Kenneth C. Macdonald

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Kenneth C. Macdonald
KC Macdonald EPR map.png
Macdonald and map of East Pacific Rise crest at 9°N
Born1947 (age 75–76)
NationalityAmerican
Alma materUC Berkeley MIT
Known forocean spreading centers deep sea hydrothermal vents
Awards
  • Fellow Geological Soc. America
  • Fellow Amer. Geophys. Union
  • Fellow Amer. Assoc. Adv. Science
  • Member, American Academy of Arts and Sciences
  • Cody Medal
  • Newcomb Cleveland Prize of Amer. Assoc. Adv. Science
Scientific career
Institutions
Doctoral advisor Bruce Luyendyk, Tanya Atwater
Website www.geol.ucsb.edu/faculty/macdonald/index.php

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.

Contents

Early life and education

Macdonald grew up in El Cerrito and Richmond, California, and graduated from Harry Ells High School in 1966. He attended UC Berkeley graduating with a B.S. in engineering in 1970. Funded by a National Science Foundation Graduate Fellowship, he attended the Massachusetts Institute of Technology in 1970, graduating from the MIT/Woods Hole Oceanographic Institution Joint Program in Oceanography specializing in marine geophysics in 1975. He was awarded a Cecil H. and Ida Green Research Fellowship to work at the Institute of Geophysics and Planetary Physics with James Brune in 1975. He joined the research staff at the Scripps Institution of Oceanography in 1976 as Research Geophysicist working with Fred Spiess. In 1979, he joined the faculty of the Department of Geological Sciences at UCSB and the Marine Sciences Institute as an associate professor and research geophysicist.

Career and impact

His PhD work focused on the tectonic and magnetic properties of the Mid-Atlantic Ridge on Project FAMOUS expeditions led by Bruce Luyendyk. [1] [2] [3] (his other primary advisor was Tanya Atwater [4] [5] ).

He was co-chief scientist of the RISE project - a research expedition which discovered superheated "black smoker" hydrothermal vents on the East Pacific Rise in 1979, [6] and was the first to calculate their contribution to global geothermal heat flux. [7] He was also chief scientist and lead diver on the expedition which documented in situ, the recording of magnetic reversals in the volcanic rocks of the deep seafloor, an important aspect of proving seafloor spreading and plate tectonics. [8] [9]

Macdonald led expeditions which mapped the Vema and Tamayo Transform faults, showing that the plate boundary intersection of an oceanic ridge and transform fault is sharp, only a few km in area, and documenting that these two types of plate boundaries are narrow. [10] [11] Their work demonstrated that the inside corner region is an area of diffuse deformation caused by extreme tectonic extension. [12]

He was chief scientist on the expedition which discovered “Overlapping Spreading Centers” (OSCs). [13] In this geometry two active spreading centers overlap, apparently pushing against each other, which would violate one of the rules of plate tectonics: plates are rigid. This paradox is solved by the fact that the OSCs are non-steady-state, and propagate along the ridge; as one segment lengthens, the neighboring segment shortens, and the overlapped region migrates. [14]

Previous to this discovery, it was thought that mid-ocean ridges were offset only by transform faults, usually at right angles. The expedition found that the ridge is segmented on a length scale of hundreds of kilometers by transform faults, but also at much shorter scales, km to tens of kilometers, by Overlapping Spreading Centers and other types of nontransform discontinuities. [15] The long segments persist for millions of years, while the finer scale segments are shorter-lived, hundreds of thousands of years or less. The shorter segments are important because they define the scale at which individual volcanoes function on the ridge, which, in turn, control the creation of new oceanic crust and hydrothermal activity [16] [17]

Awards and honors

In recognition of his work he was the first marine geophysicist to be awarded the Cody gold medal and prize for his outstanding work and leadership in the Ocean Sciences as well as election as Fellow to the American Academy of Arts and Sciences, Fellow of the American Association for the Advancement of Science, Fellow of the American Geophysical Union (1995), Fellow of the Geological Society of America (1995) and co-recipient of the Newcomb Cleveland Prize for the most important article published in Science magazine in 1980 for the discovery and analysis of black smoker vents.

