator of changes in the phase of the EASM. We suggest that Stalagmite δ 18 O records combined with other unambiguous proxy indicators from Stalagmites can provide a more comprehensive history of changes of the EASM.
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relationships between climate change human environmental impact and megafaunal extinction inferred from a 4000 year multi proxy record from a Stalagmite from northwestern madagascar
Quaternary Science Reviews, 2020Co-Authors: Bruce L Railsback, Hai Cheng, George A Brook, Laura A Dupont, Fuyuan Liang, David A Burney, Lawrence R EdwardsAbstract:Abstract Stalagmite ANJ94-2 from Anjohibe Cave in northwestern Madagascar provides an exceptionally detailed and precisely dated record of changing environmental conditions that, combined with previously published data from Stalagmites, wetland deposits, and archaeological sites, allows insights into past climate change, human environmental impact, and megafaunal extinction. Proxies of past conditions recovered from Stalagmite ANJ94-2 include ratios of carbon and oxygen stable isotopes (δ13C and δ18O), mineralogy (calcite and aragonite), layer-bounding surfaces, layer-specific width, and detrital material. Those proxies suggest that the natural environment changed in response to changes in rainfall at time scales of a few decades to multiple centuries; comparison with distant proxies suggests that wetter conditions in northwestern Madagascar may have been linked to cooling in the Northern Hemisphere. Carbon isotope data nonetheless suggest that the greatest environmental change in the area coincided with human introduction of swidden (tavy) agriculture about 1200 years ago, during a time not of drought but perhaps of slightly increasing wetness. The timing and extent of environmental change 1200 to 600 years ago seen in Stalagmite and wetland data suggest that human modification of the landscape had a causal role in the extinction of Madagascar’s megafauna. On the other hand, the results combine with other recent research to indicate that drought was not the cause of the megafaunal extinction.
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three distinct holocene intervals of Stalagmite deposition and nondeposition revealed in nw madagascar and their paleoclimate implications
Climate of The Past, 2017Co-Authors: Hai Cheng, R L Edwards, Ny Riavo G Voarintsoa, Loren Bruce Railsback, George A Brook, Lixin Wang, Gayatri Kathayat, Amos Fety Michel RakotondrazafyAbstract:Abstract. Petrographic features, mineralogy, and stable isotopes from two Stalagmites, ANJB-2 and MAJ-5, respectively from Anjohibe and Anjokipoty caves, allow distinction of three intervals of the Holocene in NW Madagascar. The Malagasy early Holocene (between ca. 9.8 and 7.8 ka) and late Holocene (after ca. 1.6 ka) intervals (MEHI and MLHI, respectively) record evidence of Stalagmite deposition. The Malagasy middle Holocene interval (MMHI, between ca. 7.8 and 1.6 ka) is marked by a depositional hiatus of ca. 6500 years. Deposition of these Stalagmites indicates that the two caves were sufficiently supplied with water to allow Stalagmite formation. This suggests that the MEHI and MLHI intervals may have been comparatively wet in NW Madagascar. In contrast, the long-term depositional hiatus during the MMHI implies it was relatively drier than the MEHI and the MLHI. The alternating wet–dry–wet conditions during the Holocene may have been linked to the long-term migrations of the Intertropical Convergence Zone (ITCZ). When the ITCZ's mean position is farther south, NW Madagascar experiences wetter conditions, such as during the MEHI and MLHI, and when it moves north, NW Madagascar climate becomes drier, such as during the MMHI. A similar wet–dry–wet succession during the Holocene has been reported in neighboring locations, such as southeastern Africa. Beyond these three subdivisions, the records also suggest wet conditions around the cold 8.2 ka event, suggesting a causal relationship. However, additional Southern Hemisphere high-resolution data will be needed to confirm this.
