Seminars on Science
Karen Hanghoj

I am a geologist and associate research scientist at Lamont Doherty Earth Observatory of Columbia University. I came here after four years at the Woods Hole Oceanographic Institution in Massachusetts.

I grew up in Denmark - a country practically without rocks, and I decided to become a geologist based on some pretty vague ideas about what Geology was. I had a general interest in science and a notion that I would probably get to travel to cool places with real rocks! As it turned out I immediately knew that it was the right decision for me. I loved studying Geology, and the most difficult part was choosing what topic to work on because I was interested in everything - petrology, paleontology, Quaternary geology and much more. Probably the most defining event in making my choice and shaping my carrier came with the opportunity to do fieldwork in Greenland. I worked on the famous Skaergaard Intrusion, which is a tiny fraction of the North Atlantic Igneous Province, formed during the continental break-up of Europe, Greenland and North America and the genesis of the Atlantic Ocean about 55 million years ago. This work was so fascinating that I became an igneous petrologist.

Zohar Ris
Karen Hanghoj in Alaska. ©AMNH

Greenland is one of those places that you either don't care for or a place that you keep trying to go back to. It is an incredible wilderness. There are very few people and they are concentrated in a few towns and villages. There are no roads between these towns, just vast mountains and glaciers and fjords.  For a geologist it’s heaven. The outcrops are fantastic and there are rocks of almost every geological age and process of formation, allowing us to study a variety of geological problems. Obviously I’m one of those people that keep trying to go back and last year I spent my 10th summer in Greenland. The first years my work focused on break-up related rocks like the Skaergaard Intrusion and coastal dyke swarms, which are literally thousands of lava filled fractures that formed as the two continental masses pulled apart and hot magma ascended to the surface where it was erupted.  Lately I have studied the genesis of the earth’s old continents, formed more than 3 billion years ago, by looking at mantle xenoliths, which are tiny fragments of the roots of the continent, that accidentally (or luckily rather!) were brought to the surface. Another geological interest that I have been able to pursue in Greenland is mineral exploration. From my earliest student years, and still to this day, I have occasionally participated in looking at gold and platinum group element mineralizations. This is great fun. While it still basically all comes down to looking at rocks and interpreting the geology, it involves different logistical challenges in working with diamond drillers and making a project run smoothly.

Of course there has been fieldwork and fieldtrips in places other than Greenland. For example I’ve worked in Norway, Alaska, Cyprus, Iceland, California and Oregon. And, while I was a PhD student, I got the chance to dive in Alvin, the deep sea submersible from Woods Hole Oceanographic Institution. We dove on the Mid-Atlantic ridge to look at the rocks exposed in the rift valley at a depth of 4500 m. This was an amazing experience. Everything that we learn about geology is hinged on the model of plate tectonics and the existence of plate margins where crust is being destroyed (by subduction of oceanic crust) and constructed (by volcanism at the mid ocean ridges). Being able to actually go see a mid-ocean ridge, see that it is really a mountain chain at the bottom of the ocean, see that there are fresh lavas and evidence of tectonic movement, and see some of the unbelievably cool creatures that live in this eternally dark environment, was truly a mind-blowing experience.

Today my research focuses on the mantle and lower crust from different tectonic environments, i.e., the oceanic, continental and arc settings. I work on rocks from Oman, Alaska, Greenland and the oceans to study the composition, structure and evolution of the crust and the processes that generate the very different types of crust we see. I still love being out in the field and thinking about how our observations there teach us about the processes that form and shape the earth.

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