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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Carbon-14 Chronology Of Anatolia In Early Bronze Age

Uncu, Hakki 01 December 2010 (has links) (PDF)
This study is a conclusion of radiocarbon datings which are depend on evaluations of archaeologists or scholars who publishes these datings. So it is very attached to observations of those scholars especially for determining sub-phases of samples which are dated. According to these datings, the radiocarbon story of Anatolian Early Bronze Age starts with a dating from Troia from 3760 cal. BC and ends with a dating from &Ccedil / adirh&ouml / y&uuml / k in 1630 cal. BC. Of course these dates are the lower and higher borders of the 68% probability band. As a result of assessments of all datings it can be said that the beginning of Early Broze Age in Anatolia is started equally more or less in every region at the same time interval that corresponds 3700/3400 BC and continued 800 years approximately. Although error deviation bands overlap onto each other, it is possible to say that the EB2 period of Anatolia ruled between 2800-2400 BC roughly. In this work it can be observed that the ending of the Early Bronze Age in Anatolia generally not ocured simultaneously. Sos H&ouml / y&uuml / k for example in the East Anatolia for example, drawing a very special profile with an ending date 2300 BC for the Early Bronze Age. Some other sites giving results as late as nearly in 18th. and 17th. century BC. For the timing of the end of Early Bronze Age in Anatolia, it can be said that, inequality among the sites are more likely other than regions.
92

チベット高原南東部プマユムツォ湖大島から採取した土壌(陸成堆積物)の^<14>C年代測定

KAKEGAWA, Takeshi, NARA Watanabe, Fumiko, HORIUCHI, Kazuho, SAKAI, Takahiro, MATSUNAKA, Tetsuya, NISHIMURA, Mitsugu, NAKAMURA, Toshio, WATANABE, Takahiro, ZHU, Liping, 掛川, 武, 奈良, 郁子, LIN, Xiao, 堀内, 一穂, 酒井, 貴悠, 松中, 哲也, 西村, 弥亜, 中村, 俊夫, 渡邊, 隆広 03 1900 (has links)
第22回名古屋大学年代測定総合研究センターシンポジウム平成21(2009)年度報告
93

シベリア・チベット地域の湖沼から採取した湖底柱状堆積物の放射性炭素年代測定一4 : PY608E-PC コア試料(チベット・プマユムツォ湖)

ZHU, Liping, WANG, Junbo, KAKEGAWA, Takeshi, NARA Watanabe, Fumiko, MATSUNAKA, Tetsuya, NISHIMURA, Mitsugu, NAKAMURA, Toshio, WATANABE, Takahiro, ZHU, Liping, WANG, Junbo, 掛川, 武, 奈良, 郁子, 松中, 哲也, 西村, 弥亜, 中村, 俊夫, 渡邊, 隆広 03 1900 (has links)
No description available.
94

Environmental changes associated with Native American land use practices a geoarcheological investigation of an Appalachian watershed /

Mihindukulasooriya, Lorita N. January 2009 (has links)
Thesis (M.S.)--Ohio University, November, 2009. / Title from PDF t.p. Includes bibliographical references.
95

Tropical Atlantic and Caribbean climate variations during the past eight centuries

Kilbourne, Kelly Halimeda 01 June 2006 (has links)
The Caribbean Sea is a key region from which to generate paleoclimate records because instrumental temperature data indicate that surface temperatures in the Caribbean region are correlated with global surface temperature. Heat and salt fluxes in the Caribbean have been implicated in major reorganizations in Atlantic Meridional Overturning Circulation on glacial time scales [Schmidt et al., 2004] and it has been proposed that the Tropical Atlantic (including the Caribbean Sea) may play a role in smaller-scale changes in the Atlantic basin [Vellinga and Wu, 2004]. A theme of past Caribbean paleoclimate research has been to hypothesize about the interaction between mean climate state and seasonality, but little work has actually been done with sub-annually resolved climate proxies, and many questions still remain unanswered. This work focuses on reconstructing ocean conditions in the northern Caribbean from the geochemistry of corals growing offshore of southwestern Puerto Rico (17.9°N, 67.0°W). Annually resolved records of Sr/Ca and δ18O were generated for the years 2004 to 1751 from one continuous core. The same annual samples were analyzed for Î?14C between 2004 and 1950, and every 5 years between 1955-1751. Short (14-4 years) monthly-resolved records of δ18O and Sr/Ca were generated from this core and two other cores to investigate the role of seasonal variability during mean climate state variations. Substantial multidecadal variability in delta-18-O and Delta-14-C was found to correlate temporally with the intensity of the trade winds during recent times and over the last 250 years. Strong trade winds are associated with isotopic depletion in the coral geochemistry with respect to both 18-O and 14-C, and this is interpreted as an increase in the amount of equatorial or southern Caribbean Sea water in the northern Caribbean. Other findings include a 2 degree C cooling in the Caribbean during the Maunder solar minimum and no change in coral delta-18-O seasonality during significant mean state variations. Inter-colony geochemical variability in the coral species Montastraea faveolata was quantified, and the median difference between Sr/Ca and delta-18-O in corals growing on the same reef at the same time is 0.047 mmol/mol and 0.11 permil, respectively.
96

