Tanya Marie Atwater | |
---|---|
Born | 1942 Los Angeles, California |
Nationality | American |
Education | Scripps Institution of Oceanography |
Scientific career | |
Fields | Tectonics Marine geophysics |
Institutions | University of California, Santa Barbara |
Thesis | Implications of Plate Tectonics for the Cenozoic Tectonic Evolution of Western North America (1972) |
Tanya Atwater (born 1942) is an American geophysicist and marine geologist who specializes in plate tectonics. She is particularly renowned for her early research on the plate tectonic history of western North America.
Atwater was born in Los Angeles, California in 1942. [1] Her father was an engineer and her mother was a botanist. Atwater was one of the first women to research the ocean floor in terms of its geology.[ citation needed ]
Atwater began her education in 1960 at the Massachusetts Institute of Technology, then received her B.A. in geophysics from the University of California, Berkeley in 1965. [2] She earned a Ph.D. (1972) in marine geophysics from Scripps Institution of Oceanography, University of California, San Diego. She is director of the University of California, Santa Barbara Educational Multimedia Visualization Center where she is an emerita professor of geological sciences. She was a professor at the Massachusetts Institute of Technology before joining the faculty at UCSB in 1980. Atwater retired from UCSB in 2007. [3]
Atwater was a professor of tectonics, in the Department of Geological Sciences, now the Department of Earth science, at the University of California, Santa Barbara before retiring. She authored and co-authored 50 articles in international journals, professional volumes, and major reports. Seven of these papers were published in the journals Nature or Science . In 1975, she became a Fellow of the American Geophysical Union for her work in tectonophysics. [4] From 1975 to 1977, Atwater was a Sloan Postdoctoral Fellowship Recipient in Physics. [5] In 1984, she won the Encouragement Award from the Association for Women Geoscientists. [6] Atwater is a member of the U.S. National Academy of Sciences [7] elected for her contributions to marine geophysics and tectonics. In 2019 she received the highest award of the Geological Society of America, the Penrose Medal. [8] In 2022 she received the Wollaston medal from the Geological Society of London, its highest award. [9]
Atwater was involved in oceanographic expeditions using deep towed instruments to explore the ocean floor. To date, she has participated in 12 deep water dives in the deep-ocean submersible Alvin . She researched the volcano-tectonic processes responsible for creating new oceanic crust at seafloor spreading centers. In 1968, she co-authored a research paper featuring groundbreaking work into the faulted nature of spreading centers. [10] With Jack Corliss, Fred Spiess, and Kenneth Macdonald, she played key roles in expeditions that uncovered the distinct biology of ocean floor warm springs, which led to the discovery during the RISE project of the high temperature black smokers, undersea hydrothermal vents.
In Atwater's research on propagating rifts near the Galapagos Islands, [11] she discovered that propagating rifts were created when spreading centers along the seafloor were disturbed by tectonic movement or magma and therefore had to change direction to realign. This helped to explain the complex pattern of the seafloor.
Atwater is perhaps best known for her work on the plate tectonic history of western North America. [12] She wrote two major research papers outlining the history of plate tectonic evolution of North America and tectonic problems of the San Andreas Fault, which assisted in documenting the history of the San Andreas Fault. [13] [14]
She also studied geometric evolution, integrating and comparing the global plate motion records with the regional continental geologic records. She found emerging relationships that revealed the origins of many large-scale geologic features (e.g. Rocky Mountains, Yellowstone, Death Valley, Cascade volcanoes, California Coast Ranges). [7]
Atwater's research paper, "Implications of Plate Tectonics for the Cenozoic Tectonic Evolution of Western North America", [13] established the essential framework for the plate tectonics of western North America. In her work, she explains that approximately 40 million years ago, the Farallon Plate was subducting underneath the North American Plate and the Pacific Plate. The lower half of the Farallon plate was entirely subducted under Southern California and the upper half did not sink, which eventually became known as the Juan de Fuca Plate. Since the southern section of Farallon completely disappeared, the boundary of southern California was now between the Pacific Plate and the North American Plate. The San Andreas Fault is unique because it acts as a major fault line as well as a border between the Pacific Plate and the North American Plate. [13] She updated this work in 1989. [15]
Atwater is interested in communication and education at all levels. She has developed electronic multi-media (Educational Multimedia Visualization Center at UCSB) to enhance geologic visualization and understanding, particularly related to the histories of tectonic plates. [16]
The Paleogene Period is a geologic period and system that spans 43 million years from the end of the Cretaceous Period 66 Ma to the beginning of the Neogene Period 23.03 Ma. It is the first period of the Cenozoic Era and is divided into the Paleocene, Eocene, and Oligocene epochs. The earlier term Tertiary Period was used to define the time now covered by the Paleogene Period and subsequent Neogene Period; despite no longer being recognized as a formal stratigraphic term, "Tertiary" still sometimes remains in informal use. Paleogene is often abbreviated "Pg", although the United States Geological Survey uses the abbreviation "Pe" for the Paleogene on the Survey's geologic maps.
The San Andreas Fault is a continental right-lateral strike-slip transform fault that extends roughly 1,200 kilometers (750 mi) through the U.S. state of California. It forms part of the tectonic boundary between the Pacific Plate and the North American Plate. Traditionally, for scientific purposes, the fault has been classified into three main segments, each with different characteristics and a different degree of earthquake risk. The average slip rate along the entire fault ranges from 20 to 35 mm per year.
