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| activités | bourse | liens | membres | contact | ||
date |
Vendredi, 10 février 2006 |
lieu |
Pavillon
Adrien-Pouliot (salle 4118),
Université Laval |
| heure
|
11h30 |
| Mairi
Best Department
of Earth and Planetary Sciences, McGill University
|
|
Carbonate
preservation in shelf environments
|
Calcium
carbonate skeletons (e.g. shells), are our primary source of paleo-biological
information, and the primary way carbon is transferred from the atmosphere-ocean
to the earth’s crust in the carbon cycle. The fossil record
is our view on past life and environments on Earth, through which
we can observe the effects of such long term processes as climate
change, sea level change, and evolution. By examining past patterns
of diversity and extinction, we can better understand whether we
are having an unprecedented effect on the natural environment, and
if so what the results of this will be in terms of long term diversity
on the planet. When we look to the fossil record for understanding about current global processes such as climate change and extinctions, we need to be able to make broad comparisons across latitudes. This research tests whether processes of skeletal preservation are different among latitudes. My previous work in the tropics tested for differences in preservation across coastal environments. Recent work on the Atlantic and Pacific coasts of Canada suggests that comparable environments do not preserve skeletal material in the same way as in the tropics. Current work completes the framework for latitudinal comparison by extending into polar seas. My integrated approach in all study areas compares the condition of naturally occurring shell material with that of experimental shells, all in the context of environmental variables such as sediment composition, biologic community, and water composition. The shell assemblages are also assessed for their use in capturing modern abundance and diversity, for example for use in environmental surveys. This research assesses processes, agents and rates of modification during modern shell accumulation across latitudes, thereby greatly increasing our confidence in turning to these records for both short and long-term environmental baselines and in comparing shell accumulations through time as a proxy for tracking climate change or evolutionary patterns. In addition, as the burial patterns of skeletal carbonate become better understood at a global scale, it will then be possible to assemble a burial model of carbonate and assess where the major carbonate sinks are, thereby clarifying a poorly understood part of the carbon cycle. |
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