earth's core
Original Drawing Created by Keelin Murphy

compreslogotiny.jpg COMPRES, the Consortium for Materials Properties Research in Earth Sciences is a community-based consortium whose goal is to enable Earth Science researchers to conduct the next generation of high-pressure science on world-class equipment and facilities. It facilitates the operation of beam lines, the development of new technologies for high pressure research, and advocates for science and educational programs to the various funding agencies.

COMPRES has New President

Dear COMPRES community,

It is our great pleasure to announce Carl Agee as the next president of COMPRES, effective September 1, 2015. We are delighted that Carl, currently head of the Institute of Meteoritics and Professor at the University of New Mexico, has agreed to take on this critical community responsibility, and look forward to his leadership of our organization!

The executive committee wishes to extend many thanks to Jay Bass for his service and leadership as president from 2010-2015, including guiding the organization through its COMPRES-III renewal.  We also thank the search committee, Bob Liebermann, Mike Brown, Kanani Lee, Tom Duffy, Guy Masters, and Bill McDonough for their extensive work in identifying and recruiting candidates for the position.

Wendy Panero,
On behalf of the COMPRES Executive Committee 


COMPRES Technology Center (COMPTECH ) is COMPRES's presence at the Advanced Photon Source, Argonne National Laboratory. It provides tools, software, development and support for High-pressure research at APS.



nsf1.jpgNSF supports COMPRES, the Consortium for Materials Properties Research in Earth Sciences under NSF Cooperative Agreement EAR 11-43050.

 Earth’s Most Abundant Mineral Finally Has a Name

Tschauner, O., Ma, C., Beckett, J., Prescher, C., Prakapenka, V., Rossman, G., Science 346, 1100 (2014)



An optical image showing the Tenham Chondrite thin section USNM 7703 where bridgmanite was identified in a shock vein. The shock melt veins are dark brown to black over the thickness of the thin section of about 30 µm.

Summary:(Mg,Fe)SiO3 in the perovskite structure is known to make up about 80% of the lower mantle of the Earth and about 38% of Earth’s volume in total.

However, until a recent study by researchers from the COMPRES member institutions UNLV, Caltech, and CARS-University of Chicago this important phase has never been established as a mineral. (Mg,Fe)SiO3 in the perovskite structure is now called bridgmanite [Tschauner, O. et al, Science 346, 1100 (2014), see also: Sharp, T., Science 346, 1057 (2014)].
The elusiveness of bridgmanite is result of its limited metastability at ambient conditions – about 24 GPa lower than the pressures of its stability field: Any terrestrial material originating from the lower mantle is transformed to low pressure minerals upon upwelling to shallower regions in Earth. However, not only the Earth’s interior but also shocked meteorites are a repository of high-pressure minerals. Previous attempts of detecting bridgmanite with electron microscopy were insufficient to establish this phase as a mineral through structural and chemical analysis. Finally, the use of micro-focused high energy X-ray synchrotron beams in combination with SEM-imaging and EPMA chemical analysis provided sufficient evidence for establishing bridgmanite as a mineral occuring in the highly shocked Tenham L6 Chondrite.
The mineral was named after 1964 Nobel laureate and pioneer of high-pressure experimental research Percy W. Bridgman. The naming does more than remove a vexing gap in petrological terminology. The crystal chemistry of natural bridgmanites also will aid our understanding of the deep Earth.

posted December 23, 2014

Dehydration melting at the top of the lower mantle


Brandon Schmandt, Steven D. Jacobsen, Thorsten W. Becker, Zhenxian Liu, Kenneth G. Dueker; Science 344, 1265-1268 doi: 10.1126/science.1253358




(A) Single-crystal of hydrous ringwoodite (blue crystal) containing 1 wt % H2O inside a diamond-anvil cell at 30 GPa. The sample was laser heated to 1600°C in several spots (orange circles) to perform direct transformation to bridgmanite and (Mg,Fe)O. Laser heating was conducted at Sector 13 (GSECARS) of the APS. (B) Synchrotron-FTIR spectra of the recovered sample were collected at beamline U2A of the NSLS. Spectrum 1 is an unheated spot, characteristic of hydrous ringwoodite. Spectra 2 and 3 from within the laser heated spots exhibit modified IR-absorption spectra in the OH region, with a broad and asymmetric band at 3400 cm-1 (characteristic of OH in quenched glass) and a sharp peak (3680 cm-1) associated with brucite. On conversion to bridgmanite plus (Mg,Fe)O, dehydration melting occurred as intergranular melt, viewed by TEM in panel C. In this study, dehydration melting was detected just beneath the mantle transition zone from P-to-S converted phases using seismic data from NSF-Earthscope, US-Array.



The high water storage capacity of minerals in Earth’s mantle transition zone (410- to 660-kilometer depth) implies the possibility of a deep H2O reservoir, which could cause dehydration melting of vertically flowing mantle. We examined the effects of downwelling from the transition zone into the lower mantle with high-pressure laboratory experiments, numerical modeling, and seismic P-to-S conversions recorded by a dense seismic array in North America. In experiments, the transition of hydrous ringwoodite to perovskite and (Mg,Fe)O produces intergranular melt. Detections of abrupt decreases in seismic velocity where downwelling mantle is inferred are consistent with partial melt below 660 kilometers. These results suggest hydration of a large region of the transition zone and that dehydration melting may act to trap H2O in the transition zone.

Posted July 2, 2014