Faster seafloor spreading and lithosphere production during the mid-Cenozoic
Faster seafloor spreading and lithosphere production during the mid-Cenozoic
复制标题
新生代中期更快的海底扩张和岩石圈生产
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
C. Lithgow‐Bertelloni
中科院分区：
文献类型：
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作者：
C. Conrad;C. Lithgow‐Bertelloni
自白垩纪中期以来，海水化学、海平面和气候的同步变化被认为是全球山脊岩石圈生产速度持续下降的结果。然而，如果岩石圈的生产速度在过去180万年中几乎是恒定的，那么当今海底年龄的面积分布最容易解释。我们检查了当今海底年龄的空间梯度，并推断了法拉龙板块的俯冲年龄，以构建约140 Ma以来每个主要海洋盆地的扩张速度历史，揭示了戏剧性的新生代事件。在全球范围内，由于太平洋盆地板块速度的增加，海底扩张率在新生代早期增加了大约20%。从那时起，快速扩张的太平洋-法拉隆脊系统的俯冲作用导致全球平均扩张速度下降了12%，最保守的估计是岩石圈生产的总速度下降了18%或更多。这些在新生代的快速变化违背了稳定的海底形成模式，并证明了地球板块构造的时代性和演化性。
Concurrent changes in seawater chemistry, sea level, and climate since the mid-Cretaceous are thought to result from an ongoing decrease in the global rate of lithosphere production at ridges. The present-day area distribution of seafloor ages, however, is most easily explained if lithosphere production rates were nearly constant during the past 180 m.y. We examined spatial gradients of present-day seafloor ages and inferred ages for the subducted Farallon plate to construct a history of spreading rates in each major ocean basin since ca. 140 Ma, revealing dramatic Cenozoic events. Globally, seafloor spreading rates increased by similar to 20% during the early Cenozoic due to an increase in plate speeds in the Pacific basin. Since then, subduction of the fast-spreading Pacific-Farallon ridge system has led to a 12% decrease in average global spreading rate and an 18% or more decrease in the total rate of lithosphere production by the most conservative estimates. These rapid changes during the Cenozoic defy models of steady-state seafloor formation, and demonstrate the time-dependent and evolving nature of plate tectonics on Earth.