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Hunting for Hydrothermal Vents Along the Galã¡Pagos Spreading Center University of South Carolina Scholar Commons Faculty Publications Earth, Ocean and Environment, School of the 12-2007 Hunting for Hydrothermal Vents Along the Galápagos Spreading Center Rachel M. Haymon University of California - Santa Barbara Edward T. Baker Joseph A. Resing Scott M. White University of South Carolina - Columbia, [email protected] Ken C. Macdonald University of California - Santa Barbara Follow this and additional works at: https://scholarcommons.sc.edu/geol_facpub Part of the Earth Sciences Commons Publication Info Published in Oceanography, Volume 20, Issue 4, 2007, pages 100-107. Haymon, R. M., Baker, E. T., Resing, J. A., White, S. M., & Macdonald, K. C. (2007). Hunting for hydrothermal vents along the Galápagos Spreading Center. Oceanography, 20 (4), 100-107. © Oceanography 2007, Oceanography Society This Article is brought to you by the Earth, Ocean and Environment, School of the at Scholar Commons. It has been accepted for inclusion in Faculty Publications by an authorized administrator of Scholar Commons. For more information, please contact [email protected]. or collective redistirbution of any portion of this article by photocopy machine, reposting, or other means is permitted only with the approval of The Oceanography Society. Send all correspondence to: [email protected] ofor Th e The to: [email protected] Oceanography approval Oceanography correspondence all portionthe Send Society. ofwith any permitted articleonly photocopy by Society, is of machine, reposting, this means or collective or other redistirbution This article has This been published in S P E C I A L Iss U E O N O C E A N E XPL O RATI on B Y R AC H E L M . H AY mon , E D WA R D T. B A K E R , J os EP H A . R E S I ng , Oceanography SC O T T M . Wh I T E , K E N C . M A C D on A L D , A N D T H E G a l APA G o S T EA M , Volume 20, Number 4, a quarterly journal of The 20, NumberOceanography 4, a quarterly Society. , Volume Hunting for Hydrothermal Vents C Along the Galápagos Spreading Center The 2007 by opyright Oceanography Society. A ll rights reserved. P ermission is granted to copy this article for use in teaching and research. article use for research. and this copy in teaching to granted is ermission ...searching for hydrothermal vents in the vastness of the deep ocean floor is not as easy as one might think. This is the story of how we did it. P O Box 1931, R ockville, M R epublication, systemmatic reproduction, reproduction, systemmatic epublication, D 20849-1931, U S A . 100 Oceanography Vol. 20, No. 4 In 1972, at a location in the eastern equatorial Pacific ~ 200 miles north- east of the Galápagos Islands, a young graduate student researcher was using surplus US Navy sonobuoys to listen 4°N to the portion of the global mid-ocean ridge known as the Galápagos Spreading Center (GSC) (Figure 1). The global mid-ocean ridge is a giant volcanic seam 0° where Earth’s lithospheric plates repeat- edly rip apart and erupt lava to form new seafloor in a process known as seafloor spreading. Ken Macdonald was listening for the sounds of ripping and volcanic 4°S eruptions produced by seafloor spread- 95°W 90°W 85°W ing, and he was quite excited when he Figure 1. Location of the Galápagos Spreading Center (GSC) and the Galápagos Islands in the eastern heard a swarm of such sounds (80 earth- equatorial Pacific. The GSC is the boundary between the Cocos and Nazca Plates; yellow arrows show quakes per hour!) through his head- directions of relative plate motion and seafloor spreading. The first hydrothermal vents to be found in the phones. When he went out on the deck deep sea on the global mid-ocean ridge were discovered in 1977 at the Rose Garden site (white triangle). White arrows mark the portion of the GSC surveyed during the 2005–2006 GalAPAGoS Expedition, of the ship, he saw many dead fish float- which was jointly funded by the US National Science Foundation (Marine Geology and Geophysics ing on the sea surface, and quickly real- Program) and National Oceanic and Atmospheric Administration (Ocean Exploration Program). The GalAPAGoS surveys spanned the portion of the GSC overlying the mantle hotspot that feeds magma to ized that these were benthic fish, which the volcanoes of the Galápagos Islands. live near the seafloor at great depth. He logically concluded that the fish had been killed by the seafloor events pro- ducing the sounds detected by his sono- buoys, and he published a paper in 1974 GSC hydrothermal vent communities thermal activity is a global-scale pro- to propose that the crest of the GSC near became the first known examples of cess profoundly affecting the chemical, 86°W had experienced a volcanic erup- light-independent ecosystems. Shortly biological, and physical properties of tion (Macdonald and Mudie, 1974). thereafter, also in 1979, submersible our planet (Humphris et