Ultraslow crustal accretion at the Mid-Cayman Spreading Center: Mantle exhumation or magmatism?

开曼中部扩张中心的超慢地壳增生：地幔折返还是岩浆作用？

• 批准号: 1356895
• 负责人: Harm Van Avendonk
• 金额: $ 69.91万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-03-15 至 2018-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1356895&HistoricalAwards=false
• 关键词: Ultraslow; crustal; accretion; Mid; Cayman

The seismic structure of the Mid-Cayman Spreading Center (MCSC) will be investigated to determine the extent to which magmatism contributes to crustal structure of an ultra-slow oceanic rift segment. As part of a larger international project, seismic data will be acquired along five profiles, from the ridge axis to ~10 Myr old flank, and from the spreading segment center to the transform walls. Two main ideas will be addressed: (1) Whether the MCSC hosts oceanic core complexes of exhumed crustal or mantle materials; (2) Whether crustal thickness variations in the MCSC reflect inhibition of magmatism as the spreading-segment ends are approached. Ocean bottom seismograph data will constrain tomographic models of velocity structure, from which crustal thickness, its variability, and/or mantle properties can be inferred. Recently acquired bathymetry and gravity data will be combined with prior trackline data and used as the basis for integrated seismic, gravity, and morphologic interpretation.Up to 20-30% of the world's oceanic spreading centers rift at ultraslow rates of less than 20 mm/yr, and expose a range of lower-crustal and upper mantle rock. These ultraslow systems host hydrothermal fields with chemical and biological activity that are distinct from faster spreading chemosynthetic systems, and have relevance for understanding the development of early life on Earth. This joint US-German-UK project strengthens international collaboration on studies of seafloor spreading. A graduate student will participate in all phases of the US portion of the study, receiving training in a range of marine geophysical techniques.

将研究开曼中部传播中心（MCSC）的地震结构，以确定岩浆作用对超慢海洋裂谷段的地壳结构的影响程度。作为一个更大的国际项目的一部分，将沿着五个剖面采集地震数据，从山脊轴到约 10 Myr 的旧侧翼，以及从扩展段中心到转换墙。将讨论两个主要观点：（1）MCSC 是否拥有由挖出的地壳或地幔物质组成的海洋核心复合体； (2)当接近扩张段末端时，MCSC中地壳厚度的变化是否反映了岩浆活动的抑制。海底地震仪数据将限制速度结构的层析模型，从中可以推断出地壳厚度、其变化性和/或地幔特性。最近获得的测深和重力数据将与先前的轨迹线数据相结合，并用作综合地震、重力和形态学解释的基础。世界上多达 20-30% 的海洋扩张中心以小于 20 毫米/的超慢速率裂谷。年，并暴露了一系列下地壳和上地幔岩石。这些超慢系统拥有具有化学和生物活性的热液场，与传播速度更快的化学合成系统不同，并且与了解地球早期生命的发展相关。这个美国-德国-英国联合项目加强了海底扩张研究的国际合作。一名研究生将参加该研究美国部分的所有阶段，接受一系列海洋地球物理技术的培训。