Abstract Mantle convection is the principal mechanism by which heat is transferred from the deep Earth to the surface. Cold subducting slabs sink into the mantle and steadily warm, whilst upwelling plumes carry heat to the base of lithospheric plates where it can subsequently escape by conduction. Accurate estimation of the total heat carried by these plumes is important for understanding geodynamic processes and Earth's thermal budget. Existing estimates, based upon swell geometries and velocities of overriding plates, yield a global heat flux of ∼2 TW and indicate that plumes play only a minor role in heat transfer. Here, we revisit the Icelandic and Hawaiian plumes to show that their individual flux estimates are likely to be incorrect due to the assumption that buoyancy is mainly produced within the lithosphere and therefore translates at plate velocities. We develop an alternative methodology that depends upon swell volume, is independent of plate velocities, and allows both for decay of buoyancy through time and for differential motion between asthenospheric buoyancy and the overlying plate. Reanalysis of the Icelandic and Hawaiian swells yields buoyancy fluxes of 4.0 ± 0.5 Mg s−1 and 2.9 ± 0.6 Mg s−1, respectively. Both swells are used to calibrate a buoyancy decay timescale of ∼45 Myr for the new volumetric approach, which enables buoyancy fluxes to be estimated for a global inventory of 53 swells. Estimates from magmatic hotspots yield a cumulative lower bound on global plume flux of 2 TW, which increases to 6 TW if amagmatic swells are also included and if all buoyancy is assumed to be thermal in origin. Our results suggest that upwelling plumes play a significant role in the transfer of heat into the uppermost mantle.

中文翻译：

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重新审视热点和地幔柱：协调地幔传热差异

摘要 地幔对流是热量从地球深处传递到地表的主要机制。冷俯冲板块沉入地幔并稳定变暖，而上升流将热量带到岩石圈板块底部，然后通过传导逸出。准确估计这些羽流携带的总热量对于理解地球动力学过程和地球的热收支非常重要。现有估计，基于膨胀几何形状和覆盖板的速度，产生约 2 TW 的全球热通量，表明羽流在传热中只起次要作用。这里，我们重新审视冰岛和夏威夷的羽流，以表明由于浮力主要在岩石圈内产生并因此以板块速度平移的假设，它们各自的通量估计可能是不正确的。我们开发了一种替代方法，该方法取决于膨胀体积，与板块速度无关，并且允许浮力随时间衰减以及软流圈浮力与上覆板块之间的差动运动。重新分析冰岛和夏威夷的膨胀分别产生 4.0 ± 0.5 Mg s-1 和 2.9 ± 0.6 Mg s-1 的浮力通量。两种涌浪都用于为新的体积方法校准~45 Myr 的浮力衰减时间尺度，这使得可以估计全球 53 次涌浪的浮力通量。岩浆热点的估计产生了 2 TW 的全球羽流通量的累积下限，如果还包括岩浆膨胀并且假设所有浮力起源于热力，则该下限将增加到 6 TW。我们的研究结果表明，上升流羽流在热量传递到最上层地幔中起着重要作用。