Treverrow, A and Warner, RC and Budd, WF and Craven, M, Meteoric and marine ice crystal orientation fabric observations from the Amery Ice Shelf, East Antarctica, MOCA-09: Our Warming Planet, IAMAS-IAPSO-IACS Joint Assembly, 19-29 July 2009, Montreal, Canada, pp. C03.16/23412. (2009) [Conference Extract]
During the 2001/02 and 2003/04 austral summers ice cores were obtained from the AM01 and AM01b sites; approximately 100 km from the shelf front. Further cores were obtained 70 km upstream, along the same flow line, at the AM04 site during 2005/2006. At these sites, the Amery Ice Shelf has a layered structure. The upper layer consists of meteoric ice, from local accumulation and ice entering the shelf through the Lambert Glacier drainage system. The bottom layer is accreted marine ice, over 200 m thick.
Crystal orientation fabric and grain size measurements are presented for meteoric and marine ice cores. Meteoric ice samples are characterized by grain areas >50 mm2 and multiple- maxima crystal orientation fabrics. It is suggested that stress relaxation in ice flowing into the shelf from the Lambert Glacier drainage basin strongly influences the observed meteoric ice fabrics.
Vertical, large circle girdle orientation fabrics observed within the marine ice are influenced by the presence of brine and insoluble microparticle inclusions. Grain sizes in the marine ice are <10 mm2 due to microparticles restricting grain growth. A strong single maximum fabric and layered, rectangular texture w as observed in the marine ice sample obtained closest to the ice shelf base. The fabric and texture of this sample are considered to be evidence for marine ice layer accumulation by frazil ice platelet accretion.
|Item Type:||Conference Extract|
|Keywords:||marine ice, meteoric ice, Amery Ice Shelf|
|Research Division:||Earth Sciences|
|Research Group:||Physical Geography and Environmental Geoscience|
|Objective Division:||Expanding Knowledge|
|Objective Group:||Expanding Knowledge|
|Objective Field:||Expanding Knowledge in the Earth Sciences|
|UTAS Author:||Treverrow, A (Dr Adam Treverrow)|
|UTAS Author:||Warner, RC (Dr Roland Warner)|
|UTAS Author:||Budd, WF (Professor William Budd)|
|UTAS Author:||Craven, M (Mr Mike Craven)|
|Deposited By:||CRC-Antarctic Climate & Ecosystems|
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