On the regional variation of heat flow, geotherms, and lithospheric thickness☆
On the regional variation of heat flow, geotherms, and lithospheric thickness☆
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DOI：
10.1016/0040-1951(77)90215-3
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发表时间：
1977-03
期刊：
影响因子：
2.9
通讯作者：
H. Pollack;D. Chapman
中科院分区：
文献类型：
--
作者：
H. Pollack;D. Chapman
以地表热流为主要自变量的大陆岩石圈和大洋岩石圈地热族已经建立。大陆模式的特点是地热，其中地表热流与流入岩石圈底部的热量加上岩石圈内放射性衰变产生的热量平衡。该模型适应区域变化的地表热流与成比例的变化，在放射性的富硫区和更深的热流。比例性是由一个新的和一般的线性关系之间的约化热流和平均热流的一个区域（q 0.6 q 0），这使得q和平均产热的富集区，以估计从知识的平均表面热流的一个省。海洋模式的特点是瞬态冷却的半无限介质的初始温度梯度和一些近地表辐射热生产。该模型产生的热流与最古老的海洋盆地的观测结果令人满意的一致。海洋和大陆地热达到融化温度的0.85的深度被证明是一个一致的估计深度的顶部的低速通道，或覆盖通道的高速盖的厚度。我们确定的盖子作为岩石圈的同义词，并产生一个全球地图的岩石圈厚度的基础上的区域变化的表面热流。在地球仪的大部分地区，岩石圈的厚度不到100公里，但在前寒武纪的地盾和地台（低热流区）之下，岩石圈的厚度明显变厚，并且变得更加粘稠。地盾的这些特征与最近报告的板块系统驱动机制模型是一致的，后者要求在大陆面积大的板块下有更大的阻滞力。
Geotherm families in which surface heat flow is the principal independent variable have been constructed for continental and oceanic lithospheres. The continental model is characterized by geotherms in which surface heat flow is in equilibrium with heat flowing into the lithosphere at its base plus heat generated by radioactive decay within the lithosphere. The model accommodates the regional variation of the surface heat flow with proportional variations in the radioactivity of the surficial enriched zone and in the deeper heat flow. The proportionality is dictated by a new and general linear relationship between reduced heat flow and mean heat flow for a region (q∗≅ 0.6 q ̄ 0), which enables both q∗ and the mean heat production of the enriched zone to be estimated from knowledge of the mean surface heat flow of a province. The oceanic model is characterized by the transient cooling of a semi-infinite medium with an initial temperature gradient and some near-surface radiogenic heat production. The model yields a heat flow in satisfactory agreement with observations in the oldest ocean basins. The depth at which both the oceanic and continental geotherms reach~ 0.85 of the melting temperature is shown to be a consistent estimator of the depth to the top of the low-velocity channel, or the thickness of the high-velocity lid overlying the channel. We identify the lid as synonymous with the lithosphere, and produce a global map of lithospheric thickness based on the regional variation of surface heat flow. The lithosphere is less than 100 km thick over most of the globe, but thickens appreciably and becomes more viscous beneath the Precambrian shields and platforms, regions of low heat flow. These characteristics of shields are consistent with recently reported models of the driving mechanisms of the plate system, which require greater retarding forces beneath plates with large continental areas.