There are different opinions concerning the formation of geothermal field high temperature in geothermal research and the problem as to why there is a low temperature gradient in the deep part of the geothermal field. In this paper, the authors analyzed the influencing factors of geothermal field proposed by previous researchers, and adopted geothermal field forward modeling method to study two situations, i.e., anomalous heat sources heating magma pocket and heat transfer without heat source. The authors hold that the majority of anomalous heat sources such as magma pocket have a fast cooling rate and can't directly heat the geothermal field relative to the geological evolution time scale. The search for geothermal field should be mainly conducted in a good thermal cap with a certain thickness in the shallow part and the high conductive layer in the deep part. The main controlling factor for high geothermal field is the lateral heterogeneity in physical-thermal conductivity caused by tectonic movement. In geothermal field, the temperature reflects mirror image with depth in the vertical direction, i.e., geothermal gradient decreases sharply from shallow part to the deep part until "high conductive homogenization depth". The temperature measurements in lots of geothermal fields show the correctness of this conclusion.%在地热研究中地热田高地温的形成原因、为何地热田深部会出现低地温梯度等说法不一, 未有定论.本文对前人所提出的地温场影响因素逐一进行了分析, 采用地热场正演模拟手段, 对有异常热源供热-岩浆囊和无热源的热传导两种情况进行了研究.认为多数异常热源如岩浆囊, 相对于地质演化时间尺度而言, 其冷却速度较快, 并不能直接为地热田供热; 寻找地热田主要在浅部有一定厚度的好的热盖层和深部有高导层的区域进行; 构造运动所引起的物性-热传导性的横向不均匀性才是引起高地温场的主控因素; 地热田在垂向上温度随深度呈镜像倒影关系, 会呈现浅层地温高, 向深部地温梯度急剧减小, 直到"高导均化深度", 大量地热田温度实测结果说明了这一结论的正确性.
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