Relevant bibliographies by topics / Proxy paleoenvironmental

Academic literature on the topic 'Proxy paleoenvironmental'

Author: Grafiati
Published: 7 July 2024

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Contents

  1. Journal articles
  2. Dissertations / Theses
  3. Book chapters
  4. Conference papers
  5. Reports

Journal articles on the topic "Proxy paleoenvironmental":

1

Moldovan, O. T., S. Constantin, C. Panaiotu, R. D. Roban, P. Frenzel, and L. Miko. "Fossil invertebrates records in cave sediments and paleoenvironmental assessments – a study of four cave sites from Romanian Carpathians." Biogeosciences 13, no. 2 (January 25, 2016): 483–97. http://dx.doi.org/10.5194/bg-13-483-2016.

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Abstract. Fossil invertebrates from cave sediments have been recently described as a potential new proxy for paleoenvironment and used in cross-correlations with alternate proxy records from cave deposits. Here we present the results of a fossil invertebrates study in four caves from two climatically different regions of the Romanian Carpathians, to complement paleoenvironmental data previously reported. Oribatid mites and ostracods are the most common invertebrates in the studied cave sediments. Some of the identified taxa are new to science, and most of them are indicative for either warm and/or cold stages or dry and/or wetter oscillations. In two caves the fossil invertebrates records indicate rapid climate oscillations during times known for a relatively stable climate. By corroborating the fossil invertebrates' record with the information given by magnetic properties and sediment structures, complementary data on past vegetation, temperatures and hydraulic regimes could be gathered. This paper analyzes the potential of fossil invertebrate records as a paleoenvironmental proxy, potential problems and pitfalls.
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Moldovan, O. T., S. Constantin, C. Panaiotu, R. D. Roban, P. Frenzel, and L. Miko. "Fossil invertebrates records in cave sediments and paleoenvironmental assessments: a study of four cave sites from Romanian Carpathians." Biogeosciences Discussions 12, no. 11 (June 15, 2015): 8849–81. http://dx.doi.org/10.5194/bgd-12-8849-2015.

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Abstract. Fossil invertebrates from cave sediments have been recently described as a potential new proxy for paleoenvironment and used in cross-correlations with alternate proxy records from cave deposits. Here we present the results of a fossil invertebrates study in four caves from two climatically different regions of the Romanian Carpathians, to complement paleoenvironmental data previously reported. Oribatid mites and ostracods are the most common invertebrates in the studied cave sediments. Some of the identified taxa are new for science, and most of them are indicative for either warm/cold stages or dry/wetter oscillations. In two caves the fossil invertebrates records indicate rapid climate oscillations during times known for a relatively stable climate. By corroborating the fossil invertebrates' record with the information given by magnetic properties and sediment structures, complementary data on past vegetation, temperatures, and hydraulic regimes could be gathered. This paper analyses the potential of fossil invertebrate records as a paleoenvironmental proxy, potential problems and pitfalls.
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Liu, Bing, Robert K. Booth, Jaime Escobar, Zhiqiang Wei, Broxton W. Bird, Andres Pardo, Jason H. Curtis, and Jun Ouyang. "Ecology and paleoenvironmental application of testate amoebae in peatlands of the high-elevation Colombian páramo." Quaternary Research 92, no. 1 (February 18, 2019): 14–32. http://dx.doi.org/10.1017/qua.2018.143.

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AbstractWe investigated the ecology and paleoecology of testate amoebae in peatlands of the Colombian páramo to assess the use of testate amoebae as paleoenvironmental indicators. Objectives were to (1) identify environmental controls on testate amoebae, (2) develop transfer functions for paleoenvironmental inference, and (3) examine testate amoebae in a Holocene peat core and compare our findings with other proxy records. Results from 96 modern samples indicate that testate amoebae are sensitive to pH and surface moisture, and cross-validation of transfer functions indicates potential for paleoenvironmental applications. Testate amoebae from the Triunfo Peatland in the Central Cordillera provided a proxy record of pH and water-table depth for the late Holocene, and inferred changes were correlated with peat C/N measurements during most of the record. Comparison with a lake-level reconstruction suggests that at least the major testate amoeba–inferred changes were driven by climate. Our work indicates that testate amoebae are useful paleoenvironmental indicators in high-elevation tropical peatlands.
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Börner, Nicole, Bart De Baere, Qichao Yang, Klaus Peter Jochum, Peter Frenzel, Meinrat O. Andreae, and Antje Schwalb. "Ostracod shell chemistry as proxy for paleoenvironmental change." Quaternary International 313-314 (November 2013): 17–37. http://dx.doi.org/10.1016/j.quaint.2013.09.041.

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DOCIO, L., M. PAROLIN, and U. PINHEIRO. "A contribution to adequate use of freshwater sponges as a proxy in paleoenvironmental studies." Zootaxa 4915, no. 4 (January 25, 2021): 506–28. http://dx.doi.org/10.11646/zootaxa.4915.4.3.

