Climate prompts change at Rice

Martha Lou Broussard Wins Prestigious AAPG Award

Martha Lou Broussard

Martha Lou Broussard is this year’s recipient of the AAPG Halbouty Outstanding Leadership Award, a very high honor. Martha Lou has played a key role in the success of AAPG and our own EEPS.  She was the first woman to graduate from our department. She played key roles in AAPG and established the AAPG student expo, which is now the primary way the energy industry recruits students. Today, she continues to help our department stay in touch with alumni and help our students in professional development and networking. Under the Broussard fellowship, she continues to support and foster the careers of women in earth sciences.

We are lucky to have Martha Lou!
-Cin-Ty Lee

Breathing? Thank volcanoes, tectonics and bacteria

– DECEMBER 2, 2019

Study points to one cause for several mysteries linked to breathable oxygen

Earth’s breathable atmosphere is key for life, and a new study suggests that the first burst of oxygen was added by a spate of volcanic eruptions brought about by tectonics.

The evolution of life as depicted in a mural at NASA Ames Research Center in Mountain View, California.

The evolution of life as depicted in a mural at NASA Ames Research Center in Mountain View, California. The rise of oxygen from a trace element to a primary atmospheric component was an important evolutionary development. (Courtesy of NASA Ames/David J. Des Marais/Thomas W. Scattergood/Linda L. Jahnke)

The study by geoscientists at Rice University offers a new theory to help explain the appearance of significant concentrations of oxygen in Earth’s atmosphere about 2.5 billion years ago, something scientists call the Great Oxidation Event (GOE). The research appears this week in Nature Geoscience.

“What makes this unique is that it’s not just trying to explain the rise of oxygen,” said study lead author James Eguchi, a NASA postdoctoral fellow at the University of California, Riverside who conducted the work for his Ph.D. dissertation at Rice. “It’s also trying to explain some closely associated surface geochemistry, a change in the composition of carbon isotopes, that is observed in the carbonate rock record a relatively short time after the oxidation event. We’re trying explain each of those with a single mechanism that involves the deep Earth interior, tectonics and enhanced degassing of carbon dioxide from volcanoes.”

Eguchi’s co-authors are Rajdeep Dasgupta, an experimental and theoretical geochemist and professor in Rice’s Department of Earth, Environmental and Planetary Sciences, and Johnny Seales, a Rice graduate student who helped with the model calculations that validated the new theory.

Scientists have long pointed to photosynthesis — a process that produces waste oxygen — as a likely source for increased oxygen during the GOE. Dasgupta said the new theory doesn’t discount the role that the first photosynthetic organisms, cyanobacteria, played in the GOE.

James Eguchi, Johnny Seales and Rajdeep Dasgupta

Geoscientists (from left) James Eguchi, Johnny Seales and Rajdeep Dasgupta published a new theory that attempts to explain the first appearance of significant concentrations of oxygen in Earth’s atmosphere about 2.5 billion years ago as well as a puzzling shift in the ratio of carbon isotopes in carbonate minerals that followed. (Photos courtesy of Rice University)

“Most people think the rise of oxygen was linked to cyanobacteria, and they are not wrong,” he said. “The emergence of photosynthetic organisms could release oxygen. But the most important question is whether the timing of that emergence lines up with the timing of the Great Oxidation Event. As it turns out, they do not.”

Cyanobacteria were alive on Earth as much as 500 million years before the GOE. While a number of theories have been offered to explain why it might have taken that long for oxygen to show up in the atmosphere, Dasgupta said he’s not aware of any that have simultaneously tried to explain a marked change in the ratio of carbon isotopes in carbonate minerals that began about 100 million years after the GOE. Geologists refer to this as the Lomagundi Event, and it lasted several hundred million years.

One in a hundred carbon atoms are the isotope carbon-13, and the other 99 are carbon-12. This 1-to-99 ratio is well documented in carbonates that formed before and after Lomagundi, but those formed during the event have about 10% more carbon-13.

Eguchi said the explosion in cyanobacteria associated with the GOE has long been viewed as playing a role in Lomagundi.

