|
Jie (Jackie) Li Rodney C Ewing Collegiate
Professor Ph.D. Harvard University B.S. USTC |
CV Google Scholar Wiki Wiki
DAC Gallery I
am a geochemist and mineral physicist interested in understanding the
response of material properties to extreme conditions and exploring the
implications for the formation of habitable worlds. Our
studies have provided new insights into the composition, thermal state, and
dynamics of rocky planets and moons, helping to solve a number of Earth
Enigmas, Core
Conundrums, Mantle
Mysteries, and Planet
Puzzles. |
EARTH ENIGMASSynthesis Across
Disciplines
|
Phase transformations and chemical reactions
drive planetary differentiation and element cycles. What are the key
reactions governing the formation and evolution of the living Earth? Through
a Sloan Foundation - Deep Carbon Observatory grant, I led a synthesis project
“Earth in Five Reactions” to study how reactions control the movement
of life’s ingredients in Earth. We held a multi-disciplinary international
workshop in Washington DC in 2018, and published a special issue in American
Mineralogists. Understanding Earth’s inner workings requires
synthesis of geochemistry and mineral physics with seismology and
geodynamics. I have actively participated in CIDER (Cooperative
Institute for Dynamic Earth Research) for more than one decade, giving
lectures, organizing mini-symposiums, and serving as the Chair of its
Advisory Committee. Our cross-disciplinary projects have
produced unique insights into big-picture questions. “Deep
carbon cycle through five reactions” AM 2019 “How did
early Earth become our modern world?” ANEPS 2012 “Upside-down
differentiation and Generation of a “primordial” lower mantle” Nature 2010 “Precipitation
of multiple light elements to power Earth’s early dynamo” EPSL 2020 |
CORE CONUNDRUMSIron-Alloys at Extreme
Conditions
|
Earth’s core spans more than half of the
planet’s radius, hosts most of its precious metals, and generates the
geomagnetic field. How did the core form and what light elements kept the core molten and convecting? To answer these
questions we simulate the conditions of proto- and present core in laboratory
using large-volume press and diamond anvil cells, and then quantify the
effects of high pressure and high temperature on the physical properties and
chemical behavior of iron-rich alloys using microanalytical techniques and
synchrotron X-ray diffraction and spectroscopy methods. Our experimental investigations were
supported by NSF grants and have provided constraints on the formation and
composition of Earth’s core. “Hidden
carbon in Earth's inner core revealed by shear softening in dense Fe7C3”
PNAS, 2014 “Experimental constraints
on core composition” TGC, 2014 “Element
partitioning constraints on the light element composition of the Earth's
core” GRL 2001 “Geochemistry
of mantle-core differentiation at high pressure” NATURE 1996 |
MANTLE MYSTERIESCompressed Silicates
and Carbonates
|
Seismic
images revealed low-velocity regions above the Earth’s core-mantle
boundary, including small patches of ultra-low velocity zone (ULVZ) and
large low shear velocity provinces (LLSVP). What are the origins of these
structures? Through high-pressure experiments using diamond anvil cells and
synchrotron radiation, we probed the melting behavior, spin crossover, and
densities of iron-bearing metals and silicates to help elucidate the nature
of mantle heterogeneity. “Formation of large low
shear velocity provinces through disproportionation of oxidized mantle”
Nature
Comm, In press “Valence
and spin states of iron are invisible in Earth’s lower mantle” Nature
Comm, 2018 “Origin of ultra-low
velocity zones through mantle-derived metallic melt” PNAS 2016 The Earth’s mantle transition zone (MTZ)
is particularly interesting because it can hold the entire ocean’s water in
crystalline structures and may pose barrier to diamond formation and carbon
subduction. We performed experiments to test the intriguing hypothesis of
hidden ocean in the MTZ, examine the stability of carbonates, and investigate
the kinetics of diamond-forming reactions. Our observations have shed light
on the nature and dynamics of the MTZ. “Metallic iron limits
silicate hydration in Earth's transition zone” PNAS 2019 “Kinetic
control on the provenance of superdeep diamonds” GRL 2019 |
PLANET PUZZLESGeo-Cosmo-Astro |
The Earth’s magnetic field protects life from solar wind and cosmic
rays. Today active fields are rare among rocky planets and only detected on
Earth, Mercury and Ganymede. Through NASA support, we have conducted
experiments to study the freezing of iron-alloys under high pressures. Our
findings contributed new insights into the origin of planetary dynamo in
iron-rich cores. “Non-ideal liquidus curve in the Fe-S system and Mercury's snowing
core” GRL 2008 “State
and solidification of lunar core from melting experiments on Fe-Ni-S system”
EPSL 2020 Earth
was born out of the same parent nebula as other planets in the solar system,
yet it is only known habitable planet today. What determines the path of
chemical differentiation and thermal evolution for an Earth-like planet? Will
we find another home for humans elsewhere? Through an NSF INSPIRE
grant, I worked in a geo-cosmo-astro team to track Life’s Ingredients from
outer space to inner core. We have uncovered important clues to the formation
of habitable worlds. “Earth's carbon deficit caused by early loss through irreversible
sublimation” Science Adv. In press |
