From The University of Texas-Austin: “Scientists Detect Molten Rock Layer Hidden Under Earth’s Tectonic Plates”
From The University of Texas-Austin
2.6.23
Anton Caputo
anton.caputo@jsg.utexas.edu
Jackson School of Geosciences
210-602-2085
Constantino Panagopulos
costa@ig.utexas.edu
University of Texas Institute for Geophysics
512-574-7376.
The Earth with the upper mantle revealed. Researchers at The University of Texas at Austin have discovered a previously unknown layer of partly molten rock in a key region just below the tectonic plates. Credit: Leonello Calvetti/Dreamstime.
Scientists have discovered a new layer of partly molten rock under the Earth’s crust that might help settle a long-standing debate about how tectonic plates move.
Researchers had previously identified patches of melt at a similar depth. But a new study led by The University of Texas at Austin revealed for the first time the layer’s global extent and its part in plate tectonics.
The research was published Feb. 6, 2023, in the journal Nature Geoscience [below].
The molten layer is located about 100 miles from the surface and is part of the asthenosphere, which sits under the Earth’s tectonic plates in the upper mantle.
The asthenosphere is important for plate tectonics because it forms a relatively soft boundary that lets tectonic plates move through the mantle.
The reasons why it is soft, however, are not well understood. Scientists previously thought that molten rocks might be a factor. But this study shows that melt, in fact, does not appear to notably influence the flow of mantle rocks.
“When we think about something melting, we intuitively think that the melt must play a big role in the material’s viscosity,” said Junlin Hua, a postdoctoral fellow at UT’s Jackson School of Geosciences who led the research. “But what we found is that even where the melt fraction is quite high, its effect on mantle flow is very minor.”
According to the research, which Hua began as a graduate student at Brown University, the convection of heat and rock in the mantle are the prevailing influence on the motion of the plates. Although the Earth’s interior is largely solid, over long periods of time, rocks can shift and flow like honey.
Showing that the melt layer has no influence on plate tectonics means one less tricky variable for computer models of the Earth, said coauthor Thorsten Becker, a professor at the Jackson School.
“We can’t rule out that locally melt doesn’t matter,” said Becker, who designs geodynamic models of the Earth at the Jackson School’s University of Texas Institute for Geophysics. “But I think it drives us to see these observations of melt as a marker of what’s going on in the Earth, and not necessarily an active contribution to anything.”
The idea to look for a new layer in Earth’s interior came to Hua while studying seismic images of the mantle beneath Turkey during his doctoral research.
A diagram of the asthenosphere, which aids plate tectonics, where researchers at the UT Austin Jackson School of Geosciences say they detected a global layer of partial melt (shown in speckled red). Credit: Junlin Hua, UT Jackson School of Geosciences.
Intrigued by signs of partly molten rock under the crust, Hua compiled similar images from other seismic stations until he had a global map of the asthenosphere. What he and others had taken to be an anomaly was in fact commonplace around the world, appearing on seismic readings wherever the asthenosphere was hottest.
The next surprise came when he compared his melt map with seismic measurements of tectonic movement and found no correlation, despite the molten layer encompassing almost half the Earth.
“This work is important because understanding the properties of the asthenosphere and the origins of why it’s weak is fundamental to understanding plate tectonics,” said coauthor Karen Fischer, a seismologist and professor at Brown University who was Hua’s Ph.D. advisor when he began the research.
The research was funded by the U.S. National Science Foundation. Collaborating institutions included the UT Oden Institute for Computational Engineering and Sciences and Cornell University.
See the full article here .
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University of Texas-Austin campus
The University of Texas-Austin is a public research university in Austin, Texas and the flagship institution of the University of Texas System. Founded in 1883, the University of Texas was inducted into the Association of American Universities in 1929, becoming only the third university in the American South to be elected. The institution has the nation’s seventh-largest single-campus enrollment, with over 50,000 undergraduate and graduate students and over 24,000 faculty and staff.
A Public Ivy, it is a major center for academic research. The university houses seven museums and seventeen libraries, including the LBJ Presidential Library and the Blanton Museum of Art, and operates various auxiliary research facilities, such as the J. J. Pickle Research Campus and the McDonald Observatory. As of November 2020, 13 Nobel Prize winners, four Pulitzer Prize winners, two Turing Award winners, two Fields medalists, two Wolf Prize winners, and two Abel prize winners have been affiliated with the school as alumni, faculty members or researchers. The university has also been affiliated with three Primetime Emmy Award winners, and has produced a total of 143 Olympic medalists.
Student-athletes compete as the Texas Longhorns and are members of the Big 12 Conference. Its Longhorn Network is the only sports network featuring the college sports of a single university. The Longhorns have won four NCAA Division I National Football Championships, six NCAA Division I National Baseball Championships, thirteen NCAA Division I National Men’s Swimming and Diving Championships, and has claimed more titles in men’s and women’s sports than any other school in the Big 12 since the league was founded in 1996.
