Estimating the impact of the cryptic degassing of Large Igneous Provinces: A mid-Miocene case-study
Estimating the impact of the cryptic degassing of Large Igneous Provinces: A mid-Miocene case-study
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DOI：
10.1016/j.epsl.2014.06.040
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发表时间：
2014-10-01
影响因子：
5.3
通讯作者：
Foster, Gavin L.
中科院分区：
文献类型：
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作者：
Armstrong McKay, David I.;Tyrrell, Toby;Foster, Gavin L.
在整个地球历史上，都有大量的火成岩省(LIP)，在与重大环境破坏有关的长期(>；10(5)年)事件中，喷发出大量(>；10(4)公里(3))的熔岩。最大的嘴唇喷发(例如西伯利亚圈闭)被广泛认为通过玄武岩二氧化碳脱气对全球气候产生了影响，但更多更小的嘴唇的影响是有争议的。在这里，我们测试了一种假设，即嘴唇对地球气候历史的影响比之前估计的更大，这是因为侵入的和地壳污染的岩浆进行了“神秘的脱气”，在空中玄武岩的基础上注入了额外的二氧化碳。我们使用生物地球化学盒模型来研究中中新世哥伦比亚河玄武岩(CRB)的潜在影响，在那里，这一地质上相对较新的事件的多个古记录使更严格的数据模型比较成为可能。我们发现，单独来自CRB的玄武岩脱气对长期碳循环的影响可以忽略不计，但CRB在Grande Ronde玄武岩喷发期间排放的总碳为4090-5670Pg，其中3000-4000Pg，如果包括隐蔽的脱气，这一通量在可接受的估计范围内，很好地再现了中新世气候最佳时期核心时期海底三角洲C-13和大气CO2变化的记录。然而，需要除气以外的机制来驱动16.3 Ma之前的观察到的升温，以及在类似于15.4 Ma之后匹配观察到的方解石补偿深度行为。因此，我们的发现排除了仅CRB侵位就可以完全解释中新世中期记录的可能性，但它们证明了当大量神秘的脱气伴随着嘴唇侵位时发生的增强的气候影响。(C)2014爱思唯尔B.V.保留所有权利。
Large Igneous Provinces (LIPs) have been emplaced throughout Earth's history, erupting great quantities (>10(4) km(3)) of lava in long-lived (>10(5) y) events that have been linked to major environmental disruptions. The largest LIP eruptions (e.g. Siberian Traps) are widely considered to have had an impact on global climate through basalt CO2 degassing but the impact of the more numerous smaller LIPs is debated. Here we test the hypothesis that LIPs had a greater impact on Earth's climate history than previously estimated because of the 'cryptic degassing' of intruded and crust-contaminated magma, injecting extra CO2 over and above that coming from sub-aerial basalts. We use biogeochemical box models to investigate the potential impact of the Columbia River Basalts (CRB) during the mid-Miocene where multiple palaeorecords for this geologically relatively recent event enable more rigorous data-model comparison. We find that the effect on the long-term carbon cycle of basalt degassing from the CRB alone is negligible, but that a total CRB emission of 4090-5670 Pg of carbon with 3000-4000 Pg of this carbon emitted during the Grande Ronde Basalt eruptions, a flux within the acceptable estimated range when cryptic degassing is included, does well in reproducing the record of benthic delta C-13 and atmospheric CO2 change during the core of the Miocene Climatic Optimum. Nevertheless, mechanisms other than degassing are required to drive observed warmth before 16.3 Ma and to match observed calcite compensation depth behaviour after similar to 15.4 Ma. Hence, our findings rule out the possibility that CRB emplacement alone can fully explain the mid-Miocene record but they demonstrate the enhanced climate impact that occurs when substantial cryptic degassing accompanies LIP emplacement. (C) 2014 Elsevier B.V. All rights reserved.