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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Thermal diffusivity of felsic to mafic granulites at elevated temperatures
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Thermal diffusivity of felsic to mafic granulites at elevated temperatures

机译：高温下长英质质对镁铁质质颗粒的热扩散率

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The thermal diffusivity of felsic and intermediate granulites (charnockites, enderbites), mafic granulites, and amphibolite-facies gneisses has been measured up to temperatures of 550 degrees C using a transient technique. The rock samples are from the Archean and Pan-African terranes of the Southern Indian Granulite Province. Thermal diffusivity at room temperature (D-RT) for different rock types ranges between 1.2 and 2.2 mm(2) s(-1). For most of the rocks, the effect of radiative heat transfer is observed at temperatures above 450 degrees C. However, for few enderbites and mafic granulites, radiative heat transfer is negligible up to 550 degrees C. In the temperature range of conductive heat transfer, i.e., between 20 degrees and 450 degrees C, thermal diffusivity decreases between 35% and 45% with increasing temperature. The temperature dependence of the thermal diffusivity is directly correlated with the thermal diffusivity at room temperature, i.e., the higher the thermal diffusivity at room temperature, DRT, the greater is its temperature dependence. In this temperature range i.e., between 20 and 450 degrees C, thermal diffusivity can be expressed as D = 0.7 mm(2) s(-1) + 144 K (D-RT-0.7 mm(2) s(-1))/(T - 150 K), where T is the absolute temperature in Kelvin. At higher temperatures, an additional radiative contribution is observed according to CT3, where C varies from 10(-9) to 10(-10) depending on intrinsic rock properties (opacity, absorption behavior, grain size, grain boundary, etc). An equation is presented that describes the temperature and pressure dependence thermal diffusivity of rocks based only on the room-temperature thermal diffusivity. Room-temperature thermal diffusivity and its temperature dependence are mainly dependent on the major mineralogy of the rock. Because granulites are important components of the middle and lower continental crust, the results of this study provide important constraints in quantifying more accurately the thermal state of the deeper continental crust. (c) 2006 Elsevier B.V. All rights reserved.
机译：已经使用瞬变技术测量了直至550摄氏度的温度下，长英质和中间粒状花岗岩（炭黑岩，顽石），镁铁质粒状岩和闪石相片麻岩的热扩散率。岩石样品来自印度南部花岗岩省的太古代和泛非地貌。室温下（D-RT）对于不同岩石类型的热扩散率范围为1.2到2.2 mm（2）s（-1）。对于大多数岩石，在高于450摄氏度的温度下会观察到辐射传热的影响。但是，对于极少的压痕和镁铁矿粒，在550摄氏度以下，辐射传热是微不足道的。在传导传热的温度范围内，即，在20摄氏度至450摄氏度之间，随着温度的升高，热扩散率将降低35％至45％。热扩散率的温度依赖性与室温下的热扩散率直接相关，即，室温DRT下的热扩散率越高，其温度依赖性越大。在此温度范围内，即20到450摄氏度之间，热扩散率可以表示为D = 0.7 mm（2）s（-1）+ 144 K（D-RT-0.7 mm（2）s（-1）） /（T-150 K），其中T是开氏温度的绝对温度。在较高的温度下，根据CT3观察到了额外的辐射贡献，其中C根据固有岩石特性（不透明度，吸收行为，晶粒尺寸，晶界等）在10（-9）到10（-10）之间变化。提出了仅基于室温热扩散率来描述岩石的温度和压力依赖性热扩散率的方程。室温下的热扩散率及其温度依赖性主要取决于岩石的主要矿物学。由于花岗石是中低陆壳的重要组成部分，因此这项研究的结果为更准确地定量深陆壳的热状态提供了重要的约束条件。 （c）2006 Elsevier B.V.保留所有权利。

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