Results from the ANDRILL McMurdo Sound Project

Le professeur Doug Schmitt de l'Université d'Alberta vous invite à une conférence midi à l'INRS, le 10 Juillet prochain.  La conférence aura lieu au local 2417 à midi et est intitulée «Measuring stress beneath the ice in Antarctica: Results from the ANDRILL McMurdo Sound Project».

The ~43 Ma separation of Antarctica from Australia and the opening of the Drake Passage between S. America and Antarctica about 30 Ma had significant consequences for the Earth’s climate.  Prior to this communication between the Indian and Pacific Oceans was blocked.   Removing these barriers isolated Continental and formed the Southern Hemisphere Ocean and the Antarctic Circumpolar Circulation resulting in a drastic cooling and the development of the ice sheets.     

This makes Antarctica a sensitive gauge of global climate: simply put if it is warm in Antarctica the planet is also likely to overall be warm. And if Antarctica is warm then the oceans immediately surrounding Antarctica will be open water that produces quite different sediments than if the water is covered by ice. The International Antarctic Geological Drilling (ANDRILL) Program, a collaboration primarily between New Zealand, U.S., German, and Italian researchers (and one sneaky Canadian J), was developed to carry out continental scientific drilling in Antarctica to address issues of long term climate variations by studying the changes the sediments over about the last 25 Ma.  An additional secondary goal of the drilling, however, is to address the tectonics with a focus on the state of stress; and this was addressed through analysis of the complete set of core fractures, image logging, and hydraulic fracturing.  In particular, a special wireline packer system was developed to carry out such measurements. This was deployed at the end of the drilling of the South McMurdo Sound borehole at depths reaching 1500 m from the rig floor (about 1000 m into the subsea sedimentary rocks).  These measurements showed that a strike-slip stress regime exists at the location of the borehole.  

The seminar will give an overview of the climate and tectonic findings from the ANDRILL project as well as some sense for what it is like to be involved in a large, intensive geoscience scientific drilling project.  Future plans for drilling at a site from the ice shelf moving at 2 m per day! will also be mentioned.