热流和岩石生热率关系的研究

通过花岗岩体和中下地壳剖面岩石生热率的研究,显示出花岗岩体内生热率的分布至多样性;华北下地壳变质岩的生热率介于0.2-0.4μW/m³之间,其对热流的热贡献较小;地壳岩石生热率总体上是深度不连续的递减函数。中国东南地区出露着大面积的中生代花岗岩体,实测热流和岩石生热率没有得出可信的线性关系。结合对现有热流省资料的认识,提出了对热流和岩石生热率关系的新看法,解释了以往线性关系的不稳定性,估算出正常陆壳厚度的热流下限应为29.5mW/m²。

HEAT FLOW AND HEAT PRODUCTION RELATION

The discovery of empirical linear relation between heat flow and heat production is regarded as a breakthrough in theoretical geothennics. The fundamentals of the relation is that the heat production is a continuous function with depth in the crust,e. g. step, linear or exponential functions. Studies on the heat production in granites revealed that the distribution of heat production caries from place to place. The nugration of mobile uranium has an influence of 30% on total heat production. There is no intrinsic relation between the heat production of granite and of underlying rock strata. During magma evolution, heat production is controlled by ongnu, alkalinity,aluminousity and volatile contents of magma. Results from the middle-lower crust section in LVorth China displays that the heat production in the middle crust Is in the range 0.4μW/m³ to 1.9μW/m³, the average heat 0.4μW/m³, the latter has smaller contribution production in the lower crust is to heat flow. The heat production is a decreasing and discontinuous function with depth in the crust.Ther is targe area of Mesozoic granites in SE China. But no relable linear relation between heat flow and heat production has been found. In 48 existing heat flow-heat production relations, most of the linear correlation coefficients are low,the reduced heat flow and the D value change quite a lot. A new relation between heat flow and heat production is proposed in the paper, which has been used to explain the insaability of the previous one. The inferior limit of hcat flow is expcctcd to be 29.5mW/m² in continent with normal thtickness.