日本地球惑星科学連合2018年大会

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[JJ] ポスター発表

セッション記号 M (領域外・複数領域) » M-IS ジョイント

[M-IS10] 古気候・古海洋変動

2018年5月23日(水) 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:岡崎 裕典(九州大学大学院理学研究院地球惑星科学部門)、磯辺 篤彦(九州大学応用力学研究所)、北村 晃寿(静岡大学理学部地球科学教室、共同)、佐野 雅規(早稲田大学人間科学学術院)、長谷川 精(高知大学理工学部)、岡 顕(東京大学大気海洋研究所)、加 三千宣(愛媛大学沿岸環境科学研究センター)

[MIS10-P33] The evaluation of bioturbation flux based on biogenic stratification using rule based lattice model

*小川 琴奈1成瀬 元1 (1.京都大学大学院理学研究科地球惑星科学専攻地質学鉱物学教室地球生物圏史分科)

キーワード:古環境、生物撹拌強度、堆積構造

This study aimed to establish a method to estimate the magnitude of the intensity of bioturbation quantitatively from geologic records. First, we employed the percentage area of bioturbation (PAB) as a proxy of the intensity of bioturbation that is measurable in ancient deposits, and examined the relationship between PAB and the actual biological activity by numerical experiments using a rule-based lattice model of bioturbation. In this model, the migration of sediment particles due to bioturbation are determined stochastically. Experiments were conducted by changing the two dimensionless parameters of bioturbation: the dimensionless bioturbation flux and the dimensionless bioturbation length. These dimensionless parameters were arisen from the dimensional analysis of the model parameters. The first parameter can be regarded as the intensity of bioturbation, and the second is related to the size scale of the dominant tracefossil in the assemblage. As a result of the numerical experiments, we obtained a relational function to estimate the bioturbation flux from PAB and the bioturbation length. Both the parameters PAB and the bioturbation length can be measured from the images of sections of sedimentary rocks, and therefore our method to estimate the bioturbation flux is applicable for the ancient depositional successions.