1. Concentrating the Slab Fluid Input to Newberry Volcano, Oregon Goldschmidt 2008 Richard W. Carlson DTM, Carnegie Institution of Washington Timothy L. Grove EAPS, Massachusetts Institute of Technology Julie M. Donnelly-Nolan USGS, Menlo Park

2. 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 Diamond Craters Cascades Newberry

3. Calc-Alkaline vs. Fe-Enrichment, both Occur at Newberry Hawaii, Juan de Fuca, Cascade and HLP data from EarthChem

4. A Subduction Signature in Both Newberry and HLP Basalts (but only some!) Hawaii, Juan de Fuca, Cascade and HLP data from EarthChem

5. The Subduction Contribution 87Sr/86Sr = 0.70317 187Os/188Os = 0.1518 87Sr/86Sr = 0.70382 187Os/188Os = 0.1922

6. What is the “Subduction Component”? Hawaii, Juan de Fuca, Cascade and HLP data from EarthChem

7. What is the “Subduction Component”? Hawaii, Juan de Fuca, Cascade and HLP data from EarthChem

8. What is the “Subduction Component”? Hawaii, Juan de Fuca, Cascade and HLP data from EarthChem

9. How is the Subduction Signature Distributed Spatially? Ba/Nb 0 - 25 25 - 50 50 - 75 75 - 150 150 - 300 Newberry Primitive HAOT HLP Basalt Cascade Basalt Cascade and HLP data from EarthChem

10. How is the Subduction Signature Distributed Spatially? Ba/Nb 0 - 25 25 - 50 50 - 75 75 - 150 150 - 300 Newberry Primitive HAOT HLP Basalt Cascade Basalt Cascade and HLP data from EarthChem

11. Is Newberry a Cascade or HLP volcano?

12. P-Wave Velocity 125 km Depth, Roth et al. GRL, on line Graphic by Lyn Topinka, 1996 Vulcan.wr.usgs.gov/Volcanoes/ Oregon/Grpahics/framework.html

13. After Kincaid and Griffiths, G3, 2004 Why is Activity Focused at Newberry and along the HLP? A consequence of slab rollback and flow around the southern edge of the Juan-de-Fuca Down-dip subduction, No behind arc activity Slab steepening Trench parallel rear arc volcanism Plus edge flow Trench perpendicular rear arc volcanism

14. Conclusions: 1.Newberry primitive basalts include both calc-alkaline and tholeitic-trend lavas. Slab components (high Ba/Nb) strongly focused to center of Newberry shield. 2.Slab component has Pb isotopic characteristics similar to Pacific Northwest offshore sediments. 1% or less by mass of sediment plus mantle can explain isotope variation. 3.Newberry is underlain by a very local region of low seismic velocity. Implies presence of melt and/or fluid. 4.Westward propagating HLP magmatic trace with current point-source focus at Newberry consistent with wedge flow induced by steepening dip and flow around southern edge of the subducting Juan de Fuca plate.