01/14/2016 - 12:00pm
Hubbs Hall 4500
SCRIPPS INSTITUTION OF OCEANOGRAPHY FACULTY CANDIDATE SEMINAR
DATE: January 14, Thursday, 12:00 p.m.
LOCATION: Hubbs Hall 4500
SPEAKER: Jeremy Boyce, Ph.D.
TITLE: The Lunar Apatite Paradox and Other Tales
The discovery of Earth-like levels of hydrogen in the phosphate mineral apatite was the first of several new perspectives recently added to the study of volatile-depleted lunar basalts. As we work towards a unified model for the formation and evolution of the Earth-Moon system, it is a good time to stop and consider what we can learn from different kinds of geochemical and isotopic studies of lunar apatite. First, I’ll demonstrate that measured sulfur abundance and oxidation-state measurements in lunar apatite indicate that there is not only (previously undiscovered) sulfate in lunar magmas, but that there may also be a (previously undiscovered) sulfide substitution in apatite as well. I’ll describe briefly the possibility that apatite and other minerals may hold the potential to be single-phase oxybarometers. Second, I’ll discuss chlorine isotope measurements in mare basalts, and how they are best explained by planetary-scale degassing and not syneruptive magmatic degassing. A model is only as good as the testable hypotheses it produces, so I'll outline a couple of simple tests currently underway in my group. Finally, I’ll show how literature data and high school chemistry were combined to explain the high “water” contents of apatites found in “dry” rocks, a.k.a. the lunar apatite paradox. I’ll explain what this and other overlooked observations mean for apatite-based evidence for the origin and evolution of lunar hydrogen.
Faculty Host: David Hilton (email@example.com)
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