地学雑誌
Online ISSN : 1884-0884
Print ISSN : 0022-135X
総説
ドライな還元地球の誕生と大気海洋成分の二次的付加で説明されるABELモデルと,生命惑星誕生におけるABEL爆撃の重要性
丸山 茂徳戎崎 俊一丹下 慶範
著者情報
ジャーナル フリー

2018 年 127 巻 5 号 p. 647-682

詳細
抄録

 In the recently proposed ABEL model, the Earth was born as a dry planet without atmosphere and ocean components at 4.56 Ga. From 4.37 to 4.20 Ga, bio-elements, such as carbon (C), hydrogen (H), oxygen (O), and nitrogen (N), were secondarily accreted on the Earth. This two-step formation model of the Earth is referred to as the advent of the bio-elements model (ABEL Model) and the event of the advent of bio-elements (water component) is referred to as ABEL Bombardment. It is evident that the solid Earth originated from enstatite chondrite-like dry material because of its oxygen isotopic composition and similar isotopes. On the other hand, the Earth's water originated primarily from carbonaceous chondrite material based on the hydrogen isotopic ratio. The ABEL model successfully explains this enigma between solid Earth and water. In addition, the importance of the secondary accretion of oxidizing bio-elements should be emphasized because this event became a precursor to initiating the metabolism for life to emerge on a highly reductive planet. If ABEL Bombardment had not occurred, life would never have emerged on the Earth. Therefore, ABEL Bombardment was one of the most important events for this planet to evolve into a habitable planet. Moreover, ABEL Bombardment is thought to be the trigger to switch from stagnant lid tectonics to plate tectonics on this planet because of the injection of volatiles into the initial dry Earth.

著者関連情報
© 2018 公益社団法人 東京地学協会
前の記事 次の記事
feedback
Top