Collborative Research: Nazca-South America Convergence and Continental Growth in the Central Andes via Global Positioning System (GPS) Measurements

尽管从达尔文开始的几个世纪的研究，像安第斯山脉这样位于大洋-大陆会聚边缘的大型山脉带的起源仍然是个谜。人们提出了各种各样的假说来解释安第斯山脉，但似乎没有一种假说能够解释这一巨大的地壳升高和增厚区域的形成。例如，研究人员的初步GPS数据表明，安第斯山脉今天正在以大致长期平均的速度增长，尽管自中新世以来俯冲作用显着放缓，这对于仅呼吁快速俯冲形成安第斯山脉的模型来说是有问题的。这个来自迈阿密大学和西北大学的合作小组提出了一系列全球定位系统测量，利用1994年首次使用的网络，加上相关的地震研究，旨在了解安第斯山脉的形成过程。他们将把重点放在秘鲁和玻利维亚的中部安第斯山脉，那里高而宽的阿尔蒂普拉诺高原最发达，那里有一个活跃的褶皱和冲断带，可以容纳地壳的迅速缩短。为了提高他们辨别模型和保护资源的能力，测量将在平坦和正常俯冲区域的两个横穿整个板块边界区的断面中进行加密。新的测量将持续四年，以获得新地点的速度精度，足以区分几个相互竞争的假设。

EAR-0003621 Dixon EAR-0004031 Stein The origin of large mountain belts like the Andes at ocean-continent convergent margins remains enigmatic despite centuries of study beginning with Darwin. Various hypotheses have been advanced to explain the Andes, but by themselves none seem capable of explaining the formation of this vast region of elevated, thickened crust. For example, the investigator's preliminary GPS data suggest that the Andes are growing today at roughly their long term average rate despite significant slowing of subduction since the Miocene, problematic for models that call on fast subduction alone to form the Andes. This collaborative team from the University of Miami and Northwestern University proposes a series of GPS measurements that exploit a network first occupied in 1994, coupled with related seismic studies, aimed at understanding the processes forming Andean mountain belts. They will focus on the Central Andes of Peru and Bolivia, where the high, wide Altiplano plateau is best developed, and where an active fold and thrust belt accommodates rapid crustal shortening. To enhance their ability to discriminate models and to conserve resources, the measurements will be densified in two transects that cross the entire plate boundary zone, in regions of flat and normal subduction. The new measurements will span a total of four years to obtain velocity accuracy at the new sites adequate to distinguish among several competing hypotheses.