“Cyanobacteria prefer to take carbon-12 relative to carbon-13,” he said. “So when you start producing more organic carbon, or cyanobacteria, then the reservoir from which the carbonates are being produced is depleted in carbon-12.”

Eguchi said people tried using this to explain Lomagundi, but timing was again a problem.

A figure that illustrates how inorganic carbon cycles through the mantle more quickly than organic carbon, which contains very little of the isotope carbon-13.

This figure illustrates how inorganic carbon cycles through the mantle more quickly than organic carbon, which contains very little of the isotope carbon-13. Both inorganic and organic carbon are drawn into Earth’s mantle at subduction zones (top left). Due to different chemical behaviors, inorganic carbon tends to return through eruptions at arc volcanoes above the subduction zone (center). Organic carbon follows a longer route, as it is drawn deep into the mantle (bottom) and returns through ocean island volcanos (right). The differences in recycling times, in combination with increased volcanism, can explain isotopic carbon signatures from rocks that are associated with both the Great Oxidation Event, about 2.4 billion years ago, and the Lomagundi Event that followed. (Image by J. Eguchi/University of California, Riverside)

“When you actually look at the geologic record, the increase in the carbon-13-to-carbon-12 ratio actually occurs up to 10s of millions of years after oxygen rose,” he said. “So then it becomes difficult to explain these two events through a change in the ratio of organic carbon to carbonate.”

The scenario Eguchi, Dasgupta and Seales arrived at to explain all of these factors is:

  • A dramatic increase in tectonic activity led to the formation of hundreds of volcanoes that spewed carbon dioxide into the atmosphere.
  • The climate warmed, increasing rainfall, which in turn increased “weathering,” the chemical breakdown of rocky minerals on Earth’s barren continents.
  • Weathering produced a mineral-rich runoff that poured into the oceans, supporting a boom in both cyanobacteria and carbonates.
  • The organic and inorganic carbon from these wound up on the seafloor and was eventually recycled back into Earth’s mantle at subduction zones, where oceanic plates are dragged beneath continents.
  • When sediments remelted into the mantle, inorganic carbon, hosted in carbonates, tended to be released early, re-entering the atmosphere through arc volcanoes directly above subduction zones.
  • Organic carbon, which contained very little carbon-13, was drawn deep into the mantle and emerged hundreds of millions of years later as carbon dioxide from island hotspot volcanoes like Hawaii.

“It’s kind of a big cyclic process,” Eguchi said. “We do think the amount of cyanobacteria increased around 2.4 billion years ago. So that would drive our oxygen increase. But the increase of cyanobacteria is balanced by the increase of carbonates. So that carbon-12-to-carbon-13 ratio doesn’t change until both the carbonates and organic carbon, from cyanobacteria, get subducted deep into the Earth. When they do, geochemistry comes into play, causing these two forms of carbon to reside in the mantle for different periods of time. Carbonates are much more easily released in magmas and are released back to the surface at a very short period. Lomagundi starts when the first carbon-13-enriched carbon from carbonates returns to the surface, and it ends when the carbon-12-enriched organic carbon returns much later, rebalancing the ratio.”

Eguchi said the study emphasizes the importance of the role that deep Earth processes can play in the evolution of life at the surface.

Earth's atmosphere as seen from the International Space Station July 20, 2006

Earth’s atmosphere as seen from the International Space Station July 20, 2006. (Image courtesy of NASA)

“We’re proposing that carbon dioxide emissions were very important to this proliferation of life,” he said. “It’s really trying to tie in how these deeper processes have affected surface life on our planet in the past.”

Dasgupta is also the principal investigator on a NASA-funded effort called CLEVER Planets that is exploring how life-essential elements might come together on distant exoplanets. He said better understanding how Earth became habitable is important for studying habitability and its evolution on distant worlds.

“It looks like Earth’s history is calling for tectonics to play a big role in habitability, but that doesn’t necessarily mean that tectonics is absolutely necessary for oxygen build up,” he said. “There might be other ways of building and sustaining oxygen, and exploring those is one of the things we’re trying to do in CLEVER Planets.”

The research was supported by the National Science Foundation, NASA and the Deep Carbon Observatory.

