Collaborative Research: Tracing the Geomorphic Signature of Strike-Slip Faulting in Marlborough Hill Country, South Island, New Zealand

合作研究：追踪新西兰南岛马尔堡丘陵地区走滑断层的地貌特征

• 批准号: 1321735
• 负责人: Rebecca Flowers
• 金额: $ 11.35万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1321735&HistoricalAwards=false
• 关键词: Collaborative; Research; Tracing; Geomorphic; Signature

When active, strike-slip faults are among the most dangerous geologic features on Earth. At present, characterizing in detail their slip rates, seismic hazard, and evolution over a range of timescales challenges the earth science community. An under-exploited tool in strike-slip fault characterization is quantitative analysis of the geomorphic response to lateral fault motion to extract tectonic information directly from the landscape. At present, studies of this nature typically focus solely on vertical motion in mountain systems. This research will develop a new framework for applying geomorphic analysis to strike-slip fault systems and in doing so, will move the scientific community toward a more comprehensive and quantitative understanding of the geomorphic response to lateral crustal motion, which we currently lack. A suite of parallel right-lateral strike-slip faults known as the Marlborough Fault System (MFS), South Island, New Zealand offers an excellent natural laboratory for this problem. From north to south, fault initiation ages as well as cumulative fault displacement are thought to decrease whereas slip rates increase over four fold, providing snapshots of different stages of fault evolution. Using the MFS as a natural experiment, this project will test the degree to which surface processes and landforms can be used as a quantitative indicator of lateral fault activity. Geomorphology, thermochronology, and numerical modeling will be applied to document regional erosion history, identify differences (or similarities) in landscape morphology between regions of variable slip rate, fault age, and degree of vertical motion, and make quantitative predictions about the surficial response to different strike-slip fault scenarios using landscape evolution models.The primary goal of this work is to test the degree to which landscape response can be used as an indicator of strike-slip fault activity. Studying the landscape response to strike-slip faulting within the Marlborough Fault System has the potential to improve our understanding of horizontal fault zone activity and the geomorphic response to fault motion, at this location and in general; ultimately mitigating the hazards associated with living in and around strike-slip faults. Seismic activity occurs frequently within the greater Marlborough region, including along faults that were previously unknown (as in the case of the destructive Darfield 2010 magnitude 7.1 and Christchurch 2011 magnitude 6.3 earthquakes). Results from this work will benefit seismic hazard assessment at this location, as well as at many other locations around the world where far less is known about active strike-slip faulting. Detailed study of the timing and magnitude of vertical motion along the primary fault strands as well as along the secondary contractional structures within the MFS will also provide new constraints on the tectonic evolution of the New Zealand orogen and foster already strong international collaboration between U.S. and New Zealand geologists.

当走滑断层活跃时，它是地球上最危险的地质特征之一。目前，详细描述它们的滑移率、地震灾害和在一系列时间尺度上的演化对地球科学界提出了挑战。走滑断层表征中尚未充分利用的工具是对横向断层运动的地貌响应进行定量分析，以直接从地貌中提取构造信息。目前，这种性质的研究通常只关注山地系统的垂直运动。这项研究将开发一个新的框架，将地貌分析应用于走滑断层系统，从而推动科学界对地壳横向运动的地貌响应有更全面、更定量的理解，而这正是我们目前所缺乏的。新西兰南岛的一组平行的右旋走滑断层被称为马尔堡断层系（MFS），为解决这个问题提供了一个极好的天然实验室。从北到南，断层起始年龄和累积断层位移被认为减少，而滑移率增加四倍以上，提供了断层演化不同阶段的快照。该项目将利用MFS作为自然实验，测试地表过程和地貌作为横向断层活动定量指标的程度。地貌学、热年代学和数值模拟将用于记录区域侵蚀历史，识别不同滑移率、断层年龄和垂直运动程度的区域之间景观形态的差异（或相似性），并对地表响应进行定量预测。使用景观演化模型的不同走滑断层场景。这项工作的主要目标是测试景观响应可以在多大程度上用作走滑断层活动的指标。研究马尔堡断层系内走滑断层的景观响应有可能提高我们对水平断层带活动的理解以及该位置和总体上对断层运动的地貌响应；最终减轻与走滑断层及其周围生活相关的危险。大马尔堡地区经常发生地震活动，包括沿着以前未知的断层（例如 2010 年达菲尔德 7.1 级破坏性地震和 2011 年基督城 6.3 级破坏性地震）。这项工作的结果将有利于该地点以及世界上许多其他地点的地震危险性评估，这些地点对活动走滑断层作用知之甚少。对沿着主断层带以及沿着 MFS 内的次级收缩结构的垂直运动的时间和幅度的详细研究也将为新西兰造山带的构造演化提供新的约束，并促进美国和新西兰之间业已强大的国际合作。新西兰地质学家。