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.
The Basin and Range Province is a vast physiographic region covering much of the inland Western United States and northwestern Mexico. It is defined by unique basin and range topography, characterized by abrupt changes in elevation, alternating between narrow faulted mountain chains and flat arid valleys or basins. The physiography of the province is the result of tectonic extension that began around 17 million years ago in the early Miocene epoch.
The North American Plate is a tectonic plate containing most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of 76 million km2 (29 million sq mi), it is the Earth's second largest tectonic plate, behind the Pacific Plate.
The Juan de Fuca Plate is a small tectonic plate (microplate) generated from the Juan de Fuca Ridge that is subducting beneath the northerly portion of the western side of the North American Plate at the Cascadia subduction zone. It is named after the explorer of the same name. One of the smallest of Earth's tectonic plates, the Juan de Fuca Plate is a remnant part of the once-vast Farallon Plate, which is now largely subducted underneath the North American Plate.
The Farallon Plate was an ancient oceanic tectonic plate. It formed one of the three main plates of Panthalassa, alongside the Izanagi Plate and the Phoenix Plate, which were connected by a triple junction. The Farallon Plate began subducting under the west coast of the North American Plate—then located in modern Utah—as Pangaea broke apart and after the formation of the Pacific Plate at the centre of the triple junction during the Early Jurassic. It is named for the Farallon Islands, which are located just west of San Francisco, California.
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million km2 (40 million sq mi), it is the largest tectonic plate.
The Transverse Ranges are a group of mountain ranges of southern California, in the Pacific Coast Ranges physiographic region in North America. The Transverse Ranges begin at the southern end of the California Coast Ranges and lie within Santa Barbara, Ventura, Los Angeles, San Bernardino, Riverside and Kern counties. The Peninsular Ranges lie to the south. The name is due to the ranges' east–west orientation, making them transverse to the general northwest–southeast orientation of most of California's coastal mountains.
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.
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 Phoenix Plate was a tectonic plate that existed during the early Paleozoic through late Cenozoic time. It formed a triple junction with the Izanagi and Farallon plates in the Panthalassa Ocean as early as 410 million years ago, during which time the Phoenix Plate was subducting under eastern Gondwana.
The Gorda Ridge, aka Gorda Ridges tectonic spreading center, is located roughly 200 kilometres (120 mi) off the northern coast of California and southern Oregon. Running NE – SW it is roughly 300 kilometres (190 mi) in length. The ridge is broken into three segments; the northern ridge, central ridge, and the southern ridge, which contains the Escanaba Trough.
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 Farallon Trench was a subduction related tectonic formation located off the coast of the western California continental margin during the late to mid Cenozoic era, around 50 miles southeast of modern-day Monterey Bay. The time duration of subduction began from around 165 Ma when the Farallon Plate replaced the Mezcalera promontory, until the San Andreas Fault straightening around 35 Ma. As data accumulated over time, a common view developed that one large oceanic plate, the Farallon Plate, acted as a conveyor belt, conveying accreted terranes onto the North American west coast. As the continent overran the subducting Farallon Plate, the denser plate became subducted into the mantle below the continent. When the plates converged, the dense oceanic plate sank into the mantle to form a slab below the lighter continent. Rapid subduction under the southwestern North America continent began 40 to 60 million years ago (Ma), during the mid Paleocene to mid Eocene epochs. This convergent subduction margin created a distinctive geomorphologic feature called an oceanic trench, which occurs at a convergent plate boundaries as a heavy metal rich, lithospheric plate moves below a light silica rich continental plate. The trench marks the position at which the flexed subducting slab begins to descend beneath and deform the continental plate margin. By 43 Ma, during the Eocene, worldwide plate motions changed and the Pacific Plate began to move away from North America and subduction of the Farallon Plate slowed dramatically. By around 36 Ma, the easternmost part of the East Pacific Rise, located between the Pioneer and Murray fracture zones at that time, approached the trench and the young, hot, buoyant lithosphere appears to have clogged part of the subduction zone, resulting in widespread dramatic uplift on land. The eventual complete subduction of this plate, consequential contact of the Pacific Plate with the California continental margin, and creation of the Mendocino Triple Junction (MTJ), took place around 30 to 20 Ma. The partial complete subduction and division of the Farallon Plate by the Pacific Plate, created the Juan de Fuca Plate to the north and the Cocos Plate to the south. The final stages of the evolution of California's continental margin was the growth of the San Andreas transform fault system, which formed as the Pacific Plate came into contact with the continental margin and the MTJ was formed. As subduction of the Pacific Plate continued along this margin, and the contact zone grew, the San Andreas proportionally grew as well.
This is a list of articles related to plate tectonics and tectonic plates.
The Gulf of California Rift Zone (GCRZ) is the northernmost extension of the East Pacific Rise which extends some 1,300 km (800 mi) from the mouth of the Gulf of California to the southern terminus of the San Andreas Fault at the Salton Sink.
The San Quintín Volcanic Field is a collection of ten or eleven volcanic cinder cones situated along the Pacific coast of the Baja California peninsula in Mexico. The field formed by repeated eruptions beginning in the Pleistocene and ending about 3000 years ago. It is one of several known Quaternary period volcanic fields in Baja. The lava shields appear to have first grown as subaqueous volcanoes that emerged as islands.
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.
Joann Stock is a professor at California Institute of Technology known for her research into plate tectonics, particularly on changes in plate boundaries over geological time.
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