Telecom cables offer undersea seismic-sensing bonanza

– NOVEMBER 28, 2019

Cutting-edge tech comes to new Rice lab on heels of Science study

Undersea telecommunications cables that connect the continents may help measure earthquakes and detect other seismic events, according to a newly published paper based on research conducted by a Rice University professor and his colleagues.

But proof that the technique works might not have happened without some arduous ditch-digging.

Jonathan Ajo-Franklin

Jonathan Ajo-Franklin

Scientists led by University of California, Berkeley, graduate student Nate Lindsey and Rice geophysicist Jonathan Ajo-Franklin confirmed that telecommunication cables may be useful to collect seismic readings from the seafloor and at great distances.

Their high-profile paper in this week’s Science serves as a nice homecoming for Ajo-Franklin, a 1998 Rice alumnus (Brown College) who rejoined the university this summer as a professor of Earth, environmental and planetary sciences. (A separate article in the issue further describes the research.)

Ajo-Franklin comes to Rice from his position as a staff scientist at Lawrence Berkeley National Laboratory (LBNL), where he and Lindsey, a National Science Foundation graduate research fellow, led an experiment that turned 20 kilometers of fiber-optic cable into the equivalent of 10,000 seismic stations along the ocean floor. The fiber was made available by the Monterey Bay Aquarium Research Institute (MBARI) and co-author Craig Dawe.

During a four-day experiment in Monterey Bay, they recorded a 3.5 magnitude quake and seismic scattering from underwater fault zones using a technique called distributed acoustic sensing (DAS).

DAS employs a photonic device that sends short pulses of laser light down the cable and detects backscattering created by strain in the cable caused by stretching. With interferometry, used to decode interference between the returning signals, they measured the strain signals every 2 meters (6 feet), effectively turning a 20-kilometer cable into 10,000 individual motion sensors.

Researchers had previously confirmed DAS with land-based “dark” fibers, optical fibers buried underground but unused or leased for short-term use, unlike “lit” internet fibers. The latest advance could significantly advance scientists’ reach.

The technique was inspired by a study that led Ajo-Franklin and Lindsey to Fairbanks, Alaska, five years ago. “It involved laying fibers and using ambient noise to detect zones of permafrost thaw in the Arctic,” Ajo-Franklin said. “It was a backbreaking effort to get the fibers in the ground.

“I remember we had a long conversation; like, ‘We know there are fibers in the ground already for telecom,’” he said. “We thought, ‘What if we use those instead of digging these kilometer-long trenches?’ That was the genesis of the idea.”

Ajo-Franklin said the new study is “on the frontier of seismology, the first time anyone has used offshore fiber-optic cables for looking at these types of oceanographic signals or for imaging fault structures. One of the blank spots in the seismographic network worldwide is in the oceans.”

Researchers piggybacked on a fiber-optic telecommunications cable to sense seismic activity in Monterey Bay, turning 20 kilometers of cable (in pink) into the equivalent of 10,000 seismic stations along the ocean floor. The cable is normally used to communicate with an off-shore science node (the Monterey Accelerated Research System, or MARS). During a four-day test, scientists detected a magnitude 3.5 earthquake 45 kilometers away in Gilroy, California, and mapped previously uncharted fault zones (yellow circle). Illustration by Nate Lindsey

Researchers piggybacked on a fiber-optic telecommunications cable to sense seismic activity in Monterey Bay, turning 20 kilometers of cable (pink) into the equivalent of 10,000 seismic stations along the ocean floor. The cable is normally used to communicate with an off-shore science node (the Monterey Accelerated Research System, or MARS). During a four-day test, scientists detected a magnitude 3.5 earthquake 45 kilometers away in Gilroy, California, and mapped previously uncharted fault zones (yellow circle). Illustration by Nate Lindsey

The ultimate goal, he said, is to use the dense fiber-optic networks around the world — probably more than 10 million kilometers in all, on both land and under the sea — as sensitive measures of Earth’s movement, allowing earthquake monitoring in regions that don’t have expensive ground stations like those that dot much of earthquake-prone California and the Pacific Coast.

“The existing seismic network tends to have high-precision instruments, but is relatively sparse, whereas this gives you access to a much denser array,” Ajo-Franklin said. “These systems are sensitive to changes of nanometers to hundreds of picometers for every meter of length. That is a one-part-in-a-billion change.”