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This paper provides a comprehensive review of the environments where freshwater sponges occur and evaluates the use of sponge spicules as a proxy in paleoenvironmental studies in the Neotropical region. The paper aims to: I) review the information about the ecology of inland sponges to facilitate the use of spicules as a paleoenvironmental tool; and II) identify possible incongruities in the use of this information in paleoenvironmental reconstructions that have been conducted in Neotropical regions. The study compiled data on 77 sponge species, specialist or generalist that occur under certain environmental conditions, such as: substrate type for growth, hydrodynamic types, as well as salinity and acidity concentrations. In addition, it provides a comparison of the paleoenvironmental conditions applied to reconstruction studies that have been carried out within this biogeographic region, highlighting incongruities regarding the current ecology of the sponges.
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Bowen, Gabriel J., Brenden Fischer-Femal, Gert-Jan Reichart, Appy Sluijs, and Caroline H. Lear. "Joint inversion of proxy system models to reconstruct paleoenvironmental time series from heterogeneous data." Climate of the Past 16, no. 1 (January 9, 2020): 65–78. http://dx.doi.org/10.5194/cp-16-65-2020.

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Abstract. Paleoclimatic and paleoenvironmental reconstructions are fundamentally uncertain because no proxy is a direct record of a single environmental variable of interest; all proxies are indirect and sensitive to multiple forcing factors. One productive approach to reducing proxy uncertainty is the integration of information from multiple proxy systems with complementary, overlapping sensitivity. Mostly, such analyses are conducted in an ad hoc fashion, either through qualitative comparison to assess the similarity of single-proxy reconstructions or through step-wise quantitative interpretations where one proxy is used to constrain a variable relevant to the interpretation of a second proxy. Here we propose the integration of multiple proxies via the joint inversion of proxy system and paleoenvironmental time series models in a Bayesian hierarchical framework. The “Joint Proxy Inversion” (JPI) method provides a statistically robust approach to producing self-consistent interpretations of multi-proxy datasets, allowing full and simultaneous assessment of all proxy and model uncertainties to obtain quantitative estimates of past environmental conditions. Other benefits of the method include the ability to use independent information on climate and environmental systems to inform the interpretation of proxy data, to fully leverage information from unevenly and differently sampled proxy records, and to obtain refined estimates of proxy model parameters that are conditioned on paleo-archive data. Application of JPI to the marine Mg∕Ca and δ18O proxy systems at two distinct timescales demonstrates many of the key properties, benefits, and sensitivities of the method, and it produces new, statistically grounded reconstructions of Neogene ocean temperature and chemistry from previously published data. We suggest that JPI is a universally applicable method that can be implemented using proxy models of wide-ranging complexity to generate more robust, quantitative understanding of past climatic and environmental change.
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Mitchell, Edward A. D., Richard J. Payne, Willem O. van der Knaap, Łukasz Lamentowicz, Maciej Gąbka, and Mariusz Lamentowicz. "The performance of single- and multi-proxy transfer functions (testate amoebae, bryophytes, vascular plants) for reconstructing mire surface wetness and pH." Quaternary Research 79, no. 1 (January 2013): 6–13. http://dx.doi.org/10.1016/j.yqres.2012.08.004.

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AbstractPeatlands are widely exploited archives of paleoenvironmental change. We developed and compared multiple transfer functions to infer peatland depth to the water table (DWT) and pH based on testate amoeba (percentages, or presence/absence), bryophyte presence/absence, and vascular plant presence/absence data from sub-alpine peatlands in the SE Swiss Alps in order to 1) compare the performance of single-proxy vs. multi-proxy models and 2) assess the performance of presence/absence models. Bootstrapping cross-validation showing the best performing single-proxy transfer functions for both DWT and pH were those based on bryophytes. The best performing transfer functions overall for DWT were those based on combined testate amoebae percentages, bryophytes and vascular plants; and for pH, those based on testate amoebae and bryophytes. The comparison of DWT and pH inferred from testate amoeba percentages and presence/absence data showed similar general patterns but differences in the magnitude and timing of some shifts. These results show new directions for paleoenvironmental research, 1) suggesting that it is possible to build good-performing transfer functions using presence/absence data, although with some loss of accuracy, and 2) supporting the idea that multi-proxy inference models may improve paleoecological reconstruction. The performance of multi-proxy and single-proxy transfer functions should be further compared in paleoecological data.
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Cruz, J. Alberto, Julián A. Velasco, Joaquín Arroyo-Cabrales, and Eileen Johnson. "Paleoclimatic Reconstruction Based on the Late Pleistocene San Josecito Cave Stratum 720 Fauna Using Fossil Mammals, Reptiles, and Birds." Diversity 15, no. 7 (July 24, 2023): 881. http://dx.doi.org/10.3390/d15070881.

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Advances in technology have equipped paleobiologists with new analytical tools to assess the fossil record. The functional traits of vertebrates have been used to infer paleoenvironmental conditions. In Quaternary deposits, birds are the second-most-studied group after mammals. They are considered a poor paleoambiental proxy because their high vagility and phenotypic plasticity allow them to respond more effectively to climate change. Investigating multiple groups is important, but it is not often attempted. Biogeographical and climatic niche information concerning small mammals, reptiles, and birds have been used to infer the paleoclimatic conditions present during the Late Pleistocene at San Josecito Cave (~28,000 14C years BP), Mexico. Warmer and dryer conditions are inferred with respect to the present. The use of all of the groups of small vertebrates is recommended because they represent an assemblage of species that have gone through a series of environmental filters in the past. Individually, different vertebrate groups provide different paleoclimatic information. Birds are a good proxy for inferring paleoprecipitation but not paleotemperature. Together, reptiles and small mammals are a good proxy for inferring paleoprecipitation and paleotemperature, but reptiles alone are a bad proxy, and mammals alone are a good proxy for inferring paleotemperature and precipitation. The current paleoclimatic results coupled with those of a previous vegetation structure analysis indicate the presence of non-analog paleoenvironmental conditions during the Late Pleistocene in the San Josecito Cave area. This situation would explain the presence of a disharmonious fauna and the extinction of several taxa when these conditions later disappeared and do not reappear again.
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SOWA, Kohki, Tsuyoshi WATANABE, Michiyo SHIMAMURA, Tatsuhiko SAKAMOTO, and Seiya NAGAO. "Coral skeletal luminescence- its causes and availability as a paleoenvironmental proxy." Journal of the Japanese Coral Reef Society 12 (2010): 1–15. http://dx.doi.org/10.3755/jcrs.12.1.

