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Showing 1 to 20 of 67 for “"Palaeoclimate"”.
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The Aral Sea : a palaeoclimate archive
… 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, …
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HOLOCENE PALAEOCLIMATE RECONSTRUCTION FROM N EW ZEALAND PEATLANDS
A selection of palaeoecological proxies were tested on two raised, ombrotrophic, restiad peat bog sites from the North Island of New Zealand. With varying degrees of success, peat humification, testate amoebae, plant macrofossil and charcoal analyses contributed to determining the palaeomoisture …
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THE CORAL CLADOCORA CAESPITOSA AS A HIGH RESOLUTION PALAEOCLIMATE ARCHIVE
High resolution proxy data (stable isotopes, trace elements) from coral skeletons is an established method to reconstruct seawater growth temperatures for palaeoenvironmental studies. In this work the temperate, colonial, Mediterranean scleractinian coral Cladocora caespitosa was investigated. …
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Multi-proxy palaeoclimate reconstruction of the permian-triassic mass extinction event
The Permian/Triassic (P/Tr) boundary is widely assumed to have been a time of extreme environmental upheaval and change. In the terrestrial realm, a negative anomaly in 813C isotope values has been reported from organic carbon in Antarctica, Australia, India and Madagascar, and from marine …
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GEOCHEMISTRY AND PETROGRAPHY OF SPELEOTHEMS FROM TURKEY AND IRAN: PALAEOCLIMATE AND DIAGENESIS
Abstract Speleothems contain key archives of palaeoclimatic information, which can be interpreted through multiple geochemical and petrographic proxies, and precisely dated by Uranium Series dating. As U/Th dating is only viable for samples up to approximately 700 kyr of age, U/Pb dating must be …
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Heuweltjies : a window into the palaeoclimate and palaeovegetation of the Western Cape?
Late Pleistocene terrestrial climate information in the Western Cape. South Africa may be preserved in oxygen and carbon isotope ratios in paedogenic calcrete that bas Conned in zeuweltjies (large circular earth mounds). He11weltjles are common landscape features and their potential as …
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‘Organics in ice’: Novel organic compounds in ice cores for use in palaeoclimate reconstruction
The majority of current ice core studies focus on analysing the inorganic component of atmospheric aerosol, trapped and preserved in the ice as a record of past atmosphere. However, this does not fully represent the make-up of atmospheric aerosol, which can be up to 50% organic. This thesis aims to …
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Late Jurassic to Early Cretaceous stable isotope and geochemical records from the northern high latitudes: implications for palaeoclimate
The Jurassic and Cretaceous periods are widely accepted as being dominated by greenhouse conditions with elevated CO2 levels and warm polar regions. Although much compelling evidence to support this idea of global warmth exists, some recent studies propose that the greenhouse climate may at times …
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Application of Hydrogen and Oxygen Isotope Ratios of Water to the Study of Evaporation, Palaeoclimate, and Ancient Marine Conditions
… An application of these findings is made to palaeoclimate data, and an expansion of the use of water isotopes from hydrated minerals is applied to a novel mineral system. Of fundamental importance to the hydrological cycle is the process of evaporation. Yet, under- standing how water isotopes …
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Rates of natural climate change : a study of speleothems
… growing speleothems is a strong proxy for global palaeoclimate, both geographically and through time. A database of speleothem U-Th ages shows some evidence for an early transition from the penultimate glacial to the last interglacial at -140 Ka BP. The database suggests an age of 63 Ka BP for the …
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Innovative water tracers and water isotopes enhance Antarctic research with climate models
… of sea level changes, polar amplification, and palaeoclimate dynamics. While instrumental records are often too short to distinguish anthropogenic impacts from natural variability, Antarctic ice cores preserve valuable information about past climate evolution. As the interpretation of ice core …
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Differential Thermal Isotope Analysis: A Method for the Study of Past Climates
… This thesis shows the potential DTIA has to aid palaeoclimate reconstruction in a number of geological settings. DTIA can be applied both to isolated hydrated minerals and to assemblages of hydrated minerals to better understand the formation environments of these minerals, and thus gain insight …
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Speleothem Palaeoclimatology in the Maya Lowlands of Northwestern Yucatán, Mexico
… are the low chronological resolution of local palaeoclimate records, and the lack of quantitative reconstructions of palaeorainfall changes. I present new proxy records of climate in the Maya Classic Period from two speleothems in northwestern Yucatán which help address these issues. First, I …
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Reconstructing Australia’s late Quaternary climate from the geochemistry of lake sediments and snail shells
… therefore presents both new late Quaternary palaeoclimate data and new methods for inferring past climate across the Australian continent, through the following research components: 1) A record of late Quaternary moisture balance, inferred from highly resolved x-ray fluorescence and organic …
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Environmental change and human interaction in the western Mediterranean over the long term: a comparative study from Sardinia
… sediment cores, as independent indicators of palaeoclimate conditions, and geomorphological and pedological data at a microscopic and outcrop scale from on-site archaeological sites, as direct indicators of local human-induced environmental changes. Micromorphological evidence of buried soil …
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Sedimentology of the lower Uitenhage Group in the Middle to Late Mesozoic Oudtshoorn Basin, South Africa
… and directions, location of sediment sources and palaeoclimate during the deposition of the lower Uitenhage Group in the Oudtshoorn Basin. In addition to the sediment transit patterns from source to sink via palaeocurrent measurements and petrographic studies, the sedimentary architecture was …
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