“The beauty of fiber-optic seismology is that you can use existing telecommunications cables without having to put out 10,000 seismometers,” Lindsey said. “You just walk out to the site and connect the instrument to the end of the fiber.”

During the underwater test, according to a University of California, Berkeley, press release, the technique allowed the researchers to measure a broad range of frequencies of seismic waves from a magnitude 3.4 earthquake that occurred 45 kilometers inland near Gilroy, California, and map multiple known and previously unmapped submarine fault zones, part of the San Gregorio Fault system. They also were able to detect steady-state ocean waves — so-called ocean microseisms — as well as storm waves, all of which matched buoy and land seismic measurements.

Ajo-Franklin plans to next test fiber-optic monitoring of seismic events in a geothermal area south of Southern California’s Salton Sea. This work, partnering with LBNL where Ajo-Franklin remains a faculty scientist, will also evaluate temperature profiling using the same network.

“We’re going to do seismic imaging over an active geothermal zone there to see if we can identify the faults that provide fluids to deep reservoirs,” he said. “It’s a dark fiber project where we’re planning to utilize fiber owned by a telecom company.”

Some of that work will come to his new lab, Ajo-Franklin said. “We just purchased a DAS box for Rice and will have a facility to test cables and try different installations and special environments,” he said. “And we’ll use this technology in field deployments around the world in places that are seismically interesting or have structural imaging targets.”

Though southeast Texas lacks the seismic activity that characterizes regions around fault zones, Ajo-Franklin plans to take full advantage of benefits he sees in the local environment.

“If you’re interested in ambient noise imaging, this is actually a good place to be,” he said. “We work a lot on what’s called ambient noise seismology, using all the random noises propagating through the Earth. If you do a bit of signal processing, you get something that looks like an active-source seismic section.”

He said DAS could be used to measure the effects of hydraulic fracturing for oil production, as well as wave action in the Gulf of Mexico and local hydrogeologic processes.

The research was funded by the U.S. Department of Energy, the National Science Foundation, and the David and Lucile Packard Foundation.

Richard Gordon, W.M. Keck Professor of Earth, Environmental and Planetary Sciences is elected AAAS fellow

– NOVEMBER 26, 2019

Richard Gordon is honored by scientific society

Rice geophysicist Richard Gordon

Richard Gordon

AAAS fellows are elected by their peers, and Gordon and Miranda are among 443 new fellows announced this week by the 120,000-member association. Fellows are selected for scientifically or socially distinguished efforts to advance science or its applications.

Gordon, the W.M. Keck Professor of Earth, Environmental and Planetary Sciences, was selected “for distinguished contributions to the fields of tectonic geophysics and geodesy through forefront research on diffuse oceanic plate boundaries and true polar wander.”

Gordon joined Rice in 1995 and studies the movement and deformation of tectonic plates, the patterns those movements leave in the paleogeographic record and the geophysical consequences of tectonic motions and deformation, including earthquakes, the building of mountain ranges and the evolution of ocean basins. He has discovered and investigated a number of diffuse boundaries that separate distinct tectonic plates in the oceans, and his investigations of “true” polar wander, instances when Earth shifted relative to its spin axis, have helped explain puzzling features of the paleomagnetic record. Gordon’s many honors include the American Geophysical Union’s Macelwane Medal in 1989 and the Geological Society of America’s Day Medal in 2002.

The 2019 AAAS Fellows will be acknowledged in the Nov. 29 issue of Science and honored at a Feb. 15 ceremony at the 2020 AAAS annual meeting in Seattle.

Two EEPS graduate students awarded NASA FINESST grants

CLEVER Planets Rajdeep Dasgupta publishes a book on carbon

By Mejs Hasan
Clever Planets Website, Education & Outreach Coordinator

One of the main tasks of CLEVER Planets is to study how elements like carbon, hydrogen, oxygen, and others ended up on Earth. And not just ended up on Earth, but in places on Earth where they could be accessed by emerging life-forms that must have them (i.e., not buried deeply beneath the surface.)

