GEOLOGICAL-GEOPHYSICAL CHARACTERISTICS OF ENHANCED GEOTHERMAL SYSTEMS(HOT DRY ROCKS) IN GONGHE-GUIDE BASIN
GEOLOGICAL-GEOPHYSICAL CHARACTERISTICS OF ENHANCED GEOTHERMAL SYSTEMS(HOT DRY ROCKS) IN GONGHE-GUIDE BASIN
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发表时间：
2013
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通讯作者：
Xue Jian
中科院分区：
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作者：
Xue Jian
青海共和-贵德盆地位于秦岭-昆仑造山带的新生代地堑盆地内，活动断裂、岩浆岩多，热液活动强烈，有6处温泉温度超过60 ℃，最热的达93.5 ℃，该盆地地温场较高，根据三个地热钻孔揭露的花岗岩，QR 1969 m深的钻孔底部暴露温度为70 ℃，DR 11455 m深的钻孔底部暴露温度为87 ℃，R21709.56m深的钻孔底部甚至暴露温度为97 ℃，地温梯度高达6-7 ℃/100 m，是正常梯度的两倍。地热变暖随深度增加，低重力异常推断的基底深度与CSAMT和地震资料不一致根据相应的磁异常和钻探证据，认为重磁异常是燕山期花岗岩引起的，由于钻孔深部有热而无水相交，认为该盆地可能存在热干岩作为热源。
The Gonghe-Guide basin of Qinghai Province is located in a Cenozoic graben basin of the Qingling-Kunlun orogenic belt,where there are many active faults,magmatites and intense hydrothermal activities.There are 6 hot springs whose temperatures are over 60 ℃,with the hottest one reaching 93.5 ℃,which is beyond the local boiling point(92 ℃) and is hence defined as a boiling spring.The geothermal field is high in this basin.According to three geothermal drill holes that uncovered granite,the drill hole named QR1 969 m in depth exposed 70 ℃ at the bottom,the drill hole named DR1 1 455 m in depth exposed 87 ℃ in the bottom,the drill hole named R2 1 709.56 m in depth even exposed 97 ℃ at the bottom.Geothermal gradient is up to 6-7 ℃ per 100 meter,being two times of the normal gradient.The geothermal warming increases with the depth,and the authors inferred that the temperature in the depth of 3000 m is about 150 to 200 ℃.The basement depth inferred by low gravity anomaly is not consistent with the CSAMT and seismic reflection results.With corresponding magnetic anomaly and drilling evidence,the authors believe that the gravity and magnetic anomaly is caused by Yanshanian granite.As the deep drill holes intersect heat but no water,the authors hold that there may exist hot dry rock as the heat source of this basin.