前陆冲断带深度剖面的建立及三维可视化研究——以酒泉盆地南缘金佛寺冲断带为例

金佛寺冲断带因无法直接获取花岗岩体速度数据，且岩体本身属地震波高反射介质，导致岩体下伏深部构造在时间 域与深度域地震剖面影像的形态产生较大的偏差。本文利用已获取的模拟花岗岩体地下深部温压条件下波速与深度的实验 室测试数据，定量化花岗岩体地下深度与波速的关系，进行金佛寺冲断带二维地震剖面的时深转换，并进行深度域剖面与 时间域剖面之间掩伏构造形态的分析比较。在此基础上利用gocad软件对冲断带构造进行三维可视化建模，并讨论其深部构 造特征，认为下伏中新生界整体为南西倾单斜，局部发育掩伏构造，掩伏构造高点埋深较大，两翼倾角减小。

Establishment and 3-D Visualization of Deep Structures in Foreland Thrust Belts: Taking the Jinfosi Thrust Belt in the Southern Margin of Jiuquan Basin as an Example

Jinfosi Pluton  is seismically highly  reflective medium and  it has been difficult  to obtain velocity data of  the pluton directly. The deep structures of Jinfosi  thrust belt  revealed by  time-domain and depth-domain seismic data show significant difference. We used the velocity data that were derived in laboratory under high temperatures and pressures simulating conditions at depth  to quautify  the  relationship between velocity and depth underground. This allows  time-depth conversion  for  the 2-D seismic data of  the Jinfosi pluton and comparison of  the deep structures of Jinfosi  thrust belt  revealed by  the  time-domain and depth-domain seismic data. Based on  the new depth data and  interpretation, GOCAD software was employed  to establish a 3-D geological model, which allowed further discussion of the deep structures. The model shows that the Mesozoic-Cenozoic rocks form a deeply buried monocline which dips SW and structural highs are relatively deeply buried with dips diminishing toward the two limbs.