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Early Neanderthal constructions deep in Bruniquel Cave in southwestern France
Nature, 2016Co-Authors: Jerome Jaubert, Michel Soulier, Christian Burlet, Serge Delaby, Hubert Camus, Sophie Verheyden, Dominique Genty, Dominique Blamart, Hai Cheng, Damien DeldicqueAbstract:Very little is known about Neanderthal cultures1, particularly early ones. Other than lithic implements and exceptional bone tools2, very few artefacts have been preserved. While those that do remain include red and black pigments3 and burial sites4, these indications of modernity are extremely sparse and few have been precisely dated, thus greatly limiting our knowledge of these predecessors of modern humans5. Here we report the dating of annular constructions made of broken Stalagmites found deep in Bruniquel Cave in southwest France. The regular geometry of the Stalagmite circles, the arrangement of broken Stalagmites and several traces of fire demonstrate the anthropogenic origin of these constructions. Uranium-series dating of Stalagmite regrowths on the structures and on burnt bone, combined with the dating of Stalagmite tips in the structures, give a reliable and replicated age of 176.5 thousand years (±2.1 thousand years), making these edifices among the oldest known well-dated constructions made by humans. Their presence at 336 metres from the entrance of the cave indicates that humans from this period had already mastered the underground environment, which can be considered a major step in human modernity.
Gianella Valentina - One of the best experts on this subject based on the ideXlab platform.
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Le variazioni climatiche dell'Olocene ottenute dallo studio delle concrezioni dell'Antro del Corchia (Alpi Apuane).
Pisa University, 2050Co-Authors: Gianella ValentinaAbstract:Lo scopo della presente Tesi di Laurea è stato quello di ricostruire la variabilità climatica olocenica attraverso lo studio di stalagmiti prelevate all’interno dell’Antro del Corchia, una grotta situata nella porzione sud – occidentale del massiccio apuano. In particolare il sito di campionamento, denominato “Galleria delle Stalattiti”, è situato ~400 m al di sotto della superficie e ~500 m dalla più vicina entrata della grotta. Nel corso di questi anni sono stati prelevati numerosi frammenti di concrezioni utilizzati per poter analizzare le variazioni climatiche che si sono susseguite nel corso dell’Olocene. Questi sono risultati particolarmente adatti per le ricostruzioni paleoclimatiche grazie al loro elevato contenuto in uranio e alla loro crescita lenta e consistente in una zona profonda e stabile del sistema carsico. Per il presente studio sono state analizzate tre stalagmiti: CC4, CC27 e CC53; per queste sono state eseguite le analisi degli isotopi stabili presso la facoltà di geologia dell’Università di Newcastle, Australia e quelle degli isotopi radioattivi all’Università di Melbourne, Australia. Le concrezioni sono state campionate, a diversa risoluzione, attraverso l’uso di trapani da dentista con punte da 1 a 0.7 mm e successivamente analizzate per determinarne la composizione isotopica (ossigeno e carbonio). Inoltre sono stati prelevati, sempre attraverso appositi trapani, anche i campioni per le datazioni i quali hanno permesso di ricostruire dei modelli preliminari d’età. In particolare, in questo lavoro, è stata analizzata nel dettaglio la Stalagmite CC27. Essa copre all’incirca l’intervallo temporale che va da ca. 16000 a ca. 2500 anni fa. Nei grafici elaborati è stato possibile riconoscere, partendo dalla base della concrezione, il picco positivo dell’Oldest Dryas con valori di δ13C intorno a 4,00‰ e di δ18O pari a -3,00‰, il BØlling – AllerØd e lo Younger Dryas. Successivamente la Stalagmite ha registrato un miglioramento delle condizioni climatiche, probabilmente al passaggio Younger Dryas – Preboreale con valori di δ18O e di δ13C più negativi rispetto al periodo precedente (in accordo con un periodo caldo umido). In seguito la Stalagmite presenta due hiatus, denominati H1 e H2. Lo hiatus principale H1 è stato interpretato come caratteristico di un periodo caldo umido correlabile con la deposizione del sapropel S1 in accordo con altre stalagmiti studiate in precedenza. Tra ca. 5000 e ca. 4000 anni fa, nelle curve isotopiche di ossigeno e carbonio, sono stati osservati picchi positivi indicativi di deterioramenti climatici ai quali è associato anche il collasso di alcune civiltà del Mondo Antico. Infine, a partire da 3500 anni si osserva un trend verso condizioni aride
Nocchi Chiara - One of the best experts on this subject based on the ideXlab platform.
