The British Mid-Ocean Ridge Initiative (the BRIDGE Programme) was a multidisciplinary scientific investigation of the creation of the Earth's crust in the deep oceans. It was funded by the UK's Natural Environment Research Council (NERC) from 1993 to 1999.
Mid-Ocean ridges are active volcanic mountain ranges snaking through the depths of the Earth's oceans. They occur where the edges of the Earth's tectonic plates are separating, allowing mantle rock to rise to the seafloor and harden, creating new crust. The addition of this crust can cause ocean basins to widen perpendicular to the ridge. This seafloor spreading is the engine of continental drift. [lower-alpha 1] At intervals along the mid-ocean ridges super-heated mineral-rich fluids are vented from the seabed. These hydrothermal vents are populated by animal and bacterial species not found elsewhere on Earth. [1]
BRIDGE investigated the geological setting of the ridge, the geochemistry of vent fluids, and ways in which biological communities survive in this apparently hostile environment. To achieve this the programme developed novel deep-ocean technologies for deployment from surface ships and manned submersibles. It also conducted experimental research into the mechanical and chemical nature of the rocks and underlying crust in these active volcanic regions. The scale of the investigation ranged from extensive regional studies mapping unexplored seafloor to microscopic and chemical analyses at individual vent sites. To achieve the programme's objectives work was focused at five contrasting locations: the Mid-Atlantic Ridge at 24–30°N; the Mid-Atlantic Ridge at 36–39°N; Iceland and the Reykjanes Ridge to its south west; the Scotia back-arc basin (SW Atlantic); and the Lau basin (SW Pacific). Intensive localised studies were made within these areas. [bnl 1]
The idea for a British mid-ocean ridge research programme was developed by Professors Joe Cann of Leeds University and Roger Searle of Durham University after they attended a meeting in Oregon in 1987 where the idea for a US mid-ocean ridge research programme (the RIDGE Program) was being developed. [bnl 2] [lower-alpha 2] In the UK researchers in many disciplines were already studying mid-ocean ridges but it was felt this research could be better integrated to produce new multidisciplinary approaches yielding results of wider significance. [2]
The 'BRIDGE' branding of research commenced before research council funding was sought for a formal programme. BRIDGE was mentioned by name in The Independent newspaper in February 1989. [bnl 3] By this time the community of researchers in this field were referring to themselves as the BRIDGE Consortium. Deep-ocean science cruises were being identified as BRIDGE cruises by 1990. [bnl 4] The first BRIDGE newsletter appeared in 1991.
Once the idea of BRIDGE was in place an application for funding was made to the Natural Environment Research Council. This was successful and full funding commenced in 1993 for a programme that would run until 1999. [bnl 5] The final budget was £13M. [lower-alpha 3]
This last aim was achieved directly and by participation in the international InterRidge network.
From the wide range of scientific problems that could be addressed by mid-ocean ridge research, BRIDGE identified six that were of most relevance to UK research.
The scientific aims and objectives of the programme were directed by an international steering committee which met twice a year. The programme held a series of annual funding rounds to which scientists and engineers in the field submitted research proposals. Following a peer-review assessment of each proposal by independent referees the steering committee ranked the most highly rated proposals on their scientific merit and contribution to the programme's objectives. This short-list was then recommended to NERC for funding. [bnl 6]
From 1993 to 1995 programme management (day-to-day administration and budget oversight) was undertaken by NERC head office in Swindon. A separate Science Coordinator role (incorporating, among other duties, responsibility for expanding the BRIDGE Consortium, organising national conferences and publishing the newsletter) was based at Leeds University where the BRIDGE Chief Scientist, Joe Cann, was chairman of Earth Sciences.
