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Mars Volcano, Earth's Dinosaurs Went Extinct About the Same Time
Jet Propulsion Laboratory
March 20, 2017

New NASA research reveals that the giant Martian volcano Arsia Mons produced one new lava flow at its summit every 1 to 3 million years during the
final peak of activity. The last volcanic activity there ceased about
50 million years ago -- around the time of Earth's Cretaceous-Paleogene extinction, when large numbers of our planet's plant and animal species (including dinosaurs) went extinct.

Located just south of Mars' equator, Arsia Mons is the southernmost member
of a trio of broad, gently sloping shield volcanoes collectively known
as Tharsis Montes. Arsia Mons was built up over billions of years, though
the details of its lifecycle are still being worked out. The most recent volcanic activity is thought to have taken place in the caldera-the bowl-shaped

depression at the top -- where 29 volcanic vents have been identified.
Until now, it's been difficult to make a precise estimate of when this volcanic field was active.

"We estimate that the peak activity for the volcanic field at the summit
of Arsia Mons probably occurred approximately 150 million years ago --
the late Jurassic period on Earth -- and then died out around the same
time as Earth's dinosaurs," said Jacob Richardson, a postdoctoral researcher at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "It's possible, though, that the last volcanic vent or two might have been active in the
past 50 million years, which is very recent in geological terms."

Richardson is presenting the findings on March 20, 2017, at the Lunar
and Planetary Science Conference in The Woodlands, Texas. The study also
is published in Earth and Planetary Science Letters.

Measuring about 68 miles (110 kilometers) across, the caldera is deep
enough to hold the entire volume of water in Lake Huron, and then some. Examining the volcanic features within the caldera required high-resolution imaging, which the researchers obtained from the Context Camera on NASA's
Mars Reconnaissance Orbiter.

The team mapped the boundaries of the lava flows from each of the 29 volcanic vents and determined the stratigraphy, or layering, of the flows. The researchers also performed a technique called crater counting -- tallying
up the number of craters at least 330 feet (100 meters) in diameter --
to estimate the ages of the flows.

Using a new computer model developed by Richardson and his colleagues
at the University of South Florida, the two types of information were
combined to determine the volcanic equivalent of a batting order for Arsia Mons' 29 vents. The oldest flows date back about 200 million years. The youngest flows probably occurred 10 to 90 million years ago -- most likely around 50 million years ago.

The modeling also yielded estimates of the volume flux for each lava flow.
At their peak about 150 million years ago, the vents in the Arsia Mons' caldera probably collectively produced about 0.25 to 2 cubic miles (1
to 8 cubic kilometers) of magma every million years, slowly adding to
the volcano's size.

"Think of it like a slow, leaky faucet of magma," said Richardson. "Arsia
Mons was creating about one volcanic vent every 1 to 3 million years at
the peak, compared to one every 10,000 years or so in similar regions
on Earth."

A better understanding of when volcanic activity on Mars took place is important because it helps researchers understand the Red Planet's history
and interior structure.

"A major goal of the Mars volcanology community is to understand the anatomy and lifecycle of the planet's volcanoes. Mars' volcanoes show evidence
for activity over a larger time span than those on Earth, but their histories of magma production might be quite different," said Jacob Bleacher, a planetary geologist at Goddard and a co-author on the study. "This study
gives us another clue about how activity at Arsia Mons tailed off and
the huge volcano became quiet."

Malin Space Science Systems, San Diego, built and operates the Context
Camera. NASA's Jet Propulsion Laboratory, Pasadena, manages the Mars Reconnaissance
Orbiter for NASA's Science Mission Directorate, Washington. For more information
about NASA missions investigating Mars, visit:

https://mars.nasa.gov/

News Media Contact
Elizabeth Zubritsky
Goddard Space Flight Center, Greenbelt, Md.
301-614-5438
elizabeth.a.zubritsky@nasa.gov

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
guy.webster@jpl.nasa.gov

Laurie Cantillo / Dwayne Brown
NASA Headquarters, Washington
202-358-1077 / 202-358-1726
laura.l.cantillo@nasa.gov / dwayne.c.brown@nasa.gov

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