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| Zimmerman, Susan H.; Hemming, Sidney R.; Kent, Dennis V.; Searle, Stephanie Y.. |
| Lakes are highly sensitive recorders of climate processes, but are extremely difficult to correlate precisely to ice-core and marine records, especially in the absence of reliable radiocarbon dates. Relative paleointensity (RPI) of Earth's magnetic field is an independent method of correlating high-resolution climate records, and can be applied to both marine and terrestrial sediments, as well as (inversely) correlated to the cosmogenic nuclide records preserved in ice cores. Here we present the correlation of an RPI record from Mono Lake, California to GLOPIS, the Global PaleoIntensity Stack, which increases the age estimation of the basal Mono Lake sediments by > 20000 yr (20 kyr), from similar to 40 ka (kyr before present) to 67 ka. The Mono Lake... |
| Tipo: Text |
Palavras-chave: Paleointensity; GLOPIS; Argon; Great Basin; Mono Lake excursion; Laschamp. |
| Ano: 2006 |
URL: https://archimer.ifremer.fr/doc/00234/34500/33454.pdf |
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| Boswell, Steven; Toucanne, Samuel; Creyts, Timothy T.; Hemming, Sidney R.. |
| We introduce a methodology for determining the transport distance of subglacially comminuted and entrained sediments. We pilot this method on sediments from the terminal margin of the Baltic Ice Stream, the largest ice stream of the Fennoscandian Ice Sheet during the Last Glacial Maximum. A strong correlation (R2 = 0.83) between the εNd and latitudes of circum-Baltic river sediments enables us to use εNd as a calibrated measure of distance. The proportion of subglacially transported sediments in a sample is estimated from grain size ratios in the silt fraction (<63 μm). Coupled εNd and grain size analyses reveal a common erosion source for the Baltic Ice Stream sediments located near the Åland sill, more than 850 km upstream from the terminal moraines.... |
| Tipo: Text |
Palavras-chave: Fennoscandian Ice Sheet; Baltic Ice Stream; Provenance; Epsilon Nd; Grain size; EMMA. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00434/54567/57539.pdf |
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| Hemming, Sidney R.. |
| Millennial climate oscillations of the glacial interval are interrupted by extreme events, the so-called Heinrich events of the North Atlantic. Their near-global footprint is a testament to coherent interactions among Earth's atmosphere, oceans, and cryosphere on millennial timescales. Heinrich detritus appears to have been derived from the region around Hudson Strait. It was deposited over approximately 500 +/- 250 years. Several mechanisms have been proposed for the origin of the layers: binge-purge cycle of the Laurentide ice sheet, jokulhlaup activity from a Hudson Bay lake, and an ice shelf buildup/collapse fed by Hudson Strait. To determine the origin of the Heinrich events, I recommend (1) further studies of the timing and duration of the events,... |
| Tipo: Text |
Palavras-chave: Climate; Heinrich layers; Heinrich events; Ice-rafted detritus. |
| Ano: 2004 |
URL: https://archimer.ifremer.fr/doc/00224/33549/32033.pdf |
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