Monday, January 17, 2011

Chasing volcanic intruders on Greenland

As a follow-up to the Arctic adventure from the last blog post, I will show some of the geological gems of West Greenland. Along Vaigat north of Ilulissat, volcanic rocks belonging to the North Atlantic igneous province crop out. The volcanism took place in a near-shore environment about 55-56 million years ago. At the same time, the Earth experienced a 200.000 year period of global warming (the so called Paleocene-Eocene thermal maximum; PETM). I went there the summer of 2006 to sample sills, dikes, and metamorphic sediments, as I work with an hypothesis linking the volcanism to the climate change.

The pictures of the week show 1) igneous dikes cross-cutting Cretaceous sandstone and coal beds, and 2) a sill intrusion outcropping like a big massive whale. Spectacular outcrops, indeed. 

The whale:

An interesting feature of volcanic intrusions is that they heat the surrounding sediments. This may sometimes lead to mobilization of the sediments. The picture below shows a sandstone intrusion into coal beds, possibly mobilized as a consequence of volcanic activity – although high pressures in the sand layer (for instance due to high water content and rapid burial) could have played a role as well. 

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