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教授在哥斯达黎加的休假提供部分支持，以计算沿哥斯达黎加西北部的河流阶地序列确定的隆起率，并将该数据与相邻的地震科科斯岭俯冲的板块构造模型联系起来。该研究将提供哥斯达黎加东南部Cocos Ridge俯冲期间哥斯达黎加西北部“正常”俯冲所导致的地壳抬升速率的关键数据。该地点为确定所需的构造数据提供了理想的位置，因为该地区的四世纪板块构造历史是众所周知的。以海洋高原、地震脊或非常年轻的岩石圈形式出现的浮力海洋岩石圈的俯冲可能是沿收敛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问题在很大程度上仍未得到解决。哥斯达黎加的太平洋海岸为研究这些现象中的一种特殊情况提供了一个无与伦比的地点：地壳在俯冲的海洋岩石圈附近的垂直运动，其中包含一个地震带。这项研究是由美国国家科学基金会支持的一项更大研究的一部分，将涉及来自国家地理研究所、哥斯达黎加大学和哥斯达黎加电力研究所的科学家。特别是哥斯达黎加大学的Ana Chinchilla教授将正式参加实地工作。通过让哥斯达黎加的科学家密切参与这项研究，该奖项有助于推进“发展中国家科学项目”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.