来自大盆地静脉石的25万年气候记录:对米兰科维奇理论的含义
概括
来自大盆地的大陆氧气-18 (delta(18) O) 变化的连续记录表明,最后的间冰期阶段比以前的日期早得多. 这挑战了现有的海洋时间表和轨道强迫在普世冰河时代的主要作用.
科学领域:
- 古气候学 古气候学
- 地质化学 地质化学
- 四年纪地质学四年纪地质学
背景情况:
- 了解纪气候动态对于重建地球气候历史至关重要.
- 来自海洋沉积物和冰核的氧同位素记录 (delta(18) O) 提供了关于过去气候变化的关键见解.
- 现有的普世气候事件的时间表,特别是海洋氧同位素阶段5,是基于间接约会方法.
研究的目的:
- 为了建立一个连续的,独立的日期记录大陆水层氧-18变化在中晚普莱斯托时代.
- 为了比较从大陆记录中获得的气候事件的时间与已建立的海洋和冰芯记录.
- 调查现有的海洋氧同位素时间表所需的潜在修订,并重新评估浮纪冰河时代的驱动因素.
主要方法:
- 来自内华达州魔鬼洞的静脉的系列约会 (U-Th).
- 氧-18 (delta(18) O) 变化在静脉中的分析,代表了大陆地下水.
- 推导的三角洲时间序列与海洋和南极冰芯 (Vostok) 三角洲 (Vostok) 记录的比较.
主要成果:
- 一个连续的三角洲记录从南部的大盆地覆盖50到310万年前 (ka) 产生.
- 大陆三角洲(18) O曲线与海洋和沃斯托克冰芯记录有相似之处,但时间差异很大.
- 最后一个冰河间阶段 (海洋氧同位素阶段5) 的年代是147 +/- 3ka之前,比海洋记录显示的要早得多.
结论:
- 大陆水层记录表明,海洋氧同位素时间表可能需要修订.
- 关键的普世气候事件的时间可能与基于海洋记录的当前解释有所不同.
- 轨道强迫可能不是普世冰河时代的唯一或主要驱动因素,这表明其他因素也参与其中.
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