Transcript What is Newberry Volcano?

What is Newberry Volcano?
Julie Donnelly-Nolan, USGS Menlo Park CA,
Tim Grove, MIT, & Rick Carlson, Carnegie Institution
View of Newberry edifice from the northeast
view south of the Newberry edifice from Bend, Oregon
Cascades or not?
High Lava Plains volcano?
Is it a volcanic field, not a volcano?
Cascades arc
not equal to
Cascade Range
Newberry Volcano Sited at the Intersection of the Cascades
and the High Lava Plains Magmatic Province
Colored Regions Show Volcanic Deposits Younger than 17 Million Years
(Smith and Luedke, 1984)
South Sister, Oregon
Washington
< 5 5-10 10-17 Ma
Basalt
Andesite
Rhyolite
Dacite
Montana
Idaho
Oregon
Wyoming
Cascades
California
Utah
Nevada
Diamond Craters
Arizona
Newberry
Newberry margin
Three
Sisters
Newberry edifice
Newberry lavas
cover ~3000 km2
For comparison,
MSH
10 m DEM
Focused on
Newberry Caldera
view from Paulina Peak
At least 3 calderas, 300 ka - 80 ka
Highest point on
caldera rim is
Paulina Peak at
nearly 8000 ft.,
~4000 ft. higher
than surrounding
terrain
View of Paulina Peak from Paulina Lake
Newberry Volcano
Medicine Lake volcano
Slide courtesy of Mike Poland
Newberry Volcano
Medicine Lake volcano
Geologic Map of
Newberry Volcano
By MacLeod, Sherrod,
Chitwood, & Jensen
Qba
~35 mapped Newberry
units
Scanned map courtesy of
Templeton, Taylor, Giles,
& Rowe (WOU, OSU)
Field challenges --
field
assistant
& Mazama
& lots of similar rocks
The Subduction Contribution
Sr = 1124 ppm
~4% H2O
Sr = 300 ppm
87Sr/86Sr
= 0.70317
= 0.1518
187Os/188Os
87Sr/86Sr
= 0.70382
= 0.1922
187Os/188Os
(Carlson data)
(Carlson isotope data)
What is the “Subduction Component”?
(Carlson data)
He isotope data
Graham, et al.
JVGR 2009
NV
Grove et al. model
WVF
Figure adapted from B. Jordan PhD thesis
Newberry rhyolites are lower in SiO2
than HLP rhyolites
Newberry Volcano
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A subduction-related volcano, not an HLP volcano
Calc-alkaline basalts as well as HAOT-type basalts
Is isotopically like Cascades lavas
Lies behind the arc axis = rear-arc volcano
Extensional terrain; strong magmatic focus
Edifice with central caldera eruptions; not a volcanic field
Mt. Jefferson
Tectonic setting
Of Newberry:
interaction of
tectonism and
volcanism a
key feature
WVF
High Lava Plains
Crater Lake
Interpretation:
Fore-arc, arc axis, & rear-arc
volcanoes
Behind-the-arc Quaternary
volcanism
From Donnelly-Nolan et al., JVGR 2008
Preliminary version of Newberry geologic mapping will be on
display Monday at poster booth 288
View of Newberry edifice from the southeast
Acknowledgments: with thanks to Robert Jensen, Dave Ramsey, Duane Champion,
Andy Calvert, Marvin Lanphere, Larry Chitwood