摘要
青海共和—贵德盆地处在秦岭—昆仑造山带"秦昆岔口",是新生代断陷盆地。盆缘活动断裂、岩浆岩发育,水热活动强烈、温泉密集,超过60℃的温泉6处,最高可达93.5℃,超过当地沸点(92℃)为沸泉。盆地内地温场高,据地热钻井揭露见花岗岩的三个孔,QR1孔深969 m,孔底温度为70℃,DR1孔深1 455 m,孔底温度87℃,R2孔深1 709.56 m,孔底温度可达97℃,地温梯度高达6～7℃/100 m,是正常地温梯度2倍,地热增温随深度增大而升高,推测3 000 m温度可达150～200℃,重力低异常推断基底凹陷与可控源音频大地电磁测深、地震反射波勘探推断基底界面深度不一致,并有磁异常对应,又经钻探证实。由此认为重、磁异常为花岗岩引起。花岗岩为燕山期,进入花岗岩钻孔深部有热无水,故认为盆地可能存在干热岩。
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.
出处
《物探与化探》
CAS
CSCD
2013年第1期35-41,共7页
Geophysical and Geochemical Exploration
