东海地区热流特征及其地质意义

Characteristic of Heat Flow and Its Geological Significance In the East China Sea Area

东海地区热流特征及其地质意义毕传学，杨凌，吴国华，张梅中国极地研究所，上海，２００１２９江苏省地矿局，南京，２１００１８关键词：地热梯度，热流，地壳厚度，热阻法，中国东海ＣｈａｒａｃｔｅｒｉｓｔｉｃｏｆＨｅａｔＦｌｏｗａｎｄＩｔｓＧｅｏｌｏｇｉｃａｌ...

The thermal resistance method.developed by D.S.Chapman, can be used to judge the utility of petroleum or natural gas well bottom-hole temperature in accordance with surface heat flow and subsurface temperature patterns in a sedimentary basin.The method has been used to the shelf basin in the East China Sea.Calculating results combined with the observed values in the vicinity based on R.S.Lu et al show that average geothermal gradients for the western and eastern Zhedong depressions and Taibei depression are 27. 9℃/km,42. 8℃/km and 33. 8℃/km respectively and that the heat flow values in this area are higher than 60 mWm￣(-2)and change greatly:70-90 mWm￣(-2) for the Zhejiang-FuJian upwelling area and western area in the East China Sea basin, 90 -100 mWm￣(-2) for the eastern area in the East China Sea basin.The Okinawa Trough with an average heat flow value,177.7mWm￣(-2) belongs to a margiual back-arc basin at a young stage of evolutioi that has developed along a continental margin.According to the Sclater's equation,the stretch of Okinawa Trough has been found by further calculation since 7.1Ma.The relationship between regional geotherms and lithosphere thickness shows that lithosphere thickness is 80-90 km for the Shanghai and Zhedong depressions,50-60 km for the Taibei depression,less than 30 km for the Okinawa Trougk and 110-200 km for the Ryukyu uplifting and folding area which is a active volcanic arc.Although it is difficult to form large scale of petroleum and natural air reserves in Taibei depression based on the geotherm evaluation of the hasin.the distribution characteristics of heat flow values are very important for the evaluation and exploitation of petroleum and natural gas in the East China Sea.