Astronomical constraints on global carbon-cycleperturbation during Oceanic Anoxic Event 2 (OAE2)
Astronomical constraints on global carbon-cycleperturbation during Oceanic Anoxic Event 2 (OAE2)
复制标题
海洋缺氧事件 2 (OAE2) 期间全球碳循环扰动的天文限制
DOI：
10.1016/j.epsl.2017.01.007
复制
发表时间：
2017
影响因子：
5.3
通讯作者：
Ma Lifeng
中科院分区：
文献类型：
--
作者：
Li Yong-Xiang;Montañez Isabel P.;Liu Zhonghui;Ma Lifeng
摘要海洋缺氧事件2（OAE 2）是由火山爆发引起的全球碳循环和短暂气候变化的一次重大扰动。尽管这种对海洋-大气系统的充分研究的扰动提供了一个独特的机会，可以更好地理解气候突变对CO2强迫的响应，事件的演化和持续时间仍然存在争议，这在很大程度上是由于现有OAE 2记录的时间分辨率以及整个扰动持续时间的不确定性和其中的C循环移位。在这里，我们报告了耦合磁化率（中国西藏南部OAE 2扩展层段分辨率为2.5 ~ 5± 0.5kyr的碳同位素时间序列。MS周期性表明短偏心调制，允许构建高精度的轨道时标，当与高分辨率δ 13 C carb记录结合时，通过恢复OAE 2完全限制了开始的时间和性质，揭示了比以前认识到的更精细的尺度结构。δ 13 C carb和MS的突然耦合变化，以及与高和低长偏心率之间的过渡同步变化的相位关系，表明海洋碳循环和季风动力学叠加在重复的大规模海洋变化上的轨道相关变化。特别是，高分辨率的西藏记录揭示了MS和δ 13 C相位关系的动态变化，这表明海洋缺氧的开始可能不是轨道强迫的。这一发现与轨道强迫海洋缺氧的范例形成鲜明对比。相反，新记录表明，缺氧的终止可能是轨道强迫的，并叠加在戏剧性的海洋变化上。
Abstract Oceanic Anoxic Event 2 (OAE2) was a major disturbance in global carbon cycling and transient climate disruption, triggered by a pulse of volcanic CO 2. Although this well-studied perturbation to the ocean–atmosphere system offers a unique opportunity to better understand abrupt climate change in response to CO 2-forcing, the origin, evolution and duration of the event are still debated due in large part to the temporal resolution of existing OAE2 records and uncertainty over the duration of the overall perturbation and C cycle shifts within it. Here we report coupled magnetic susceptibility (MS) and carbon-isotope time-series of∼ 2.5 to 5±0.5 kyr resolution from an expanded OAE2 interval from southern Tibet, China. MS cyclicity indicates short eccentricity modulation, permitting the construction of a high-precision orbital timescale which, when integrated with the high resolution δ 13 C carb record, fully constrains the timing and nature of onset through recovery of OAE2, revealing finer-scale structure than previously recognized. Abrupt coupled shifts in δ 13 C carb and MS, and changing phase relationships in-step with transitions between high and low long eccentricity, indicate orbitally linked changes in marine carbon cycling and monsoon dynamics superimposed on repeated wholesale oceanographic changes. In particular, the high-resolution Tibetan record reveals dynamic shifts in the phasing relationship of MS and δ 13 C, which suggests that the initiation of ocean anoxia was probably not orbitally forced. This finding is in sharp contrast with the paradigm of orbitally forced ocean anoxia. Conversely, the new record suggests that termination of anoxia was likely orbitally forced and superimposed on a dramatic oceanographic change.