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最近二十年间,通过地震测深和重磁测量.在衬西哥伦比亚的地壳的研究中发现,它同南美的安第斯山南段相比,具有极其异常的地壳构造.急剧的重力样度和地震波速的差异分布显示出,在中、西安第斯山之间具有从海洋向大陆过渡的特征. 刚得的重力和高度的反向变化以及三条50到100 km长的东西向剖面,与西安第斯山的典型正布格重力异常相关程度非常好,而后者反映着该处均衡的不稳定性.有两条剖面的重力值减小0.5一1 .0 mGal,中间的一条重力位有所增加,相应的重力对视高度变化之比为一20 mGal加,这可用深部的密度变化予以解释.本文推断,位于太平洋纳斯卡板块的无震洋脊和大陆之间的碰撞与近代仰冲过程可能同上述现象有关.
In the last two decades, seismic sounding and gravimetric-magnetic measurements have been passed, and in the study of the crust in western Colombia, it was found to have extremely anomalous crustal structures compared to the southern Andes of South America. The drastic gravity scales and earthquakes The distribution of wave velocities shows that there is a transitional feature from the ocean to the mainland between the Central and the Andes in the Antelope, just the reverse of gravity and altitude reversal, and three east-west profiles of 50 to 100 km, Of the typical positive Bouguer gravity anomalies correlate well with the latter reflecting the equilibrium instability in that there are two sections where the gravitational value is reduced by 0.5 to 1.0 mGal and the middle one of the gravitational levels is increased correspondingly The gravity to apparent height change ratio is 20 mGal plus, which can be explained by deep density changes.This paper concludes that the collision between the unconverted ocean ridge in the Pacific Nasca plateau and the mainland may be similar to that of the modern overthrust The above phenomenon related.