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

Ear-0003621 Dixon Ear-0004031 Stein尽管从达尔文开始进行了数百年的研究，但像安第斯山脉这样位于大洋-大陆交汇边缘的大型山脉的起源仍然是个谜。人们提出了各种假说来解释安第斯山脉，但似乎没有一种假说本身能够解释这一巨大的隆起、增厚的地壳区域的形成。例如，这位研究人员的初步GPS数据表明，尽管自中新世以来，安第斯山脉的俯冲速度显著放缓，但目前安第斯山脉的增长速度与长期平均速度大致相同，这对于仅要求快速俯冲形成安第斯山脉的模型来说是有问题的。迈阿密大学和西北大学的这个合作团队提出了一系列GPS测量，利用1994年首次占据的网络，结合相关的地震研究，旨在了解形成安第斯山脉带的过程。他们将把重点放在秘鲁和玻利维亚的中央安第斯山脉，那里高大而宽阔的高原最发达，活动的褶皱和冲断带容纳了快速的地壳缩短。为了提高他们辨别模型的能力和节约资源，测量将在横跨整个板块边界区域的两个横断面上致密，在平坦和正常俯冲区域。新的测量将跨越总共四年的时间，在新的地点获得足够的速度精度，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.