Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 45 for “"millennial-scale"”.
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Linking millennial scale variability to orbital frequencies using a high resolution foraminiferal climate record spanning the Pleistocene
I hypothesize that millennial-scale variability in the subtropical northwest Atlantic Ocean is a result of advective communication from the Equator of a nonlinear response to orbital scale insolation forcing. To test the hypothesis, I have reconstructed sea surface hydrography in the northwestern …
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A study of sub-orbital and millennial-scale climate variability over the past 1.4 million years in the Northern Atlantic
… years. The study focuses on the suborbital and millennial-scale regime (~ 1 .5 - 20.0 kyr periodicities) at Site 980 and 983, two deep sea drill sites in the North Atlantic gathered by the Ocean Drilling Program in 1995. The study suggests one such narrow band oscillation in the sediment profile …
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Identifying Overwash Deposits in Arid Environments: Towards a Millennial-Scale Record of Cyclones and Makran Trench Tsunamis from Sur Lagoon, Oman
… decadal instrumental record of events to include millennial timescales in regions without rich historical records (i.e., Oman). On November 28, 1945 a 8.1 M<sub>w</sub> MSZ earthquake generated a tsunami that inundated coastlines of the Arabian sea with wave heights as high as 13m. The …
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Paleoceanographic variability on a millennial scale: a high resolution record of the latest deglaciation from the Blake Outer Ridge, western North Atlantic
… and NADW fluctuated on a decadal to century scale between 14,000 and 10,000 14C years BP. Furthermore, between 13,500 and 13,300 14C years BP and 10,900 and 10,600 14C years BP, the coincidence of benthic foraminifera abundance maxima and benthic δ13C minima from C. wuellerstorfi indicate an …
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Paleoceanographic variability on a millennial scale: a high resolution record of the latest deglaciation from the Blake Outer Ridge, western North Atlantic
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1998.
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Tracing hydrological millennial-scale cycles in the late Quaternary of the Cariaco Basin and the southern Gulf of Cádiz using coccoliths and dinoflagellate cysts
… micropalaeontological study of hydrological millennial-scale cycles during Late Quaternary times: the Cariaco Basin, an anoxic basin offshore Venezuela and the Southern Gulf of Cádiz, offshore Morocco. Because of the high sedimentation rates, both sites contain a relatively undisturbed Late …
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Laurentide ice sheet meltwater influences and millennial-scale climate oscillations on the northwestern slope of the Gulf of Mexico during Marine Isotope Stage 6 and Termination II
… of planktonic foraminifer G. ruber contains millennial-scale climate oscillations during MIS 6, a series of meltwater spikes, and a climate reversal during Termination II. Paired delta18O -- Mg/Ca data across these events reveal that the unusually large amplitudes in the delta 18O record …
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Late Holocene Uplift of the Chihshang segment of the Longitudinal Valley Fault at Fuli, Eastern Taiwan
… Taiwan, were analyzed in order to determine millennial-scale uplift and horizontal shortening rates of the Longitudinal Valley fault. Detrital charcoal fragments collected from three terraces within the Bieh River drainage yield ages between 1395 and 555 cal. yr B.P, suggesting an average …
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Modeling the Lafourche Delta network in the Mississippi Delta Complex
… the past two decades. However, the long-term (millennial scale) simulation of real delta systems remains rare. Here, we attempt to reconstruct the Lafourche Delta channel network, active 1600-600 years before present, with a simple numerical model (Moving Boundary Model for Distributary …
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Speleothem climate capture of the Neanderthal demise
… through wet-dry proxies (δ18O, δ13C, Mg and Sr). Millennial-scale events coincident with the timing of North Atlantic Heinrich Events have been identified and the sub-orbital climate variability resembles that of North Atlantic Dansgaard-Oeschger cycles. Therefore, evidence from the speleothems …
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Constraining Respired Carbon Storage in the Eastern Tropical Pacific Over the Last 25 Thousand Years Using Benthic Foraminiferal Boron/Calcium Ratios
… role in regulating both glacial-interglacial and millennial-scale atmospheric CO<sub>2</sub> concentrations (Broecker and Barker 2007; Sigman et al., 2010). A recent study by Loveley et al. (2017) showed that sedimentary authigenic uranium (aU) concentrations, a proxy for suboxic bottom-water …
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Varve Chronology, Proxy Calibration, and Holocene Climate of Minnesota
… regional climatic changes to possible larger-scale forcing. With solid 14C chronologies, the multi-proxy records from SL and WOL revealed (1) that the abrupt transition from the early- to mid-Holocene postdated the 8.2 ka event at the 95% confidence level of 14C dates, (2) that the two …
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Resolving abrupt palaeoenvironmental changes in a lake sediment sequence from Ioannina, northwest Greece
… Ioannina, seeking to characterise last glacial millennial-scale palaeoenvironmental change at the site through study of core I-08. Detailed visible and ‘crypto-’ tephra analysis identifies deposits associated with explosive volcanism at Italian volcanic sources, including Campi Flegrei, …
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Geochemical tools and paleoclimate clues : multi-molecular and isotopic investigations of tropical marine sediments and alpine ice
… climate records and were found to parallel local millennial-scale climate changes between the late Glacial and Preboreal periods, which were characterized by migrations of the inter-tropical convergence zone. Differences in δD between C16-C18 and C24-C30 n-alkanoic acids suggest a marine source …
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Geochemistry of karst deposits in Borneo detailing hydroclimate variations in the Warm Pool across the late Pleistocene
… tropical ocean-atmospheric system causes global scale climate anomalies, most evident in the El Niño-Southern Oscillation’s coupled climate feedbacks. Despite being an area of high interest, many questions still remain regarding the west Pacific warm pool’s response to external forcing, …
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Geochemical tools and paleoclimate clues : multi-molecular and isotropic investigations of tropical marine sediments and alpine ice
… climate records and were found to parallel local millennial-scale climate changes between the late Glacial and Preboreal periods, which were characterized by migrations of the inter-tropical convergence zone.
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A new hypothesis for the 1470-year cycle of abrupt warming events in the last ice-age
… According to the hypothesis, two century-scale solar cycles could explain the regularity in the timing of the DO events, since the periods of these two cycles are close to integer factors of 1470 years. This hypothesis is tested with a coupled climate model of intermediate complexity. It …
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The Evolution and Impact of Weddell Sea Deep Water
… stages. These transitions are accompanied by millennial-scale increases in atmospheric CO2, a rise in temperature, and global sea-level rise. The evolution of formation and export of deep water sourced from the Weddell Sea is examined with a multi-proxy approach to obtain a thorough …
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The Evolution of the El Niño-Southern Oscillation and Tropical Pacific Climate Across the Last Deglaciation
… is known about how ENSO varied in response to millennial-scale climate events over the last 25,000 years. Here, I present new records of tropical Pacific mean state and ENSO variability over the last 25,000 years reconstructed from a high-resolution sediment core recovered from the Eastern …
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The impact of past land-use change on floristic diversity in southern Sweden : a quantitative approach based on high-resolution pollen data
… past evenness at regional and local spatial scales, which enable estimates of the rate and degree of change in land-use and floristic diversity. The results show that agricultural land-use was most widespread AD 350-1850 at a regional scale, and a period of land-use expansion followed by …
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