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Le variazioni climatiche dell'Olocene ottenute dallo studio delle concrezioni dell'Antro del Corchia (Alpi Apuane)
Pisa University, 2050Co-Authors: Nocchi ChiaraAbstract:Lo scopo della presente Tesi di Laurea è quello di ricostruire delle curve paleoclimatiche in grado di rappresentare come le condizioni climatiche siano cambiate nel corso dell'Olocene. A tal scopo sono state prese in esame tre stalagmiti provenienti dall'Antro del Corchia, il più esteso sistema carsico italiano, articolato in 60 km di gallerie e pozzi, sito nella porzione occidentale delle Alpi Apuane, nel settore nord-occidentale della Toscana. Le stalagmiti in esame rappresentano solo una piccola frazione di tutto il materiale a disposizione riguardo tale grotta, poiché, fin dall'inizio dei lavori per l'apertura al pubblico, essa ha destato nei ricercatori un grande interesse. Queste concrezioni, denominate CC53, CC4 e CC27, come la maggior parte dei campioni, provengono dalla "Galleria delle Stalattiti", una condotta freatica all'interno della grotta, posta alla quota media di 871 m.s.l.m. Esse sono state campionate ed analizzate presso il Laboratorio della Facoltà di Geologia dell'Università di Newcastle, per quanta riguarda gli isotopi stabili, e presso il laboratorio della Facoltà di Scienze della Terra dell'Università di Melbourne, per ciò che concerne le misure di età. Le analisi degli isotopi stabili, ossigeno e carbonio, sono state effettuate con uno spettrometro di massa GV2003 ed hanno permesso di costruire delle curve preliminari in cui si sono potuti riconoscere dei picchi positivi e negativi, rispettivamente riferibili a periodi più freddi/aridi e più caldi/umidi. In seguito sono state condotte misure di età, mediante il metodo 234U/230Th, con lo scopo di inserire in un contesto temporale le curve costruite. Per la loro realizzazione è stato utilizzato uno spettrometro MC-ICPMS per la determinazione dei rapporti isotopici. Sulla base delle misure di età ottenute sono stati costruiti dei modelli di età per trasformare i dati isotopici in serie temporali. Le stalagmiti CC53 e CC4 sono state, in particolare, oggetto di studio della presente Tesi di Laurea. La Stalagmite CC53 ha mostrato un periodo di concrezionamento compreso tra circa 6000 e 400 anni fa, cioè la seconda parte dell'Olocene, e negli andamenti di ossigeno e carbonio è stato possibile riconoscere la parte terminale dell'Hhypsithermal, seguito dal Neoglaciale, caratterizzato da un trend in aumento dei valori. Nella transizione tra questi due periodi, tra ca. 5000 e ca. 4000 anni fa, è stato possibile riconoscere dei picchi positivi, caratteristici di deterioramenti climatici, a cui è associato anche il collasso di importanti civiltà mesopotamiche. Molto evidenti risultano inoltre il Periodo Caldo Medievale (intorno a 1000 anni fa), in cui i valori sono nettamente più negativi, e la Piccola Età Glaciale, registrata negli ultimi 100 anni di concrezionamento. La Stalagmite CC4, per cui non si dispone ancora di un modello di età convincente, mostra un periodo di accrescimento compreso tra ca. 6000 e 2000 anni fa. Nei record isotopici si osservano, anche in questo caso, alcune variazioni, in accordo con quanto evidenziato per la Stalagmite CC53
Dominik Fleitmann - One of the best experts on this subject based on the ideXlab platform.
