Speaker: David James
Affiliation: UCLA, EPSS
Date: Wednesday, June 3, 2026
Time: 9:00 AM
Mentor:
Dr. Lars Stixrude
Location:
Slichter 3853
Category: Seminar
Geochemistry (235): Peng Ni – Young age of fibrous diamonds from East Africa revealed by in situ Rb-Sr geochronology
Speaker: Peng Ni
Affiliation: UCLA, EPSS
Date: Thursday, June 4, 2026
Time: 12:00 PM
Abstract
Constraining the age of individual diamonds is challenging because diamond itself lacks radioactive parent–daughter nuclides in its lattice for direct dating. I show that recent advancements in mass spectrometry enable in situ Rb–Sr isotope analysis of diamonds containing high-density fluid micro-inclusions. Application of this technique to a suite of diamonds from Kankan, Guinea, demonstrates its high efficiency in Rb-Sr isotope analysis compared with previous bulk methods. The improved spatial resolution also enables potential isochron Rb-Sr dating of these diamonds. One zoned diamond, ON-KAN-381, is found to be 73 ± 81 Ma in age, overlapping kimberlite eruption ages in West Africa. Together, these results place a quantitative constraint on the formation of Kankan fibrous diamonds, indicating that they originated from mantle metasomatism events in the West African continental lithospheric mantle within tens of millions prior to the kimberlite eruption.
Colloquium (193/295): Prof. Brandan Meade – Kinematic imaging and evolution of the California earthquake system without all the stress
Speaker: Prof. Brandan Meade
Affiliation: Harvard
Date: Tuesday, September 29, 2026
Time: 3:30 PM
Location: 3853 Slichter Hall
Speaker Website: https://eps.harvard.edu/research-group/meade-group/
Abstract
Large earthquakes are infrequent while motion across fault systems is persistent. With the modern volume of geodetic data, the problem is no longer data scarcity but inference robustness: what can and cannot be resolved about kinematics on a three-dimensional fault network, and with what uncertainty. Here we describe a method for probabilistic imaging of fault system activity that achieves resolving power through the combination of dense geodetic observations, non-linear coupling constraints, and Hamiltonian Monte Carlo sampling. Applied to the California fault system, we infer heterogeneous interseismic coupling behavior with no general spatial relationship to microseismicity. These estimates of decadal scale fault system state are combined with a statistical seismicity model (without the concepts of stress or friction) to generate synthetic earthquake sequences that provide realizations of coseismic slip partitioning.
Speaker Bio
TBA
Research Expertise
Geodesy/earthquake cycle
Colloquium (193/295): Prof. Matt Jackson – TBA
Speaker: Prof. Matt Jackson
Affiliation: UCSB
Date: Tuesday, October 6, 2026
Time: 3:30 PM
Location: 3853 Slichter Hall
Speaker Website: https://www.matthewgjackson.com
Abstract
TBA
Speaker Bio
TBA
Research Expertise
mantle geochemistry
Colloquium (193/295): Prof. Amy Mainzer – TBA
Speaker: Prof. Amy Mainzer
Affiliation: UCLA
Date: Tuesday, October 13, 2026
Time: 3:30 PM
Location: 3853 Slichter Hall
Speaker Website: https://epss.ucla.edu/amy-mainzer/
Abstract
TBA
Speaker Bio
TBA
Research Expertise
asteroids, comets, and near-Earth objects
Colloquium (193/295): Prof. Lars Hansen – TBA
Speaker: Prof. Lars Hansen
Affiliation: University of Minnesota Twin Cities
Date: Tuesday, October 27, 2026
Time: 3:30 PM
Location: 3853 Slichter Hall
Speaker Website: https://cse.umn.edu/esci/lars-hansen
Abstract
TBA
Speaker Bio
TBA
Research Expertise
Rock deformation
Colloquium (193/295): Prof. Samer Naif – TBD
Speaker: Prof. Samer Naif
Affiliation: Georgia Tech & UCSD
Date: Tuesday, November 3, 2026
Speaker Website: https://egl.eas.gatech.edu/members/samer-naif/
Abstract
TBD
Research Expertise
magnetotellurics
Colloquium (193/295): Dr. Athina Peidou – TBA
Speaker: Dr. Athina Peidou
Affiliation: JPL
Date: Tuesday, November 10, 2026
Time: 3:30 PM
Location: 3853 Slichter Hall
Speaker Website: https://www.jpl.nasa.gov/site/research/peidou/
Abstract
TBA
Speaker Bio
TBA
Research Expertise
Geodesy
Colloquium (193/295): Prof. Owen Weller-Gibbs – TBA
Speaker: Prof. Owen Weller-Gibbs
Affiliation: Cambridge University, UK
Date: Tuesday, November 17, 2026
Time: 3:30 PM
Location: 3853 Slichter Hall
Speaker Website: https://www.esc.cam.ac.uk/people/owen-weller-gibbs-ne-weller
Abstract
TBA
Speaker Bio
TBA
Research Expertise
Metamorphic Petrology
Colloquium (193/295): Prof. Jiaqi Li – TBA
Speaker: Prof. Jiaqi Li
Affiliation: Peking University
Date: Tuesday, December 1, 2026
Time: 3:30 PM
Location: 3853 Slichter Hall
Speaker Website: https://geophy.pku.edu.cn/pubtphp/lijiaqi/english/
Abstract
TBA
Speaker Bio
TBA
Research Expertise
seismology/planetary seismology