Modeling the Accumulation and Transition to the Relic State of Methane Hydrates in the Permafrost of Northwestern Siberia

IF 0.9 4区地球科学 Q4 GEOCHEMISTRY & GEOPHYSICS Izvestiya, Physics of the Solid Earth Pub Date : 2023-06-17 DOI:10.1134/S1069351323020040

M. M. Arzhanov, V. V. Malakhova

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Abstract—This paper presents the results of numerical modeling of the permafrost thermal regime and thermobaric conditions of methane hydrates in the north of Western Siberia over the past 70 thousand years. The area of hydrate formation was determined and the rate of accumulation of hydrates was estimated in connection with the migration of fluid from the underlying gas-saturated layers under the conditions of cover glaciation. The estimates obtained for the change in hydrate saturation as a result of fluid migration during the 10 thousand-year glaciation period, depending on the permeability of the soil, are from 6 to 40% in the upper 350 m. Based on quantitative characteristics of the equilibrium and metastable states of methane hydrates, the conditions for the preservation of relict methane hydrates in permafrost under the paleoclimatic scenario were determined, taking into account periods of ice cover and transgression. It is shown that due to the effect of self-preservation at temperatures below –4°C, it is possible to preserve relict methane hydrates in the upper 200 m of soil under non-equilibrium conditions. The effect of lowering the temperature while the hydrates dissociate prevents the complete decomposition of the deposit and leads to an increase in the thickness of the frozen soil.

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西伯利亚西北部多年冻土带甲烷水合物积累与向残余状态过渡的模拟

摘要:本文介绍了西伯利亚西部北部近7万年来多年冻土热状态和甲烷水合物热压条件的数值模拟结果。根据覆盖冰川条件下下伏含气饱和层流体的运移，确定了水合物的形成面积，并估计了水合物的聚集速率。根据土壤渗透性的不同，在1万年冰期期间流体迁移导致的水合物饱和度变化的估计值在350米以上为6%至40%。基于甲烷水合物平衡态和亚稳态的定量特征，考虑冰盖期和海侵期，确定了古气候情景下多年冻土中残余甲烷水合物的保存条件。结果表明，由于在-4℃以下温度下的自保存作用，在非平衡条件下可以保存土壤上部200 m的残余甲烷水合物。当水合物解离时，降低温度的效果阻止了沉积物的完全分解，并导致冻土厚度的增加。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Izvestiya, Physics of the Solid Earth 地学-地球化学与地球物理

CiteScore

1.60

自引率

30.00%

发文量

审稿时长

6-12 weeks

期刊介绍： Izvestiya, Physics of the Solid Earth is an international peer reviewed journal that publishes results of original theoretical and experimental research in relevant areas of the physics of the Earth''s interior and applied geophysics. The journal welcomes manuscripts from all countries in the English or Russian language.