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Black carbon traces of human activities in Stalagmites from Turkey
Journal of Archaeological Science, 2020Co-Authors: Koray Koç, Hai Cheng, R. Lawrence Edwards, Erdal Koşun, Ferdi Demirtaş, Dominik FleitmannAbstract:Abstract Speleothems are recognized as sensitive recorders of climatic fluctuations in the past and provide precisely dated and highly resolved environmental records. However, their potential as an archaeological archive is not fully acknowledged yet. Here we present several Stalagmites containing soot and charcoal layers from various caves in Turkey and provide evidence that these black carbon layers are directly related to human activity. The archaeological artefacts found in Tabak and Kocain caves in SW Turkey support the linkage between soot and charcoal layers existence and human activity in the caves. For this study, we focus on Stalagmites from Tabak and Kocain cave. To explore the age and nature of the soot and charcoal layers within Stalagmites Ta-9, Ta-10 and Ko-1, Uranium series dating, scanning electron microscope (SEM) and thin section analyses were performed. The episodic soot and charcoal deposition in Stalagmites Ta-9 and Ta-10 occurred between 7424 ± 225 yr BP and 6670 ± 218 yr BP while the soot and charcoal layers in Stalagmite Ko-1 formed between 2830 ± 189 yr BP and 470 ± 56 yr BP. In combination with the archaeological inventory in Tabak Cave, the soot and charcoal layers within Stalagmites Ta-9 and Ta-10 show that the cave was used repeatedly as a burial site during Chalcolithic period. In Kocain Cave was also used repeatedly between the Iron Age and Medieval Period, most likely for ritual activities and for providing animals with water from a small spring in the entrance to the cave. The soot and charcoal layers within Stalagmites from Turkey prove that speleothems are also important as archaeological archives.
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noble gas based temperature reconstruction on a swiss Stalagmite from the last glacial interglacial transition and its comparison with other climate records
Earth and Planetary Science Letters, 2018Co-Authors: Dominik Fleitmann, Nadia Vogel, Matthias S. Brennwald, Elaheh Ghadiri, Colin Maden, Anamaria Diana HauselmannAbstract:Abstract Here we present the results of a first application of a “Combined Vacuum Crushing and Sieving (CVCS)” system to determine past (cave/soil) temperatures from dissolved noble gas concentrations in Stalagmite samples grown under ‘cold’ climatic conditions (e.g. close to freezing point of water) during the last glacial–interglacial transition. To establish noble gas temperatures (NGTs) also for Stalagmites grown in cold regions, we applied the CVCS system to samples from Stalagmite M2 precipitated in the Milandre Cave, located in the Swiss Jura Mountains. The investigated Stalagmite M2 covers the Allerod–Younger Dryas–Holocene transitions. Noble gas temperatures are determined by using a new algorithm based on noble gas and water abundances and not from concentrations. Noble gas results indicate annual mean temperatures in the Milandre Cave were 2.2 ± 1.8 °C during the late stages of the Allerod, then dropping to 0 ( − ) + 2.6 ° C at the onset of the Younger Dryas. Such temperatures indicate conditions near to the freezing point of water during the first part of the Younger Dryas. During the last part of the Younger Dryas, the temperature increased to 6.3 ± 2.3 °C. No early Holocene temperature could be determined due the non-detectable water abundances in these samples, however one late Holocene sample indicates a cave temperature of 8.7 ± 2.7 °C which is close to the present day annual mean temperature. NGTs estimated for the Allerod–Younger Dryas–Holocene are in good agreement with paleo-temperature reconstructions from geochemical and biological proxies in lake sediments. The observed deviations between the different paleo-temperature reconstructions are minor if the according temperatures are rescaled to annual mean temperatures and are primarily attributed to the chronological tuning of the different records. As in other Stalagmites, NGT reconstructions of the recently precipitated Stalagmite (‘young’) samples again are biased, most likely due to diffusive gas loss during sample processing. We speculate that a reduced retentivity of noble gases during experimental sample processing is a general feature of recently precipitated Stalagmite fabrics. Therefore, the recently precipitated Stalagmite samples do not allow the reliable NGT determination given the currently available experimental methods. Nevertheless, this study makes the case that noble gas thermometry can be applied to Stalagmites for paleo-temperature reconstruction based on a physical method including Stalagmites that grew during cold climatic conditions.
