羌塘盆地白云湖凹陷航空重磁异常特征及其油气勘探意义

Airborne gravity-magnetic anomalies in the Baiyunhu sag,Qiangtang Basin:Characteristics and implications for oil and gas exploration

航空重磁数据是揭示盆地深部构造的有效手段,本文通过最新测量的航空重磁数据结合野外实测物性资料,阐述了白云湖凹陷航空重、磁异常特征及其地质成因,利用航空重磁资料识别出白云湖凹陷断裂与岩浆岩的分布情况,采用人工切线法、功率谱分析法和Parker-Oldenburg迭代反演算法,计算了白云湖凹陷基底埋藏深度与中生界底面构造形态,并通过重点剖面重磁综合解释,对构造分层结果进行了验证。研究结果表明白云湖凹陷中生界、古生界沉积层的起伏变化是引起重力异常的主要因素,区域航磁异常则主要反映了前寒武纪基底展布特征。白云湖凹陷基底埋深较深,中生界分布连续且厚度较大,区域断裂—岩浆活动不发育,整体受构造运动影响较少,具有较好的油气勘探前景。

Airborne gravity-magnetic data are effective in revealing the deep structures of a basin.Based on the latest airborne gravity-magnetic data,combined with field-measured physical property data,this study expounded the characteristics and geological origin of airborne gravity-magnetic anomalies present in the Baiyunhu sag.Using the airborne gravity-magnetic data,this study identified the dis-tribution of faults and magmatic rocks in the Baiyunhu sag.Furthermore,it calculated the burial depth of the magnetic basement and the structural morphologies of the Mesozoic basement in the sag using the artificial tangent method,power spectrum analysis method,and Parker-Oldenburg iterative inversion algorithm.Additionally,this study verified the structural stratification results through the integrated interpretations of gravity and magnetism in target sections.The findings suggest that the undulations of the Mesozoic and Paleozoic sedi-ments in the Baiyunhu sag are the primary cause of gravity anomalies,while the regional airborne magnetic anomaly primarily reflects the distribution features of the Precambrian basement.The deeply buried basement of the Baiyunhu sag,featuring continuously distribu-ted,thick Mesozoic strata and the lack of regional faulting and magmatic activity,is scarcely affected by tectonic movements and posses-ses great potential for oil and gas exploration.