华北平原及其邻近地区大地热流资料报道与讨论

本文报道的我国第一批正式热流数据,系几年来我们在开展地温普查、矿山地温等工作的同时,选取了一部分较为理想的钻孔进行大地热流测量的结果。测点主要位于华北平原及其近邻的山区,个别在江淮地区。这项工作得到煤炭、地质、冶金等部门的大力协助。

REPORT ON THE DATA OF TERRESTRIAL HEAT FLOW IN NORTH CHINA PLAIN AND ADJACENT REGIONS AND ITS STUDY

There are to be reported in this article twenty-five heat flow measurements from Northern Chino. Of them eleven values are taken from the spots situated in the denudation area of the North China Platform (Precambrian platform); twelve others are from the Meso-Cenozoic subsiding zone (roughly corresponding to North China Plain) of the same platform; the remainder of two values are from south-western Anhwei, which belongs to early-Palaeozoic depression region (Yangtze-Qianitang Para-geosyneline).Heat flow measurements in these three geological regions are different from each other. In the first region, the values of heat flow range from 0.6 to 1.3 μcal/cm2· s, with the average of 1.1. In the second region, values measured are from 1.45 to 2.0. However in view of the fact that most of the measurements are taken from the uplifted region of basement rocks, the surface heat flow there may have been locally increased by 10-15%, it is preferable to take 1.5 as a representative value of this region. In the third region the average measured value is 1.84 μcal/cm2·s.Drill hole temperatures and the thermal conductivities of rocks are determined by temperature logger and thermo-conductivity apparatus respectively, both of them are designed by the Geothermal Research Group.Preliminary conclusions obtained are as follows:(1) In comparison with other similar tectonic elements of the world, the heat flow in Northern China has obviously higher values, except in the denudation area of the North China Platform.(2) The principal cause for higher heat flow in N. China is the more intense geological activity prevailing there, which has been justified by a number of geological data. Local cause for this may be the situation of some of the points where the measurements have been taken on the uplifted zones of the basement rocks or in the shallow parts of the earth’s crust where the contents of radioactive elements are relatively high.(3) Regional geological activities and the tectonic history control the geothermal field in the depths of the earth’s crust. On the other hand, obvious temperature difference in the depths of the crust may serve as one of the driving forces for tectonic movements. If we bring geothermal data in comparison with active fault belts and seismic belts, then this conclusion may well be obtained.