U-Pb日付の流石は,南アフリカの初期のホミニン記録を乾燥した気候段階に制限する
Robyn Pickering1,2, Andy I R Herries3,4, Jon D Woodhead5
1Department of Geological Sciences, University of Cape Town, Cape Town, South Africa. robyn.pickering@uct.ac.za.
Nature
|November 23, 2018
まとめ
南アフリカ の 流石
科学分野:
- 古人類学
- 地質年代学
- 古代気候学
背景:
- 人類の進化を理解するために 極めて重要なものです
- この地域でのホミニン化石の年代測定は 進化論の研究を妨げています
- フローストーンは 確固たる年代測定の 可能性のある方法を提供します
研究 の 目的:
- 人類の誕生の地で ヒト類の化石が発見される 確実な時間軸を確立するためです
- 化石の保存と古生物学環境との関連付け
- 南アフリカにおける 過去の気候の変動を再構築する.
主な方法:
- 8つの洞窟からの流石層のウラン-鉛 (U-Pb) 年代測定.
- 成長間隔記録に29U-Pbの年齢を組み合わせた核密度の推定.
- 流石の成長が湿った段階であり,化石の堆積が乾燥した段階であると解釈する.
主要な成果:
- 流石は320万年前から130万年前までの6つの異なる間隔に遡ります
- 主要な湿気段階 (流石の成長) と乾燥段階 (化石の蓄積) を特定した.
- 化石の保存は 乾燥期に限定され ホミニン記録に偏りがあります
結論:
- フローストーンのU-Pb年代測定は 人類の誕生の確固たる年代表を示しています
- ホミニンの化石記録は 乾燥期に偏っており 進化の理解に影響しています
- フローストーンは 過去のアフリカの気候の変動と ホミニンの生息地への影響を 洞察することができます
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