KC Macdonald on RISE project expedition KC Macdonald ALVIN RISE exped.png
KC Macdonald on RISE project expedition

Leadership in the profession

He has contributed to the advancement of ocean sciences by serving on the Ocean Studies Board of the National Academy of Sciences (1980–83), the Oceanic Lithosphere Panel for the Advanced Drilling Project (Deep Sea Drilling Project) (1983–85), member of the ALVIN Review Committee (1979–82), founding member of the RIDGE Steering Committee (1987–90), member of the U.S. Geodynamics Committee (of the National Research Council) (1999-2000), Chairman National Undersea Research Panel of the National Undersea Research Program (NOAA) (2002), member of the Woods Hole Oceanographic Institution Corporation, and numerous panels and future planning committees for the National Science Foundation, in particular for NSF Ocean Sciences program.

He has also served in the following editorial capacities: associate editor, Journal of Geophysical Research ; associate editor, Earth and Planetary Science Letters ; co-editor, Marine Geophysical Researches; section editor, Encyclopedia of Ocean Sciences; section editor, Encyclopedia of Geology.

Public outreach and media

His work has been featured in the National Geographic, [18] [19] [20] the New York Times (on page 1), [21] Physics Today, [22] Islands Magazine, [23] and Esquire Magazine. [24] He has written for Scientific American, [25] [26] Oceanus Magazine, [27] [28] and American Scientist. [29]

Selected works

Related Research Articles

<span class="mw-page-title-main">Plate tectonics</span> Movement of Earths lithosphere

Plate tectonics is the scientific theory that Earth's lithosphere comprises a number of large tectonic plates which have been slowly moving since about 3.4 billion years ago. The model builds on the concept of continental drift, an idea developed during the first decades of the 20th century. Plate tectonics came to be accepted by geoscientists after seafloor spreading was validated in the mid-to-late 1960s.

<span class="mw-page-title-main">Seafloor spreading</span> Geological process at mid-ocean ridges

Seafloor spreading, or seafloor spread, is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge.

<span class="mw-page-title-main">Transform fault</span> Plate boundary where the motion is predominantly horizontal

A transform fault or transform boundary, is a fault along a plate boundary where the motion is predominantly horizontal. It ends abruptly where it connects to another plate boundary, either another transform, a spreading ridge, or a subduction zone. A transform fault is a special case of a strike-slip fault that also forms a plate boundary.

<span class="mw-page-title-main">Divergent boundary</span> Linear feature that exists between two tectonic plates that are moving away from each other

In plate tectonics, a divergent boundary or divergent plate boundary is a linear feature that exists between two tectonic plates that are moving away from each other. Divergent boundaries within continents initially produce rifts, which eventually become rift valleys. Most active divergent plate boundaries occur between oceanic plates and exist as mid-oceanic ridges.

<span class="mw-page-title-main">Oceanic crust</span> Uppermost layer of the oceanic portion of a tectonic plate

Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic cumulates. The crust overlies the rigid uppermost layer of the mantle. The crust and the rigid upper mantle layer together constitute oceanic lithosphere.

<span class="mw-page-title-main">East Pacific Rise</span> A mid-oceanic ridge at a divergent tectonic plate boundary on the floor of the Pacific Ocean

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-southwest towards Antarctica, near New Zealand. Much of the rise lies about 3,200 km (2,000 mi) off the South American coast and rises about 1,800–2,700 m (5,900–8,900 ft) above the surrounding seafloor.

<span class="mw-page-title-main">Mid-ocean ridge</span> Basaltic underwater mountain system formed by plate tectonic spreading

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.

<span class="mw-page-title-main">Juan de Fuca Ridge</span> Divergent plate boundary off the coast of the Pacific Northwest region of North America

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. 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.

