漳州地区岩石放射性地球化学特征及岩石圈热结构

Radiogenic heat production of rocks from Zhangzhou, Southeast China and its implications for thermal regime of lithosphere

对漳州地区的地表和钻孔岩石进行了岩石密度、放射性生热元素含量和岩石导热率测试。结果显示,岩石密度的平均值在2.60 g/cm^3左右,与世界范围内花岗岩的密度平均值一致;花岗岩放射性生热率的平均值为3.7μW/m^3,高于中酸性火山岩和基性岩脉等其他类型岩石的放射性生热率值,热贡献率主要来自Th和U的放射性衰变热。研究区岩石导热率的平均值为2.83W/mK,接近世界范围内上地壳岩石的平均值。结合前人地质学、地球物理学和地热学研究成果,认为地幔对地表热流贡献率要高于地壳,漳州地区为典型的"冷壳热幔"型岩石圈热结构。

Rock density, radioelement content and rock thermal conductivity of rock from the ground surface and drilling holes within Zhangzhou region, southeast China were measured. The results show that the weighted mean value of rock density was 2.60 g/cm^3, in good agreement with the average density of granite worldwide. The average radiogenic heat production of the investigated granite was3.7 μW/m^3, which is apparently higher than that of volcanic rock, mafic dykes and sedimentary rock from the same region. What is more, the main heat production was sourced from the decay of U and Th. The average rock thermal conductivity was 2.83 W/m K,approaching that of the middle-upper crustal rock. Our new data, together with previous geological, geophysical and geothermal data,indicate that the mantle contributes more heat flow than the crust to the surface heat flow, i.e., Qm/Qc1, thus Zhangzhou region is a typical region with cold crust and hot mantle type lithospheric thermal regime.