共和盆地地热能分布特征与聚集机制分析

Distribution and Aggregation Mechanism of Geothermal Energy in Gonghe Basin

位处青藏高原北部的青海省共和盆地，是一个自中生代以来形成的断陷盆地，周界由深大活动断裂控制，其内堆积有大厚度的第四纪和新近纪地层，揭露厚度达900～1440m，基底由印支期花岗岩组成，调（勘）查资料显示，盆地内具有热流值较高的特征，基底花岗岩地热梯度大于5℃，热异常明显。青藏高原宽频地震探测资料显示，共和盆地所在的东昆仑地块上地幔存在着一条宽达150km的低速带，其与巴颜喀拉地块深地幔中以大型低速异常体为特征的地幔热柱相关联，该低速带延伸到地壳，在共和盆地及其周边一带地表以下1～40km的不同部位形成热流异常区，导致在盆地浅部形成丰富的以干热岩、地下热水为主的地下热能资源，其不仅在城镇供暖方面具有现实推广意义，而且在发电等能源利用中潜力巨大。

Gonghe Basin of Qinghai Province, which locates in northern Tibetan Plateau, is a faulted basin formed since mesozoic era. Around the basin is controlled by large active faults; inside the basin is the accumulation of large thickness of Quaternary and Neogene strata, the exposed thickness is up to 900-1440m, and the substrate is formed by Indosinian granite. Exploration results display that the value of heat flow is high inside the basin. Besides, the basement granite geothermal gradient is greater than 5℃, thermal anomaly is obvious. According to the broad band seismic observation data on the Qinghai-Tibet Plateau, there is a 150km low- velocity zone on the east Kunlun orogen where Gonghe Basin lies in. It is associated with the mantle plume in deep mantle of the Bayan Har orogen, which is characterized by huge low- velocity abnormity. The low-velocity zone extends to the earth crust and forms an abnormal area of heat flux at different parts with 1-40km below the earth＇s surface in Gonghe Basin and its sur- roundings, accounting for the forming of geothermal energy based on abundant hot-dry rocks and geothermal water in shallow part of the basin. It is significant not only for the city＇s heating system but also for electricity generation.