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Beaudoin, Alwynne B. "On the Identification and Characterization of Drought and Aridity in Postglacial Paleoenvironmental Records from the Northern Great Plains." Géographie physique et Quaternaire 56, no. 2-3 (October 7, 2004): 229–46. http://dx.doi.org/10.7202/009108ar.

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Abstract The Northern Great Plains region is especially sensitive to drought and is likely to be even more drought-prone under projected global warming. Drought has been invoked as an explanatory factor for changes seen in postglacial paleoenvironmental records. These proxy records may extend drought history derived from instrumental data. Moreover, in the last decade, some paleoenvironmental studies have been expressly undertaken for the examination of long-term drought history. Nevertheless, few such studies explicitly define drought. This makes it difficult to compare results or to understand what the results mean in terms of the operational drought definitions that are used in resource management. Operational drought is defined as usually short-term; longer sustained dry intervals reflect a shift to aridity. Therefore, high resolution paleoenvironmental proxies (annual or subdecadal) are best for the investigation of drought history. Such proxies include tree rings and some lake records. However, most lake-based records are sampled at lower resolution (decadal or subcentury) and are therefore providing aridity signals.
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Journal articles Dissertations / Theses

Dissertations / Theses on the topic "Proxy paleoenvironmental":

1

Chawchai, Sakonvan. "Paleoenvironmental and paleoclimatic changes in northeast Thailand during the Holocene." Doctoral thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-107185.

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The long-term climatic and environmental history of Southeast Asia is still fragmentary. This thesis therefore aims at studying lake sediment/peat sequences using a multi-proxy approach to reconstruct the environmental history and the impact of past changes in monsoon variability and intensity on lake ecosystems in Thailand. The study focuses on two lakes located in northeast Thailand: the larger Lake Kumphawapi and the smaller Lake Pa Kho. The comparison of multiple sediment sequences and their proxies from Kumphawapi suggests a strengthening of the summer monsoon between c. 10,000 and 7000 cal yr BP. Parts of the lake had been transformed into a wetland/peatland by c. 7000 cal yr BP, while the deeper part of the basin still contained areas of shallow water until c. 6600 cal yr BP. This gradual lowering of the lake level can point to a weakening of the summer monsoon. Paleoenvironmental information for the time interval between 6200 and 1800 cal yr BP is limited due to a several thousand-year long hiatus. This new investigation demonstrates that arguments using the phytolith and pollen record of Lake Kumphawapi to support claims of early rice agriculture in the region or an early start of the Bronze Age are not valid, because these were based upon the assumption of continuous deposition. The lithostratigraphy and multi-proxy reconstructions for Pa Kho support a strengthened summer monsoon between 2120-1580 cal yr BP, 1150-980 cal yr BP, and after 500 cal yr BP; and a weakening of the summer monsoon between 1580-1150 cal yr BP and between 650-500 cal yr BP. The increase in run-off and higher nutrient supply after AD 1700 can be linked to agricultural intensification in the region. Conclusively, the Holocene records from northeast Thailand add important paleoclimatic information for Southeast Asia and allow discussing past monsoon variability and movements of the Intertropical Convergence Zone in greater detail.

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Accepted. Paper 5: Manuscript.

2

Stephenson, Richard Javier. "Tropical land snails as precipitation proxies: Oxygen stable isotopes of shells from Trinidad Island." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563273765452653.

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Noses, Spinola Diogo [Verfasser], and Peter [Akademischer Betreuer] Kühn. "Early Eocene paleosols on King George Island, Maritime Antarctica as a paleoenvironmental proxy / Diogo Noses Spinola ; Betreuer: Peter Kühn." Tübingen : Universitätsbibliothek Tübingen, 2018. http://d-nb.info/1198972327/34.

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Lugo, Mendez Anastasia M. "By Proxy: A Radiocarbon Perspective on Prehistoric Mobility Using Summed Probability Distributions and Paleoenvironmental Reconstructions in Wyoming and Montana." DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7447.

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Stone circles are among the most common and understudied archaeological features in the Rocky Mountains and High Plains. Their widespread availability coupled with increased archaeological research accompanying oil and natural gas exploration in the region has expanded the availability and size of the region’s radiocarbon database. The dates as data approach uses radiocarbon ages as variables from a larger sample. This thesis compiles radiocarbon ages associated with tipi ring sites in Wyoming and Montana and creates a summed probability distribution from these ages to serve as a proxy for prehistoric mobility. The distribution is corrected for taphonomic bias, or data loss, and compared to two paleoenvironmental proxies from northwestern Wyoming lakes to determine whether prehistoric mobility meets the expectations of the patch choice model. Running correlation windows provide statistical comparisons between datasets. Although a weak statistical relationship is apparent between mobility and the paleoenvironmental reconstructions over the 5000-year study period, no statistically significant correlations were identified at 150-or 200-year scales. Moderate strength correlations between the environmental data and mobility proxy when mobility is lagged suggest a delayed relationship between the datasets. Future research must include expanding the radiocarbon database and obtaining finer-scale paleoenvironmental reconstructions.
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Carlson, Tessa Boe. "Volcanic Glass as a Paleoenvironmental Proxy: Comparing Preparation Methods on Ashes from the Lee of the Cascade Range in Oregon, USA." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4472.

