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Earth Institute Staff Directory

Dr. Dallas Abbott

Adjunct Research Scientist , Marine Geology & Geophysics , Lamont-Doherty Earth Observatory (LDEO) , The Earth Institute

103 Oceanography
61 Route 9W
PO Box 1000
Palisades, NY 10964

BIOGRAPHY: Dallas Abbott has worked in the areas of Marine Geology, Geophysics, Precambrian Geology, and Impact Geology. Over the past 13 years, Abbott has developed the microtechniques necessary to study the fine debris from oceanic impacts. Deep-sea impacts pose several problems. The first is a very restricted sample size compared to subaerial impacts. The second is a lack of large quartz grains in most settings, resulting in a reduced abundance of or no shocked quartz. Her collaborators and she have developed microtechniques to study oceanic impacts. They use the scanning electron microscope and analyses of thin sections of tiny grains to find and confirm impact ejecta.

Abbott has also learned how to separate out particulates from ice cores at ages of suspected Holocene impacts. They measured the highest concentration ever of marine diatoms in the GISP2 ice core. The diatoms are low latitude and originate from a source on a continental shelf with high biological productivity. Several other types of dust, including micrometer sized CaCO3 crystals, accompany the diatoms. The latter may have caused a dust veil and climate downturn that lasted for 18 months (Feb. 536 to June 537 AD). Some dust with both substantial Ni and K may be impact ejecta. They are still developing these microtechniques but they have already yielded some important scientific results. By combining proxies for continental dust with historical accounts of unusual dust storms, they have managed to date their ice core samples to within a calendar year. This allows us to tie our scientific results into the historical record-a mix that should attract students of both Earth Science and History. One accomplishment is documenting oldest primary native Fe ever found. Abbott and her collaborators found 1.6 Ga native Fe in the Chaibasa Formation in India. This is the worlds oldest primary native Fe by over a billion years.

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