Structure and magnitude of the carbon isotope excursion during the Paleocene-Eocene thermal maximum
Structure and magnitude of the carbon isotope excursion during the Paleocene-Eocene thermal maximum
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DOI：
10.1016/j.gr.2017.02.016
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发表时间：
2017-06
影响因子：
6.1
通讯作者：
Qinghai Zhang;I. Wendler;Xiaoxia Xu;H. Willems;L. Ding
中科院分区：
文献类型：
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作者：
Qinghai Zhang;I. Wendler;Xiaoxia Xu;H. Willems;L. Ding
古新世-始新世最热期 (PETM) 是地质学上发生的一次快速且短暂的变暖事件，发生时间约为 10 年。 5600万年前（马）。它与明显的负碳同位素偏移（CIE）以及大气、水圈和生物圈的深刻变化有关。这一事件反映出大量碳被注入大气-海洋系统，但是，是否是单次或多次碳释放导致了这一事件尚不确定。在这里，我们提供了来自定日（西藏南部）两个平行石灰岩剖面的大量碳酸盐的碳同位素数据，这里的石灰岩在 PETM 期间沉积在热带碳酸盐坡道上。两个剖面的大块碳酸盐的碳同位素数据几乎相同，显示出大幅度的扩展阶梯式 CIE 剖面。阶梯式 CIE 剖面由三个碳同位素值递减的离散区间组成，这些区间可以在不同沉积环境（湖泊、碳酸盐坡道、大陆坡和公海）的剖面之间在区域间尺度上进行关联。这些相关性的一致性意味着 CIE 内至少发生了三次碳释放，并表明 PETM 期间碳注入的复杂过程。此外，定日记录的~7‰的CIE震级初步解释为反映了大气和海洋表层碳同位素的变化，该值大于普遍接受的~4‰的值，但仍在之前一些记录的范围内。
The Paleocene-Eocene Thermal Maximum (PETM) was a geologically rapid and transient warming event that occurred ca. 56 million years ago (Ma). It was associated with a pronounced negative carbon isotope excursion (CIE) and with profound changes in the atmosphere, hydrosphere and biosphere. This event reflects injections of large amounts of carbon into the atmosphere-ocean system, but, whether single or multiple episodes of carbon release caused this event is uncertain. Here, we present carbon isotope data of bulk carbonate from two parallel limestone sections at Tingri (south Tibet), where the limestone was deposited on a tropical carbonate ramp during the PETM. Carbon isotope data of bulk carbonate from both sections are almost identical, displaying an expanded stepped CIE profile with large magnitude. The stepped CIE profile consists of three discrete intervals of decreasing carbon isotope values, which can be correlated on an inter-regional scale between sections from different depositional environments (lake, carbonate ramp, continental slope, and open ocean). The consistency of these correlations implies occurrence of at least three carbon releases within the CIE and indicates complex processes of carbon injection during the PETM. Moreover, the CIE magnitude of ~ 7‰ recorded at Tingri is tentatively interpreted to reflect carbon isotope changes in the atmosphere and the surface ocean, which is larger than the generally accepted value of ~ 4‰ but is still within the range of some previous records.