重力剖面反演莱阳南凹陷深度

Inversion of the Depth of South Laiyang Depression by Gravity Profile

摘要:

莱阳南凹陷沉积中心位于山东省莱阳市南，在布格重力场上反映为西宽东窄近EW走向的重力低值闭合异常。垂直于异常走向，在布格重力异常中心及周围布设了五条重力剖面，以地层密度资料为基础，通过2.5D反演计算，大致查明了莱阳南凹陷的空间分布形态，并对其基底形态做了详细分析，计算结果表明中生界最大沉积厚度为4km左右。在其中一条剖面上布设可控源音频大地电磁测深测量工作，从岩层的电性角度出发推断了凹陷深度，二者结论基本一致。

Abstract:

The sedimentary center of Laiyang South Depression is located in the south of Laiyang city in Shandong province. The depression reflects the low gravity anomaly close to the east-west direction in the Bouguer Gravity Field. Five gravitational profileswhich are perpendicular to the anomaly direction are arranged around the Bouguer gravity anomaly center. Based on the data of stratigraphic density, the spatial distribution pattern of Laiyang South Depression is roughly identified by 2.5D inversion calculation. In addition, a detailed analysis of the depressed base morphology is done, and the result shows that the maximum deposition thickness of Mesozoic is about 4km. Besides, the controllable source audio frequency magnetotelluric surveying work is deployed in one of the gravitational profiles, through which the depth of the depression is inferred from the electrical properties of the formation, and the results of the two methods have good agreement.