[A-OS11] 陸域海洋相互作用-惑星スケール物質循環

[AOS11-03] Re-entry of giant-impact fragments and early evolution of the Earth's ocean

*佐々木 貴教¹ (1.京都大学 大学院理学研究科 宇宙物理学教室)

キーワード：地球、海洋、巨大衝突

The late stages of Earth's formation remain a mystery. No building blocks remain in Earth's orbit and no geological evidence is available for the first 700 million years Earth's history. Herein we propose that protoplanetary fragments produced by the giant impacts during terrestrial planet formation may give some important clues to the era. Iron-bearing giant impact fragments provide significant reducing agent that could transform primitive CO2–H2O atmosphere and ocean into more reducing H2-bearing atmosphere. Re-entry of the giant-impact fragments into eary Earth would be important for the origin of Earth’s life and its early evolution.