Geomorphic Evidence for Crustal Uplift Adjacent to a Subducting Aseismic Ridge, Pacific Coast of Costa Rica

该奖项将为宾夕法尼亚州立大学的Thomas Gardner教授在哥斯达黎加休假提供部分支持，以计算从哥斯达黎加西北部河流阶地序列确定的抬升速率，并将该数据与相邻无地震科科斯山脊俯冲的板块构造模型联系起来。这项研究应提供有关哥斯达黎加东南部科科斯山脊俯冲期间哥斯达黎加西北部“正常”俯冲造成的地壳隆升速率的关键数据。该地点为确定所需的构造数据提供了理想的地点，因为该地区的四面线板块构造历史是众所周知的。漂浮的大洋岩石圈以大洋高原、无地震海脊或非常年轻的岩石圈的形式俯冲，可能是沿着会聚的板块边界的异常构造活动的原因。虽然后一种活动可能被广泛理解，但其具体原因和量化在很大程度上仍然没有得到解决。哥斯达黎加的太平洋海岸是研究这些现象中的一个具体案例的无与伦比的地点：地壳在俯冲的大洋岩石圈附近的垂直运动，该岩石圈包含一个无地震隆起。这项研究是由国家科学基金会资助的一项更大规模研究的一部分，将有来自国家地理研究所、哥斯达黎加大学和Costarricense de Electric研究所的科学家参与。特别是哥斯达黎加大学的Ana Chinchilla教授将正式参加实地工作。通过让哥斯达黎加科学家密切参与这项研究，该奖项有助于推进发展中国家科学计划的目标。

This award will provide partial support to Prof. Thomas Gardner of The Pennsylvania State University for a sabbatical stay in Costa Rica to calculate uplift rates determined from fluvial terrace sequences along the northwestern portion of Costa Rica and to relate that data to the plate tectonic model for subduction of the adjacent aseismic Cocos Ridge. The research should provide critical data on crustal uplift rates resulting from "normal" subduction in northwestern Costa Rica during the time of subduction of the Cocos Ridge in southeastern Costa Rica. The proposed site provides the ideal location for determining the needed tectonic data because the Quatenary plate tectonic history of the region is well known. The subduction of buoyant, ocean lithosphere in the form of oceanic plateaus, aseismic ridges, or very young lithosphere may be responsible for anomalous tectonic activity along convergent plate boundaries. While the latter activity may be broadly understood, its specific causes and quantifications remain largely unaddressed. The Pacific coast of Costa Rica represents an unsurpassed site for a study of one specific case among these phenomena: the vertical motions of the crust in proximity to a subducting oceanic lithosphere that contains an aseismic ridge. This study, which is part of a larger study supported by the NSF, will involve scientists from the Instituto Geografico Nacional, the Universidad de Costa Rica, and the Instituto Costarricense de Electricidad. In particular, Prof. Ana Chinchilla of the Universidad de Costa Rica will formally participate in the field work. By closely involving scientists from Costa Rica in the research, this award serves to advance the objectives of the Science in Developing Countries Program.