LPI Seminar Series
Effective January 1, 2011, LPI seminars will be held on Fridays.
LPI seminars are held from 3:30–4:30 p.m. in the Lecture Hall at USRA, 3600 Bay Area Boulevard, Houston, Texas. Refreshments are served at 4:30 p.m. For more information, please contact Yann Sonzogni (phone: 281-486-2199; e-mail:email@example.com) or Ross Potter (phone: 281-486-2144; e-mail: firstname.lastname@example.org). A map of the Clear Lake area (PDF format) is available here. The Acrobat Reader 8.0 is available from Adobe. This schedule is subject to revision.
- Friday, June 21, 2013 - Lecture Hall, 3:30 PM
Francis McCubbin, University of New Mexico
Magmatic Volatiles in the Inner Solar System: Constraints from Apatite in Planetary Materials and Apatite-Melt Partitioning Experiments TBD
Magmatic volatiles like water, C-species, S- species, N-species, and the halides play many important roles in geologic processes on Earth, from magma genesis to climate change. Furthermore, these components are the basis of organic chemistry and they are required for life. However, little is known about the origin, abundances, and roles of magmatic volatiles among the other terrestrial bodies in our Solar System. In the present study, we attempt to gain a first-order understanding of the magmatic volatiles H2O, F, and Cl through analyses and experimental work centered around the calcium-phosphate mineral apatite. The mineral apatite contains F, Cl, and OH as essential structural constituents, and it is ubiquitous in planetary materials. Consequently, we have analyzed apatites from Earth, Moon, Mars, 4-Vesta, and ordinary chondrites to gain a better understanding of the magmatic volatile inventories and distributions within those bodies. Importantly, apatite does not mirror the magmatic volatile load of a fluid or melt from which it formed; therefore, we have conducted petrologic experiments to investigate the partitioning behavior of H2O, F, and Cl between apatite and silicate melts. These experiments allow one to develop quantitative models to to infer concentrations of volatiles in magmatic liquids and source regions. Our work has shown that the inner Solar System is looking much wetter than it has in the past, raising important questions about the origin of volatiles in the terrestrial planets.
- Friday, June 28, 2013 - Lecture Hall, 3:30 PM
Rosalind Armytage, University of Houston
- Friday, July 26, 2013 - Lecture Hall, 3:30 PM
Oliver White, Lunar and Planetary Institute
Crater Relaxation on the Saturnian Mid-Sized Icy Satellites and its Relation to their Thermal Histories
Evidence for relaxation of impact crater topography has been observed on many icy satellites, including those of Saturn, and the magnitude of relaxation can be related to past heat flow. Earlier surveys of crater morphologies using shadow lengths and photoclinometry (shape-from-shading) processing of Voyager imagery have yielded depth/diameter measurements for only a limited number of craters across a fairly narrow size range. We have used new stereo- and photoclinometry-derived global digital elevation models (DEMs) of the surfaces of these satellites that we have generated from Cassini data to obtain measurements for many more craters across a much wider size range than was previously possible. For the satellites Rhea, Iapetus, Dione and Tethys, we have obtained enough measurements to define a scale of relaxation for the craters. We have performed relaxation simulations to determine what heat flow magnitudes and durations are necessary in order to achieve the current morphologies of certain relaxed and unrelaxed craters. When combined with age estimates based on crater counting, these results contain strong implications for the thermal histories and heating mechanisms of these satellites, and aid in constraining models for their origins.