Tectonic evolution of the Central Andean Plateau and implications for ore distribution

在整个安第斯山脉，中央安第斯高原(CAP)异常宽，西部俯冲带与最东端形变锋之间的距离可达600-800公里。CAP还拥有70公里厚的地壳：南美洲最厚的地壳。履约协助方案经历了垂直轴的旋转，导致玻利维亚造山斜的形成，并比北部或南部地区的缩短幅度更大。盖层还赋存于环盖层的始新世(约4500万-3500万年前)铜、锡和银矿床中。其中一些矿床是世界上最大的矿床之一，因此了解驱动始新世盆地形成的地球动力学过程也有助于深入了解形成大型矿床的过程。人们提出了包括上盘和下盘效应在内的多种假说来解释CAP的演化及其异常特征。这些机制中的许多机制所涉及的大范围需要同样大规模的观测。然而，由于缺乏可测年的材料，尤其是在古近纪碎屑岩中，对这些假说的验证一直受到阻碍。缺乏可测年的材料阻碍了整个CAP的地层对比，从而阻碍了对容纳泥沙堆积的沉降率(地壳向下运动)的评估。下沉的时间和速度是导致地壳垂直位移的特定地球动力学机制的征兆。这项提议寻求资金，以建立玻利维亚古近纪地层之间的初步对比。我们将利用古近纪地层中碎屑锆石的U-Pb年代学，在玻利维亚多个纬度建立独立的年代地层学。这将在新获得的横跨高原的地震线的背景下进行解释和对比。这项提议将使皮塞勒和合作者拉莫斯及其学生之间进行新的合作和研究访问。

In the entirety of the Andes, the Central Andean Plateau (CAP) is anomalously wide, with distances between the subduction zone in the west and the easternmost deformation front up to 600-800 km. The CAP also hosts 70 km thick crust: the thickest in South America. The CAP has experienced vertical-axis rotations resulting in formation of the Bolivian orocline and greater shortening than regions to the north or south. The CAP also hosts copper, tin, and silver in Eocene (~45-35 million years ago) deposits ringing the CAP. Some of these deposits are among the largest in the world and therefore understanding the geodynamic processes that drove Eocene basin formation also provides insight into the processes that form large ore deposits.Multiple hypotheses, including both upper and lower plate effects, have been advanced to explain the evolution of the CAP and its anomalous characteristics. The large scale implicated by many of these mechanisms requires equally large-scale observations. However, testing these hypotheses has been hampered by a lack of datable material, particularly in Paleogene clastic strata. The lack of datable material has hampered stratigraphic correlations across the CAP, and therefore evaluation of the rate of subsidence (downward crustal movement) which accommodated sediment accumulation. The timing and rate of subsidence are symptomatic of specific geodynamic mechanisms acting to cause vertical crustal displacement. This proposal seeks funding to develop a preliminary correlation among Paleogene strata in Bolivia. We will use U-Pb geochronology of detrital zircons in Paleogene strata to develop independent chronostratigraphies at multiple latitudes in Bolivia. This will be interpreted and correlated in the context of newly acquired seismic lines across the Altiplano. This proposal will enable a new collaboration and research visits between PI Saylor and collaborator Ramos and their students.