Enhanced continental chemical weathering during the multiple early Eocene hyperthermals: New constraints from the southern Indian Ocean
Enhanced continental chemical weathering during the multiple early Eocene hyperthermals: New constraints from the southern Indian Ocean
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早始新世多次高温期间大陆化学风化作用增强：来自南印度洋的新限制
DOI：
10.1016/j.gca.2022.05.022
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发表时间：
2022
影响因子：
5
通讯作者：
Kato Yasuhiro
中科院分区：
文献类型：
--
作者：
Tanaka Erika;Yasukawa Kazutaka;Ohta Junichiro;Kato Yasuhiro
多个短期（<105年）的全球变暖事件（“高温”）发生在整个始新世早期。大陆硅酸盐岩石的化学风化被认为是通过消耗过量的大气CO2从这些短暂的全球变暖事件中恢复的关键作用。然而，虽然这种负反馈的证据已被报道为古新世-始新世热最高峰（PETM），在其他瞬态高温化学风化的有效性仍然不受约束。在这里，我们新报告的始新世早期海洋Os同位素记录，包括始新世热最大值2（ETM 2），I1事件，和ETM 3在大洋钻探计划网站752在南印度洋。我们证明，海洋187Os/188Os增加的超高温事件，不太严重的比PETM。与背景条件相比，ETM 2、I1事件和ETM 3期间的大陆硅酸盐风化强度分别增加了18%-22%、17%-21%和13%-16%。基于重新考虑的Os质量平衡模型，重新评估了PETM期间大陆硅酸盐风化的强度，相对于PETM前水平增加了34%-42%。因此，在始新世高温大陆化学风化通量可能已高达一半的PETM大。值得注意的是，在这些事件中，大陆硅酸盐风化变化的顺序与海水温度升高的顺序并不一致。这种气候变暖的不一致性可能归因于（1）由于大火成岩省（LIP）的就位和相关的玄武岩风化，如北大西洋火成岩省和北美西部的Siletzia，可能低估了大陆硅酸盐风化，（2）风化强度背景水平的变化，和/或（3）通过长期持续的早始新世变暖趋势，大陆耐候性的长期下降。
Multiple short-term (<105years) global warming events (“hyperthermals”) occurred throughout the early Eocene. Chemical weathering of continental silicate rocks is considered to have played a key role in recovery from these transient global warming events via consumption of excess atmospheric CO2. However, although evidence of this negative feedback has been reported for the Paleocene–Eocene Thermal Maximum (PETM), the effectiveness of chemical weathering during other transient hyperthermals remains poorly constrained. Here, we newly report early Eocene marine Os isotope records including Eocene Thermal Maximum 2 (ETM2), the I1 event, and ETM3 at Ocean Drilling Program Site 752 in the southern Indian Ocean. We demonstrate that marine187Os/188Os increased during the hyperthermal events that were less severe than the PETM. The intensity of continental silicate weathering increased by 18%–22%, 17%–21%, and 13%–16% during ETM2, the I1 event, and ETM3, respectively, compared to the background conditions. Based on a reconsidered formulation of an Os mass-balance model, the intensity of continental silicate weathering during the PETM was reassessed to be a 34%–42% increase relative to the pre-PETM level. Thus, the continental chemical weathering flux during the Eocene hyperthermals may have been up to half as large as that of the PETM. It is noteworthy that the ordering of the changes in continental silicate weathering did not agree with the ordering of the seawater temperature rise among these events. This weathering–warming inconsistency might be attributable to (1) potential underestimation of continental silicate weathering due to the emplacement of Large Igneous Provinces (LIPs) and related basalt weathering, such as the North Atlantic Igneous Province and Siletzia in western North America, (2) changes in the background level of weathering intensity, and/or (3) a secular decrease in continental weatherability through the long-lasting early Eocene warming trend.
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影响因子：
18.3
作者：
Gernon, Thomas M.;Hincks, Thea K.;Mueller, R. Dietmar
通讯作者：
Mueller, R. Dietmar
影响因子：
3.5
作者：
Kato, Y;Fujinaga, K;Suzuki, K
通讯作者：
Suzuki, K
影响因子：
3.5
作者：
E. Thomas;F. Boscolo-Galazzo;B. Balestra;S. Monechi;B. Donner;U. Röhl
通讯作者：
E. Thomas;F. Boscolo-Galazzo;B. Balestra;S. Monechi;B. Donner;U. Röhl
影响因子：
18.3
作者：
Abels, Hemmo A.;Clyde, William C.;Lourens, Lucas J.
通讯作者：
Lourens, Lucas J.
影响因子：
4.9
作者：
Dallanave, Edoardo;Agnini, Claudia;Slotnick, Benjamin S.
通讯作者：
Slotnick, Benjamin S.