Along-Axis Continuity of Oceanic Detachment Faults

大洋拆离断层的沿轴连续性

基本信息

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

项目摘要

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.

新的海底在地球深海的中心不断形成，那里的构造板块分开，导致热岩浆上升到地表，板块分开的速度更慢，就像大西洋、印度洋和大西洋的大片地区所发生的那样。北冰洋是地幔中的深层岩石，它们被巨大的、长期存在的断层（称为分离层）的滑移带上来，但这些断层上的滑移并没有形成新的大洋海底。人们对最近发现的断层知之甚少，但它们可能在铺平地球表面的大部分过程中发挥着重要作用。了解这些断层行为的最佳方法之一是研究由小地震引发的地震波。该项目检查了北纬 13° 附近大西洋中脊一段的地震数据，这些数据是由英国科学家于 2016 年放置在海底的仪器记录的。作为了解海洋脱离断层作用的更广泛协调的国际努力的一部分，该项目促进了美国、英国和法国之间的国际合作，并为早期职业研究人员提供了支持。迄今为止，对海洋脱离断层作用的观测大多仅限于海底采样和研究。目前，有关海底结构和过程的许多问题尚未得到解答，其中一个最关键的悬而未决的问题是，沿轴相邻的海洋分离是否是通过地下连续断层连接的一种有效方式。解决这个问题的方法是研究分离断层系统中发生变形时产生的自然地震活动，从而可以对断层结构和表面进行直接成像。虽然目前已经在海洋分离部分进行了一些局部地震活动调查，但没有一个进行部署。具有足够孔径的地震网络，以限制各个分离的沿轴范围。该项目使用部署在北纬 13° 的大西洋中脊上的 58 个海底地震仪 (OBS) 的数据。沿山脊轴约 30 公里，提供对两个活动分离断层和中间山脊轴的密集空间覆盖。该网络由英国科学家部署，用于记录活动源地震实验的气枪射击，包含数以万计的局部微地震。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个断层面连接。

项目成果

期刊论文数量（2）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

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：
2018-09
期刊：
Geosystems
影响因子：
0
作者：
Parnell;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

通过海洋分离处记录的应变局部化来确定波纹断层面的成因