Regional uplift, gas hydrate dissociation and the origins of the Paleocene–Eocene Thermal Maximum
Regional uplift, gas hydrate dissociation and the origins of the Paleocene–Eocene Thermal Maximum
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DOI：
10.1016/j.epsl.2006.01.069
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发表时间：
2006-05
影响因子：
5.3
通讯作者：
J. Maclennan;Stephen M. Jones
中科院分区：
文献类型：
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作者：
J. Maclennan;Stephen M. Jones
北大西洋地区的大部分地区在最近的古新世经历了数百米的瞬时隆升。区域抬升应该引起储存在海洋沉积地层中的气体水合物的解离，随后向大气中释放的碳应该通过温室效应加强变暖。我们开发了隆起的空间分布模型，以匹配北大西洋边缘沉积盆地的观测约束。为了提供对抬升时释放的碳的定量估计，这些模型与海底天然气水合物中碳储存的简单参数相结合。模拟结果表明，隆升可以释放大量的碳，有些模型的碳释放量超过2000Gt。根据目前的地层学观测或地幔对流模型，不能排除最新一次古新世区域隆升发生在与古新世-始新世最高温度(PETM)开始相同的时间间隔内的可能性。在这种情况下，仅是抬升机制就可以解释与PETM相关的碳同位素漂移的幅度和时间。或者，如果最新一次古新世隆升的持续时间更接近约1Myr的上限，或者如果其他古新世隆升事件同样重要，那么天然气水合物在隆升时的解离可能有助于整个晚古新世海洋温度和碳同位素组成的较长期变化。这些温度变化，再加上北大西洋大陆桥在最新一次古新世隆升的顶峰期间的发展，可能能够迫使大洋环流发生快速变化，并导致诸如PETM等现象。
Much of the North Atlantic region experienced hundreds of metres of transient uplift during the latest Paleocene. Regional uplift should cause dissociation of gas hydrates stored in marine sedimentary strata, and the subsequent release of carbon to the atmosphere should enhance warming through the greenhouse effect. We have developed models of the spatial distribution of uplift to match observational constraints from sedimentary basins fringing the North Atlantic. In order to provide quantitative estimates of the carbon released upon uplift, these models are coupled to a simple parameterisation of carbon storage in sub-seafloor gas hydrates. Results of modelling indicate that large quantities of carbon can be released by uplift, with some models generating over 2000Gt of carbon release. The possibility that latest Paleocene regional uplift occurred over the same time interval as onset of the Paleocene–Eocene Thermal Maximum (PETM, around 30kyr) cannot be ruled out using current stratigraphical observations or mantle convection models. In this case, the uplift mechanism alone can account for the magnitude and timing of the carbon isotope excursion associated with the PETM. Alternatively, if the duration of latest Paleocene uplift was closer to the upper bound of around 1Myr or if other Paleocene uplift events were equally significant, then gas hydrate dissociation upon uplift could have contributed to longer-term changes in ocean temperature and carbon isotope composition through the late Paleocene. These temperature changes, in combination with development of the North Atlantic land bridge during the latest Paleocene culmination of uplift, may be able to force rapid changes in ocean circulation and cause phenomena such as the PETM.