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.

当活动时，走滑断层是地球上最危险的地质特征之一。目前，详细描述它们的滑动速率、地震危险性和在一系列时间尺度上的演化是地球科学界的挑战。一个未充分利用的工具，在走滑断层表征是定量分析地貌的横向断层运动的反应，直接从景观提取构造信息。目前，这种性质的研究通常只集中在山区系统的垂直运动。这项研究将开发一个新的框架，应用地貌分析走滑断层系统，并在这样做，将推动科学界走向更全面和定量的了解地貌的横向地壳运动的反应，我们目前缺乏。新西兰南岛的一组平行右旋走滑断层被称为马尔伯勒断层系统（MFS），为这个问题提供了一个很好的天然实验室。从北到南，断层起始年龄以及累积断层位移被认为是减少，而滑动速率增加超过四倍，提供断层演化的不同阶段的快照。利用MFS作为自然实验，该项目将测试地表过程和地貌可用作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，（或相似性）在景观形态之间的变化滑动速率，断层年龄，和垂直运动的程度，并对不同走向的地表响应进行定量预测，滑断层的情况下，使用景观演化模型。这项工作的主要目标是测试在何种程度上景观响应可以作为一个指标的走滑断层活动。研究景观响应走滑断层内的马尔伯勒断层系统有可能提高我们的水平断层带活动和地貌响应断层运动的理解，在这个位置和一般，最终减轻与生活在走滑断层及其周围的危害。大马尔伯勒地区经常发生地震活动，包括以前未知的沿着断层（如破坏性的达菲尔德2010年7.1级和基督城2011年6.3级地震）。这项工作的结果将有利于在这个位置，以及在世界各地的许多其他地方的地震危险性评估，远低于已知的活动走滑断层。详细研究垂直运动的时间和幅度沿着主要故障链以及沿着次级收缩结构内MFS也将提供新的约束新西兰造山带的构造演化和促进美国和新西兰地质学家之间已经强大的国际合作。