Multichannel Seismic Study of the Deep Structure of a Cordilleran Orogen: The Southernmost Andes

安第斯造山带是由构造和岩浆作用形成的山脉的典型例子，这些作用主要是由海洋岩石圈在大陆边缘下的俯冲作用引起的。然而，对山脉和大陆边缘深层结构的了解，仅仅是基于20世纪60年代获得的有限的地震折射剖面。南安第斯山脉的地表地质测绘表明，由于与俯冲有关的构造作用、南美洲纳斯卡板块的逆冲作用以及由此产生的与俯冲有关的岩浆活动，大陆地壳的增厚和缩短产生了山脉带。目前推荐的奖金将支持使用海洋多通道地震反射技术研究安第斯山脉下的地壳结构。将在穿越安第斯山脉的峡湾以及邻近的大陆架地区获取数据。这些数据将与其他关于山脉下地壳结构的研究进行比较，以检验它们形成的模型，并检验大陆地壳演化的假设。这是德克萨斯大学和拉蒙特-多尔蒂地质观测站的科学家的合作项目。野外数据将在康拉德号上获取。

The Andean orogen is the type example of a mountain range formed by tectonic and magmatic processes resulting primarily from the subduction of oceanic lithosphere beneath a continental margin. Knowledge of the deep structure of the mountain range and continental margin, however, is based on only limited seismic refraction profiles obtained in the 1960s. Surface geologic mapping in the southern Andes indicates that the mountain belt has been produced by both thickening and shortening of the continental crust in response to subduction related tectonism, underthrusting of the Nazca Plate beneath South America, and resulting magmatic activity related to this subduction. The present recommended award will support a study of the crustal structure beneath the Andes using marine multichannel seismic reflection techniques. Data will be acquired in fjords which traverse the Andean range, as well as in the adjacent continental shelf areas. These data will be compared to other studies of crustal structure beneath mountain ranges to test models for their formation and to examine hypotheses for the evolution of the continental crust. This is a cooperative project involving scientists at the Univ. of Texas and Lamont-Doherty Geological Observatory. Field data will be acquired aboard the R.V. Conrad.