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| Small, David; Parrish, Randall R.; Austin, William E. N.; Cawood, Peter A.; Rinterknecht, Vincent. |
| Understanding the provenance of ice-rafted debris (IRD) provides a means to link the behavior of individual ice sheets to proxy records of climate change. Here we present a new approach to determining IRD provenance using U-Pb geochronology of detrital minerals rutile and zircon. We characterize potential source regions from Scotland using detrital rutile from modern fluvial systems, and demonstrate that their unimodal rutile U-Pb ages reflect the timing of the last amphibolite facies metamorphism of the source rocks, imparting a distinctive source signature. Contrasts between these spectra and the bimodal IRD (ca. 470 Ma and ca. 1800-2000 Ma) rutile age signatures rule out Scotland as the sole source and suggest a Laurentian contribution; IRD zircon ages... |
| Tipo: Text |
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| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00181/29197/27590.pdf |
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| Small, David; Rinterknecht, Vincent; Austin, William E. N.; Bates, Richard; Benn, Douglas I.; Scourse, James D.; Bourles, Didier L.; Hibbert, Fiona D.. |
| Geochronological constraints on the deglaciation of former marine based ice streams provide information on the rates and modes by which marine based ice sheets have responded to external forcing factors such as climate change. This paper presents new 36Cl cosmic ray exposure dating from boulders located on two moraines (Glen Brittle and Loch Scavaig) in southern Skye, northwest Scotland. Ages from the Glen Brittle moraines constrain deglaciation of a major marine terminating ice stream, the Barra-Donegal Ice Stream that drained the former British-Irish Ice Sheet, depending on choice of production method and scaling model this occurred 19.9 ± 1.5–17.6 ± 1.3 ka ago. We compare this timing of deglaciation to existing geochronological data and changes in a... |
| Tipo: Text |
Palavras-chave: Deglaciation; Scotland; Cosmogenic exposure ages; Chlorine-36. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00349/46010/83047.pdf |
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| Small, David; Austin, William; Rinterknecht, Vincent. |
| A sediment core from the north-east North Atlantic contains high-resolution co-registered foraminiferal O-18 and ice-rafted detritus (IRD) records for the last deglaciation. These reveal a distinct ice-rafting event that occurred at the time of Greenland Interstade 1d (GI-1d), a feature also seen in other high-resolution cores from the North Atlantic. The occurrence of a geographically widespread peak in IRD at ice distal sites at a time when increased freshwater flux to the surface ocean is inferred to have caused rapid cooling suggests a mechanistic link between the processes, analogous to the Younger Dryas (GS-1) cooling episode. The general absence of IRD at southern locations at other times during GI-1 when the flux of icebergs from surviving ice... |
| Tipo: Text |
Palavras-chave: Deglaciation; Hydrography; Ice-rafted detritus; North Atlantic; Sea surface temperature. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00291/40180/39238.pdf |
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