罗布泊盐湖盆地结构新发现及找钾意义

New discovery of Lop Nur salt basin structure and its significance for potash deposit exploration

首次将重力探测技术引入到罗布泊盐湖盆地结构及钾盐勘探中,通过对重力资料的处理和反演,发现罗布泊盆地北部地区由南北两个局部次级盆地(凹地)组成:南盆地第四系沉积厚度小于或近于300m,北盆地则为库鲁克塔格山前隐伏断陷凹地的次级延伸,其中心第四系沉积层厚度大于700m,山前主盆地——库鲁克塔格山前隐伏断陷凹地的中心埋深大于1200m。同时在罗北凹地内还发现了8～9条相间分布的断裂构造,认为这是控制成钾凹地、储集富钾卤水、张性断裂控制的地堑式断裂带。在对罗布泊盐湖盆地结构新发现的基础上,圈定了罗布泊北部找钾远景靶区,初步确定了寻找深部钾盐矿床的探索孔位,并提出了深部隐伏钾盐矿勘探的方法技术组合。

Gravity exploration method was employed for the first time in the study of the Lop Nur salt lake basin structure and the exploration of potash resources. Based on processing and inversion of gravity data,the authors have found that northern depressions of the Lop Nur salt lake are composed of two local sub-depressions arrayed from south to north. The southern depression is only a sub-depression of the main depression located in the southeast of the Lop Nur salt lake and formed in the late period,with its Quaternary sediments equal to or less than 300 m. The northern depression is a sub-depression buried off Kuruktag piedmont,with the Quaternary sediments at the center more than 700 m. The center of the northern depression of the Lop Nur salt lake （Kuruktag piedmont depression） is deeper than 1 200 m. 8～9 interval fault structures were found in the northern depression of the Lop Nur salt lake basin by geophysical exploration. The authors consider that these faults are graben-type faults which controlled the migration of potassium into canyons,reservoir K-rich brine and tensile fracture-controlled faults. On the basis of new discovery of the Lop Nur salt lake basin,the authors delineated several long-term targets for potash deposit exploration and determined drill hole locations in search for deep potash resources. The combination of exploration methods in prospecting for deep concealed potash resources is also put forward in this paper.