Surface evolution during the mid-Proterozoic stalled by mantle warming under Columbia–Rodinia
Surface evolution during the mid-Proterozoic stalled by mantle warming under Columbia–Rodinia
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DOI：
10.1016/j.epsl.2023.118055
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发表时间：
2023-04
影响因子：
5.3
通讯作者：
Yinqiao Zou;R. Mitchell;Xu Chu;Michael Brown;Jilian Jiang;Qiuli Li;Lei Zhao;M. Zhai
中科院分区：
文献类型：
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作者：
Yinqiao Zou;R. Mitchell;Xu Chu;Michael Brown;Jilian Jiang;Qiuli Li;Lei Zhao;M. Zhai
地幔的热状态影响岩石圈动力学和地球表面的演化。地球动力学模拟预测，聚集的大陆可能充当有效的隔热体，导致底层地幔变暖（地幔变暖假说）。地幔变暖削弱了大陆岩石圈，这会导致板块边缘分布更多的应变，并导致造山带的地势较低，变质峰压力（peak-P）较低，变质岩的冷却和折返速度较慢。为了检验地幔变暖假说，我们根据新太古代和较年轻的造山带编制的新数据集确定了变质冷却和折返速率的长期变化。我们发现中元古代（1.85-0.85 Ga；又名钻孔十亿）期间缓慢的冷却和折返与变质岩的较低峰值 P 和较高温压（温度/压力，T/P）比相关。这一结果与中元古代大陆岩石圈减弱以及在较温暖的地幔条件下形成较热的低地势造山带是一致的。我们认为，长寿的哥伦比亚-罗迪尼亚超大陆可能起到了隔热体的作用，导致大陆岩石圈下方的地幔变暖，从而形成了独特的中元古代造山作用。低地势的中元古代造山带折返缓慢，反过来又减少了大陆侵蚀，限制了生物必需营养物质向海洋的输送，并降低了有机碳埋藏率，从而阻碍了大气中氧气的积累。海洋中持续的营养缺乏和大气氧合作用的抑制可能在这无聊的十亿年里阻碍了地表演化。
The thermal state of the mantle impacts lithospheric dynamics and Earth's surface evolution. Geodynamic simulations predict that aggregated continents may act as an effective thermal insulator leading to the warming of the underlying mantle (mantle warming hypothesis). Mantle warming weakens the continental lithosphere, which should lead to more distributed strain at plate margins, and result in lower-relief orogens, with lower metamorphic peak pressures (peak-P), and slower cooling and exhumation of metamorphic rocks. To test the mantle warming hypothesis, we determine the secular change of metamorphic cooling and exhumation rates based on a new dataset compiled from Neoarchean and younger orogens. We find that sluggish cooling and exhumation during the mid-Proterozoic (1.85–0.85 Ga; aka the boring billion) correlate with lower peak-Pand higher thermobaric (temperature/pressure,T/P) ratios of metamorphic rocks. This result is consistent with a weakened continental lithosphere and the development of hotter lower-relief orogens under warmer mantle conditions during the mid-Proterozoic. We posit that the long-lived Columbia–Rodinia supercontinents may have acted as a thermal insulator that led to the mantle warming beneath the continental lithosphere and thus a distinctive style of mid-Proterozoic orogenesis. Low-relief mid-Proterozoic orogens with sluggish exhumation, in turn, reduced continental erosion and restricted delivery of bio-essential nutrients to the oceans, and decreased rates of organic carbon burial and thereby hindered oxygen accumulation in the atmosphere. The persistent nutrient deficiency in the oceans and suppressed atmospheric oxygenation may have stalled the surface evolution during the boring billion.