Kimberlites and the start of plate tectonics
Kimberlites and the start of plate tectonics
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DOI：
10.1130/g38024.1
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发表时间：
2016-10
期刊：
影响因子：
5.8
通讯作者：
R. Stern;M. Leybourne;T. Tsujimori
中科院分区：
文献类型：
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作者：
R. Stern;M. Leybourne;T. Tsujimori
我们想知道板块构造何时开始，并将考虑任何重要的地球特征，显示显着的时间演变。金伯利岩是钻石的主要来源，是罕见的火成岩特征。我们分析了它们在整个地球历史中的分布;大多数都是年轻的（约95%小于0.75 Ga），但很少有例子可以追溯到太古代（大于2.5 Ga）。虽然有不同的解释，这种年龄的不对称性（缺乏保护，缺乏曝光，地幔柱少，或缺乏古老的厚岩石圈在太古代和元古代），我们认为，金伯利岩喷发是现代风格的板块构造的结果，特别是俯冲的水合洋壳和沉积物深入地幔。这种循环自现代板块构造运动开始以来。1Ga的地幔CO2和H2O含量大幅增加，导致含金刚石金伯利岩岩浆的快速爆发性上升。金伯利岩的年龄分布，结合其他大规模的构造指标，仅在过去的1001 Ga（蓝片岩，蓝闪石的榴辉岩;柯石英或金刚石的超高压变质岩;硬硅钙石的变质岩;硬玉岩），表明板块构造，如今天所观察到的，只占地球历史的25%。
We want to know when plate tectonics began and will consider any important Earth feature that shows significant temporal evolution. Kimberlites, the primary source of diamonds, are rare igneous features. We analyze their distribution throughout Earth history; most are young (∼95% are younger than 0.75 Ga), but rare examples are found as far back as the Archean (older than 2.5 Ga). Although there are differing explanations for this age asymmetry (lack of preservation, lack of exposure, fewer mantle plumes, or lack of old thick lithosphere in the Archean and Proterozoic), we suggest that kimberlite eruptions are a consequence of modern-style plate tectonics, in particular subduction of hydrated oceanic crust and sediments deep into the mantle. This recycling since the onset of modern-style plate tectonics ca. 1 Ga has massively increased mantle CO2 and H2O contents, leading to the rapid and explosive ascent of diamond-bearing kimberlite magmas. The age distribution of kimberlites, combined with other large-scale tectonic indicators that are prevalent only in the past ∼1 Ga (blueschists, glaucophane-bearing eclogites; coesite- or diamond-bearing ultrahigh-pressure metamorphic rocks; lawsonite-bearing metamorphic rocks; and jadeitites), indicates that plate tectonics, as observed today, has only operated for <25% of Earth history.