Regional Precipitation Response to Enhanced Monsoon Circulation through the Holocene Using Closed-Basin Paleolakes on the Tibetan Plateau

Hudson, Adam Michael January 2015 (has links)
The history of climatic changes in the Asian Summer Monsoon system over the Tibetan Plateau during the Holocene has been the subject of significant research due to the importance of the plateau as the headwaters for many major rivers providing water resources to the surrounding large, populous countries. In general, previous research has concluded that monsoon rainfall and summer temperatures peaked during the early Holocene (9-11 ka BP) in Tibet, coincident with peak Northern Hemisphere summer insolation. Atmospheric teleconnections with upstream Northern Hemisphere westerly circulation patterns influenced by North Atlantic sea surface temperature changes have also been noted at millennial and centennial timescales. However, recent studies have noted that the timing of peak monsoon warmth and wetness during the Holocene are not synchronous across the entirety of the Tibetan Plateau, and studies of modern precipitation indicate several distinct regions of monsoon precipitation variability at interannual scales, suggesting the monsoon response to past and future climate change may be regionally heterogeneous for the plateau. Clear assessment of this regionality within the monsoon climate region is a topic of continuing research, but it has been hindered by lack of climate records in remote areas, dating difficulties, and concerns over the comparability of interpreted climate-proxy relationships between the many different biological, hydrological, and geochemical proxies applied. The first part of this dissertation uses ¹⁴C and U-Th series geochronology, sedimentology, and GIS analysis of exposed lake shoreline sediments surrounding the numerous closed-basin lake systems of the central and western Tibetan Plateau to investigate regional heterogeneity in monsoon rainfall, and to develop a new well-dated lake level record from the Ngangla Ring Tso lake system in the poorly studied southwestern region. The major conclusions are: 1) peak early Holocene monsoon rainfall, recorded by the highest paleoshorelines surrounding 130 lake systems, intensified more relative to today in the western part (west of 86°E longitude) of the Tibetan Plateau when compared to eastern regions, closely following regions of modern rainfall variability; 2) monsoon rainfall in the Ngangla Ring Tso region peaked during the early Holocene insolation maximum, consistent with other records, remained significantly higher than modern until ~6.0 ka BP, but with abrupt reductions in monsoon rainfall associated with North Atlantic ice-rafted debris peaks. The warm and wet period of the early and middle Holocene was also likely coincident with the first major colonization of the Tibetan Plateau by prehistoric humans. Current research suggests early foragers employing stone tools first forayed into the middle elevation areas above 3,000 m elevation on the northeastern fringe of the plateau as early as 14.8 ka BP, and therefore the dominant hypothesis suggests plateau colonization proceeded from this direction, heading westward through the Holocene. However, well studied and dated archaeological sites from the high plateau are exceedingly rare, requiring further investigation. The second part of this dissertation presents new age controls for the Holocene Zhongba microlithic site in the southwestern Tibetan Plateau, using ¹⁴C dating of organic and carbonate-rich paleo-wetlands sediments hosting in situ stone artifacts. The major conclusions of this study are: 1) artifacts at the Zhongba site, which are typologically similar to microlithics across the plateau, can be no older than 6.5 ka BP, consistent with the prevailing east-to-west colonization hypothesis, and 2) microlithic tools continued to be important as late as 1.3 ka BP at the site, even though metal is found in sites of similar age elsewhere in Tibet.
97

Tectonic Geomorphology and Paleoseismicity of the Northern Esk Fault, North Canterbury, New Zealand

Noble, Duncan Paul January 2011 (has links)
Geomorphic, structural and chronological data are used to establish the late Quaternary paleoseismicity of the active dextral-oblique Northern Esk Fault in North Canterbury, New Zealand. Detailed field mapping of the preserved c. 35 km of surface traces between the Hurunui River and Ashley Head reveals variations in strike ranging from 005° to 057°. Along with kinematic data collected from fault plane striae and offset geomorphic markers along the length of the fault these variations are used to distinguish six structural subsections of the main trace, four dextral-reverse and two dextral-normal. Displacements of geomorphic markers such as minor streams and ridges are measured using differential GPS and rangefinder equipment to reveal lateral offsets ranging from 3.4 to 23.7 m and vertical offsets ranging from < 1 to 13.5 m. Characteristic single event displacements of c. 5 m and c. 2 m have been calculated for strike-slip and reverse sections respectively. The use of fault scaling relationships reveals an anomalously high displacement to surface rupture length ratio when compared to global data sets. Fault scaling relationships based on width limited ruptures and magnitude probabilities from point measurements of displacement imply earthquake magnitudes of Mw 7.0 to 7.5. Optically Stimulated Luminescence (OSL) ages from displaced Holocene alluvial terraces at the northern extent of the active trace along with OSL and radiocarbon samples of the central sections constrain the timing of the last two surface rupturing events (11.15 ±1.65 and 3.5 ± 2.8 ka) and suggest a recurrence interval of c. 5612 ± 445 years and late Quaternary reverse and dextral slip rates of c. 0.31 mm/yr and 0.82 mm/yr respectively. The results of this study show that the Northern Esk Fault accommodates an important component of the c. 0.7 – 2 mm/yr of unresolved strain across the plate boundary within the North Canterbury region and affirm the Esk Fault as a source of potentially damaging ground shaking in the Canterbury region.
98