In 1995 NERC began contracting out programme management for their large programmes. [bnl 7] BRIDGE programme management absorbed the science coordination role and a new programme manager was appointed, based at Leeds University. The Leeds BRIDGE office was the programme hub until the end of March 1999 after which the conclusion of the programme was administered by NERC. [bnl 8]
BRIDGE funded 44 research projects: 4 multidisciplinary; 15 geology; 6 biology; 11 studies of the hydrothermal environment at vent fields (9 of the ocean floor and 2 of the overlying water column); and 8 engineering projects to develop the required technologies. [lower-alpha 4] More than 200 scientists in 28 research centres around the UK contributed to this programme. [bnl 9] There were 26 BRIDGE deep-ocean research cruises to the North Atlantic, SW Atlantic, SE Pacific, SW Pacific and Indian oceans, 18 of which were directly funded by the programme. [bnl 10]
To discuss and publicise the programme's results BRIDGE organised its own science conferences at Durham University (1991), the Institute of Oceanographic Sciences Deacon Laboratory (IOSDL), Wormley (1992), Leeds University (1993), Oxford University (1994), the Geological Society of London (1994, 1995 and 1997), Cambridge University (1996), Southampton Oceanography Centre (1997) and Bristol University (1998). [bnl 11] In addition BRIDGE science was reported at other meetings nationally and internationally, for example: at the Royal Society meeting Mid-Ocean Ridges: Dynamics of Processes Associated with Creation of New Ocean Crust (1996), [bnl 12] the 1996 British Association for the Advancement of Science annual science festival at Birmingham in a BRIDGE session entitled Abyssal Inferno: Seafloor volcanoes, hot vents and exotic life at the mid-ocean ridges, [bnl 13] at Geoscience 98, Keele University (1998), [bnl 14] at the meeting Technology for Deep-Sea Geological Investigations at the Geological Society of London (1998) [bnl 15] and at meetings of the American Geophysical Union. [3]
Three of the BRIDGE conferences resulted in books published by the Geological Society of London, presenting in greater detail the science reported at the meetings. [4] [5] [6]
Throughout the programme rapid publication of results was effected through The BRIDGE Newsletter. In style this was an academic journal (but without peer review) comprising BRIDGE science results together with conference announcements, meeting reports, cruise reports, updates from the mid-ocean ridge programmes of other nations and general news items of relevance to this field of research. [lower-alpha 5] It was published twice a year in spring and autumn. The first issue of eight stapled sheets appeared in August 1991 but after NERC funding commenced it was commercially printed and bound. By issue 10, in April 1996, it had grown to 100 pages and was being distributed to more than 600 researchers and interested parties in 20 countries. [bnl 16] The last newsletter, No. 17, was produced in autumn 1999 as a magazine called The Fiery Deep, Exploring a New Earth summarising the programme and its results to that time. [7] On 16 November 1999 at the Natural History Museum, London these results were presented to invited guests at a formal end of programme meeting.
As the programme ended, Joe Cann reported, "As a result of the BRIDGE initiative, several groups of UK scientists are at the forefront of international research in mid-ocean ridge science. The areas of expertise of these scientists range from marine geophysics and geodynamics, physical and chemical oceanography, to marine biology." [8] "Every area had success. Here are a few examples. We found new pools of molten rock below the ocean floor where none was expected. We discovered large fields of hot springs, where the wisdom of the time said there should be none. We followed the strange lifecycle of the blind shrimp that live around hot springs in the Atlantic. We made sonar images of the first of a family of enormous faults that slice through the ocean floor, bringing deep rock to the surface. We showed how the flow of one of the big, hot spring fields was affected by scientific drilling. We traced the relationships between animals in hot spring communities up and down the Atlantic. We built new instruments, too, that can operate in these hostile regions". [bnl 17]
In addition to the results of the researches, which are still quoted, [9] the BRIDGE Programme left an interdisciplinary community of deep-ocean scientists with a proven track record of collaboration and new equipment for working at depths of over 3,500 metres. [bnl 18]
BRIDGE had purchased for the UK research fleet a Simrad multibeam echosounder for mapping the seafloor from a surface ship. To increase detail in any geographical areas of interest it also funded upgrades to the existing UK Towed Ocean Bottom Instrument (TOBI), which made 3D images of the seabed as it was towed 300m above the ocean floor. TOBI was modified to increase its resolution, to add a gyrocompass and to add a three component magnetometer for measuring the magnetic field of the seafloor rock over which it was towed. [bnl 19]
The BRIDGE Towed instrument (BRIDGET), was developed for hunting and studying the plumes of warm, mineral rich fluids rising into the water column from vent fields. This "hot-spring sniffer" was towed at depth behind a ship in areas where vent fields were suspected to occur and fed geochemical data back to the ship in real time. [bnl 20]