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speleothems as sensitive recorders of volcanic eruptions the bronze age minoan eruption recorded in a Stalagmite from turkey
Earth and Planetary Science Letters, 2014Co-Authors: Hai Cheng, Dominik Fleitmann, Silvia Frisia, S Badertscher, Andrea Borsato, R L Edwards, Okan TuysuzAbstract:Mounting evidence exists that variations in sulphur content in Stalagmites are closely linked to changes in volcanic or anthropogenic atmospheric sulphur. The strong dependency of sulphur on soil pH and ecosystem storage, however, can result in a delay of several years to decades in the registration of volcanic eruptions and anthropogenic emissions by Stalagmites. Here we present synchrotron-radiation based trace element analysis performed on a precisely-dated section of a Stalagmite from Sofular Cave in Northern Turkey. As this section covers the time interval of the intensively studied Minoan volcanic eruption between 1600 and 1650 BC, we can test whether this vigorous eruption can be traced in a Stalagmite. Of all measured trace elements, only bromine shows a clear short-lived peak at 1621±251621±25 BC, whereas sulphur and molybdenum show peaks later at 1617±251617±25 and 1589±251589±25 respectively. We suggest that all trace element peaks are related to the Minoan eruption, whereas the observed phasing of bromine, molybdenum and sulphur is related to differences in their retention rates in the soil above Sofular Cave. For the first time, we can show that bromine appears to be an ideal volcanic tracer in Stalagmites, as it is a prominent volatile component in volcanic eruptions, can be easily leached in soils and rapidly transferred from the atmosphere through the soil and bedrock into the cave and Stalagmite respectively. Highly resolved oxygen and carbon isotope profiles indicate that the Minoan eruption had no detectable climatic and environmental impact in Northern Turkey.
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Stalagmite water content as a proxy for drip water supply in tropical and subtropical areas
Climate of The Past, 2012Co-Authors: Nadia Vogel, Dominik Fleitmann, Yvonne Scheidegger, Matthias S. Brennwald, Simon Figura, Rainer Wieler, Rolf KipferAbstract:In this pilot study water was extracted from samples of two Holocene Stalagmites from Socotra Island, Yemen, and one Eemian Stalagmite from southern continental Yemen. The amount of water extracted per unit mass of Stalagmite rock, termed "water yield" hereafter, serves as a measure of its total water content. Based on direct correlation plots of water yields and δ18Ocalcite and on regime shift analyses, we demonstrate that for the studied Stalagmites the water yield records vary systematically with the corresponding oxygen isotopic compositions of the calcite (δ18Ocalcite). Within each Stalagmite lower δ18Ocalcite values are accompanied by lower water yields and vice versa. The δ18Ocalcite records of the studied Stalagmites have previously been interpreted to predominantly reflect the amount of rainfall in the area; thus, water yields can be linked to drip water supply. Higher, and therefore more continuous drip water supply caused by higher rainfall rates, supports homogeneous deposition of calcite with low porosity and therefore a small fraction of water-filled inclusions, resulting in low water yields of the respective samples. A reduction of drip water supply fosters irregular growth of calcite with higher porosity, leading to an increase of the fraction of water-filled inclusions and thus higher water yields. The results are consistent with the literature on Stalagmite growth and supported by optical inspection of thin sections of our samples. We propose that for a Stalagmite from a dry tropical or subtropical area, its water yield record represents a novel paleo-climate proxy recording changes in drip water supply, which can in turn be interpreted in terms of associated rainfall rates.
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Liquid-vapour homogenisation of fluid inclusions in Stalagmites: Evaluation of a new thermometer for palaeoclimate research
Chemical Geology, 2011Co-Authors: Yves Krüger, Dominik Marti, Rita Hidalgo Staub, Dominik Fleitmann, Martin FrenzAbstract:We present a new approach to determine palaeotemperatures (mean annual surface temperatures) based on measurements of the liquid–vapour homogenisation temperature of fluid inclusions in Stalagmites. The aim of this study is to explore the potential and the limitations of this new palaeothermometer and to develop a reliable methodology for routine applications in palaeoclimate research. Therefore, we have investigated recent fluid inclusions from the top part of actively growing Stalagmites that have formed at temperatures close to the present-day cave air temperature. A precondition for measuring homogenisation temperatures of originally monophase inclusions is the nucleation of a vapour bubble by means of single ultra-short laser pulses. Based on the observed homogenisation temperatures (Th(obs)) and measurements of the vapour bubble diameter at a known temperature, we calculated Stalagmite formation temperatures (Tf) by applying a thermodynamic model that takes into account the effect of surface tension on liquid–vapour homogenisation. Results from recent Stalagmite samples demonstrate that calculated Stalagmite formation temperatures match the present-day cave air temperature within ± 0.2 °C. To avoid artificially induced changes of the fluid density we defined specific demands on the selection, handling and preparation of the Stalagmite samples. Application of the method is restricted to Stalagmites that formed at cave temperatures greater than ~ 9–11 °C.