Lake sediments around the Antarctic Peninsula : archives of climatic and environmental changes

Zale, Rolf January 1993 (has links)
Lakes and lake sediments from four areas around the Antarctic Peninsula are described. The concentrations of trace metals in sediment are found to be a useful tool in distinguishing between the different sedimentary phases during a transition from marine to limnic environment. A tephrochronology based on Deception Island tephra is developed, and used to cross date sediments from different lakes in order to overcome the radiocarbon dating problem of the area. The fluctuating concentrations of copper and phosphorus from penguin guano in the sediment of Lake Boeckella are used as a proxy for the penguin inpact on the sediment, and the size of the penguin rookery on the shores of the lake. Anthropogenic activities in the area, as well as climatic changes are discussed in relation to the rookery size. A radiocarbon dating model developed for the sediment of Lake Boeckella showed that the radiocarbon correction factor in the sediment depends on the amount and apparent age of the penguin guano washed down into the lake, and the amount of particulate carbon from the watershed present in the sediment. Neither the "old" meltwater from the glaciers nor dissolved carbonates contributes significantly to the correction factor. The model is used to achieve more accurate radiocarbon dates of the Lake Boeckella sediment. This model, or a modified version, may contribute to a higher dating accuracy and a better understanding of the dating problems in Antarctica. Deglaciation dates, as well as data on the climatic and environmental history of Byers Peninsula on Livingston Island, South Shetland Islands, of Hope Bay, Antarctic Peninsula and of Hidden Lake area, James Ross Island are given. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1993, härtill 6 uppsatser.</p> / digitalisering@umu
99

炭素14と宇宙線変動 : 奈良時代の異変

Nakamura, Toshio, Nagaya, Kentarou, Miyake, Fusa, Masuda, Kimiaki, 中村, 俊夫, 永冶, 健太朗, 三宅, 芙沙, 増田, 公明 03 1900 (has links)
名古屋大学年代測定総合研究センターシンポジウム報告
100

The Geochemistry and Runoff Process in Wolf Creek Research Basin, Whitehorse, Yukon Territory

Li, Tianjiao 05 December 2013 (has links)
This study investigates the runoff process and groundwater behavior in a subarctic watershed called Wolf Creek Research Basin, in Whitehorse, Yukon Territory, Canada. This basin is underlain by discontinuous permafrost that is typical of high latitude watersheds. Goundwater supports the stream flow year round and dominated the hydrology in most of the study period as baseflow. The baseflow was concentrated in dissolved ions. However, the baseflow was diluted during the melt season in May and June of 2012. Multiple chemical and isotopic tracers were used to develop a robust three-component (groundwater, soilwater and precipitation) mixing model for runoff generation. The concentrations of weathering ions decreased with the increased discharge during the melt. Soilwater was responsible for about 60% of the streamwater on the hydrograph in the melt season. The infiltration of the meltwater from the snowpack and the thawed water from the seasonal frost to the baseflow existed. The tritium concentrations indicated that there was fast moving hydrogeological system within the basin. The baseflow was also characterized as relatively enriched in both 13C and 14C, and concentrated in DIC. DIC was the major loss of carbon in Wolf Creek Research Basin.Le pergélisol est grandement sous-jacent dans les bassins-versants à haute latitude. Cette étude examine le processus de ruissellement et le comportement des eaux souterraines dans un bassin-versant subarctique de Wolf Creek, à Whitehorse, territoire du Yukon au Canada. Les eaux souterraines soutenaient l’écoulement fluvial et dominaient l’hydrographe comme débit de base durant la majorité de la période d’étude. Le débit de base était concentré d’ions dissipés. Par contre, le débit de base était dilué durant la saison des fontes au mois de mai et juin 2012. Plusieurs traceurs chimiques et isotopiques étaient utilisé afin de développer un modèle de trois composants (eau souterraine, eau interstitielle de sol et précipitation) de ruissellement. Les concentrations de la déségrégation des ions diminuaient avec l’augmentation du débit durant la fonte. Les eaux interstitielles des sols étaient responsables de 60% de l’eau de ruisseau sur l’hydrographe durant la saison de fontes. L’infiltration de l’eau de fonte du manteau neigeux et l’eau du gel du débit de base existaient. Les concentrations de tritium indiquent qu’il y avait un système hydrogéologique qui se déplaçait à grande vitesse dans les limites du bassin. Le débit de base était aussi caractérisé comme étant enrichi en 13C et 14C, avec des concentrations en carbone inorganique dissous.

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