The occurrence of microbially induced smectite-to-illite (S-I) reaction has challenged both the notions of solely inorganic chemical control for this reaction and the conventional concept of a semiquantitative illite geothermometer for the reconstruction of the thermal and tectonic histories of sedimentary basins. Here, we present evidence for a naturally occurring microbially induced S-I transition, via biotic reduction of phyllosilicate structural Fe(III), in mudstones buried at the Nankai Trough, offshore Japan (International Ocean Discovery Program Site C0023). Biotic S-I reaction is a consequence of a bacterial survival and growth strategy at diagenetic temperatures up to 80 °C within the Nankai Trough mudstones. These results have considerable implications for petroleum exploration, modification of fault behavior, and the understanding of microbial communities in the deep biosphere.
Bibliographical noteFunding Information:
We thank International Ocean Discovery Program Expedition 370 scientists (Yusuke Kubo, Lena Maeda, Stephen Bowden, Margaret Cramm, Takehiro Hirose, Kira Homola, Tatsuhiko Hoshino, Akira Ijiri, Hiroyuki Imachi, Nana Kamiya, Masanori Kaneko, Lorenzo Lagostina, Hayley Manners, Harry-Luke McClel-land, Kyle Metcalfe, Natsumi Okutsu, Donald Pan, Maija Jocelyn Raudsepp, Justine Sauvage, Florence Schubotz, Satoshi Tonai, Tina Treude, Man-Yin Tsang, Bernhard Viehweger, David T. Wang, Emily Whita-ker, Yuzuru Yamamoto, and Masataka Kinoshita) for extensive comments and discussion. This work was supported by a National Research Foundation of Korea (NRF) grant funded by the South Korea government (NRF-2018R1A2B6002036) to J. Kim, and the Korea International Ocean Discovery Program (KIODP) funded by the Ministry of Oceans and Fisheries, South Korea, to G. Kim. We are grateful to Lynda Williams and Warren Huff for their constructive comments.
© 2019 Geological Society of America.
All Science Journal Classification (ASJC) codes