Once fields had been detected the fluids venting from the sea-floor could be studied directly using the MEDUSA instrument. Deployed by a deep submergence vehicle, this could be placed over individual vents for extended time periods to record the characteristics of the fluids as they emerge. At the BRIDGE programme's close six MEDUSA instruments had been built with BRIDGE funding, three more were constructed for the Geological Survey of Japan, and the next generation was being developed for various US agencies including NASA. [bnl 21]
For examining the rock of the mid-ocean ridge a new deep ocean drill, the BRIDGE Drill, was developed which marked the core as it drilled. The marking of the core allowed the original north-south orientation of the core to be known after it had been removed. This permitted the magnetic alignment of the rock from which the sample was taken to be determined, providing information on sea-bed movements that had taken place after the rock had formed. [bnl 22]
For study of the dispersal of animals found at the vent fields, the biologists developed a Planktonic Larval Sampler for Molecular Analysis (PLASMA). This was designed to take samples of water to catch the dispersing larvae of animals living around the vents. PLASMA could be left on the sea-bed in the vicinity of a vent field for up to a year if required, sampling at programmed intervals and preserving any larvae for DNA analysis after the recovery of the equipment. [bnl 23]
BRIDGE collected and compiled: multibeam bathymetry, sonar imagery, seismic data, electromagnetic data, gravimetry, petrology (including rock sections, cores, sediments and analytical data), chemical and physical oceanography (samples and analytical data), macro- and microbiology (specimens, film and analytical data); numerical models and audiovisual records. [10] For the benefit of future researchers a BRIDGE data archive was lodged with the UK's National Oceanography Centre at Southampton. [bnl 24]
The Gakkel Ridge is a mid-oceanic ridge, a divergent tectonic plate boundary between the North American Plate and the Eurasian Plate. It is located in the Eurasian Basin of the Arctic Ocean, between Greenland and Siberia. Geologically, it connects the northern end of the Mid-Atlantic Ridge with the Laptev Sea Rift.
Hydrothermal circulation in its most general sense is the circulation of hot water. Hydrothermal circulation occurs most often in the vicinity of sources of heat within the Earth's crust. In general, this occurs near volcanic activity, but can occur in the shallow to mid crust along deeply penetrating fault irregularities or in the deep crust related to the intrusion of granite, or as the result of orogeny or metamorphism. Hydrothermal circulation often results in hydrothermal mineral deposits.
Hydrothermal vents are fissures on the seabed from which geothermally heated water discharges. They are commonly found near volcanically active places, areas where tectonic plates are moving apart at mid-ocean ridges, ocean basins, and hotspots. The dispersal of hydrothermal fluids throughout the global ocean at active vent sites creates hydrothermal plumes. Hydrothermal deposits are rocks and mineral ore deposits formed by the action of hydrothermal vents.
An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3,000 and 6,000 metres. Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth's surface. They are among the flattest, smoothest, and least explored regions on Earth. Abyssal plains are key geologic elements of oceanic basins.
The East Pacific Rise (EPR) is a mid-ocean rise, at a divergent tectonic plate boundary, located along the floor of the Pacific Ocean. It separates the Pacific Plate to the west from the North American Plate, the Rivera Plate, the Cocos Plate, the Nazca Plate, and the Antarctic Plate. It runs south from the Gulf of California in the Salton Sea basin in Southern California to a point near 55°S130°W, where it joins the Pacific-Antarctic Ridge (PAR) trending west-south-west towards Antarctica, near New Zealand. Much of the rise lies about 3,200 km (2,000 mi) off the South American coast and reaches a height about 1,800–2,700 m (5,900–8,900 ft) above the surrounding seafloor.
The Lost City Hydrothermal Field, often referred to simply as Lost City, is an area of marine alkaline hydrothermal vents located on the Atlantis Massif at the intersection between the Mid-Atlantic Ridge and the Atlantis Transform Fault, in the Atlantic Ocean. It is a long-lived site of active and inactive ultramafic-hosted serpentinization, abiotically producing many simple molecules such as methane and hydrogen which are fundamental to microbial life. As such it has generated scientific interest as a prime location for investigating the origin of life on Earth and other planets similar to it.
Marine geology or geological oceanography is the study of the history and structure of the ocean floor. It involves geophysical, geochemical, sedimentological and paleontological investigations of the ocean floor and coastal zone. Marine geology has strong ties to geophysics and to physical oceanography.
A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics. It typically has a depth of about 2,600 meters (8,500 ft) and rises about 2,000 meters (6,600 ft) above the deepest portion of an ocean basin. This feature is where seafloor spreading takes place along a divergent plate boundary. The rate of seafloor spreading determines the morphology of the crest of the mid-ocean ridge and its width in an ocean basin.
