Abstract: This study explores the geothermal features of the Mahu Sag and Ke-Wu fault zone, including the present-day
geothermal gradient, terrestrial heat flow, formation temperatures at depths of 5000-8000 m, and the lithosphere’s thermal structure, utilizing data from 70 wells and 98 rock samples, and establishes a geothermal genetic model for the Mahu-Ke-Wu region. In the Mahu-Karamay-Wuerhe region, the thermal conductivity of Carboniferous-Paleogene rocks ranges from 1.5 to 3.03 W/（m·K）, exhibiting a stepwise increase with the age of the strata. The geothermal gradient in the study area ranges from 16.25 to 22.42 ℃ /km (Avg: 21.18 ℃ /km）. The heat flow ranges from 34.73 to 52.62 mW/m2 (Avg: 44.01 mW/m2）. The temperature of strata at 5000 meters depth ranges from 85.4 to 126.5 ℃ (Avg:113.2 ℃）. At 6000 meters depth, the temperature ranges from 104.9 to 144.2 ℃ (Avg: 134.9 ℃）. At 7000 meters depth, the temperature ranges from 120.9 to 167.9 ℃ (Avg: 153.6 ℃）. At 8000 meters depth, the temperature ranges from 133.8 to 182.3 ℃ (Avg: 170.8 ℃）. Vertically, the geothermal gradient decreases by 2 ℃ /km. The heat flow ratio between the fault zone and the sag crust-mantle is 0.77 and 1.20, respectively, indicating a typical cold crust and cold mantle structure. The geothermal genetic model of the Mahu-Karamay-Wuerhe region shows that the crustal structure of different tectonic units, along with variations in thermal conductivity between the sedimentary cover and the folded basement rocks, is the key factor governing the distribution of the geothermal field in the study area. The varying depths of the Moho surface in the sag and fault zones provide different amounts of heat to the surface, and the differences in rock thermal conductivity allows redistribution of heat in the shallow strata, resulting in a convex high-concave low heat flow distribution pattern.

Key words: Western Junggar Basin, geothermal gradient, geothermal heat flow, lithospheric thermal structure, geothermal field
genesis model, fixed depth temperature