Now, CLEVER Planets researchers have helped to write “Deep carbon: Past to present“, a book that “offers a critical summary” of what is known about deep carbon. “Deep” carbon refers to buried carbon. It may be buried, but scientists are discovering that deep carbon still has a large impact on oceans, the atmosphere, and life on the surface of the planet.

The new book delves into topics like: how much deep carbon is there? Where does it come from and how does it affect the global carbon cycle? These are questions that 1200 members of the global Deep Carbon Observatory have been wrestling with over the last 10  years.

The book will be available in hardback form in December, but you can read it on-line for free right now. It is 670 pages long in total.

The book was co-edited by Rajdeep Dasgupta, the head of CLEVER Planets research.

Dasgupta and his student Daman Grewal also wrote the second chapter in the book: “Origin and early differentiation of carbon and associated life-essential volatile elements on Earth.”

A quartet of CLEVER Planets co-investigators, post-docs, and collaborators also wrote chapter 11: “A framework for understanding whole Earth carbon cycling.”​

 


More information:

This is an Open Access publication

The ‘universal break-up criterion’ of hot, flowing lava

– AUGUST 30, 2019

Thomas Jones’ “universal break-up criterion” won’t help with meltdowns of the heart, but it will help volcanologists study changing lava conditions in common volcanic eruptions.

Thomas Jones

Thomas Jones is a Rice Academy Postdoctoral Fellow in Rice University’s Department of Earth, Environmental and Planetary Sciences. (Photo courtesy of T. Jones)

Jones, of Rice University, studies the behavior of low-viscosity lava, the runny kind that’s found at most volcanoes. About two years ago, he began a series of lab experiments and field observations that provided the raw inputs for a new fluid dynamic model of lava break-up. The work is described in a paper in Nature Communications.

Low-viscosity lava is the red-hot, flowing type one might see at Hawaii’s famed Kilauea volcano, and Jones said it usually behaves in one of two ways.

“It can bubble or spew out, breaking into chunks that spatter about the vent, or it can flow smoothly, forming lava streams that can rapidly move downhill,” he said.

But that behavior can sometimes change quickly during the course of an eruption, and so can the associated dangers: While spattering eruptions throw hot lava fragments into the air, lava flows can threaten to destroy whole neighborhoods and towns.

Jones’ model, the first of its kind, allows scientists to calculate when an eruption will transition from a spattering spray to a flowing stream, based upon the liquid properties of the lava itself and the eruption conditions at the vent.

USGS photo of Kilauea lava fountain

Lava fountains at Kilauea in Hawaii created a spatter cone, which was estimated to be 180 feet tall in this June 2018 photo. (Image courtesy of U.S. Geological Survey)

Jones said additional work is needed to refine the tool, and he looks forward to doing some of it himself.

“We will validate this by going to an active volcano, taking some high-speed videos and seeing when things break apart and under what conditions,” he said. “We also plan to look at the effect of adding bubbles and crystals, because real magmas aren’t as simple as the idealized liquid in our mathematical model. Real magmas can also have bubbles and crystals in them. I’m sure those will change things. We want to find out how.”

Jones said pairing the new model with real-time information about a lava’s liquid properties and eruption conditions could allow emergency officials to predict when an eruption will change style and become a hazard to at-risk communities.

flowing lava on Kilauea in Hawaii in 2018

Lava from a fountain on Hawaii’s Kilauea volcano flows over a spillway into an established channel in June 2018. (Image courtesy of U.S. Geological Survey)

“We want to use this as a forecasting tool for eruption behavior,” he said. “By developing a model of what’s happening in the subsurface we can then watch for indications that it’s about to cross the tipping point and change behavior.”

Jones is a Rice Academy Postdoctoral Fellow in the Department of Earth, Environmental and Planetary Sciences and can be followed on Twitter @Thomas_JJones.

The study was co-authored by C.D. Reynolds of the University of Birmingham in the United Kingdom and S.C. Boothroyd of Durham University, also in the UK. The research was supported by the UK’s National Environment Research Council and Rice University.

Cin-Ty Lee

Cin-Ty Lee awarded 2019 Fellow of the Geochemical Society

2019 Paul W. Gast Lecture Honoree: Caroline Masiello