Along-Axis Continuity of Oceanic Detachment Faults

大洋拆离断层的沿轴连续性

• 批准号: 1736547
• 负责人: Ross Parnell-Turner
• 金额: $ 9.54万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-01 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1736547&HistoricalAwards=false
• 关键词: Along; Axis; Continuity; Oceanic; Detachment

New seafloor is continuously formed at the center of Earth?s deep oceans, where the tectonic plates spread apart and cause hot magma to rise to the surface. Where the plates move apart more slowly, as happens over vast tracts of the Atlantic, Indian and Arctic oceans, deep-seated rocks from Earth?s mantle are exhumed, dragged up by slip on enormous, long-lived, faults called detachments and without significant eruption of lava. Creation of new oceanic seafloor by slip on these recently discovered faults is poorly understood, yet may play a fundamental role in paving a large part of our planet?s surface. One of the best ways to understand the behavior of these faults is to study the seismic waves caused by the small earthquakes that are triggered as the faults slip. This project examines earthquake data from a segment of the Mid-Atlantic Ridge near 13°N, where detachment faults are prevalent. The data were recorded by instruments placed on the seabed in 2016 by scientists from the UK, as part of a wider coordinated international effort to understand oceanic detachment faulting. This project fosters international collaboration between the USA, UK and France, and supports an early-career researcher.Observations of oceanic detachment faulting to date have mostly been limited to seabed sampling and mapping, leaving many questions about the structure and processes taking place beneath the seafloor unanswered. One of the most critical outstanding questions today is whether or not along-axis adjacent oceanic detachments are connected by a continuous fault in the sub-surface. An effective way to tackle this question is by studying naturally occurring seismicity generated as deformation takes place in the detachment fault system, which allows for direct imaging of fault structures and surfaces. While several local seismicity surveys have now been conducted at oceanic detachments, none of them has deployed a seismic network with sufficient aperture to constrain the along-axis extent of individual detachments. This project uses data from a 58 ocean bottom seismometer (OBS) deployment on the Mid-Atlantic Ridge at 13°N that extends ~30 km along the ridge axis and provides dense spatial coverage over two active detachment faults and the intervening ridge axis. This network, deployed by UK scientists to record airgun shots from an active-source seismic experiment, contains tens of thousands of local microearthquakes that will help determine whether or not the two core complexes at 13°20'N and 13°30'N are connected by a single fault surface.

在地球中心--S深海，不断形成新的海底，那里的构造板块分散开来，使炽热的岩浆上升到地表。在那里，板块移动得更慢，就像在大西洋、印度洋和北冰洋的大片海域上发生的那样，地球上的深层岩石？S地幔被挖掘出来，被称为滑脱的巨大、长寿的断层拖上来，没有明显的熔岩喷发。在这些新近发现的断层上滑动而形成的新的大洋海底，目前还知之甚少，但可能在铺设我们星球的一大部分--S表面--中起着重要的作用。了解这些断层行为的最好方法之一是研究断层滑动时触发的小地震所产生的地震波。这个项目研究了大西洋中部海脊13°N附近的一段地震数据，那里的滑脱断层很常见。这些数据是由来自英国的科学家于2016年放置在海底的仪器记录的，这是了解海洋分离断层的更广泛协调国际努力的一部分。该项目促进了美国、英国和法国之间的国际合作，并支持了一名职业生涯早期的研究人员。到目前为止，对海洋分离断层的观测大多局限于海底采样和测绘，留下了许多关于海底结构和过程的问题没有得到解答。当今最关键的悬而未决的问题之一是，沿轴线相邻的海洋支流是否由地下连续的断层连接起来。解决这个问题的一个有效方法是研究在滑脱断层系统中发生变形时产生的自然发生的地震活动，这使得可以直接成像断层结构和表面。虽然现在已经在海洋支队进行了几次地方性地震活动调查，但没有一次部署了具有足够孔径的地震台网，以限制个别支队沿轴线的范围。该项目使用部署在北纬13°的中大西洋海脊上的58个海底地震仪(OBS)的数据，该海脊沿海脊轴线延伸约30公里，在两个活动的滑脱断层和中间的海脊轴线上提供了密集的空间覆盖。该网络由英国科学家部署，用于记录活跃震源地震实验的气枪射击，包含数以万计的当地微震，这将有助于确定北纬13°20‘和北纬13°30’的两个核心复合体是否由单一断裂面连接。

项目成果

The Final Stages of Slip and Volcanism on an Oceanic Detachment Fault at 13°48′N, Mid-Atlantic Ridge

大西洋中脊北纬 13°48° 处海洋滑脱断层上滑动和火山活动的最后阶段

• DOI: 10.1029/2018gc007536
• 发表时间: 2018
• 期刊: Geosystems
• 作者: Parnell-Turner, R. E.;Mittelstaedt, E.;Kurz, M. D.;Jones, M. R.;Soule, S. A.;Klein, F.;Wanless, V. D.;Fornari, D. J.
• 通讯作者: Fornari, D. J.

Genesis of corrugated fault surfaces by strain localization recorded at oceanic detachments

• DOI: 10.1016/j.epsl.2018.06.034
• 发表时间: 2018-09
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: R. Parnell‐Turner;J. Escartín;J. Olive;Deborah K. Smith;S. Petersen