郯庐断裂带地温场研究

笔者根据郯庐断裂带两侧(东经115°-121°、北纬30°-40°)117个热流数据,绘制了该区热流值平面图,并从断裂带两侧热流值的分布及高、中、低热流值频度分布特点,得出该断裂带中、南段(鲁西、皖北地区)热流值在50-80mW/m2范围内的频度最高,总平均值为67.67mW/m2,明显高于全球平均值(63mW/m2),也比中国大陆平均值(66mW/m2)略为偏高。沿断裂带存在一条明显的热流梯度递变带,东侧平均热流值(67.78mW/m2)明显高于西侧平均值(55.35mW/m2)。3条热流值剖面图显示由西向东穿过断裂带热流值有台阶、折线及跳跃型上升特点。笔者认为,这种东高西低的形貌反映了郯庐断裂带东、西侧地壳结构存在明显差异,这种差异与地震测深、大地电磁测深等地球物理量反映的东侧下地壳存在低速低阻层及莫霍面位置偏高相一致。 

THE GEOTHERMAL FIELD AROUND THE TANCHENG LUJIANG FAULT ZONE IN EAST CHINA

A heat flow plot from 117 measurements on both sides of the Tancheng-Lujiang Fault Zone shows a larger frequency of heat flows between 50 mW/m² and 80mW/m² in the central south segment of the fault with an average of 67.67mW/m²,notably higher than the average global value(63mW/m²),also somewhat higher than that of the China Continent (66mW/m²).There is a gradient zone from the west to the east side of the fault zone,rising from an average of 55.35mW/m² on the west side to an average of 67.78mW/m² on the east side.This suggests there may be remarkable difference in the crustal structure of both sides of the fault,as is agreeable to the existence of a low velocity,low resistance layer in the lower crust and a higher Moho on the east side of the fault revealed by geophysical survey.