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Deuterium ratios (δD) of hydrated volcanic glass have been used to reconstruct paleoenvironments, although the reliability and proper sample preparation protocol have been debated. In this study, hydrated volcanic ash samples from the lee of the Cascades were prepared using two separate methods. Method 1 involves sonicating and rinsing samples with hydrochloric acid (HCl) followed by hand-selection of glass shards (125-212µm). Method 2 requires hydrochloric acid (HCl) and hydrofluoric acid (HF) abrasion as well as heavy liquid separation of shards (70-150µm). Method 2 produced more consistent results with decreased intra-replicate variability in both water content (-0.92 wt. %) and deuterium values (-2.5‰ δD). Method 2 δD values of ≥99% isotropic glass were also 2.5-10 % more negative relative to Method 1 values, with an increasing discrepancy with age (3.68-32.66 Ma). Method 2 results suggest volcanic glass did not re-equilibrate with modern water, based on 1) < 2‰ discrepancies between samples of the same ash flow taken from unique sample localities and 2) a ~20‰ difference between samples of different ages (~8 Ma apart) from the same locality. These results support the specified use of HF abrasion and heavy liquid separation on 70-150 µm glass shards to minimize the impact of contaminants on reconstructed paleowater δD values.
6

Newell, Sarah D. "An analysis of compound specific carbon isotopes of lipid biomarkers a proxy for paleoenvironmental change in the Maya lowlands of Peten, Guatemala /." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0009584.

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Kwiecien, Olga. "Paleoenvironmental changes in the Black Sea region during the last 26000 years a multi-proxy study of lacustrine sediments from the western Black Sea /." Potsdam : GFZ, 2009. http://d-nb.info/993233236/34.

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Kwiecien, Olga. "Paleoenvironmental changes in the Black Sea region during the last 26,000 years : a multi-proxy study of lacustrine sediments from the western Black Sea." Phd thesis, Universität Potsdam, 2008. http://opus.kobv.de/ubp/volltexte/2008/1918/.

