中国北方沉积盆地热演化史的对比

中国沉积盆地多为叠合型盆地,古地温场的改造或改变普遍存在。根据古地温场的改造或改变作用方式的不同可划分为深埋改造型、热事件改造型和应力改造型。由于区域地质背景与盆地演化历程的不同,中国北方各盆地的古地温场存在较大差异。古生代华北盆地、塔里木盆地位于稳定克拉通之上,克拉通面积大,沉积构造稳定,地温梯度低;吐哈盆地、准噶尔盆地位于哈萨克斯坦板块之上,经历了裂陷作用,构造活动性强,地温梯度高。中生代晚期阿尔金断裂以东沉积盆地地温梯度普遍高于阿尔金断裂以西沉积盆地,构造活动性强,强烈的构造运动引发了岩浆活动及地壳深部热活动,表明存在一期强烈的具有区域规模的构造热事件;阿尔金断裂以西为挤压坳陷型盆地,地温梯度普遍较低。新生代以来中国东部处于拉张背景,沉积盆地地温梯度及大地热流值高;而西部处于地壳挤压增厚构造背景,沉积盆地地温梯度及大地热流值较低。

COMPARISON OF THERMAL EVOLUTION HISTORY IN SEDIMENTARY BASINS,NORTH CHINA

Most sedimentary basins in China belong to superimposed basins,their palaeogeothermal fields were generally reformed or changed.According to different reformation types of palaeogeothermal fields,the reformations can been classified into deep buried reformation,thermal event reformation and stress reformation.Because of differences in regional geology background and evolution history,there were greater differences in palaeogeothermal fields of the basins in North China.North China Basin and Tarim Basin were located in stable craton in Paleozoic,and characterized by stable sedimentary structures,and low geothermal gradients;Turpan-Harmi Basin and Junggar Basin were located in Hasakestain Plate,underwent fault subsidence and strong tectonic activities,and their geothermal gradients were high.Geothermal gradients of the basins in the eastern of Algin Rift were higher than those of the basins in western of Algin Rift in Late Mesozoic,and tectonic activities were stronger,indicating a strong regional tectonic thermal event.The basins on the western of Algin Rift were all compressive depressions,their geothermal gradients were lower.Sine Cenozoic,the eastern region of China has been in stretching background,geothermal gradient and heat flow are high in the basins;the west part of China has been in the crust compression and thickening background,geothermal gradient and heat flow are lower in the basins.