Geocheminar - winter-2013

Jan. 8, 2013
noon - 1 p.m.
Geology 4677

Presented By:

• Sarah Palaich - UCLA

Raman spectroscopy, X-ray diffraction and first principles calculations shed light on the high pressure behavior of the complex ionic minerals hanksite and tychite.

Jan. 15, 2013
noon - 1 p.m.
Geology 4677

Presented By:

• Daniel Hummer - UCLA

In many oxide mineral systems, the initial product of precipitation from a fluid is a metastable phase, seemingly violating our understanding of thermodynamics. A possible explanation is that phase stability depends not only on temperature and pressure, but also on particle size due to a surface energy term prominent in nano-sized crystals. Powerful new in situ experimental techniques combined with ab initio calculations have revealed the origin of this excess energy, and how it influences the crystallization of TiO2 during its earliest stages. The results suggest that some minerals may have a much richer history than previously imagined.

Jan. 29, 2013
noon - 1 p.m.
Geology 4677

Presented By:

• Claire Waller - CalTech

Silicate melts are a major driving force of planetary differentiation and play a large role in the thermal and chemical evolution of the earth. During crystallization of a putative magma ocean and also during partial melting events in predominantly solid mantle environments, the formation of chemically distinct reservoirs controlled by gravitational differentiation is intimately linked to the solid and liquid equations of state (EOS). Hence, a fundamental knowledge of silicate liquid volumes at extreme pressure and temperature conditions is necessary for understanding the evolution of the earth, yet melts are complex materials that can create many challenges to experimental and theoretical prediction of their properties. I will be presenting the results and challenges of constraining liquid EOS using shock wave pre-heated sample techniques. Specific to these results, I will discuss our current understanding of the temperature dependence of sound speed in ultramafic liquids and also explore the question of whether a liquid could be gravitationally stable at the core-mantle boundary.

Feb. 5, 2013
noon - 1 p.m.
Geology 4677

Presented By:

• Ellen Kooijman - UCSB

Seminar Description coming soon.

Feb. 12, 2013
noon - 1 p.m.
Geology 4677

Presented By:

• Anke Watenphul - UCLA

Seminar Description coming soon.

Feb. 19, 2013
noon - 1 p.m.
Slichter 3853

Presented By:

• Alan Rubin - UCLA

Seminar Description coming soon.

Feb. 26, 2013
noon - 1 p.m.
Slichter 3853

Presented By:

• Haolan Tan - University of Chicago

60Fe have proven to be extremely useful for studying the birth of the solar system, however the initial abundance of 60Fe as well as its distribution was still in debate. We developed a new method to analyze Ni isotopic composition as well as Fe/Ni ratio in achondrites and chondritic constituents. We derived a lower initial 60Fe/56Fe as 11.5*10^-9 at CAI condensation, and conclude that 60Fe was homogeneously distributed among the planetary bodies. This low ratio is consistent with derivation of 60Fe from galactic background implying that the stellar source for 26Al must be reconsidered to be rich in 26Al but poor in 60Fe.

March 5, 2013
noon - 1 p.m.
Slichter 3853

Presented By:

• Beth Ann Bell - UCLA

Seminar Description coming soon.

March 12, 2013
noon - 1 p.m.
3853 Slichter

Presented By:

• Andrew Barth - IUPUI

Seminar Description coming soon.

Jan. 17, 2014
noon - 1 p.m.
Slichter 3853

Presented By:

• Terry Plank - Lamont-Doherty

Seminar Description coming soon.

March 11, 2014
noon - 1 p.m.
Slichter 3853

Presented By:

• Winnie Wu - UCLA

Seminar Description coming soon.