日本地球惑星科学連合2018年大会

講演情報

[EE] ポスター発表

セッション記号 S (固体地球科学) » S-CG 固体地球科学複合領域・一般

[S-CG55] Various interactions between solid Earth and climates

2018年5月21日(月) 13:45 〜 15:15 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:中川 貴司(海洋研究開発機構数理科学・先端技術研究分野)、横山 祐典(東京大学 大気海洋研究所 高解像度環境解析研究センター)、奥野 淳一(国立極地研究所、共同)、山崎 雅(産業技術総合研究所)

[SCG55-P01] マリノアンスノーボールアースの氷床融解に伴う海水準変動

*入江 芳矢1中田 正夫1奥野 淳一2バオ フイミン3 (1.九州大学、2.国立極地研究所、3.ルイジアナ州立大学)

キーワード:全球凍結、海水準、グレイシオアイソスタシー

The Marinoan snowball Earth, which ended at ~635 Ma, offers us a set of sedimentary and geochemical records for studying a relative sea level (RSL) history of Earth system response to a large perturbation and its accompanied changes in the atmosphere and biosphere. An accurate perdition of post-Marinoan RSL changes would set independent constraints on the rate of recovery of the Earth system from a snowball state. Here we examine RSL changes due to glacial isostatic adjustment (GIA) associated with Marinoan snowball deglaciation by chiefly considering two RSL change patterns, (i) an RSL drop followed by RSL rise in the syn-deglacial phase (melting phase) inferred from the cap dolostones deposited on the continental slope in Namibia, and (ii) an RSL drop followed by RSL rise in the post-deglacial phase (time after the complete melting) inferred from the cap dolostones deposited on the continental shelf in South China, West Africa and Canada. We show that the physical mechanisms responsible for (i) and (ii) mainly depend on the coastline geometry, the syn-deglacial duration and mantle viscosity structure. Our modeling suggests that the RSL change patterns (i) and (ii) are explained by adopting the coastline geometry like a peninsula, a syn-deglacial duration of 10–20 kyr and a viscosity of ~1023 Pa s in the deep mantle. The deep mantle viscosity of ~1023 Pa is roughly equal to that inferred from the recent analyses using GIA data sets due to the last deglaciation.