...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Non-steady state carbonate recycling and implications for the evolution of atmospheric P_(CO_2)
【24h】

Non-steady state carbonate recycling and implications for the evolution of atmospheric P_(CO_2)

机译：非稳态碳酸盐的再循环及其对大气P_（CO_2）演化的影响

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Most treatments of the Phanerozoic evolution of the carbon dioxide content of the atmosphere (P_(CO_2)) assume a steady state closed system. Release of CO_2 by mantle degassing and by biogenic precipitation of carbonates and their metamorphism in subduction zones balances the consumption by continental aluminosilicate weathering. Small perturbations in this balance bring about changes in P_(CO_2), but given the small size of the atmospheric CO_2 reservoir relative to the rate of fixation by weathering, mechanisms that maintain this apparently precarious balance dominate current thinking. At present, the Atlantic and Indian oceans are major depocenters of CaCO_3, but subduction of ocean floor and the deposits on it is minimal in these basins. The locus of metamorphic regeneration of CO_2 is restricted to the trenches off Central America. This is due to global asymmetries in the age of crust being subducted, in the distribution of oceanic carbonate productivity, and in the carbonate compensation depth, coupled with the poor preservation of old carbonate sediments. There is no causal relationship between the metamorphic release and weathering uptake of CO_2 and subsequent deposition of carbonate on timescales shorter than a complete cycle of opening and closure of a basin. We hypothesize that the low present-day P_(CO_2) is maintained by a time lag between: (1) mantle outgassing and metamorphic regeneration related to orogenic events in the geologic past, and (2) consumption driven by recent mountain building in the Tethyan zone and in the Western Americas. If this is true, then at the present 'kinetic minimum' both the terrestrial biosphere and the weathering rates are CO_2 limited. Atmospheric P_(CO_2) levels are controlled by weathering reactions only at this limit. In epochs of tectonic stability, outgassed CO_2 can accumulate in the atmosphere to very high concentrations with no obvious limit. Thus, as in the past, the current ice age will persist for tens of millions of years, possibly until the closure of the Atlantic recycles the first deep carbonate depocenter since the destruction of the Tethys. A greater understanding of all these processes is required for the geochemical evolution of the Earth surface environment to be simulated.
机译：大气中二氧化碳含量（P_（CO_2））的多生代演化的大多数处理都采用稳态的封闭系统。地幔脱气和碳酸盐的生物成因沉淀及其在俯冲带的变质释放CO_2，可以平衡大陆性铝硅酸盐风化的消耗。这种平衡的微小扰动会引起P_（CO_2）的变化，但是鉴于大气CO_2储集层的大小相对于风化作用的固定速率而言，维持这种明显不稳定的平衡的机制主导了当前的思想。目前，大西洋和印度洋是CaCO_3的主要沉积中心，但在这些盆地中海底俯冲及其上的沉积物很少。 CO_2的变质再生轨迹仅限于中美洲以外的海沟。这是由于地壳年龄的全球不对称性，海洋碳酸盐生产力的分布以及碳酸盐补偿深度的不对称，以及对旧碳酸盐沉积物的不良保护。在比整个盆地打开和关闭的完整周期短的时间尺度上，变质释放与CO_2的风化吸收以及随后的碳酸盐沉积之间没有因果关系。我们假设当前的低P_（CO_2）通过以下时间间隔得以维持：（1）与地质过去的造山活动有关的地幔放气和变质再生，以及（2）特提斯山最近的山体建造驱动的消耗区和西美洲。如果这是真的，那么在目前的“动力学最小值”下，陆地生物圈和风化率都受到CO_2的限制。大气中的P_（CO_2）水平仅在此极限下受风化反应控制。在构造稳定的时期内，放出的CO_2可以在大气中积累到很高的浓度，没有明显的限制。因此，与过去一样，当前的冰河时代将持续数千万年，可能直到大西洋的关闭回收了自特提斯号被毁以来的第一个深层碳酸盐沉积中心。要模拟地球表面环境的地球化学演化，需要对所有这些过程有更深入的了解。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号