在白纪中期,温暖的热带海洋表面和全球无氧气
1Southampton Oceanography Centre, School of Ocean & Earth Sciences, European Way, Southampton SO14 3ZH, UK. paw1@soc.soton.ac.uk
Nature
|July 27, 2001
概括
纪海洋经历了极端的变暖和无氧事件. 新的研究表明,热带大西洋海面温度比以前3-5°C更高,在OAE-1d期间分层崩,挑战了以前的气候稳定性假设.
科学领域:
- 古海洋学是古海洋学.
- 气候科学 气候科学
- 地质化学 地质化学
背景情况:
- 纪中期 (120-80万年前) 出现了温暖的极地,热带珊瑚礁沉没和海洋无氧事件 (OAE).
- 高大气二氧化碳水平被怀疑是白时期温暖的驱动因素,但OAE的原因仍在争论中,包括高生产率或海洋停滞等理论.
- 以前的观点表明,过去的温暖气候比现在的条件更稳定.
研究的目的:
- 调查白纪中期西部热带大西洋地表水的热结构和变化.
- 分析海洋分层,海洋表面温度和海洋无氧事件 (OAE) 之间的关系.
- 将OAE-1d的地化学特征与其他主要中生代OAE进行比较.
主要方法:
- 对来自多种类动物物种的稳定同位素记录的分析.
- 过去海面温度和上层海洋热结构的重建.
- 对OAE-1d与其他中生代OAE进行地化学比较.
主要成果:
- 西热带大西洋的海面温度比今天高3-5°C,大约在1亿年前.
- 在地表水中观察到明显的热变化.
- 在OAE-1d (Breistroffer事件) 期间发生了上层海洋分层的崩.
- OAE-1d表现出与主要中生代OAE的地化学相似之处.
结论:
- 温室气体强迫可能导致白纪气温升高.
- 这些发现与基于海洋停滞的OAE解释相矛盾.
- 这些结果挑战了过去温暖时期气候稳定性更高的传统观点.
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