High thermal conductivity of stishovite promotes rapid warming of a sinking slab in Earth's mantle
High thermal conductivity of stishovite promotes rapid warming of a sinking slab in Earth's mantle
复制标题
DOI：
10.1016/j.epsl.2022.117477
复制
发表时间：
2022-04
影响因子：
5.3
通讯作者：
W. Hsieh;Enrico Marzotto;Yi‐Chih Tsao;T. Okuchi;Jung‐Fu Lin
中科院分区：
文献类型：
--
作者：
W. Hsieh;Enrico Marzotto;Yi‐Chih Tsao;T. Okuchi;Jung‐Fu Lin
俯冲板片和地幔的热输运对它们的热化学演化和动力学有着重要的影响，其中热导率控制着传导热传递的大小。在这里，我们调查的高压热传导的斯铁橄榄石和新六方铝（NAL）相，在浅下地幔的两个主要的板片矿物，以及它们对板片动力学的影响。在25-60 GPa和300 K下，纯的和含铝的斯氏橄榄岩的电导率分别为60-70和30-40 W m− 1 K −1，远高于含铁的NAL（10-33 W m− 1 K −1）和一个热解地幔或俯冲玄武质地壳的组合。数值模拟表明，俯冲地壳物质，特别是与当地的二氧化硅富集将有有效的热传导，促进更快的下沉板片升温，改变板片材料的动力学稳定性，并导致板片停滞和地壳拆离在浅下地幔。下地幔浅部俯冲板沿着硅富集区的传导热传递对地幔动力学的影响可能比以前认为的更大。
Thermal transport in subducted slabs and mantle critically influences their thermo-chemical evolution and dynamics, where the thermal conductivity controls the magnitude of conductive heat transfer. Here we investigate high-pressure thermal conductivities of stishovite and new-hexagonal-aluminous (NAL) phase, two major slab minerals in the shallow lower mantle, and their impacts on slab dynamics. Pure and Al-bearing stishovite exhibit conductivities of 60–70 and 30–40 W m−1K−1, respectively, at 25–60 GPa and 300 K, much higher than the Fe-bearing NAL, 10–33 W m−1K−1, and assemblage of a pyrolitic mantle or subducted basaltic crust. Numerical simulations indicate that subducted crustal materials particularly with local silica-enrichment would have efficient thermal conduction which promotes faster warming of a sinking slab, altering dynamic stability of slab materials and leading to slab stagnation and crust detachment in the shallow lower mantle. Conductive heat transfer in silica-enriched regions along subducted slabs in the shallow lower mantle can be more influential on mantle dynamics than previously thought.