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Thermal Structure of the Ionian Slab

机译：爱奥尼亚平板的热结构

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We propose a thermal model of the subducting Ionian microplate. The slab sinks in an isothermal mantle, and for the boundary conditions we take into account the relation between the maximum depth of seismicity and the “thermal parameter” L th of the slab, which is a product of the age of the subducted lithosphere and the vertical component of the convergence rate. The surface heat-flux dataset of the Ionian Sea is reviewed, and a convective geotherm is calculated in its undeformed part for a surface heat flux of 42 mW m−2, an adiabatic gradient of 0.6 mK m−1, a mantle kinematic viscosity of 1017 m2 s−1 and an asthenosphere potential temperature of 1300°C. The calculated temperature-depth distribution compared to the mantle melting temperature indicates the decoupling limit between lithosphere and asthenosphere occurs at a depth of 105 km and a temperature of 1260°C. A 70–km thick mechanical boundary layer is found. By considering that the maximum depth of the seismic events within the slab is 600 km, a L th of 4725 km is inferred. For a subduction rate equal to the spreading rate, the corresponding assimilation and cooling times of the microplate are about 7 and 90 Myr, respectively. The thermal model assumes that the mantle flow above the slab is parallel and equal to the subducting plate velocity of 6 cm yr−1, and ignores the heat conduction down the slab dip. The critical temperature, above which the subduced lithosphere cannot sustain the stress necessary to produce seismicity, is determined from the thermal conditions governing the rheology of the plate. The minimum potential temperature at the depth of the deepest earthquake in the slab is 730°C.
机译：我们提出了俯冲爱奥尼亚微板的热模型。平板下沉在等温地幔中，对于边界条件，我们考虑了最大地震活动深度与平板“热参数” L th 之间的关系，该温度是平板年龄的乘积。俯冲岩石圈和垂直分量的收敛速度。审查了爱奥尼亚海的表面热通量数据集，并在其未变形部分计算了对流地热，其表面热通量为42 mW m-2 ，绝热梯度为0.6 mK m-1 ，地幔运动粘度为1017 m2 s-1 ，软流圈势能温度为1300°C。与地幔融化温度相比，计算得出的温度-深度分布表明岩石圈和软流圈之间的解耦极限发生在深度为105 km和温度为1260°C的情况下。发现了一个70公里厚的机械边界层。通过考虑平板内地震事件的最大深度为600 km，可以推断出L th 为4725 km。对于等于扩散速率的俯冲速率，微板的相应吸收和冷却时间分别约为7和90 Myr。热模型假设板坯上方的地幔流平行且等于俯冲板速度6 cm yr-1 ，而忽略了板坯垂下的热传导。临界温度是由控制板流变性的热条件确定的，在该温度下俯冲的岩石圈无法承受产生地震活动所必需的应力。平板中最深地震的最低潜在温度为730°C。

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