<span class="mw-page-title-main">Izu–Bonin–Mariana Arc</span> Convergent boundary in Micronesia

The Izu–Bonin–Mariana (IBM) arc system is a tectonic plate convergent boundary in Micronesia. The IBM arc system extends over 2800 km south from Tokyo, Japan, to beyond Guam, and includes the Izu Islands, the Bonin Islands, and the Mariana Islands; much more of the IBM arc system is submerged below sealevel. The IBM arc system lies along the eastern margin of the Philippine Sea Plate in the Western Pacific Ocean. It is the site of the deepest gash in Earth's solid surface, the Challenger Deep in the Mariana Trench.

An oceanic core complex, or megamullion, is a seabed geologic feature that forms a long ridge perpendicular to a mid-ocean ridge. It contains smooth domes that are lined with transverse ridges like a corrugated roof. They can vary in size from 10 to 150 km in length, 5 to 15 km in width, and 500 to 1500 m in height.

<span class="mw-page-title-main">Southwest Indian Ridge</span> A mid-ocean ridge on the bed of the south-west Indian Ocean and south-east Atlantic Ocean

The Southwest Indian Ridge (SWIR) is a mid-ocean ridge located along the floors of the south-west Indian Ocean and south-east Atlantic Ocean. A divergent tectonic plate boundary separating the Somali Plate to the north from the Antarctic Plate to the south, the SWIR is characterised by ultra-slow spreading rates (only exceeding those of the Gakkel Ridge in the Arctic) combined with a fast lengthening of its axis between the two flanking triple junctions, Rodrigues (20°30′S70°00′E) in the Indian Ocean and Bouvet (54°17′S1°5′W) in the Atlantic Ocean.

<span class="mw-page-title-main">Bruce P. Luyendyk</span> American geophysicist and oceanographer (born 1943)

Bruce Peter Luyendyk is an American geophysicist and oceanographer, currently professor emeritus of marine geophysics at the University of California, Santa Barbara. His work spans marine geology of the major ocean basins, the tectonics of southern California, marine hydrocarbon seeps, and the tectonics and paleoclimate of Antarctica. His research includes tectonic rotations of the California Transverse Ranges, participation in the discovery of deep-sea hydrothermal vents, quantitative studies of marine hydrocarbon seeps, and geologic exploration of the Ford Ranges in Marie Byrd Land, Antarctica.

<span class="mw-page-title-main">Overlapping spreading centers</span> Feature of spreading centers at mid-ocean ridges

Overlapping spreading centers are a feature of spreading centers at mid-ocean ridges.

<span class="mw-page-title-main">Propagating rift</span> Seafloor feature associated with spreading centers at mid-ocean ridges and back-arc basins

A propagating rift is a seafloor feature associated with spreading centers at mid-ocean ridges and back-arc basins. They are more commonly observed on faster rate spreading centers. These features are formed by the lengthening of one spreading segment at the expense of an offset neighboring spreading segment. Hence, these are remnant features produced by migration of the tip of a spreading center. In other words, as the tip of a spreading center migrates or grows, the plate itself grows at the expense of the shrinking plate, transferring lithosphere from the shrinking plate to the growing plate.

<span class="mw-page-title-main">RISE project</span> 1979 international marine research project

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.

<span class="mw-page-title-main">Project FAMOUS</span> Marine scientific exploration by manned submersibles of a diverging tectonic plate boundary

Project FAMOUS was the first-ever marine scientific exploration by manned submersibles of a diverging tectonic plate boundary on a mid-ocean ridge. It took place between 1971 and 1974, with a multi-national team of scientists concentrating numerous underwater surveys on an area of the Mid-Atlantic Ridge about 700 kilometers west of the Azores. By deploying new methods and specialized equipment, scientists were able to look at the sea floor in far greater detail than ever before. The project succeeded in defining the main mechanisms of creation of the median rift valley on the Mid-Atlantic Ridge, and in locating and mapping the zone of oceanic crustal accretion.

<span class="mw-page-title-main">Marine geophysics</span>

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.

Suzanne Carbotte is a marine geophysicist known for her research on the formation of new oceanic crust.

Rachel Haymon is a marine geologist known for her work linking geological and biological processes occurring at deep-sea hydrothermal vents. In 2005 she was elected a fellow of the Geological Society of America.