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Paleoenvironmental records provide ample information on the Late Quaternary climatic evolution. Due to the great diversity of continental mid-latitude environments the synthetic picture of the past mid-latitudinal climate changes is, however, far from being complete. Owing to its significant size and landlocked setting the Black Sea constitutes a perfect location to study patterns and mechanisms of climate change along the continental interior of Central and Eastern Europe and Asia Minor. Presently, the southern drainage area of the Black Sea is characterized by a Mediterranean-type climate while the northern drainage is under the influence of Central and Northern European climate. During the Last Glacial a decrease in the global sea level disconnected the Black Sea from the Mediterranean Sea transforming it into a giant closed lake. At that time atmospheric precipitation and related with it river run-off were the most important factors driving sediment supply and water chemistry of the Black ‘Lake’. Therefore studying properties of the Black Sea sediments provides important information on the interactions and development of the Mediterranean and Central and North European climate in the past. One significant outcome of my thesis is an improved chronostraphigraphical framework for the glacial lacustrine unit of the Black Sea sediment cores, which allowed to refine the environmental history of the Black Sea region and enabled a reliable correlation with data from other marine and terrestrial archives. Data gathered along a N-S transect presented on a common time scale revealed coherent changes in the basin and its surrounding. During the glacial, the southward-shifted Polar Front reduced moisture transport to the northern drainage of the Black Sea and let the southern drainage become dominant in freshwater and sediment supply into the basin. Changes in NW Anatolian precipitation reconstructed from the variability of the terrigenous input imply that during the glacial the regional rainfall variability was strongly influenced by Mediterranean sea surface temperatures and decreased in response to the cooling associated with the North Atlantic Heinrich Events H1 and H2. In contrast to regional precipitation changes, the hydrological properties of the Black Sea remained relatively stable under full glacial conditions. First significant modification in the freshwater/sediment sources reconstructed from changes in the sediment composition, lithology, and 18O of ostracods took place at around 16.4 cal ka BP, simultaneous to the early deglacial northward retreat of the oceanic and atmospheric polar fronts. Meltwater pulses, most probably derived from the disintegrating European ice sheets, changed the isotopic composition of the Black Sea and increased the supply from northern sediment sources. While these changes signalized a mitigation of the Northern European and Mediterranean climate, a decisive increase in local temperature was indicated only later at the transition from the Oldest Dryas to the Bølling around 14.6 cal ka BP. At that time the warming of the Black Sea surface initiated massive phytoplankton blooms, which in turn, induced the precipitation of inorganic carbonates. This biologically triggered process significantly changed the water chemistry and was recorded by simultaneous shifts in the elemental composition of ostracod shells and in the isotopic composition of the inorganically-precipitated carbonates. Starting with the B/A warming and continuing through the YD cold interval and the Early Holocene warming, the Black Sea temperature signal corresponds to the precipitation and temperature changes recorded in the wider Mediterranean region. Early Holocene conditions, similar to those of the Bølling/Allerød, were punctured by the marine inflow from the Mediterranean at ~ 9.3 cal ka BP, which terminated the lacustrine phase of the Black Sea and had a substantial impact on the chemical and physical properties of its water.
Aus Paläoumweltdaten lassen sich detaillierte Informationen über die spätquartäre Klimaentwicklung gewinnen. Für die kontinentalen mittleren Breiten ist das Gesamtbild der Klimaänderungen während dieses Zeitraumes aufgrund seiner Vielfältigkeit allerdings noch immer unvollständig. Eine ideale Loka-tion, das Muster und die Mechanismen der Klimaänderungen in Osteuropa und Kleinasien zu untersu-chen, ist das Schwarze Meer mit seiner bedeutenden Größe und seiner kontinentalen Lage. Gegenwärtig ist das südliche Einzugsgebiet des Schwarzen Meeres durch ein mediterranes Klima ge-prägt, während die nördlichen Regionen von zentral- bzw. nordeuropäischem Klima beeinflusst werden. Als im letzten Glazial der Meeresspiegel so stark sank, dass das Schwarze Meer vom Mittelmeer abge-trennt und zu einem großen, abflusslosen See wurde, waren der atmosphärische Niederschlag und der damit verbundene Abfluss die wesentlichen Steuerfaktoren für Sedimenteintrag und Wasserchemie des Schwarzen „Sees“. Deshalb liefert die Untersuchung der Sedimente des Schwarzen Meeres wichtige Informationen über die früheren Zusammenhänge sowie die Entwicklung von mediterranem und zentral- bzw. nordeuropäischem Klima. Das bedeutsamste Ergebnis meiner Doktorarbeit ist ein verbessertes Altersmodell für Sedimentkerne aus dem westlichen Schwarzen Meer; dieses erlaubt eine genauere Rekonstruktion der Entwicklungsge-schichte dieses Binnenmeeres und seiner Umgebung und ermöglicht einen fundierten Vergleich mit an-deren marinen und terrestrischen Archiven. Daten, die entlang eines N-S Transektes im westlichen Be-reich des Schwarzen Meeres erfasst wurden und auf einer gemeinsamen Zeitskala dargestellt werden, lassen die folgenden zusammenhängenden Entwicklungen im Becken und seiner Umgebung erkennen: Während des Glazials war der Feuchtigkeitstransport zum nördlichen Einzugsgebiet des Schwarzen Meeres aufgrund der südwärts verlagerten Polarfront vermindert, so dass Süßwasser und Sedimente vor-rangig aus dem südlichen Einzugsgebiet in das Becken gelangten. Die Rekonstruktion von Nieder-schlagsänderungen mit Hilfe von Schwankungen des terrigenen Eintrags zeigt, dass der regionale Nie-derschlag im Glazial stark von den Wasseroberflächentemperaturen des Mittelmeeres beeinflusst wurde und als Folge der Abkühlung während der nordatlantischen Heinrich-Ereignisse H1 und H2 abnahm. Im Gegensatz dazu blieb das Schwarze Meer während des Hochglazials hydrologisch relativ stabil. Die Sedimentzusammensetzung, Lithologie und δ18O-Werte von Ostracoden zeigen, dass erste signifi-kante Änderungen im Frischwasser- und Sedimenteintrag zeitgleich mit dem frühglazialen nordwärtigen Rückzug der ozeanischen und atmosphärischen Polarfronten um 16.4 cal ka BP auftraten. Der Schmelz-wassereintrag abschmelzender europäischer Eisflächen veränderte die Isotopenzusammensetzung des Wassers und erhöhte die Sedimentzufuhr aus den nördlichen Quellen. Während diese Änderungen auf ein bereits milderes Klima in Nordeuropa und im Mittelmeerraum hin-deuten, zeigt sich ein Anstieg der lokalen Temperaturen erst während des Übergangs von der Älteren Dryas zum Bølling/Allerød um etwa 14.6 cal. ka BP. Zu diesem Zeitpunkt führte ein wahrscheinlicher Anstieg der Wasseroberflächentemperaturen im Schwarzen Meer zu einem massiven Phytoplankton-wachstum, welcher die Ausfällung anorganischen Karbonats zur Folge hatte. Dieser biologisch ausgelös-te Prozess veränderte maßgeblich die Wasserchemie und spiegelt sich in simultanen Veränderungen der Elementzusammensetzung von Ostracoden und der Isotopenzusammensetzung von anorganisch ausge-fälltem Karbonat wieder. Beginnend mit dem Bølling/Allerød, durch die Jüngere Dryas Kälteperiode und die frühholozäne Erwärmung hindurch, deckt sich das Temperatursignal des Schwarzen Meeres mit den Niederschlags- und Temperaturänderungen des weiteren Mittelmeerraumes. Das Frühholozän war, ähnlich wie das Bølling/Allerød, durch das Einströmen salzhaltigen Meerwassers aus dem Mittelmeer gekennzeichnet (~9.5 cal. ka BP), welches die lakustrine Phase des Schwarzen Mee-res beendete und einen erheblichen Einfluss auf seine chemischen und physikalischen Wassereigen-schaften ausübte.
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Krauß, Lydia [Verfasser], Frank [Akademischer Betreuer] Lehmkuhl, and Eileen Sandra [Akademischer Betreuer] Eckmeier. "Paleoenvironmental reconstruction of the last interglacial-glacial cycle of the quaternary in Central Europe applying a multi-proxy approach investigating loess-paleosol sequences / Lydia Krauß ; Frank Lehmkuhl, Eileen Sandra Eckmeier." Aachen : Universitätsbibliothek der RWTH Aachen, 2017. http://d-nb.info/1162450932/34.

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Guida, Manrique Leydy Carolina. "Mécanismes contrôlant la séquestration du gadolinium, du rhénium et du sélénium dans des conditions de faible teneur en oxygène." Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALU015.

