IGPP Seminar Series

Eltanin: The Ocean Impact

by Frank Kyte
UCLA, IGPP

Abstract

The late Pliocene (2.5 Ma) Eltanin impact is the only known impact of a km-sized asteroid into a deep-ocean (5 km) basin. This impact was originally discovered in 1980 in three sediment cores collected in the 1960s. Expeditions of the FS Polarstern in 1995, 2001, and 2009 mapped 80,000 km^2 of the ocean floor and collected 22 new sediment cores with impact deposits. Since the impact target was seawater, the ejecta from this impact is composed of meteoritic material with a few percent salt. The impact severely disturbed sediments locally, ripping up and redepositing sediments as old as Eocene (~50 Ma) in a well-characterized impact deposit composed of chaotic boulders grading into laminated sands and silts. The meteoritc ejecta, which settled into the top of the impact deposit, is 90% mm-sized shock-melted asteroid, 10% unmelted meteorites (low-metal mesosiderite) and trace impact spherules. The first half of the talk will review the impact and its deposits. The second half will concentrate on recent work on impact spherules formed in the impact plume. These record processes such as accretionary growth and chemical fractionation due to condensation/distillation.
Tuesday, 18 May 2010
3853 Slichter Hall
Refreshments at 3:45 PM
Lecture at 4:00 PM