Establishment
The first mention of a public university in Texas can be traced to the 1827 constitution for the Mexican state of Coahuila y Tejas. Although Title 6, Article 217 of the Constitution promised to establish public education in the arts and sciences, no action was taken by the Mexican government. After Texas obtained its independence from Mexico in 1836, the Texas Congress adopted the Constitution of the Republic, which, under Section 5 of its General Provisions, stated “It shall be the duty of Congress, as soon as circumstances will permit, to provide, by law, a general system of education.”
On April 18, 1838, “An Act to Establish the University of Texas” was referred to a special committee of the Texas Congress, but was not reported back for further action. On January 26, 1839, the Texas Congress agreed to set aside fifty leagues of land—approximately 288,000 acres (117,000 ha)—towards the establishment of a publicly funded university. In addition, 40 acres (16 ha) in the new capital of Austin were reserved and designated “College Hill”. (The term “Forty Acres” is colloquially used to refer to the University as a whole. The original 40 acres is the area from Guadalupe to Speedway and 21st Street to 24th Street.)
In 1845, Texas was annexed into the United States. The state’s Constitution of 1845 failed to mention higher education. On February 11, 1858, the Seventh Texas Legislature approved O.B. 102, an act to establish the University of Texas, which set aside $100,000 in United States bonds toward construction of the state’s first publicly funded university (the $100,000 was an allocation from the $10 million the state received pursuant to the Compromise of 1850 and Texas’s relinquishing claims to lands outside its present boundaries). The legislature also designated land reserved for the encouragement of railroad construction toward the university’s endowment. On January 31, 1860, the state legislature, wanting to avoid raising taxes, passed an act authorizing the money set aside for the University of Texas to be used for frontier defense in west Texas to protect settlers from Indian attacks.
Texas’s secession from the Union and the American Civil War delayed repayment of the borrowed monies. At the end of the Civil War in 1865, The University of Texas’s endowment was just over $16,000 in warrants and nothing substantive had been done to organize the university’s operations. This effort to establish a University was again mandated by Article 7, Section 10 of the Texas Constitution of 1876 which directed the legislature to “establish, organize and provide for the maintenance, support and direction of a university of the first class, to be located by a vote of the people of this State, and styled “The University of Texas”.
Additionally, Article 7, Section 11 of the 1876 Constitution established the Permanent University Fund, a sovereign wealth fund managed by the Board of Regents of the University of Texas and dedicated to the maintenance of the university. Because some state legislators perceived an extravagance in the construction of academic buildings of other universities, Article 7, Section 14 of the Constitution expressly prohibited the legislature from using the state’s general revenue to fund construction of university buildings. Funds for constructing university buildings had to come from the university’s endowment or from private gifts to the university, but the university’s operating expenses could come from the state’s general revenues.
The 1876 Constitution also revoked the endowment of the railroad lands of the Act of 1858, but dedicated 1,000,000 acres (400,000 ha) of land, along with other property appropriated for the university, to the Permanent University Fund. This was greatly to the detriment of the university as the lands the Constitution of 1876 granted the university represented less than 5% of the value of the lands granted to the university under the Act of 1858 (the lands close to the railroads were quite valuable, while the lands granted the university were in far west Texas, distant from sources of transportation and water). The more valuable lands reverted to the fund to support general education in the state (the Special School Fund).
On April 10, 1883, the legislature supplemented the Permanent University Fund with another 1,000,000 acres (400,000 ha) of land in west Texas granted to the Texas and Pacific Railroad but returned to the state as seemingly too worthless to even survey. The legislature additionally appropriated $256,272.57 to repay the funds taken from the university in 1860 to pay for frontier defense and for transfers to the state’s General Fund in 1861 and 1862. The 1883 grant of land increased the land in the Permanent University Fund to almost 2.2 million acres. Under the Act of 1858, the university was entitled to just over 1,000 acres (400 ha) of land for every mile of railroad built in the state. Had the 1876 Constitution not revoked the original 1858 grant of land, by 1883, the university lands would have totaled 3.2 million acres, so the 1883 grant was to restore lands taken from the university by the 1876 Constitution, not an act of munificence.
On March 30, 1881, the legislature set forth the university’s structure and organization and called for an election to establish its location. By popular election on September 6, 1881, Austin (with 30,913 votes) was chosen as the site. Galveston, having come in second in the election (with 20,741 votes), was designated the location of the medical department (Houston was third with 12,586 votes). On November 17, 1882, on the original “College Hill,” an official ceremony commemorated the laying of the cornerstone of the Old Main building. University President Ashbel Smith, presiding over the ceremony, prophetically proclaimed “Texas holds embedded in its earth rocks and minerals which now lie idle because unknown, resources of incalculable industrial utility, of wealth and power. Smite the earth, smite the rocks with the rod of knowledge and fountains of unstinted wealth will gush forth.” The University of Texas officially opened its doors on September 15, 1883.
Expansion and growth
In 1890, George Washington Brackenridge donated $18,000 for the construction of a three-story brick mess hall known as Brackenridge Hall (affectionately known as “B.Hall”), one of the university’s most storied buildings and one that played an important place in university life until its demolition in 1952.
