Spatial and Temporal Patterns in Petrogenic Organic Carbon Mobilization During the Paleocene-Eocene Thermal Maximum
Spatial and Temporal Patterns in Petrogenic Organic Carbon Mobilization During the Paleocene-Eocene Thermal Maximum
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DOI：
10.1029/2023pa004773
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发表时间：
2024-02-01
影响因子：
3.5
通讯作者：
Inglis，G. N.
中科院分区：
文献类型：
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作者：
Hollingsworth，E. H.;Elling，F. J.;Inglis，G. N.
古新世-始新世最热期（PETM）是一次短暂的全球变暖事件，在地质记录中通过长期的负碳同位素偏移（CIE）得到认可。 CIE的发生是由于13 C贫化碳快速流入海洋-大气系统。然而，维持负 CIE 所需的机制仍不清楚。石化有机碳 (OCpetro) 的增强动员和氧化已被用来解释 CIE 发生后大气中二氧化碳浓度升高的原因。然而，现有证据仅限于中纬度地区和亚热带地区。在这里，我们确定：(a) OCpetroin 海洋沉积物的增强流动和随后的掩埋是否是一种全球现象； (b) 它是否发生在整个 PETM 期间。为了实现这一目标，我们利用脂质生物标志物方法来追踪和量化全球 PETM 年龄浅海遗址（n = 7，包括五个新遗址）中的 OCpetroburial。我们的结果证实，在 PETM 期间，亚热带和中纬度地区的 OC 石油质量积累率 (MAR) 有所增加，这与较高的物理侵蚀率和强烈的偶发性降雨事件的证据一致。在 PETM 和 OCpetroMAR 略有增加或保持稳定期间，高纬度地区的有机碳来源并未表现出剧烈变化，这可能是由于更稳定的水文状况。至关重要的是，我们还证明 OCpetroMAR 在 PETM 的恢复阶段仍然保持较高水平。尽管 OC 石油氧化可能是整个 PETM 的重要正反馈机制，但我们表明这种反馈在空间和时间上都是可变的。
The Paleocene‐Eocene Thermal Maximum (PETM) was a transient global warming event and is recognized in the geologic record by a prolonged negative carbon isotope excursion (CIE). The onset of the CIE was due to a rapid influx of13C‐depleted carbon into the ocean‐atmosphere system. However, the mechanisms required to sustain the negative CIE remains unclear. Enhanced mobilization and oxidation of petrogenic organic carbon (OCpetro) has been invoked to explain elevated atmospheric carbon dioxide concentrations after the onset of the CIE. However, existing evidence is limited to the mid‐latitudes and subtropics. Here, we determine whether: (a) enhanced mobilization and subsequent burial of OCpetroin marine sediments was a global phenomenon; and (b) whether it occurred throughout the PETM. To achieve this, we utilize a lipid biomarker approach to trace and quantify OCpetroburial in a global compilation of PETM‐aged shallow marine sites (n= 7, including five new sites). Our results confirm that OCpetromass accumulation rates (MARs) increased within the subtropics and mid‐latitudes during the PETM, consistent with evidence of higher physical erosion rates and intense episodic rainfall events. High‐latitude sites do not exhibit drastic changes in the source of organic carbon during the PETM and OCpetroMARs increase slightly or remain stable, perhaps due a more stable hydrological regime. Crucially, we also demonstrate that OCpetroMARs remained elevated during the recovery phase of the PETM. Although OCpetrooxidation was likely an important positive feedback mechanism throughout the PETM, we show that this feedback was both spatially and temporally variable.