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Les éléments traces, malgré leur rareté (moins de 100 parties par million) sur Terre, remplissent diverses fonctions : certains agissent comme des micronutriments, tandis que d'autres, appelés métaux critiques, possèdent des applications industrielles et médicales uniques. Dans les systèmes aquatiques naturels dépourvus d'oxygène, les transferts d'électrons impliquent des réactions biogéochimiques catalysées par le fer, le soufre et les éléments traces. Comprendre leur réactivité dans ces environnements reste un défi. Ma recherche de doctorat se concentre sur combler cette lacune de connaissance concernant trois éléments spécifiques (rhénium (Re), sélénium (Se) et gadolinium (Gd)). Ils existent sous diverses formes chimiques aqueuses dans l'eau : anion monovalent (perrhénate, ReO4—), anion divalent (sélénate, SeO42— et sélénite, SeO32—) ou cation (gadolinium, Gd3+). Le rhénium est un métal critique, tandis que le sélénium est un élément bioessentiel à faibles niveaux et devient toxique à des concentrations plus élevées. Le gadolinium est un élément des terres rares et un métal critique également, en raison de son utilisation étendue comme agent de contraste dans l'imagerie par résonance magnétique (IRM).Ces éléments sont les plus concentrés dans les sédiments marins formés dans des environnements dépourvus d'oxygène. Les phases minérales courantes comprennent la pyrite (FeS2) et la magnétite (Fe3O4), selon la teneur en sulfure dans ces environnements et l'origine (autogène vs détritique, par exemple, à partir de roches volcaniques) des particules. Ma recherche, présentée sur quatre chapitres, étudie les processus de réduction de surface (Re(VII), Se(VI) et Se(IV)) et la sorption (Gd(III)) sur/dans les particules de magnétite et de pyrite. En utilisant diverses méthodes analytiques telles que la spectroscopie XAFS, la spectroscopie STEM-EELS et le MC-ICP-MS, notre étude révèle des voies réactives distinctes. Re(VII) réagit avec l'eau sulfurée pour former des nanoparticules de Re(III, IV, V)2S7, tandis qu'à des concentrations plus faibles, le Re est réduit et incorporé dans les particules, selon des voies caractérisées par une fraction isotopique moindre avec la pyrite qu'avec la magnétite. Nous montrons également que les nanoparticules de pyrite réduisent le Se(VI) et le Se(IV), jusqu'à obtenir du Se(0) en surface ou du Se(-I) en structure, selon que l'adsorption ou la co-précipitation se produit. Enfin, le Gd se substitue au Fe(III) dans les nanoparticules de magnétite jusqu'à une substitution de 5% de Fe par Gd. Nous tentons d'unifier le comportement d'affinité de ces éléments traces et d'autres avec les sédiments riches en Fe anoxiques à la lumière du principe des acides et des bases durs et mous.L'étude apporte de nouvelles perspectives sur les mécanismes qui régissent la séquestration des métaux et métalloïdes dans les environnements sédimentaires. La signification de cette recherche réside dans sa pertinence pour les entreprises scientifiques et technologiques contemporaines, en particulier pour comprendre comment les processus dans les systèmes riches en Fe et en sulfures fonctionnent, tels que les éléments traces, la mobilité du Fe et du S, l'équilibre des masses dans les cycles sédimentaires mondiaux, jusqu'à l'exploration, l'exploitation minière et le recyclage des gisements potentiels de métaux. De plus, elle améliore notre compréhension actuelle de l'utilisation des proxies paléoenvironnementaux pour reconstruire la formation de la Terre. Enfin, cette étude a également des implications pour le traitement des déchets nucléaires et de la pollution, en particulier dans la gestion de la contamination par le sélénium (Se) et le gadolinium (Gd)
Trace elements, despite their scarcity (less than 100 parts per million) on Earth, serve diverse purposes: some act as micronutrients, while others, known as critical metals, possess unique industrial and medical applications. In oxygen-deprived natural aquatic systems electron transfers involve biogeochemical reactions catalyzed by iron, sulfur and trace elements. Understanding their reactivity in these environments remains a challenge. My Ph.D. research focus on filling this knowledge gap concerning three specific elements (rhenium (Re), selenium (Se), and gadolinium (Gd)). They exist in various chemical aqueous species in water: monovalent anion (perrhenate, ReO4—), divalent anion (selenate, SeO42—and selenite, SeO32—) or cation (Gadolinium, Gd3+). Rhenium is a critical metal, while selenium is a bioessential element at low levels, and becomes toxic in higher concentrations. Gadolinium is a rare earth element and a critical metal as well, due to its wide use as a contrast agent in magnetic resonance imaging (MRI).These elements are most concentrated in marine sediments formed in oxygen-deprived environments. Common mineral phases include pyrite (FeS2) and magnetite (Fe3O4) depending on sulfide content in those environments, and origin (autogenic vs. detritic, e.g., from volcanic rocks) of the particles. My research, presented across four chapters, investigates surface reduction (Re(VII), Se(VI) and Se(IV)) and the sorption (Gd(III)) processes on/into magnetite and pyrite particles. Employing various analytical methods such as XAFS spectroscopy, STEM-EELS spectro microscopie and MC-ICP-MS, our study reveals distinct reactive pathways. Re(VII) reacts with sulfidic water to form Re(III, IV, V)2S7 nanoparticles, while at lower concentrations Re is reduced and incorporated into particles, in different pathways characterized by less isotopic fractionation with pyrite than with magnetite. We also show that pyrite nanoparticles reduce Se(VI) and Se(IV), down to surface Se(0) or structure Se(-I) depending on whether adsorption or co-precipitation occurs. Lastly, Gd substitutes for Fe(III) in magnetite nanoparticles up to 5% Fe substitution by Gd. We attempt to unify the affinity behaviour of these and other trace elements with anoxic Fe-bearing sediments in the light of the hard and soft acids and bases principle.The study provides new insights into the mechanisms that govern the sequestration of metals and metalloids in sedimentary settings. The significance of this research lies in its relevance to contemporary scientific and technological endeavours, particularly in understanding how processes in Fe and sulfidic systems work like trace elements, Fe and S mobility, mass balance in the global sedimentary cycles to the exploration, mining and recycling of potential repositories of metals. Furthermore, it enhances our current understanding of the use of palaeoenvironmental proxies to reconstruct the Earth's formation. Finally, this study also has implications for the treatment of nuclear waste and pollution, particularly in the management of selenium (Se) and gadolinium (Gd) contamination
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Book chapters on the topic "Proxy paleoenvironmental":