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.

References

  1. ↑ Luyendyk, B.P. and K.C. Macdonald (1977). "Physiography and structure of the Famous Rift Valley inner floor observed with a deep towed instrument package". Bull. Geol. Soc. Am. 88 (5): 648–663. doi:10.1130/0016-7606(1977)88<648:PASOTI>2.0.CO;2.
  2. ↑ Macdonald, K.C. (1977). "Near-bottom magnetic anomalies, asymmetric spreading, oblique spreading, and tectonics of the Mid-Atlantic Ridge (37°N)". Bull. Geol. Soc. Am. 88 (4): 541–555. doi:10.1130/0016-7606(1977)88<541:NMAASO>2.0.CO;2.
  3. ↑ Macdonald, K.C. and B.P. Luyendyk (1977). "Deep-tow studies of the structure of the Mid-Atlantic Ridge crest near 37°N (Famous)". Bull. Geol. Soc. Am. 88 (5): 621–636. doi:10.1130/0016-7606(1977)88<621:DSOTSO>2.0.CO;2.
  4. ↑ Atwater, T.M. and K.C. Macdonald (1977). "Are spreading centres perpendicular to their transform faults?". Nature. 270 (5639): 715–719. Bibcode:1977Natur.270..715A. doi:10.1038/270715a0. S2CID   4211338.
  5. ↑ Macdonald, K.C. and T.M. Atwater (1978). "Evolution of rifted ocean ridges". Earth Planet. Sci. Lett. 39 (3): 319–327. Bibcode:1978E&PSL..39..319M. doi:10.1016/0012-821X(78)90017-1.
  6. ↑ Spiess, F.N.; K.C. Macdonald; et al. (1980). "East Pacific Rise: Hot springs and geophysical experiments". Science. 207 (4438): 1421–1433. Bibcode:1980Sci...207.1421S. doi:10.1126/science.207.4438.1421. PMID   17779602. S2CID   28363398.
  7. ↑ Macdonald, K.C., K. Becker, F.N. Spiess and R. Ballard (1980). "Hydrothermal heat flux of the black smoker vents on the East Pacific Rise". Earth Planet. Sci. Lett. 48 (1): 1–7. Bibcode:1980E&PSL..48....1M. doi:10.1016/0012-821X(80)90163-6.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  8. ↑ Macdonald, K.C., S.P. Miller, B.P. Luyendyk, T.M. Atwater and L. Shure (1983). "Investigation of a Vine-Matthews magnetic lineation from a submersible: The source and character of marine magnetic anomalies, 1983". J. Geophys. Res. 88: 3403–3418. doi:10.1029/JB088iB04p03403.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  9. ↑ Cann, J.R. (1983). "Magnetic Reversals from a Submersible". Nature. 305 (5930): 100. doi:10.1038/305100a0. S2CID   4347321.
  10. ↑ Macdonald, K.C., K. Kastens, S.P. Miller and F.N. Spiess (1979). "Deep-tow studies of the Tamayo transform fault". Mar. Geophys. Res. 4 (1): 37–70. Bibcode:1979MarGR...4...37M. doi:10.1007/BF00286145. S2CID   128963710.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. ↑ Macdonald, K.C., D.A. Castillo, S.P. Miller, P.J. Fox, K.A. Kastens and E. Bonatti (1986). "Deep-tow studies of the Vema fracture zone I. Tectonics of a major slow slipping transform fault and its intersection with the Mid-Atlantic Ridge". J. Geophys. Res. 91 (B3): 3334–3354. Bibcode:1986JGR....91.3334M. doi:10.1029/JB091iB03p03334.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  12. ↑ Searle, R C (2013). Mid-ocean ridges. New York: Cambridge University Press. 318 pp. doi:10.1017/CBO9781139084260. ISBN   9781107017528.
  13. ↑ Macdonald, K.C. and P.J. Fox (1983). "Overlapping spreading centers: New accretion geometry on the East Pacific Rise". Nature. 301 (5903): 55–58. Bibcode:1983Natur.302...55M. doi:10.1038/302055a0. S2CID   4358534.