The Juan de Fuca Ridge is a mid-ocean spreading center and divergent plate boundary located off the coast of the Pacific Northwest region of North America, named after Juan de Fuca. The ridge separates the Pacific Plate to the west and the Juan de Fuca Plate to the east. It runs generally northward, with a length of approximately 500 kilometres (310 mi). The ridge is a section of what remains from the larger Pacific-Farallon Ridge which used to be the primary spreading center of this region, driving the Farallon Plate underneath the North American Plate through the process of plate tectonics. Today, the Juan de Fuca Ridge pushes the Juan de Fuca Plate underneath the North American plate, forming the Cascadia Subduction Zone.
The Endeavour Hydrothermal Vents are a group of hydrothermal vents in the north-eastern Pacific Ocean, located 260 kilometres (160 mi) southwest of Vancouver Island, British Columbia, Canada. The vent field lies 2,250 metres (7,380 ft) below sea level on the northern Endeavour segment of the Juan de Fuca Ridge. In 1982, dredged sulfide samples were recovered from the area covered in small tube worms and prompted a return to the vent field in August 1984, where the active vent field was confirmed by HOV Alvin on leg 10 of cruise AII-112.
InterRidge is a non-profit organisation that promotes interdisciplinary, international studies in the research of oceanic spreading centres, including mid-ocean ridge and back-arc basin systems. It does so by creating a global research community, planning and coordinating new science programmes that no single nation can achieve alone, exchanging scientific information, and sharing new technologies and facilities. InterRidge is dedicated to reaching out to the public, scientists and governments, and to providing a unified voice for ocean ridge researchers worldwide.
Kenneth Craig Macdonald is an American oceanographer and marine geophysicist born in San Francisco, California in 1947. As of 2018 he is professor emeritus at the Department of Earth Science and the Marine Sciences Institute at the University of California, Santa Barbara (UCSB). His work focuses on the tectonics and geophysics of the global mid-oceanic ridge including its spreading centers and transform faults, two of the three types of plate boundaries central to the theory of plate tectonics. His work has taken him to the north and south Atlantic oceans, the north and south Pacific oceans, the Indian Ocean, the Red Sea and the Sea of Cortez, as well as to the deep seafloor on over 50 dives in the research submersible ALVIN. Macdonald has participated in over 40 deep sea expeditions, and was chief- or co-chief scientist on 31 expeditions.
Kathleen (Kathy) Crane is an American marine geologist, best known for her contributions to the discovery of hydrothermal vents on the Galápagos Rift along the East Pacific Rise in the mid-1970s.
The RISE Project (Rivera Submersible Experiments) was a 1979 international marine research project which mapped and investigated seafloor spreading in the Pacific Ocean, at the crest of the East Pacific Rise (EPR) at 21° north latitude. Using a deep sea submersible (ALVIN) to search for hydrothermal activity at depths around 2600 meters, the project discovered a series of vents emitting dark mineral particles at extremely high temperatures which gave rise to the popular name, "black smokers". Biologic communities found at 21° N vents, based on chemosynthesis and similar to those found at the Galapagos spreading center, established that these communities are not unique. Discovery of a deep-sea ecosystem not based on sunlight spurred theories of the origin of life on Earth.
Emily M. Klein is a professor of geology and geochemistry at Duke University. She studies volcanic eruptions and the process of oceanic crust creation. She has spent over thirty years investigating the geology of mid-ocean ridges and identified the importance of the physical conditions of mantle melting on the chemical composition of basalt.
Deborah Sue Kelley is a marine geologist who studies hydrothermal vents, active submarine volcanoes, and life in these regions of the deep ocean.
Karen Louise Von Damm was an American marine geochemist who studied underseas hydrothermal vent systems. Her work on black smoker hot springs after they were first discovered on the mid-ocean ridge in 1979 significantly advanced understanding of how vent fluids acquire their chemical composition and how those chemicals support biological communities. An area of hydrothermal vents located just south of Grand Cayman in the Caribbean was named the Von Damm Vent Field in her honor.
Marine geophysics is the scientific discipline that employs methods of geophysics to study the world's ocean basins and continental margins, particularly the solid earth beneath the ocean. It shares objectives with marine geology, which uses sedimentological, paleontological, and geochemical methods. Marine geophysical data analyses led to the theories of seafloor spreading and plate tectonics.
Susan Humphris is a geologist known for her research on processes at mid-ocean ridges. She is an elected fellow of the American Geophysical Union.
Margo Helen Edwards is a marine geologist known for mapping of the seafloor and hydrothermal vents. She led the 1999 SCICEX and was the first women to live aboard a United States' Navy submarine while doing under-ice research.
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