Thermal evolution models for the Earth
Thermal evolution models for the Earth
复制标题
地球的热演化模型
DOI：
--
复制
发表时间：
1985
期刊：
影响因子：
--
通讯作者：
U. Christensen
中科院分区：
文献类型：
--
作者：
U. Christensen
对基于对流热量输送的参数化为基础的地球热演化模型进行了严格的重新审视。传统的假设是，地幔粘度的温度依赖性意味着内部温度和对流热损失是强耦合的。最近关于变粘性对流换热的数值研究表明，热流对地幔温度的依赖性实际上可能比预期的要弱得多。我比较了热演化模型与热损失对温度的强相关性和弱相关性。在相关性较弱的情况下，太古宙的板块速度和热流比今天高出不超过50%，而在相关性较强的情况下，预测的差异要大得多。在前一种情况下，太古宙地幔温度稍高，现今放射性产热与热损失的比率(Urey比率)为50%或略低。传统的参数化演化模型中的Urey比率为70%。两种模型的预测都与独立的地质、地球化学和古地磁证据进行了比较。尽管这一证据受到一些不确定性的影响，但它在所有情况下都支持基于热损失与内部温度弱耦合的演化模型。
Thermal evolution models for the earth which are based on a parameterization of the convective heat transport are critically reexamined. Traditionally, it has been assumed that the temperature dependence of the mantle viscosity implies that internal temperature and convective heat loss are strongly coupled. Recent numerical work on the heat transport by variable viscosity convection demonstrates that the dependence of the heat flow on the mantle temperature may in fact be much weaker than expected. I compare thermal evolution models with strong and weak dependence of the heat loss on the temperature. With the weaker dependence, plate velocities and heat flow in the Archean were not more than 50% higher than today, while with the strong dependence, much larger differences are predicted. In the former case the Archaean mantle temperatures are somewhat higher, and the present-day ratio of radioactive heat production over heat loss (Urey ratio) is 50% or slightly less. The Urey ratios in the traditional parameterized evolution models are >70%. The predictions of both kinds of models are compared with the independent geological, geochemical, and palaeomagnetic evidence. Although this evidence is subject to some uncertainties, it favors in every case the evolution models based on a weak coupling of heat loss to the interior temperature.