Paleogene Climate and Deep-water Evolution in the Southwest Atlantic: Seismic Reflection and Coring Investigations in Support of IODP Proposal 862-Pre

GSTDTAP

项目编号	NE/M021270/1
	Paleogene Climate and Deep-water Evolution in the Southwest Atlantic: Seismic Reflection and Coring Investigations in Support of IODP Proposal 862-Pre
	[unavailable]
主持机构	NERC British Antarctic Survey
项目开始年	2016
	2016
项目结束日期	2017-12-31
资助机构	UK-NERC
项目类别	Research Grant
国家	英国
语种	英语
英文摘要	The present-day Southwest Atlantic Ocean is a key region for: (i) the communication of deep waters between the Pacific and Atlantic ocean basins via the Antarctic Circumpolar Current (ACC); and (ii) the dispersal of deep waters produced on the Antarctic margin that fill the deepest parts of the ocean basins. The ACC is the largest oceanic current system on Earth and flows unimpeded clockwise around the Antarctic continent. Across the Drake Passage (a narrow, but deep trough between Antarctica and South America) the average volume transport of the ACC is enormous, estimated at 100 to 150 million cubic meters per second. The ACC is therefore the major conduit for surface and deep-water communication between the Pacific and Atlantic Oceans. Without this connection, global overturning circulation would not be possible, which, in the modern ocean, regulates the global transport of heat, salt, nutrients, and carbon and has a significant influence on global climate across all timescales. Our proposed project is developed to tackle several fundamental questions concerning the Paleogene time interval (~66 to 23 million years ago) that have frustrated marine geologists and palaeoclimatologists for decades: When was the ACC initiated? What was the impact of its establishment on Antarctic climate, on overturning circulation, and global latitudinal heat transport? Did the development of the ACC serve as the trigger for the initiation of Antarctic glaciation 34 million years ago or was its role completely secondary to that of declining atmospheric carbon dioxide levels? New insight into these problems can only be gained through new geological studies in key areas, such as the Southwest Atlantic Ocean. A major problem with previous palaeoceanographic studies in the Southwest Atlantic has been the lack of a depth-transect of sites, purposely situated to trace Paleogene changes in water mass properties. In this region, complex seafloor bathymetry restricts and controls the flow of both deep waters associated with the ACC and Antarctic-sourced bottom waters. The evolution of the deep passageways in this area, and their connection to the progressive development of the modern patterns of deep-water circulation, are unknown. We propose a UK-IODP Site Survey Investigation (SSI) to undertake seismic reflection survey and piston coring operations on the eastern Falkland Plateau region of the sub-Antarctic southwest Atlantic Ocean. Together with a companion Alfred Wegener Institute (AWI) cruise, these survey data will allow development of a full proposal for a new International Ocean Discovery Program (IODP) expedition to drill a depth transect of sites. These sites have been chosen to serve as a geological water mass gauging station that will allow reconstruction of deep-water circulation patterns through the Paleogene. Our primary aim is to test long-standing competing hypotheses on the relative roles of declining atmospheric carbon dioxide and the initiation of the ACC in driving the onset of Cenozoic cooling and Antarctic glaciation. The UK-IODP SSI datasets, together with data derived from the companion cruise led by AWI, will contribute new understanding of deep-water sedimentary processes, the history of drift sedimentation and bottom-current erosion in conjunction with the evolution of deep-water flow, and sediment characteristics of the Southwest Atlantic Ocean. The combined results of the UK-IODP SSI and AWI cruises will function as stand-alone, publishable datasets of interest to a large community of marine geologists and palaeoceanographers, and provide a robust foundation for a UK-led IODP drilling proposal in time for planned JOIDES Resolution operations in South Atlantic.
来源学科分类	Natural Environment Research
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/86853
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	[unavailable].Paleogene Climate and Deep-water Evolution in the Southwest Atlantic: Seismic Reflection and Coring Investigations in Support of IODP Proposal 862-Pre.2016.