哥伦比亚普图马约盆地重力场与白垩系分布特征

为了研究普图马约盆地白垩系分布特征,收集、整理、分析了盆地内相关重力资料,并综合地质、钻井等资料对其进行处理解释.通过对普图马约盆地布格重力异常、剩余重力异常、重力垂向二阶导数特征等分析以及对剖面定量拟合结果的研究,发现普图马约盆地重力异常等值线宏观走向为NE向、NNE向,盆地内重力高低相间分布,自西向东发育4个重力梯级带,将盆地分为2个重力高带和3个重力低带,形成"两隆三凹"的构造格局.认为普图马约盆地主要构造为NE向.盆地西部隆起和东部隆起基底较浅,其上覆地层厚度较薄;西部凹陷、中部凹陷、东部凹陷基底较深,其上覆地层密度低、厚度较大.盆地西部凹陷以及中部凹陷的中、北部白垩系发育,有丰富的烃源岩,为进一步勘探的有利区域.

Distribution characteristics of gravity field and Cretaceous in Putumayo Basin of Colombia

Cretaceous marine shale is the main hydrocarbon source rock in Putumayo Basin. In order to study the distribution characteristics of the Cretaceous in the basin,the gravity data is analyzed,and it is interpreted based on the geologic data and drilling data. According to the study on Bouguer gravity anomaly,residual gravity anomaly and the vertical second derivative of gravity anomaly in the basin and the quantitative fitting sections,it is found that the Bouguer gravity anomaly contour lines are macroscopically in NNE,NE direction. There are four gravity steps in the basin from west to east,and they divide the basin into 2 high gravity zones and 3 low gravity zones which alternatively distribute. Therefore a tectonic pattern of two-uplifts and three sags is formed in the basin. The main tectonics in the basin is in NE direction. The bases of the uplifts in the west and the east of the basin are shallow,and therefore their overlying strata are thin. The bases of the sags in the west,the central and the east of the basin are deep,and their overlying strata are of great density and thickness. Cretaceous developed in the western sags and in the middle and the north of the central sags,and therefore these zones are the favorable areas for further exploration.