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Dr. Joanne Johnson - Profile

Research Interests

My current project at BAS is concerned with the Pine Island Bay region of Antarctica. The Pine Island and Thwaites glaciers exhibit the most rapid elevation change, thinning and retreat in Antarctica. It has been suggested that this area may be the most likely site for initiation of collapse of the 2 million km^2 West Antarctic Ice Sheet (WAIS). This would result in global sea level rise of 5-6m!

I am using cosmogenic surface exposure dating to construct an age versus elevation record for nunataks near the Pine Island Glacier (e.g. the Hudson Mountains). This will tell us how quickly the glacier thinned in the past. I will combine these dates with radiocarbon dates from marine sediments to assess the lateral extent and retreat of the WAIS across the continental shelf in the Quaternary (last 1.8 million years). This work forms part of the QWAD (Quaternary West Antarctic Deglaciation project, within the GRADES (Glacial Retreat in Antarctica and Deglaciation of the Earth System) programme, which runs from 2005-2010. I visited the Hudson Mountains in 2006, as part of the Alfred Wegener Institute cruise ANT-XXIII/4 on the RV Polarstern. Please see Johnson et al. 2008 (Geology) for the results of this work. There is also a good article in Nature Reports Climate Change describing my work in the Amundsen Sea Embayment at

http://www.nature.com/climate/2008/0804/full/climate.2008.30.html

 

From August 2002 to April 2005, I worked on a project focusing on the origin and palaeoenvironmental implications of authigenic alteration minerals in volcaniclastic rocks from James Ross Island (Northern Antarctic Peninsula). The aim was to understand the relationship of alteration to the composition of porewaters present during eruption, and to determine whether the chemical composition of alteration products (such as zeolites and clay minerals) reflects the alteration environment. I undertook Antarctic fieldwork on James Ross Island in January 2003 and January-March 2004. This formed part of the LCHAIS (Late Cenozoic History of the Antarctic Ice Sheet) project, within the GIANTS (Global Interactions of the ANTarctic Ice Sheet) programme (which ran from 2000-2005).

For my PhD, I studied the geochemistry of a suite of alkaline lavas from the Vitim Volcanic Field in Siberia. This lies ~ 200 km east of Lake Baikal, in one of the world's major continental rift zones. My research involved using geochemical characteristics of these lavas to constrain the composition and thickness of the lithosphere in the Baikal Rift Zone, and to improve our understanding of the melting regime beneath the region during the Cenozoic.