TY - JOUR

T1 - Carbonate record of temporal change in oxygen fugacity and gaseous species in asteroid Ryugu

AU - Fujiya, Wataru

AU - Kawasaki, Noriyuki

AU - Nagashima, Kazuhide

AU - Sakamoto, Naoya

AU - Conel, Conel M.

AU - Kita, Noriko T.

AU - Kitajima, Kouki

AU - Abe, Yoshinari

AU - Aléon, Jérôme

AU - Amari, Sachiko

AU - Amelin, Yuri

AU - Bajo, Ken-ichi

AU - Bizzarro, Martin

AU - Bouvier, Audrey

AU - Carlson, Richard W.

AU - Chaussidon, Marc

AU - Choi, Byeon-Gak

AU - Dauphas, Nicolas

AU - Davis, Andrew M.

AU - Di Rocco, Tommaso

AU - Fukai, Ryota

AU - Gautam, Ikshu

AU - Haba, Makiko K.

AU - Hibiya, Yuki

AU - Hidaka, Hiroshi

AU - Homma, Hisashi

AU - Hoppe, Peter

AU - Huss, Gary R.

AU - Ichida, Kiyohiro

AU - Iizuka, Tsuyoshi

AU - Ireland, Trevor R.

AU - Ishikawa, Akira

AU - Itoh, Shoichi

AU - Kleine, Thorsten

AU - Komatani, Shintaro

AU - Krot, Alexander N.

AU - Liu, Ming-Chang

AU - Masuda, Yuki

AU - McKeegan, Kevin D.

AU - Morita, Mayu

AU - Motomura, Kazuko

AU - Moynier, Frédéric

AU - Nakai, Izumi

AU - Nguyen, Ann

AU - Nittler, Larry

AU - Onose, Morihiko

AU - Pack, Andreas

AU - Park, Changkun

AU - Piani, Laurette

AU - Qin, Liping

AU - Russell, Sara S.

AU - Schönbächler, Maria

AU - Tafla, Lauren

AU - Tang, Haolan

AU - Terada, Kentaro

AU - Terada, Yasuko

AU - Usui, Tomohiro

AU - Wada, Sohei

AU - Wadhwa, Meenakshi

AU - Walker, Richard J.

AU - Yamashita, Katsuyuki

AU - Yin, Qing-Zhu

AU - Yokoyama, Tetsuya

AU - Yoneda, Shigekazu

AU - Young, Edward D.

AU - Yui, Hiroharu

AU - Zhang, Ai-Cheng

AU - Nakamura, Tomoki

AU - Naraoka, Hiroshi

AU - Noguchi, Takaaki

AU - Okazaki, Ryuji

AU - Sakamoto, Kanako

AU - Yabuta, Hikaru

AU - Abe, Masanao

AU - Miyazaki, Akiko

AU - Nakato, Aiko

AU - Nishimura, Masahiro

AU - Okada, Tatsuaki

AU - Yada, Toru

AU - Yogata, Kasumi

AU - Nakazawa, Satoru

AU - Saiki, Takanao

AU - Tanaka, Satoshi

AU - Terui, Fuyuto

AU - Tsuda, Yuichi

AU - Watanabe, Sei-ichiro

AU - Yoshikawa, Makoto

AU - Tachibana, Shogo

AU - Yurimoto, Hisayoshi

N1 - Publisher Copyright: © 2023, The Author(s), under exclusive licence to Springer Nature Limited.

PY - 2023

Y1 - 2023

N2 - The Hayabusa2 spacecraft explored asteroid Ryugu and brought its surface materials to Earth. Ryugu samples resemble Ivuna-type (CI) chondrites—the most chemically primitive meteorites—and contain secondary phyllosilicates and carbonates, which are indicative of aqueous alteration. Understanding the conditions (such as temperature, redox state and fluid composition) during aqueous alteration is crucial to elucidating how Ryugu evolved to its present state, but little is known about the temporal changes in these conditions. Here we show that calcium carbonate (calcite) grains in Ryugu and Ivuna samples have variable 18O/16O and 13C/12C ratios that are, respectively, 24–46‰ and 65–108‰ greater than terrestrial standard values, whereas those of calcium–magnesium carbonate (dolomite) grains are much more homogeneous, ranging within 31–36‰ for oxygen and 67–75‰ for carbon. We infer that the calcite precipitated first over a wide range of temperatures and oxygen partial pressures, and that the proportion of gaseous CO2/CO/CH4 molecules changed temporally. By contrast, the dolomite formed later in a more oxygen-rich and thus CO2-dominated environment when the system was approaching equilibrium. The characteristic isotopic compositions of secondary carbonates in Ryugu and Ivuna are not observed for other hydrous meteorites, suggesting a unique evolutionary pathway for their parent asteroid(s).

AB - The Hayabusa2 spacecraft explored asteroid Ryugu and brought its surface materials to Earth. Ryugu samples resemble Ivuna-type (CI) chondrites—the most chemically primitive meteorites—and contain secondary phyllosilicates and carbonates, which are indicative of aqueous alteration. Understanding the conditions (such as temperature, redox state and fluid composition) during aqueous alteration is crucial to elucidating how Ryugu evolved to its present state, but little is known about the temporal changes in these conditions. Here we show that calcium carbonate (calcite) grains in Ryugu and Ivuna samples have variable 18O/16O and 13C/12C ratios that are, respectively, 24–46‰ and 65–108‰ greater than terrestrial standard values, whereas those of calcium–magnesium carbonate (dolomite) grains are much more homogeneous, ranging within 31–36‰ for oxygen and 67–75‰ for carbon. We infer that the calcite precipitated first over a wide range of temperatures and oxygen partial pressures, and that the proportion of gaseous CO2/CO/CH4 molecules changed temporally. By contrast, the dolomite formed later in a more oxygen-rich and thus CO2-dominated environment when the system was approaching equilibrium. The characteristic isotopic compositions of secondary carbonates in Ryugu and Ivuna are not observed for other hydrous meteorites, suggesting a unique evolutionary pathway for their parent asteroid(s).

U2 - 10.1038/s41561-023-01226-y

DO - 10.1038/s41561-023-01226-y

M3 - Journal article

AN - SCOPUS:85164334589

VL - 16

SP - 675

EP - 682

JO - Nature Geoscience

JF - Nature Geoscience

SN - 1752-0894

IS - 8

ER -