  14. ↑ Macdonald, K.C., J.-C. Sempere ,P.J. Fox and R. Tyce (1987). "Tectonic evolution of ridge axis discontinuities by the meeting, linking or self-decapitation of neighboring ridge segments". Geology. 15 (11): 993–997. Bibcode:1987Geo....15..993M. doi:10.1130/0091-7613(1987)15<993:TEORDB>2.0.CO;2.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  15. ↑ Langmuir, CH, JF Bender, and R Batiza (1986). "Petrological and tectonic segmentation of the East Pacific Rise, 5 30′–14 30′ N". Nature. 322 (6078): 422–429. doi:10.1038/322422a0. S2CID   4277581.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  16. ↑ Carbotte, Suzanne M.; Smith, Deborah K.; Cannat, Mathilde; Klein, Emily M. (2016). "Tectonic and magmatic segmentation of the Global Ocean Ridge System: a synthesis of observations". Geological Society, London, Special Publications. 420 (1): 249–295. Bibcode:2016GSLSP.420..249C. doi:10.1144/SP420.5. hdl: 10161/9478 . S2CID   129032451.
  17. ↑ Haymon, Rachel M.; White, Scott M. (October 2004). "Fine-scale segmentation of volcanic/hydrothermal systems along fast-spreading ridge crests". Earth and Planetary Science Letters. 226 (3–4): 367–382. Bibcode:2004E&PSL.226..367H. doi:10.1016/j.epsl.2004.08.002.
  18. ↑ GROSVENOR, G., 1979. INCREDIBLE WORLD OF THE DEEP-SEA OASES-STRANGE WORLD WITHOUT SUN. NATIONAL GEOGRAPHIC, 156(5), pp.680-683.
  19. ↑ Ballard, Robert and Emory Kristof, Window on Earth’s Interior, National Geographic, vol. 150, no.2, p.228-249, Aug 1976.
  20. ↑ Lutz, Richard and Rachel Haymon, Rebirth of a Deep-sea Vent, National Geographic, vol. 186, no.5, p. 114-126, Nov 1994.
  21. ↑ Nash, Nathaniel (1993). "Rumbling Up From Ocean Floor, A Vast Volcano Cluster Is Found". New York Times. Retrieved 2020-06-10.
  22. ↑ Feder, Toni (2014). "Researchers get back to the deep". Physics Today. 67 (6): 29. Bibcode:2014PhT....67f..29F. doi:10.1063/PT.3.2415 . Retrieved 2020-06-11.
  23. ↑ Reynales, Trish, “Islands of the Future”,  p.24-25, Aug. 1993.
  24. ↑ Fox, Edward, “The Deep”,  Esquire Magazine, p.104-110, April 1994.
  25. ↑ Macdonald, Ken C.; Luyendyk, Bruce P. (1981). "The Crest of the East Pacific Rise". Scientific American. 244 (5): 100–117. Bibcode:1981SciAm.244e.100M. doi:10.1038/scientificamerican0581-100. ISSN   0036-8733. JSTOR   24964420.
  26. ↑ Macdonald, Kenneth C.; Fox, Paul J. (1990). "The Mid-Ocean Ridge". Scientific American. 262 (6): 72–81. Bibcode:1990SciAm.262f..72M. doi:10.1038/scientificamerican0690-72. ISSN   0036-8733. JSTOR   24996826.
  27. ↑ Macdonald, Ken C., “Mid-Ocean Ridges:  The Quest for Order”,  Oceanus, vol. 34, no. 4, p. 9-10, 1991.
  28. ↑ Macdonald, Ken C. (1998). "Exploring-the-global-mid-ocean-ridge". Oceanus magazine. Retrieved 2020-06-11.
  29. ↑ Haymon, R.M. and Macdonald, K.C., 1985. The Geology of Deep-Sea Hot Springs: Recently discovered hot springs burst from the seafloor in areas of active volcanism and deposit metal-rich minerals on the seabed. American Scientist, 73(5), pp.441-449.
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