Department of the GeoPhysical Sciences

Geophysical Science News

• A new study from University of Chicago’s Sunny Park suggests there may be a layer of surprisingly fluid rock ringing the Earth, at the very bottom of the upper mantle.

  February 24, 2023

  The finding was made by measuring the lingering movement registered by GPS sensors on islands in the wake of a deep earthquake in the Pacific Ocean near Fiji. Published Feb. 22 in Nature, the study demonstrates a new method to measure the fluidity of the Earth’s mantle.

  “Even though the mantle makes up the largest part of Earth, there’s still a lot we don’t know about it,” said Sunyoung Park, a geophysicist with the University of Chicago and the lead author on the study. “We think there’s a lot more we can learn by using these deep earthquakes as a way to probe these questions.”

  By examining how the Earth deformed over time, they found evidence of a layer about 50-miles thick that is less viscous (that is, “runnier”) than the rest of the mantle, sitting at the bottom of the upper mantle layer. They think this layer may extend around the entire globe.

  Here is the article posted in Nature.

  And it's also a good read over at UChicago News.

• Maria Valdes Will Study Sample of 17-Pound Meteorite Discovered in Antarctica

  February 23, 2023

  The rare meteorite is about the size of a cantaloupe but weighs a hefty 17 pounds. The specimen is one of only about 100 that size or larger discovered in Antarctica, a prime meteorite-hunting location where more than 45,000 space rocks have been tracked down.

  Now, the exceptional find is heading to the Royal Belgian Institute of Natural Sciences in Brussels, where it will be studied. And Maria Valdes, a research scientist at Chicago’s Field Museum of Natural History and the University of Chicago who was part of the expedition team, has kept some of the material for her own analysis.

  Valdes’ area of focus is cosmochemistry. That “broadly means that we use meteorites to study the origin and evolution of the solar system through chemical methods,” she told CNN. She’ll take her samples and use strong acids to dissolve them before using a process called calibrated chemistry to isolate various elements that make up the rock.

  “Then I can start to think about the origin of this rock, how it evolved over time, what kind of parent body it came from, and where in the solar system that parent body formed,” Valdes said. “Those are kind of the big questions that we try to address.”

  Read the full article here

  AND listen to this brief fascinating NPR interview about finding the meteorite

• Prof. David Jablonski study shows surprising patterns of evolution of clams that can bore into solid rock

  February 17, 2023

  There are lots of ways to make a living as a clam, but probably one of the strangest is to be a “living drill bit.” Some species of clams are able to bore into solid rock or concrete—creating a burrow in a substance that is harder than their own shells.

  For years, Jablonski’s lab has studied bivalves – the category that includes all clams, such as scallops, mussels, and cockles -- as a way to understand the evolution of species over time, uncovering clues about the forces that shape bodies and lifestyles over time.

  The scientists also noticed something odd about the patterns of evolution. The borer lifestyle occurs throughout nearly the entire span of bivalve history—the first borers appeared nearly 450 million years ago—but no species has ever taken off afterward.

  “Instead, they tend to originate and then peter out, or at least never do anything special in terms of diversity, each time,” said Jablonski.

  Normally, explained Jablonski, when an organism evolves some new advantage, the number of species tends to rise dramatically, sometimes explosively. “Birds evolve flight, and they take off, so to speak,” he said. “We think this process results in much of the evolutionary diversity we see around us.”

  Learn more here

• Prof. Edwin Kite is part of a team investigating “false positives” for life on exoplanets

  February 01, 2023

  Those worlds, like Earth, are both rocky and found in their stars' habitable zones—where life as we know it could plausibly evolve and might produce atmospheric gasses that could be detected using space telescopes.

  "As the research community has come up with models for abiotic origins of gases that could mimic biosignatures, we've really focused on source processes that could operate on Earth-like worlds," says Kite. "However, habitable-zone rocky exoplanets could have compositions and processes dramatically different from Earth. We want to consider a wider range of possible abiotic methane sources to make sure we don't get fooled by 'trickster' planets that emit false positive biosignatures."

  "We don’t know much about the origin of life nor about how life is distributed in the universe," says Kite. "If the scientific community is to make a claim that alien life has been discovered through biosignature detection, it is our responsibility to ensure that we've thought long and hard about all the ways biosignatures could in fact be abiotic geosignatures."

  Get some extra (terrestrial) credit and read the whole article here!