Decarbonation efficiency in subduction zones: Implications for warm Cretaceous climates
Decarbonation efficiency in subduction zones: Implications for warm Cretaceous climates
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DOI：
10.1016/j.epsl.2010.12.049
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发表时间：
2011-02-15
影响因子：
5.3
通讯作者：
Edmonds, Marie
中科院分区：
文献类型：
--
作者：
Johnston, Fraser K. B.;Turchyn, Alexandra V.;Edmonds, Marie
俯冲带在碳的地球化学循环中起着重要作用，相关的弧火山作用被认为是地质时期大气中二氧化碳浓度的主要控制因素。弧火山作用可能在最近的白垩纪晚期的温室中特别重要，在那里，人们假设富含碳酸盐的特提斯的俯冲导致了整体较高的火山CO2释气率，从而导致气候变暖。为了验证这一假设，现代俯冲带的脱碳效率计算通过地球化学数据库，比较陆上弧CO2通量与俯冲地壳和沉积物地球化学。现代的数据被用来假设一个CO2循环和脱气的情况下，弧火山关闭的特提斯。我们的分析表明，俯冲带的热结构控制的程度和深度板脱碳，而沉积物地球化学（如碳酸盐沉积物的量）可能是次要的。现代电弧的计算脱碳效率范围为18%至70%。我们的计算支持最近的模型预测通过渗透驱动的脱碳碳循环，并在子弧深度的水的可用性的限制。这一分析使我们能够推断出潜在的火山CO2通量从俯冲的特提斯在白垩纪期间，建议之间的8和222%的现代CO2出气增加。我们认为，在白垩纪的CO2出气增加的主要原因是弧岩浆的上覆地壳中的台地碳酸盐岩的污染和增加脱碳效率。(C)2011爱思唯尔有限公司版权所有。
Subduction zones play a fundamental role in the geochemical cycle of carbon, and related arc volcanism is believed to exert primary control on atmospheric CO2 concentrations over geological time. Arc volcanism may have been particularly important in the most recent Greenhouse of the late Cretaceous, where it has been hypothesized that the subduction of the carbonate-rich Tethys contributed to overall higher volcanic CO2 outgassing rates and thus a warmer climate. To test this hypothesis, the decarbonation efficiencies of modern subduction zones were calculated through a geochemical database that compared subaerial arc CO2 fluxes with the subducting crust and sediment geochemistry. The modern data are used to postulate a CO2 recycling and degassing scenario for arc volcanism related to the closure of the Tethys. Our analysis indicates that the thermal structure of subduction zones controls the extent and depth of slab decarbonation, while the sediment geochemistry (e.g. the amount of carbonate sediment) may be of secondary importance. The calculated decarbonation efficiency of modern arcs ranges from 18 to 70%. Our calculations support recent models predicting carbon recycling through infiltration-driven decarbonation, and limited by water availability at sub-arc depths. This analysis allows us to make inferences about the potential volcanic CO2 flux from subduction of the Tethys during the Cretaceous, suggesting between an 8 and 222% increase over modern CO2 outgassing. We suggest that the primary reason for the increase in CO2 outgassing in the Cretaceous is contamination of arc magmas by platform carbonates in the overlying crust and increased decarbonation efficiency. (C) 2011 Elsevier B.V. All rights reserved.