Nadia Vogel - One of the best experts on this subject based on the ideXlab platform.
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noble gas based temperature reconstruction on a swiss Stalagmite from the last glacial interglacial transition and its comparison with other climate records
Earth and Planetary Science Letters, 2018Co-Authors: Dominik Fleitmann, Nadia Vogel, Matthias S. Brennwald, Elaheh Ghadiri, Colin Maden, Anamaria Diana HauselmannAbstract:Abstract Here we present the results of a first application of a “Combined Vacuum Crushing and Sieving (CVCS)” system to determine past (cave/soil) temperatures from dissolved noble gas concentrations in Stalagmite samples grown under ‘cold’ climatic conditions (e.g. close to freezing point of water) during the last glacial–interglacial transition. To establish noble gas temperatures (NGTs) also for Stalagmites grown in cold regions, we applied the CVCS system to samples from Stalagmite M2 precipitated in the Milandre Cave, located in the Swiss Jura Mountains. The investigated Stalagmite M2 covers the Allerod–Younger Dryas–Holocene transitions. Noble gas temperatures are determined by using a new algorithm based on noble gas and water abundances and not from concentrations. Noble gas results indicate annual mean temperatures in the Milandre Cave were 2.2 ± 1.8 °C during the late stages of the Allerod, then dropping to 0 ( − ) + 2.6 ° C at the onset of the Younger Dryas. Such temperatures indicate conditions near to the freezing point of water during the first part of the Younger Dryas. During the last part of the Younger Dryas, the temperature increased to 6.3 ± 2.3 °C. No early Holocene temperature could be determined due the non-detectable water abundances in these samples, however one late Holocene sample indicates a cave temperature of 8.7 ± 2.7 °C which is close to the present day annual mean temperature. NGTs estimated for the Allerod–Younger Dryas–Holocene are in good agreement with paleo-temperature reconstructions from geochemical and biological proxies in lake sediments. The observed deviations between the different paleo-temperature reconstructions are minor if the according temperatures are rescaled to annual mean temperatures and are primarily attributed to the chronological tuning of the different records. As in other Stalagmites, NGT reconstructions of the recently precipitated Stalagmite (‘young’) samples again are biased, most likely due to diffusive gas loss during sample processing. We speculate that a reduced retentivity of noble gases during experimental sample processing is a general feature of recently precipitated Stalagmite fabrics. Therefore, the recently precipitated Stalagmite samples do not allow the reliable NGT determination given the currently available experimental methods. Nevertheless, this study makes the case that noble gas thermometry can be applied to Stalagmites for paleo-temperature reconstruction based on a physical method including Stalagmites that grew during cold climatic conditions.
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glacial interglacial temperature change in the tropical west pacific a comparison of Stalagmite based paleo thermometers
Quaternary Science Reviews, 2015Co-Authors: Nele A Meckler, Yves Krüger, Nadia Vogel, Stephane Affolter, Yuri Dublyansky, Stefano M Bernasconi, Martin FrenzAbstract:In the tropics, geochemical records from Stalagmites have so far mainly been used to qualitatively reconstruct changes in precipitation, but several new methods to reconstruct past temperatures from Stalagmite material have emerged recently: i) liquid–vapor homogenization of fluid inclusion water ii) noble gas concentrations in fluid inclusion water, iii) the partitioning of oxygen isotopes between fluid inclusion water and calcite, and iv) the abundance of the ^(13)C^(18)O^(16)O (‘clumped’) isotopologue in calcite. We present, for the first time, a direct comparison of these four paleo-thermometers by applying them to a fossil Stalagmite covering nearly two glacial–interglacial cycles (Marine Isotope Stages (MIS) 12–9) and to two modern Stalagmites, all from northern Borneo. The temperature estimates from the different methods agree in most cases within errors for both the old and recent samples; reconstructed formation temperatures of the recent samples match within 2-sigma errors with measured cave temperatures. However, slight but systematic deviations are observed between noble gas and liquid–vapor homogenization temperatures. Whereas the temperature sensitivity of fluid inclusion δ^(18)O and clumped isotopes is currently debated, we find that the calibration of Tremaine et al. (2011) for fluid inclusion δ^(18)O and a synthetic calcite-based clumped isotope calibration (Ziegler et al., in prep.) yield temperature estimates consistent with the other methods. All methods (with the potential exception of clumped isotopes) show excellent agreement on the amplitude of glacial–interglacial temperature change, indicating temperature shifts of 4–5 °C. This amplitude is similar to the amplitude of Mg/Ca-based regional sea surface temperature records, when correcting for sea level driven changes in cave elevation. Our reconstruction of tropical temperature evolution over the time period from 440 to 320 thousand years ago (ka) adds support to the view that climate sensitivity to varying greenhouse forcing is substantial also in the deep tropics.
