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Ostwald ripening of air-hydrate crystals in polar ice sheets : A new tool for dating old meteoric ice.

Séminaire de V. Lipenkov (AARI, Russia), Mardi 11 Décembre 2018 à 10h en salle Lliboutry, Bâtiment de Glaciologie

3 décembre 2018, par Fabien Gillet-Chaulet

Ostwald ripening of air-hydrate crystals in polar ice sheets : A new tool for dating old meteoric ice.

V. Lipenkov
Arctic and Antarctic Research Institute, St. Petersburg, Russia

The post-formation growth (Ostwald ripening) of air-hydrate crystals occurs in polar ice sheets due to the diffusion of air molecules through the ice matrix from smaller crystals towards larger ones. The mathematical model of this process predicts that in old (> 400 ka) and warm (> -10°C) polar ice, the size of hydrates should increase linearly with their age. This theoretical inference has been confirmed by the experimental data – a strong linear relationship between the size of air-hydrate crystals and the age of ice has been observed in ice older than 400 ka in the well dated Dome Fuji and EDC ice cores. Given that this relationship exists, one may be able to date deep Antarctic ice from the measured sizes of air hydrates. Based on currently available data on hydrate growth, we estimated the maximum age of stratigraphically disturbed meteoric ice near the base of the Vostok ice core to be 1.22±0.15 Ma.
Future plans for the Vostok Oldest Ice Challenge (VOICE) will be presented, and possible areas of collaboration discussed.

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