中国西北部盆地岩石热导率和生热率特征

本文根据大量实测数据,首次系统地报道了中国西北地区塔里木盆地、准噶尔盆地和柴达木盆地内的岩石热导率、岩石放射性生热率数据及其分布特征.对600多个岩石热导率和100多个实测岩石生热率的统计分析表明,沉积盆地中岩石的热物理性质与其岩性、埋藏深度和地层时代密切相关.随深度和地层时代的加大,岩石热导率增大;塔里木盆地的岩石热导率的总体平均值最大,而柴达木盆地的最小.岩石生热率在上地壳的分布是随深度的增加而减小的,但在沉积盆地的深度范围内几乎不变,其分布是均匀的,仅不同岩性的生热率差别较大.估算的岩石放射性生热产生的热量可以占到盆地地表热流的25%～45%.因此,岩石热物理性质的参数不仅与盆地的地温分布和大地热流特征密切相关,还可以为该地区盆地热历史恢复及深部地球物理的研究提供有效的参数和边界条件.

CHARACTERS OF THERMAL CONDUCTIVITY AND RADIOGENIC HEAT PRODUCTION RATE IN BASINS OF NORTHWEST CHINA

The characteristics of thermal conductivity and radiogenic heat production rate of rocks in the Tarim, Junggar and Qaidam Basins, Northwest China, were analysed systematically based on a large amount of measured data. The statistics of more than 600 thermal conductivities and more than 100 radiogenic heat production values showed that they changed with the types of lithology and increasing depth and ages of the samples. The average thermal conductivity was the highest in the Tarim Basin but lowest in the Qaidam Basin. The radiogenic heat production rate in the upper crust decreased with the increasing depth. However, they were distributed uniformly within the depth scale of sedimentary basin. The radiogenic heat production rate could be up to 25%～45% of surface heat flow in the basins. The petrophysical parameters not only related to the distribution of temperature and terrestrial heat flow, but also provided some useful information and boundary data to the studied thermal history and deep seated geophysics of the basins.