柴达木盆地北缘盆山构造关系与油气勘探方向

穿过赛什腾山南侧构造边界的地震剖面显示．赛什腾山南缘断裂带总体表现为扭动特征。该断裂带在西端主要表现为向北、向上冲断；中部以高角度为特征；东缘（1001测线剖面）则表现为低角度、向盆地方向的逆冲断层，可能是走滑断裂构造端部的构造转换，为伴生构造样式。柴达木盆地北缘（柴北缘）的边界造山带并没有向盆地方向大规模逆冲，赛什腾山山前的东台1井及绿梁山山前的尕丘1井均未钻遇被山体掩覆的新地层，而是钻遇了高角度断裂带，也说明山体向南侧的逆冲规模较小。因此，新生代以来柴北缘地区的构造变形以走滑变形为主，逆冲推覆是走滑构造的伴生产物。柴北缘走滑断裂带构造变形具有反转特征．并不是厚生油气藏形成的有利地带，走滑带之间的块体可能是相对稳定的块体，具有较有利的成藏条件。图7参12

Basin-mountain tectonic pattern and hydrocarbon exploration domain in north margin of Qaidam Basin

Seismic profile crossing southern boundary of Saishiteng Mountain shows the shear tectonic characteristic of fault zone at southern boundary of Saishiteng Mountain. In the west of Saishiteng, the fault zone thrusts towards top and north; in the center, the fault zone shows high angle, in the east (line 1001 profile), it represents as low-angle and basin-toward thrusted fault, which may be converted structure at the end of strike-slip faulted structure, in pattern of associated structure. The north boundary didn't overthrust to basin; Wells Dongtai 1 and Gaqiu 1 at foothill of Saishiteng didn't penetrate into new formations overlapped by the mountains, but into associated products of high-angle faulted structure, which indicates that the mountain was less thrusted to the basin. So the structure deformation of Northern Qaidam Basin had been mainly strike slip since Cenozoic and the thrust nappe is associated with the strike-slip structure. The strike-slip faulted zone in north boundary showed reversal deformation, so it is not a favorable play to form original reservoirs; the masses between strike-slip trips, that may be stable relatively, are favorable for forming reservoirs.