title: Shock-transformation of whitlockite to merrillite and the implications for meteoritic phosphate.
abstract: Meteorites represent the only samples available for study on Earth of a number of planetary bodies. The minerals within meteorites therefore hold the key to addressing numerous questions about our solar system. Of particular interest is the Ca-phosphate mineral merrillite, the anhydrous end-member of the merrillite-whitlockite solid solution series. For example, the anhydrous nature of merrillite in Martian meteorites has been interpreted as evidence of water-limited late-stage Martian melts. However, recent research on apatite in the same meteorites suggests higher water content in melts. One complication of using meteorites rather than direct samples is the shock compression all meteorites have experienced, which can alter meteorite mineralogy. Here we show whitlockite transformation into merrillite by shock-compression levels relevant to meteorites, including Martian meteorites. The results open the possibility that at least part of meteoritic merrillite may have originally been H+-bearing whitlockite with implications for interpreting meteorites and the need for future sample return.
authors.affiliation: Department of Geoscience, University of Nevada, Las Vegas, 4505 South Maryland Parkway, Las Vegas, Nevada 89154, USA.
authors.forename: C T
authors.initials: CT
authors.lastname: Adcock
authors.affiliation: Department of Geoscience, University of Nevada, Las Vegas, 4505 South Maryland Parkway, Las Vegas, Nevada 89154, USA.|High Pressure Science and Engineering Center, University of Nevada, Las Vegas, 4505 South Maryland Parkway, Las Vegas, Nevada 89154, USA.|LSPM-CNRS, Institut Galilée, Université Paris 13, Nord, 99, av. J. B. Clément, 93430 Villetaneuse, France.|Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu, Sichuan 610031, China.
authors.forename: O
authors.initials: O
authors.lastname: Tschauner
authors.affiliation: Department of Geoscience, University of Nevada, Las Vegas, 4505 South Maryland Parkway, Las Vegas, Nevada 89154, USA.
authors.forename: E M
authors.initials: EM
authors.lastname: Hausrath
authors.affiliation: Department of Geoscience, University of Nevada, Las Vegas, 4505 South Maryland Parkway, Las Vegas, Nevada 89154, USA.
authors.forename: A
authors.initials: A
authors.lastname: Udry
authors.affiliation: Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu, Sichuan 610031, China.|The Peac Institute of Multiscale Sciences, Chengdu, Sichuan 610031, China.
authors.forename: S N
authors.initials: SN
authors.lastname: Luo
authors.affiliation: The Peac Institute of Multiscale Sciences, Chengdu, Sichuan 610031, China.|CAS Key Laboratory of Materials Behavior and Design, Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230027, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Cai
authors.affiliation: Department of Geoscience, University of Nevada, Las Vegas, 4505 South Maryland Parkway, Las Vegas, Nevada 89154, USA.
authors.forename: M
authors.initials: M
authors.lastname: Ren
authors.affiliation: GeoScienceEnviro Center for Advanced Radiation Sources, University of Chicago, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: A
authors.initials: A
authors.lastname: Lanzirotti
authors.affiliation: GeoScienceEnviro Center for Advanced Radiation Sources, University of Chicago, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: M
authors.initials: M
authors.lastname: Newville
authors.affiliation: Lawrence Berkeley National Laboratory, Advanced Light Source, University of California, Berkeley, Berkeley, California 94720, USA.
authors.forename: M
authors.initials: M
authors.lastname: Kunz
authors.affiliation: High Pressure Collaborative Access Team (HPCAT), Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439, USA.
authors.forename: C
authors.initials: C
authors.lastname: Lin