al., 1995, and Five years after the earthquake swarm, divers exploring the crest of the East references therein). Furthermore, marine a US team diving in the Alvin submers- Pacific Rise came upon much hotter hydrothermal systems may be the cru- ible, led by John Corliss, discovered the (380 + 30°C) hydrothermal vents (Spiess cible from which microbial life on Earth first deep-sea hydrothermal vents on the et al., 1980). These astonishing “black arose (Reysenbach and Shock, 2002; GSC crest at the location of Macdonald’s smokers” were blasting plumes of scald- Knoll, 2004; and references therein). volcanic eruption (Corliss et al., 1979). ing fluid, blackened by tiny metal-sulfide Although these great discoveries began Remarkably, these warm springs teemed mineral particles, into the deep ocean on the GSC at a site known as “Rose with benthic life, and were inhabited through tall mineral “chimney” conduits. Garden” (near 86°W; Figure 1), nearly by many types of animals that were The discoveries of deep-sea hydro- three decades later the rest of the GSC heretofore unknown to science. The thermal vents and animal communities remained largely unexplored for hydro- exotic animals were being nourished were among the most thrilling marine thermal activity. On the eastern GSC primarily by chemosynthetic microbes revelations of the latter twentieth cen- near Rose Garden, only a few hydrother- using vent-fluid chemicals, rather than tury. Subsequent seafloor exploration mal vents had been located, and none sunlight, as an energy source. Thus the demonstrated that submarine hydro- were hot black smokers. Oceanography December 2007 101 Figure 2. Sketch illustrating the formation of the Galápagos Spreading Center from magma that rises into the crack between two diverg- ing lithospheric plates (the Cocos plate to the north and the Nazca plate to the south). The Galápagos hotspot feeds magma from much deeper mantle sources to the Galápagos Islands and Galápagos Spreading Center. Below the GSC, a much deeper mantle ridge overlies hotspots (Ito et al., 2003); the global impact of hotspots on seafloor magma source, a so-called “hotspot,” is however, their impacts on mid-ocean hydrothermal activity. feeding the profuse volcanism that has ridge volcanism and hot-spring activ- But, searching for hydrothermal vents built the Galápagos Islands (Sinton et al., ity are not known. Some scientists have in the vastness of the deep ocean floor 2003, and references therein) (Figure 2). argued that the excess melt from hot- is not as easy as one might think. This is About one-fifth of the global mid-ocean spots is likely to produce a greater abun- the story of how we did it. dance of mid-ocean ridge hydrothermal RACHEL M. HAYmon (haymon@geol. vents and biota, and many black smokers, ThE GalAPAGoS SURVEYS ucsb.edu) is Professor, Department of while others have predicted the opposite The size of the area that we set out to Earth Science and Marine Science Institute, (e.g., Chen, 2003; Chen and Lin, 2004). explore is approximately the size of University of California, Santa Barbara, CA, Do hotspots enhance or reduce the the California coastal zone from San USA. EDWARD T. BAKER is Supervisory global magnitude of high-temperature Francisco to Los Angeles (Figure 1). Oceanographer, NOAA Vents Program, chemical exchange between the mid- None of this terra incognita had ever Pacific Marine Environmental Laboratory, ocean ridge and the oceans? If mid-ocean been seen before by human eyes. National Oceanic and Atmospheric ridge/hotspot intersections are “hydro- Hydrothermal vents on the mid-ocean Administration, Seattle, WA, USA. JosEPH thermal deserts” offering few oases for ridge typically cover areas of seafloor A. RESIng is Chemical Oceanographer, vent biota, are hotspots significant bio- no bigger than a football field, and indi- NOAA Vents Program, Pacific Marine geographical barriers to the dispersal of vidual black smokers and animal clus- Environmental Laboratory, National these organisms along the mid-ocean ters cover areas smaller than the aver- Oceanic and Atmospheric Administration, ridge? In December 2005–January 2006, age living room (Haymon et al., 1991; Seattle, WA, USA. SCOTT M. WhITE we set out to explore for hydrothermal Haymon, 2005; Humphris et al., 1995). is Assistant Professor, Department of vents along the GSC above the Galápagos To hunt for these rather small features Geological Sciences, University of South hotspot because it is an ideal place to within such a large search area, we con- Carolina, Columbia, SC, USA. KEN C. find out how a hotspot affects the types ducted a sequence of sonar, hydrother- MACDonALD is Professor, Department and abundances of hot springs, animals, mal plume, and photographic surveys of Earth Science and Marine Science and volcanic features of the mid-ocean designed to zoom in on the locations Institute, University of California, ridge.
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