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 arcnot equal to Cascade Range

Newberry Volcano Sited at the Intersection of the Cascadesand the High Lava Plains Magmatic Province

Oregon

Idaho

Montana

Wyoming

Nevada

CaliforniaUtah

Arizona

WashingtonBasalt

Andesite

DaciteRhyolite

< 5 5-10 10-17 Ma

Colored Regions Show Volcanic Deposits Younger than 17 Million Years (Smith and Luedke, 1984)South Sister, Oregon

Diamond Craters

Cascades

Newberry

ThreeSisters

Newberry margin

Newberry edifice

Newberry lavascover ~3000 km2

For comparison,MSH

10 m DEMFocused onNewberry Caldera

view from Paulina Peak

At least 3 calderas, 300 ka - 80 ka

View of Paulina Peak from Paulina Lake

Highest point on caldera rim is Paulina Peak atnearly 8000 ft.,~4000 ft. higherthan surroundingterrain

Slide courtesy of Mike Poland

Medicine Lake volcano

Newberry Volcano

Newberry Volcano

Medicine Lake volcano

Geologic Map of Newberry VolcanoBy MacLeod, Sherrod,Chitwood, & Jensen

Qba

Scanned map courtesy of Templeton, Taylor, Giles,& Rowe (WOU, OSU)

~35 mapped Newberry units

field assistant

& Mazama

Field challenges --

& lots of similar rocks

The Subduction Contribution

87Sr/86Sr = 0.70317187Os/188Os = 0.1518

87Sr/86Sr = 0.70382187Os/188Os = 0.1922

Sr = 1124 ppm

Sr = 300 ppm

~4% H2O

(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

than HLP rhyolites

Newberry rhyolites are lower in SiO2

Newberry Volcano

• 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

Tectonic settingOf Newberry:interaction of tectonism and volcanism akey feature

High Lava Plains

Crater Lake

Mt. Jefferson

WVF

From Donnelly-Nolan et al., JVGR 2008

Fore-arc, arc axis, & rear-arc volcanoes

Behind-the-arc Quaternaryvolcanism

Interpretation:

Preliminary version of Newberry geologic mapping will be ondisplay 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