Heat Sources of Hot Dry Rock in the Gonghe Basin, Northeastern Tibetan Plateau

Abstract

The Gonghe basin, which is located at the northeastern edge of the Qinghai-Tibetan Plateau, was selected as the first pilot demonstration site to explore the hot dry rock (HDR) geothermal resources in China. Several geothermal boreholes have been already drilled to target the Indosinian granite in the Gonghe basin. At a depth of 3760 m, a high bottom-hole temperature (BHT) of 210 °C is identified. The temperature gradient ranges from 12.4 to 109.6 °C km−1 and the mean heat flow is 119.3 mW m−2, which is significantly higher than the regional background of 74-75 mW m−2 at the northeastern margin of the Tibetan Plateau. A lot of geological, geophysical and geochemical work have been carried out to identify the heat sources that lead to the abnormal high heat flow, but a systematic summarization on these works is still missing. In this paper, we will review the factors of radiogenic heat production, cooling of magma chambers, fault fraction and deep water circulation in causing the high heat flow anomaly. Further work that should be done in the future will also be presented for revealing the heat sources.