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Achyuthan, Hema. "The Thar Desert Calcretes: A Proxy for Understanding Late Quaternary Paleoclimate Shifts." In Patterns and Mechanisms of Climate, Paleoclimate and Paleoenvironmental Changes from Low-Latitude Regions, 53–57. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-01599-2_13.

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Perez, Laura, Felipe García-Rodríguez, and Till J. J. Hanebuth. "Paleosalinity Changes in the Río de la Plata Estuary and on the Adjacent Uruguayan Continental Shelf over the Past 1200 Years: An Approach Using Diatoms as a Proxy." In Applications of Paleoenvironmental Techniques in Estuarine Studies, 529–49. Dordrecht: Springer Netherlands, 2017. http://dx.doi.org/10.1007/978-94-024-0990-1_21.

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Essefi, Elhoucine. "High Resolution Cyclostratigraphy During the Last Two Millennia Based on the Clayey Fraction Within the Mhabeul Wetland (Southeastern Tunisia)." In Climatic and Environmental Significance of Wetlands, 139–56. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-7998-9289-2.ch008.

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High-resolution proxy-based paleoenvironmental records derived from wetlands provide important insights into climate changes over centennial to millennial timescales. This work aims to study the climatic cyclicity of the clayey fraction along a 78 cm core from the saline system of Mhabeul, located in Southeastern Tunisia. Based on the age model of Essefi et al., the core covers the last two millennia (»2100 yr). A high-resolution sampling of 2mm was carried out to obtain 380 samples evenly distributed along the core. In terms of analyses, the cumulative curve of the grain size distribution carried out by Fritsch laser apparatus percentages of the Clayey fraction underwent the spectral analysis. Based on the spectral analysis, millennial cycles of » 2500 yr, and 1000 yr are related to solar forcing. Solar irradiation is most likely responsible for the cyclic characteristics at 500 yr (600 yr) frequency.
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Rickard, David. "Framboid Sizes." In Framboids, 21–46. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780190080112.003.0002.

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Framboid size-frequency plots show log-normal distributions with a geometric mean diameter of 6.0 μ‎m and with 95% of framboids ranging between 2.9 and 12.3 μ‎m. The largest framboids may be 250 μ‎m in diameter, although spherical aggregates of framboids, known as polyframboids, may range up to 900 μ‎m in diameter. Various spherical clusters of nanoparticles have been described which are less than 0.2 μ‎m in diameter. These do not form a continuum with framboids. There is no evidence for any significant change in framboid diameters with geologic time, and the differences in mean sizes between hydrothermal and sedimentary framboids do not, at present, appear to be statistically significant. By contrast, it appears that the mean diameters of framboids from non-marine sediments are significantly larger (7.6 μ‎m) than marine framboids (5.7 μ‎m). There is some evidence that framboids formed in the water column are smaller than those formed in sediments, but the non-critical use of this possible difference as a proxy for paleoenvironmental reconstructions is not robust. So-called microframboids and nanoframboids are discrete entities which are distinct from framboids. They are nanoparticle clusters and are not produced by the same processes as those involved in framboid formation, nor do they behave in the same way. They are more akin to atomic clusters, which form similar constructs.
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Barendregt, R. W., J. V. Matthews, V. Behan-Pelletier, J. Brigham-Grette, J. G. Fyles, L. E. Ovenden, D. H. McNeil, et al. "Biostratigraphy, Age, and Paleoenvironment of the Pliocene Beaufort Formation on Meighen Island, Canadian Arctic Archipelago." In Biostratigraphy, Age, and Paleoenvironment of the Pliocene Beaufort Formation on Meighen Island, Canadian Arctic Archipelago. Geological Society of America, 2021. http://dx.doi.org/10.1130/2021.2551(01).

