Welcome to the Hawai‘i Institute of Geophysics and Planetology.
School of Ocean and Earth Science and Technology  .  University of Hawai‘i at Mānoa
stripes Meteoritics and Cosmochemistry

Our research on meteorites, stardust, primitive Solar System materials, and Apollo lunar samples focuses on understanding the vast array of stellar and geological processes that formed and modified planets and asteroids. We make detailed compositional studies using optical and scanning electron microscopy, transmission electron microscopy, electron probe analysis, and ion microprobe measurements of isotopic and trace element abundances. Our laboratories include the Advanced Electron Microscopy Center and the W. M. Keck Cosmochemistry Laboratory.

Our team includes Faculty members John Bradley, Gary Huss, Hope Ishii, Klaus Keil (Emeritus), Sasha Krot, Kazuhide Nagashima, Ed Scott (Emeritus), and Jeff Taylor (Emeritus), along with PhD candidates Caroline Caplan and David Frank, and Post-Doctoral researchers Patrick H. Donohue and Kenta Ohtaki. We collaborate closely with other HIGP researchers: Paul Lucey, Shiv Sharma, and colleagues around the world who use additional analytical techniques to study these fascinating extraterrestrial materials.

Photomicrograph of chondrules in Semarkona chondrite meteorite   x-ray image of chondrules Primitive meteorites.

Asteroids that never melted are made of tiny metal and silicate grains and melted silicate particles called chondrules that formed before the planets existed. Meteorites from these asteroids are called chondrites. They provide a remarkable record of the processes that transformed a disk of dust and gas into a collection of planets, moons, asteroids and comets. We wish to understand how chondrules formed, how they were mixed with dust and concentrated together to form asteroids and planetesimals. Fortunately, our samples of over 20 different chondritic asteroids are extraordinarily diverse and new kinds are recovered every year from Antarctica and deserts around the world.

The top picture shows a thin section of a chondrite that is chock full of millimeter-sized chondrules; metal grains, which appear black, are rare. Below it is an X-ray image of a metal-rich chondrite that has preserved in exquisite detail grains from the earliest stages of solar system formation. These chondrites contain more metal that condensed from the hottest parts of the disk and less dust from the coolest parts than any other type of chondrite and may resemble the material from which the planet Mercury accreted.


Igneous Meteorites.

Most asteroids that melted formed metallic cores surrounded by layers of basalts and other igneous rocks. We study meteorites from the cores, mantles and surfaces of these asteroids to learn more about igneous processes on asteroids and the impacts that broke them up and delivered samples to Earth. This meteorite is a remarkable mixture of roughly equal proportions of metallic iron-nickel (white) and fragments of igneous rocks (dark), which are up to 6 cm long. Our studies suggest it formed when a melted asteroid ~300 km in diameter was split open in a gigantic collision 4.5 billion years ago. Molten metal from the core spewed into space until the debris reassembled. A 2-4 km chunk of this asteroid hit the South Pacific Ocean two million years ago causing global devastation.

Martian meteorite, Allan Hills 84001 Martian meteorites.

Martian meteorites are igneous rocks that were modified by aqueous alteration and impact processes on Mars. We study Martian meteorites to learn about the geology of Mars. How much water was there on Mars when the meteorites crystallized from magma and when they were altered? How were the magmas formed and emplaced? This transmitted light photomicrograph of a section of the famous Martian meteorite, Allan Hills 84001, shows a patch of orange carbonate grains 500 micrometers across between pyroxene crystals. We infer that carbonate grains originally formed from percolating brines but were melted by an impact on Mars. We study alteration and shock processes in all kinds of meteorites to help understand these complex rocks.

For more information on meteoritics and cosmochemistry at HIGP contact: John Bradley, Patrick Donohue, Gary Huss, Hope Ishii, Sasha Krot, Kazuhide Nagashima, Kenta Ohtaki.

For additional reading and slide sets about meteoritics and cosmochemistry, visit the Planetary Science Research Discoveries (PSRD) web site, hosted at HIGP.

Text and images courtesy Sasha Krot, Ed Scott, Jeff Taylor, and American Museum of Natural History.

  Updated 11 April 2019.

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