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Stalagmite water content as a proxy for drip water supply in tropical and subtropical areas
Climate of The Past, 2012Co-Authors: Nadia Vogel, Dominik Fleitmann, Yvonne Scheidegger, Matthias S. Brennwald, Simon Figura, Rainer Wieler, Rolf KipferAbstract:In this pilot study water was extracted from samples of two Holocene Stalagmites from Socotra Island, Yemen, and one Eemian Stalagmite from southern continental Yemen. The amount of water extracted per unit mass of Stalagmite rock, termed "water yield" hereafter, serves as a measure of its total water content. Based on direct correlation plots of water yields and δ18Ocalcite and on regime shift analyses, we demonstrate that for the studied Stalagmites the water yield records vary systematically with the corresponding oxygen isotopic compositions of the calcite (δ18Ocalcite). Within each Stalagmite lower δ18Ocalcite values are accompanied by lower water yields and vice versa. The δ18Ocalcite records of the studied Stalagmites have previously been interpreted to predominantly reflect the amount of rainfall in the area; thus, water yields can be linked to drip water supply. Higher, and therefore more continuous drip water supply caused by higher rainfall rates, supports homogeneous deposition of calcite with low porosity and therefore a small fraction of water-filled inclusions, resulting in low water yields of the respective samples. A reduction of drip water supply fosters irregular growth of calcite with higher porosity, leading to an increase of the fraction of water-filled inclusions and thus higher water yields. The results are consistent with the literature on Stalagmite growth and supported by optical inspection of thin sections of our samples. We propose that for a Stalagmite from a dry tropical or subtropical area, its water yield record represents a novel paleo-climate proxy recording changes in drip water supply, which can in turn be interpreted in terms of associated rainfall rates.
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Stalagmite water content as a proxy for drip water supply in tropical and subtropical areas
Climate of the Past Discussions, 2012Co-Authors: Nadia Vogel, Yvonne Scheidegger, Matthias S. Brennwald, Simon Figura, Rainer Wieler, D. Fleitmann, Rolf KipferAbstract:Abstract. In this pilot study water was extracted from samples of two Holocene Stalagmites from Socotra Island, Yemen, and one Eemian Stalagmite from southern continental Yemen. The amount of water extracted per unit mass of Stalagmite rock, termed "water yield" hereafter, serves as a measure for its total water content. The Stalagmites' water yield records vary systematically with the corresponding oxygen isotopic compositions of the calcite (δ18Ocalcite). Low δ18Ocalcite values are thereby accompanied by low water yields and vice versa. Based on the paleoclimatic interpretation of the δ18Ocalcite records, water yields can be linked to drip water supply. High drip water supply caused by high precipitation rates supports homogeneous deposition of calcite with low porosity and therefore a small fraction of water-filled inclusions, resulting in low water yields of the respective samples. A reduction of drip water supply fosters irregular growth of calcite with higher porosity, leading to an increase of the fraction of water-filled inclusions and thus higher water yields. The results are consistent with the literature on Stalagmite growth and supported by optical inspection of thin sections of our samples. We propose that for a Stalagmite from a tropical or subtropical area, its water yield record represents a novel paleoclimate proxy recording changes in drip water supply, which can in turn be interpreted in terms of associated precipitation rates.