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ABSTRACT Meighen Island, in the Canadian Arctic Archipelago, is one of the most important localities for study of the late Neogene Beaufort Formation because of the presence of marine sediments interbedded with terrestrial fossiliferous sands. The stratigraphic succession, fossils from the marine beds, correlation with reconstructions of sea level, and paleomagnetic data from the Bjaere Bay region of the island suggest that the Beaufort Formation on Meighen Island was likely deposited either at 3.2–2.9 Ma or during two intervals at ca. 4.5 Ma and 3.4 Ma. The exposed Beaufort Formation on Meighen Island probably encompasses at least one warm interval and eustatic sea-level highstand of the Pliocene. Fossils of plants and arthropods are abundant in the alluvial sands exposed in the Bjaere Bay region. The lower part of the sequence (Unit A), beneath the muddy marine sequence (Unit B), contains plant taxa that have not been seen above the marine beds. Sediments below the marine beds are dominated more by fossils of trees, whereas the organic debris from above marine beds contains many fossils of plants, insects, and mites characteristic of open treeless sites. Regional tree line probably occurred on Meighen Island during deposition of the upper sediments, which implies a mean July climate at least 9 °C warmer than at present. When the marine sediments were deposited, nearshore water temperatures probably did not fall below 0 °C; hence, the Arctic Ocean probably lacked perennial ice cover. This confirms recent modeling experiments exploring the causes of Arctic amplification of temperature that have found the removal of sea ice to be a key factor in resolving previous proxy-model mismatches.

Conference papers on the topic "Proxy paleoenvironmental":

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Trampush, Sheila, and Elizabeth Hajek. "UNDERSTANDING HOW DELTA DYNAMICS INFLUENCE PALEOENVIRONMENTAL PROXY RECORDS." In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-307143.

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Graniero, Lauren E., Donna Surge, and David P. Gillikin. "EVALUATING OXYGEN AND CARBON ISOTOPE RATIOS IN RANGIA CUNEATA AS A PALEOENVIRONMENTAL PROXY." In GSA Annual Meeting in Indianapolis, Indiana, USA - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018am-324245.

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Grochocki, Konrad K., Chad S. Lane, and Jay Curt Stager. "A 1900-YEAR MULTI-PROXY PALEOENVIRONMENTAL RECONSTRUCTION OF PISECO LAKE, ADIRONDACK MOUNTAINS, NEW YORK." In Joint 52nd Northeastern Annual Section and 51st North-Central Annual GSA Section Meeting - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017ne-290084.

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Graniero, Lauren E., David P. Gillikin, and Donna Surge. "CALIBRATION OF BIVALVE SHELL δ15N VALUES AS A PALEOENVIRONMENTAL PROXY IN FRESHWATER AND ESTUARINE ENVIRONMENTS." In GSA Annual Meeting in Denver, Colorado, USA - 2016. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016am-286098.

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Strasberg, Zachary, and Angel A. Garcia. "PALEOENVIRONMENTAL RECONSTRUCTION OF OWL CAVE, HIGHLAND CO., VA USING ẟ13C FROM STALAGMITE AS A PROXY." In Joint 69th Annual Southeastern / 55th Annual Northeastern GSA Section Meeting - 2020. Geological Society of America, 2020. http://dx.doi.org/10.1130/abs/2020se-344849.

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De Oliveira, B. L., H. S. Rocha, A. F. M. Freire, and V. M. J. S. Campos. "A Multi-Proxy Approach for Paleoenvironmental Insights and Operational Improvements: a Study Case in Campos Basin, Brazil." In 85th EAGE Annual Conference & Exhibition - Workshop Programme. European Association of Geoscientists & Engineers, 2024. http://dx.doi.org/10.3997/2214-4609.202410895.

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Boyd, Melissa D., Craig S. Feibel, Fredrick K. Manthi, Carol V. Ward, and J. Michael Plavcan. "A SYNTHESIS OF MULTI-PROXY PALEOENVIRONMENTAL RECONSTRUCTION METHODS: THE DEPOSITIONAL ENVIRONMENTS OF THE LOMEKWI MEMBER, NACHUKUI FORMATION, WEST TURKANA." In GSA Annual Meeting in Indianapolis, Indiana, USA - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018am-319628.

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Damick, Alison, and Tammy Buonasera. "PHYTOLITH, MOLECULAR, AND ISOTOPE ANALYSES FROM CHOLAME CREEK: A MULTI-PROXY MICROANALYTICAL APPROACH TO PALEOENVIRONMENTAL RECONSTRUCTION IN CENTRAL CALIFORNIA." In GSA Connects 2023 Meeting in Pittsburgh, Pennsylvania. Geological Society of America, 2023. http://dx.doi.org/10.1130/abs/2023am-393804.

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Dello-Russo, Robert D., Susan J. Smith, and Patrice A. Walker. "The black mat at the Water Canyon Paleoindian site near Socorro, New Mexico: A paleoenvironmental proxy data archive for the Pleistocene-Holocene transition." In 67th Annual Fall Field Conference. New Mexico Geological Society, 2016. http://dx.doi.org/10.56577/ffc-.491.

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Dello-Russo, Robert D., Susan J. Smith, and Patrice A. Walker. "The black mat at the Water Canyon Paleoindian site near Socorro, New Mexico: A paleoenvironmental proxy data archive for the Pleistocene-Holocene transition." In 67th Annual Fall Field Conference. New Mexico Geological Society, 2016. http://dx.doi.org/10.56577/ffc-67.491.

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Reports on the topic "Proxy paleoenvironmental":

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Carlson, Tessa. Volcanic Glass as a Paleoenvironmental Proxy: Comparing Preparation Methods on Ashes from the Lee of the Cascade Range in Oregon, USA. Portland State University Library, January 2000. http://dx.doi.org/10.15760/etd.6356.

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Evidence of late Quaternary wet/dry climate episodes derived from paleoclimatic proxy data recovered from the paleoenvironmental record of the Great Basin of western North America: Paleobotanical studies. Office of Scientific and Technical Information (OSTI), July 1998. http://dx.doi.org/10.2172/631154.

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