The old Victorian-Gothic Main Building served as the central point of the campus’s 40-acre (16 ha) site, and was used for nearly all purposes. But by the 1930s, discussions arose about the need for new library space, and the Main Building was razed in 1934 over the objections of many students and faculty. The modern-day tower and Main Building were constructed in its place.
In 1910, George Washington Brackenridge again displayed his philanthropy, this time donating 500 acres (200 ha) on the Colorado River to the university. A vote by the regents to move the campus to the donated land was met with outrage, and the land has only been used for auxiliary purposes such as graduate student housing. Part of the tract was sold in the late-1990s for luxury housing, and there are controversial proposals to sell the remainder of the tract. The Brackenridge Field Laboratory was established on 82 acres (33 ha) of the land in 1967.
In 1916, Gov. James E. Ferguson became involved in a serious quarrel with the University of Texas. The controversy grew out of the board of regents’ refusal to remove certain faculty members whom the governor found objectionable. When Ferguson found he could not have his way, he vetoed practically the entire appropriation for the university. Without sufficient funding, the university would have been forced to close its doors. In the middle of the controversy, Ferguson’s critics brought to light a number of irregularities on the part of the governor. Eventually, the Texas House of Representatives prepared 21 charges against Ferguson, and the Senate convicted him on 10 of them, including misapplication of public funds and receiving $156,000 from an unnamed source. The Texas Senate removed Ferguson as governor and declared him ineligible to hold office.
In 1921, the legislature appropriated $1.35 million for the purchase of land next to the main campus. However, expansion was hampered by the restriction against using state revenues to fund construction of university buildings as set forth in Article 7, Section 14 of the Constitution. With the completion of Santa Rita No. 1 well and the discovery of oil on university-owned lands in 1923, the university added significantly to its Permanent University Fund. The additional income from Permanent University Fund investments allowed for bond issues in 1931 and 1947, which allowed the legislature to address funding for the university along with the Agricultural and Mechanical College (now known as Texas A&M University). With sufficient funds to finance construction on both campuses, on April 8, 1931, the Forty Second Legislature passed H.B. 368. which dedicated the Agricultural and Mechanical College a 1/3 interest in the Available University Fund, the annual income from Permanent University Fund investments.
The University of Texas was inducted into The Association of American Universities in 1929. During World War II, the University of Texas was one of 131 colleges and universities nationally that took part in the V-12 Navy College Training Program which offered students a path to a Navy commission.
In 1950, following Sweatt v. Painter, the University of Texas was the first major university in the South to accept an African-American student. John S. Chase went on to become the first licensed African-American architect in Texas.
In the fall of 1956, the first black students entered the university’s undergraduate class. Black students were permitted to live in campus dorms, but were barred from campus cafeterias. The University of Texas integrated its facilities and desegregated its dorms in 1965. UT, which had had an open admissions policy, adopted standardized testing for admissions in the mid-1950s at least in part as a conscious strategy to minimize the number of Black undergraduates, given that they were no longer able to simply bar their entry after the Brown decision.
Following growth in enrollment after World War II, the university unveiled an ambitious master plan in 1960 designed for “10 years of growth” that was intended to “boost the University of Texas into the ranks of the top state universities in the nation.” In 1965, the Texas Legislature granted the university Board of Regents to use eminent domain to purchase additional properties surrounding the original 40 acres (160,000 m^2). The university began buying parcels of land to the north, south, and east of the existing campus, particularly in the Blackland neighborhood to the east and the Brackenridge tract to the southeast, in hopes of using the land to relocate the university’s intramural fields, baseball field, tennis courts, and parking lots.
On March 6, 1967, the Sixtieth Texas Legislature changed the university’s official name from “The University of Texas” to “The University of Texas at Austin” to reflect the growth of the University of Texas System.
Recent history
The first presidential library on a university campus was dedicated on May 22, 1971, with former President Johnson, Lady Bird Johnson and then-President Richard Nixon in attendance. Constructed on the eastern side of the main campus, the Lyndon Baines Johnson Library and Museum is one of 13 presidential libraries administered by the National Archives and Records Administration.
A statue of Martin Luther King Jr. was unveiled on campus in 1999 and subsequently vandalized. By 2004, John Butler, a professor at the McCombs School of Business suggested moving it to Morehouse College, a historically black college, “a place where he is loved”.
The University of Texas-Austin has experienced a wave of new construction recently with several significant buildings. On April 30, 2006, the school opened the Blanton Museum of Art. In August 2008, the AT&T Executive Education and Conference Center opened, with the hotel and conference center forming part of a new gateway to the university. Also in 2008, Darrell K Royal-Texas Memorial Stadium was expanded to a seating capacity of 100,119, making it the largest stadium (by capacity) in the state of Texas at the time.
The University of Texas-Austin is the home of
The Texas Advanced Computing Center
On January 19, 2011, the university announced the creation of a 24-hour television network in partnership with ESPN, dubbed the Longhorn Network. ESPN agreed to pay a $300 million guaranteed rights fee over 20 years to the university and to IMG College, the school’s multimedia rights partner. The network covers the university’s intercollegiate athletics, music, cultural arts, and academics programs. The channel first aired in September 2011.
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