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Ucla Tektite Lecture 2/26/17


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http://eamailer.support.ucla.edu/Images/Project/13388/MeteoriteBanner_06.03.16_blue.pngFeb. 2017 News from the UCLA Meteorite Gallery

One of a series of monthly letters sent to visitors to the UCLA Meteorite Gallery and to others who requested to be on the mailing list.

The Meteorite Gallery (Geology room 3697) is open with a docent present every Sunday from 1 until 4 with the exception of the last two Sundays in the calendar year. And it is open every work day from 9 until 4 but without a docent.  It is not open Saturdays.

We remind you that our website address is: http://www.meteorites.ucla.edu/. There you can find a map of our corner of the UCLA campus and instructions for parking in structure 2.

At 2:30 on Sunday Feb. 26 the speaker at our Gallery Event is the co-curator John Wasson. Although emeritus, John remains active in research with most of his efforts focused on chondrules and the formation of chondrites and iron meteorites. And, as this Sunday, on tektite formation. The title of his lecture is: “Formation of tektites in thermal plumes: no craters required”.

Summary:  Tektites are glassy samples with interesting shapes (e.g., teardrops) and compositions similar to soils and shales that formed as a result of weathering the continental crust. Since 1960 the consensus view has been that tektites are crater ejecta.  However, high concentrations of 10Be (halflife of 1.5 My) show that tektites are made from soils from the upper 50 centimeters of the crust.  The best model seems to be thermal plumes resulting from accreting weak asteroids or comets that disintegrated and deposited their entire energy in the atmosphere, similar to the 1908 Tunguska event.  Dust was entrained into these hot plumes and melted there; collisions among droplets led to the growth of the splash-form tektites.

The lecture this month is in a new location: Geology 3656, just 40 yards west of the UCLA Meteorite Gallery. This is a larger and more comfortable room than our previous venue in Slichter, and about the same distance.

 

Our next Gallery Lecture will occur on Sunday March 12. The speaker is Roger Fu, a recent Ph.D. from MIT who will be an assistant professor at Harvard starting this fall.  His title is “The water-rich interior of dwarf planet Ceres”.  New data from the NASA Dawn spacecraft has revealed that the dwarf planet Ceres (940 km diameter) shows characteristics of both "rocky" and "icy" bodies.  He will talk about how the morphology and spectroscopy of the surface point to a composition with less than 30% water ice.  Even so, intriguing features observed on Ceres suggest localized regions enriched in sub-surface ice and, possibly, the existence of an ancient global ocean during its early history.

 

Reminder: You can now find the UCLA Meteorite Gallery on Social Media. Please like us on Facebook (https://www.facebook.com/UCLAMeteorites) and follow us on Twitter (@UCLAMeteorites) and Instagram (uclameteorites).

JTW

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