During the 16th Italian Antarctic Expedition (2000/01) a geomorphological survey of permafrost-related polygons was carried out in the Mesa Range area, upper Rennick Glacier. The investigated site is located in the uppermost reaches of Pain Mesa, which forms the northern sector of the Mesa Range. An ice wedge was found in a volcanic regolith at about 2200 m a.s.l. This altitude is below a well-defined erosional trimline, located at about 2380 m a.s.l. in this sector of Pain Mesa. The ice was sampled by inserting an ice screw, with an internal diameter of 14 mm, into the ice wedge in vertical sequences. Oriented block samples for thin sections were taken. A co-isotopic study was performed, measuring both oxygen (delta O-18) and hydrogen (delta D) isotope compositions. Tritium activity was measured, and major cations and anions were determined. The delta O-18 and delta D obtained showed a strong divergence from the snowfalls expected to occur at this elevation, with extremely negative d excess values. Sublimation processes were taken into account to define the origin of the ice forming the wedge. The tritium data obtained suggest that the growth process of the ice wedge might still be active today.
Growth processes of an inland Antarctic ice wedge, Mesa Range, northern Victoria Land / Raffi, Rossana; Barbara, Stenni; Onelio, Flora; Stefano, Polesello; Marina, Camusso. - In: ANNALS OF GLACIOLOGY. - ISSN 0260-3055. - STAMPA. - 39:1(2004), pp. 379-385. (Intervento presentato al convegno 7th International Symposium on Antarctic Glaciology (ISAG-7) tenutosi a Milan, ITALY nel AUG 25-29, 2003) [10.3189/172756404781814195].
Growth processes of an inland Antarctic ice wedge, Mesa Range, northern Victoria Land
RAFFI, Rossana;
2004
Abstract
During the 16th Italian Antarctic Expedition (2000/01) a geomorphological survey of permafrost-related polygons was carried out in the Mesa Range area, upper Rennick Glacier. The investigated site is located in the uppermost reaches of Pain Mesa, which forms the northern sector of the Mesa Range. An ice wedge was found in a volcanic regolith at about 2200 m a.s.l. This altitude is below a well-defined erosional trimline, located at about 2380 m a.s.l. in this sector of Pain Mesa. The ice was sampled by inserting an ice screw, with an internal diameter of 14 mm, into the ice wedge in vertical sequences. Oriented block samples for thin sections were taken. A co-isotopic study was performed, measuring both oxygen (delta O-18) and hydrogen (delta D) isotope compositions. Tritium activity was measured, and major cations and anions were determined. The delta O-18 and delta D obtained showed a strong divergence from the snowfalls expected to occur at this elevation, with extremely negative d excess values. Sublimation processes were taken into account to define the origin of the ice forming the wedge. The tritium data obtained suggest that the growth process of the ice wedge might still be active today.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
