Slab Geometry and Mountain Building Processes in the Southern Andes

这项研究包括通过阿根廷和智利的pascal便携式宽带地震仪对安第斯山脉中南部的结构进行研究，在那里俯冲板的几何形状发生了重大变化。这项研究将与智利、阿根廷、法国和德国的研究机构合作进行。在南向约33.3度处，俯冲的Nazcaslab从北向无活动演化的水平板块几何形态，转变为南向有活动演化弧的30度倾斜板块。这种板块倾角的南北变化是全球任何地方瓦达蒂-贝尼奥夫带几何结构中最引人注目的弯曲或翘曲之一。在南纬31度处，平坦的板块向东延伸300公里，然后继续下降到地幔中。该段海拔高，构造缩短量大。在倾斜板块段上，高程降低，构造缩短量也降低。将部署两个PASSCAL横断面：一个靠近水平板段上方30.5度南侧，另一个位于倾斜板段上方36度南侧。地震数据将从自然地震中收集，并进行倒转，以回答涉及跨过渡的俯冲板块结构、周围地幔结构、造山和地震发生过程的问题。

This research involves the study, by means of PASSCAL portablebroadband seismometers in Argentina and Chile, of the structurebeneath the south central Andes where a major change in subductingslab geometry occurs. The research will be done in conjunctionwith research institutes from Chile, Argentina, France, andGermany. At approximately 33.3 degrees South, the subducting Nazcaslab changes from a horizontal slab geometry without any activevolcanism to the north, to a 30-degree dipping slab with an activevolcanic arc to the south. This north-south change in slab dip isone of the most dramatic bends or warps in a Wadati-Benioff zonegeometry anywhere globally. At 31 degrees South, the flattenedslab extends 300 km to the east before resuming its descent intothe mantle. This segment has high elevations and large amounts oftectonic shortening. Across the dipping slab segment, the elevation decreases, as does the amount of tectonic shortening.Two PASSCAL transects will be deployed: one near 30.5 degrees South above the horizontal slab segment and one at 36 degrees South above the dipping slab segment. The seismic data will be gathered from natural earthquakes and inverted to answer questions involving thestructure of the subducting slab across the transition, surroundingmantle structure, mountain building, and earthquake generationprocesses.