نتایج جستجو برای: late holocene
تعداد نتایج: 201114 فیلتر نتایج به سال:
Mirak (Semnan, Iran) is a Paleolithic site located in a dry floodplain near the northern edge of the Iranian Central Desert. The pedo-sedimentary successions of Mirak 8 are deposited from late Pleistocene to Late Holocene,. The chronological framework was established using optically stimulated luminescence (OSL) dating. The oldest studied units dating back to ~50 ± 3.0 ka. Within this stratigra...
[1] Paleoclimatic reconstruction using noble gas concentrations in the Carrizo aquifer of southwest Texas and water ages determined through simulation of groundwater age reveals abrupt late Holocene temperature increases previously unidentified through C dating. Of particular interest is a temperature increase of up to 3.4 C in the first half of the last millennium following a cold period betwe...
[1] Magnesium/calcium ratios in benthic foraminifera (Cibicidoides pachyderma) from a sediment core on the Laurentian Slope (1854 m) exhibit strong millennial-scale fluctuations during the past 4000 years. We convert these data to seawater paleotemperatures using a new monospecific linear equation. Results suggest that the temperature of upper North Atlantic Deep Water (dominated by Labrador Se...
[1] Global upper ocean evolution in the Holocene is studied in two coupled ocean-atmosphere models under orbital forcing conditions at 3, 6, 8, and 11 ka. The annual mean sea surface temperature (SST) changes in the early to mid-Holocene are found to be forced mainly by the annual mean insolation forcing with an overall symmetric response of colder equator (<0.5 C)/warmer high latitudes (<0.4 C...
A 137 cm sediment core from Fog Lake, a small upland basin that was not glaciated during the Late Wisconsinan, reveals the following stratigraphic succession: (I) basal diamicton, (II) laminated silts, (III) compacted dewatered gyttja, (IV) stratified minerogenic sediments, and (V) overlying gyttja. Units I—III, and most of unit IV, were deposited prior to the Holocene; unit V represents approx...
Analyses of lithology, organic-matter content, magnetic susceptibility, and pollen in a sediment core from Okpilak Lake, located in the northeastern Brooks Range, provide new insights into the history of climate, landscape processes, and vegetation in northern Alaska since 14,500 cal year BP. The late-glacial interval ([11,600 cal year BP) featured sparse vegetation cover and the erosion of min...
To simulate the evolution of Holocene climate, forcing factors for the northern high-latitude climate are examined using different numerical models. A global coupled atmosphere–ocean circulation model driven by astronomical forcing over the last 7,000 years shows a long-term sea-surface temperature decrease in the Nordic Seas region associated with changes in seasonal insolation. A continuous c...
Melting glaciers and ice caps on Baffin Island contribute roughly half of the sea-level rise from all ice in Arctic Canada, although they comprise only one-fourth of the total ice in the region. The uncertain future response of arctic glaciers and ice caps to climate change motivates the use of paleodata to evaluate the sensitivity of glaciers to past warm intervals and to constrain mechanisms ...
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