EAPSI: Quantifying Tectonic Controls on Changing Segmentation of Oceanic Transform Faults

EAPSI：量化构造对大洋转换断层分段变化的控制

• 批准号: 1613894
• 负责人: Thomas Morrow
• 金额: $ 0.54万
• 依托单位: Morrow Thomas A
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2017-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1613894&HistoricalAwards=false
• 关键词: EAPSI; Quantifying; Tectonic; Controls; Changing

Oceanic transform faults (TFs) are tectonic plate boundaries that are fundamental to accommodating tectonic plate motions along mid-ocean ridges (MORs). Although classically defined as a single boundary offsetting two segments of a MOR, TFs can split into several fault strands and subsequently re-unify to a single trace. Formation of segmented TFs is likely due to extensional tectonic motions across the TF. Conversely, unification of segmented TFs may be associated with compressional tectonic motions, however, the processes governing this evolution are poorly known. Structural features on the ocean floor, such as fracture zones (FZs), faults, and topography produced by lithospheric deformation, record tectonic responses to plate motions oblique to the original TF. In collaboration with Dr. Seung-Sep Kim of Chungnam National University, an expert in marine geology, flexure, and tectonics, the PI will quantify the processes that govern unification of the previously segmented Clarion FZ in the central Pacific Ocean. Segmentation and unification of TFs can alter the location of plate boundaries over time. Quantifying segmentation processes will enhance our understanding of evolving plate boundaries as well as their magmatic and seismic expressions.The research has 3 primary goals: 1) Using recently acquired high-resolution bathymetry over the Clarion FZ provided by the host researcher, Dr. Kim, we will identify styles and distributions of deformation; 2) We will analyze flexural evolution of a segmented FZ using 2D numerical models; 3) We will assess the tectonic conditions of the Clarion FZ through time by comparing model-predicted gravity anomalies (a proxy for flexural evolution of a FZ) to shipboard measurements. To quantify the hypothesized effect of compression on TF unification, our models will compare various rates and magnitudes of compressional strain, age offsets across the FZ, as well as the number, age, and geometry of intra-transform spreading segments to predicted flexural profiles. Finally, using these results we plan to develop predictive scaling laws that relate tectonic compression to the location and timing of TF unification.This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the National Research Foundation of Korea.

海洋转换断层 (TF) 是构造板块边界，对于适应沿大洋中脊 (MOR) 的构造板块运动至关重要。尽管传统上将 TF 定义为偏移 MOR 两段的单个边界，但 TF 可以分裂成多个断层链，随后重新统一为单个迹线。分段 TF 的形成可能是由于 TF 上的伸展构造运动造成的。相反，分段TF的统一可能与挤压构造运动有关，然而，控制这种演化的过程却鲜为人知。海底的结构特征，例如断裂带 (FZ)、断层和岩石圈变形产生的地形，记录了对与原始 TF 倾斜的板块运动的构造响应。 该项目负责人和海洋地质学、弯曲学和构造学专家、忠南国立大学的 Seung-Sep Kim 博士合作，将量化控制先前分割的中太平洋 Clarion FZ 统一的过程。 TF 的分割和统一可以随着时间的推移改变板块边界的位置。量化分割过程将增强我们对不断演变的板块边界及其岩浆和地震表达的理解。该研究有 3 个主要目标：1) 使用由主办研究员 Kim 博士提供的最近获得的 Clarion FZ 高分辨率测深数据，我们将识别变形的样式和分布； 2）我们将使用二维数值模型分析分段FZ的弯曲演化； 3) 我们将通过将模型预测的重力异常（FZ 弯曲演化的代表）与船上测量值进行比较，评估 Clarion FZ 随时间变化的构造条件。为了量化压缩对 TF 统一的假设影响，我们的模型将比较压缩应变的各种速率和大小、整个 FZ 的年龄偏移，以及内部变换扩展段的数量、年龄和几何形状，以预测弯曲轮廓。 最后，利用这些结果，我们计划开发预测尺度定律，将构造挤压与 TF 统一的位置和时间联系起来。该奖项属于东亚和太平洋夏季研究所计划，支持美国研究生的夏季研究，并由 NSF 共同资助和韩国国家研究基金会。