Collaborative Research: Evolution of South Atlantic Oceanic Crust: A Seismic Transect

GSTDTAP

项目编号	1537108
	Collaborative Research: Evolution of South Atlantic Oceanic Crust: A Seismic Transect
	Robert Reece
主持机构	Texas A&M University Main Campus
项目开始年	2015
	2015-08-15
项目结束日期	2018-07-31
资助机构	US-NSF
项目类别	Continuing grant
项目经费	103925(USD)
国家	美国
语种	英语
英文摘要	Although the nature of oceanic crust has been studied for decades, many questions remain unanswered, owing to a paucity of data from crust formed more than a few million years ago. With ocean basins containing crust up to 200 m.y. in age, the history of Earth's largest tectonic plates remain to be studied. Key questions relate to chemical exchange between the crust and ocean-- does this continue beyond 7 m.y. or not, and, if so, for how long? Recent work shows that irregular seafloor on older crust can be the site of geothermal circulation that transfers material from crust to ocean. Another fundamental question is how long does an oceanic spreading segment behave in the same way- in terms of amount of magmatic activity versus tectonic rifting? This project will use seismic imaging to measure the properties of the crust from the Mid-Atlantic Ridge, where new crust forms today, out to 70 m.y. old crust on the western flank of the spreading center. These data will answer questions about oceanic crustal evolution and they will provide information about where future seafloor drilling by the Integrated Ocean Discovery Program could be safely accomplished, to address questions about the evolution in ocean chemistry over long time scales. The field experiment will serve as a training platform for graduate students and early career scientists. Former veterans in a university network will be involved in aspects of the research. Seismic and drill core data from crust accreted at less than 30 mm/yr, or older than about 8 Ma are particularly sparse. This precludes assessment of whether oceanic crustal Layer 2A seismic velocities reach mature values in 7.5 Ma, or instead do they continue to evolve to older ages? Its not possible to know if the seismic structure of slow-spread crust is uniform in a magmatic segment, or if heterogeneity exists and is associated with a past change in spreading rate. This project provides geophysical data for a continuous characterization of slow-to-intermediate spread oceanic crust from the active spreading center to crust formed up to ~70 Ma, including >1500 km of seismic reflection data and collocated ocean bottom seismometer refraction data at 5 sites targeted for future scientific drilling. The resulting data will address questions about the evolution of oceanic crust on million-year timescales, the evolution and stability of slow-spreading ridges over time and, via future drilling, hydrothermal contributions to global geochemical cycles.
来源学科分类	Geosciences - Ocean Sciences
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/68468
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Robert Reece.Collaborative Research: Evolution of South Atlantic Oceanic Crust: A Seismic Transect.2015.