在土龙纪 (白纪末期) 中,微粒颗粒的行星间尘埃输入:来自同位素和组元素的证据
Hironao Matsumoto1, Akira Ishikawa2, Rodolfo Coccioni3
1Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15, Natsushima, Yokosuka, Kanagawa, 237-0061, Japan. hironao.matsumoto@jamstec.go.jp.
Scientific reports
|December 12, 2023
概括
图隆时期出现了极端的热量和外星物质的涌入. 奥斯同位素和PGE数据表明宇宙尘埃,而不仅仅是火山活动,有助于K3事件,不同于丰富信号.
科学领域:
- 地质化学 地质化学
- 古气候学 古气候学
- 太空化学 太空化学
背景情况:
- 图隆时代 (90-94亿年前) 是白时期最热的时期,被K3事件标记为沉积物中-3 (3He) 的高含量,表明外星物质输入.
- 在Cenomanian-Turonian边界的海洋无氧事件2引起了奥斯同位素 (187Os/188Os) 的转移.
研究的目的:
- 调查土龙纪期间外星物质和二氧化碳的来源,重点关注K3事件.
- 分析图隆沉积物记录中的同位素和组元素 (PGE),以了解它们与气候和外星输入的关系.
主要方法:
- 在图伦沉积岩中分析同位素比率 (187Os/188Os).
- 在相同的沉积物记录中测量组元素 (PGE) 度.
- 地化学数据与古气候和地质事件的相关性,如大型岩性省份 (LIP) 和K3事件.
主要成果:
- 同位素的比率在整个图罗尼亚持续下降,与大火热省 (LIP) 火山活动有关,但这与最温暖的间隔不一致.
- 最温暖的时期 (白纪热量最大) 可能归因于额外的二氧化碳来源,如潜伏区火山活动或金伯石形成.
- 在K3事件期间没有观察到显著的同位素转移或PGE丰富,与3He丰富形成鲜明对比.
结论:
- K3事件的3He丰富很可能来自微粒宇宙尘埃,可能来自彗星雨,而不是仅仅来自LIP或其他火山活动.
- 与3He相比,同位素和PGE数据为外星物质输入提供了不同的见解,突出了解释沉积物记录的复杂性.
- 该研究区分了白纪变暖和地球化学异常的火山和外星来源.
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