A field guide to Newberry Volcano, Oregon

Jensen, Robert A.; Donnelly‐Nolan, Julie M.; McKay, D.

doi:10.1130/2009.fld015(03)

Cited by 13 publications

(11 citation statements)

References 18 publications

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“…It exhibits bimodal volcanism with predominantly felsic, caldera-centered eruptions, and mostly mafic flank eruptions. Its dimensions are roughly 60 km by 30 km north-south and east-west, respectively, and it covers an area of 1300 km 2 with a total eruptive volume of 500 km 3 [Jensen et al, 2009;MacLeod et al, 1995]. In contrast to the edifice of the volcano, which is elongate in the north-south direction, the caldera is elongated in the east-west direction, with dimensions of about 7 km by 5 km east-west and north-south, respectively [MacLeod and Sherrod, 1988].…”

Section: Geologic Settingmentioning

confidence: 99%

Imaging the magmatic system of Newberry Volcano using joint active source and teleseismic tomography

Heath

Hooft

Toomey

et al. 2015

Geochem Geophys Geosyst

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In this paper, we combine active and passive source P wave seismic data to tomographically image the magmatic system beneath Newberry Volcano, located east of the Cascade arc. By using both travel times from local active sources and delay times from teleseismic earthquakes recorded on closely spaced seismometers (300–800 m), we significantly improve recovery of upper crustal velocity structure (<10 km depth). The tomographic model reveals a low‐velocity feature between 3 and 5 km depth that lies beneath the caldera, consistent with a magma body. In contrast to earlier tomographic studies, where elevated temperatures were sufficient to explain the recovered low velocities, the larger amplitude low‐velocity anomalies in our joint tomography model require low degrees of partial melt (∼10%), and a minimum melt volume of ∼2.5 km3. Furthermore, synthetic tests suggest that even greater magnitude low‐velocity anomalies, and by inference larger volumes of magma (up to 8 km3), are needed to explain the observed waveform variability. The lateral extent and shape of the inferred magma body indicates that the extensional tectonic regime at Newberry influences the emplacement of magmatic intrusions. Our study shows that jointly inverting active source and passive source seismic data improves tomographic imaging of the shallow crustal seismic structure of volcanic systems and that active source experiments would benefit from longer deployment times to also record teleseismic sources.

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Section: Geologic Settingmentioning

confidence: 99%

Imaging the magmatic system of Newberry Volcano using joint active source and teleseismic tomography

Heath

Hooft

Toomey

et al. 2015

Geochem Geophys Geosyst

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“…Of the 111 samples with thermobarometric estimates, 23 exhibit petrologic and/or geochemical evidence for the involvement of H 2 O during petrogenesis. All of these 23 basalts are from Newberry Volcano, which erupted both dry tholeiite and wet calc‐alkaline basalts [ Donnelly Nolan and Grove , 2009] during the last ∼500 ka [ Jensen et al , 2009]. Olivine‐plagioclase hygrometry on a representative subset of these 23 basalts indicates they contained ∼4 wt.% H 2 O prior to eruption [ Grove et al , 2009].…”

Section: Petrologic Constraintsmentioning

confidence: 99%

Mantle dynamics beneath the Pacific Northwest and the generation of voluminous back‐arc volcanism

Long

Till

Druken

et al. 2012

Geochem Geophys Geosyst

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[1] The Pacific Northwest (PNW) has a complex tectonic history and over the past $17 Ma has played host to several major episodes of intraplate volcanism. These events include the Steens/Columbia River flood basalts (CRB) and the striking spatiotemporal trends of the Yellowstone/Snake River Plain (Y/SRP) and High Lava Plains (HLP) regions. Several different models have been proposed to explain these features, which variously invoke the putative Yellowstone plume, rollback and steepening of the Cascadia slab, extensional processes in the lithosphere, or a combination of these. Here we integrate seismologic, geodynamic, geochemical, and petrologic results from the multidisciplinary HLP project and associated analyses of EarthScope USArray seismic data to propose a conceptual model for post-20 Ma mantle dynamics beneath the PNW and the relationships between mantle flow and surface tectonomagmatic activity. This model invokes rollback subduction as the main driver for mantle flow beneath the PNW beginning at $20 Ma. A major pulse of upwelling due to slab rollback and upper plate extension and consequent melting produced the Steens/CRB volcanism, and continuing trench migration enabled mantle upwelling and hot, shallow melting beneath the HLP. An additional buoyant mantle upwelling is required to explain the Y/SRP volcanism, but subduction-related processes may well have played a primary role in controlling its timing and location, and this upwelling likely continues today in some form. This conceptual model makes predictions that are broadly consistent with seismic observations, geodynamic modeling experiments, and petrologic and geochemical constraints.

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“…Newberry Volcano is a shield‐shaped composite volcano located in central Oregon, 60 km east of the axis of the Cascade arc (Figure 1). Despite its low profile Newberry is volumetrically the largest volcano in the Cascade arc, with an estimated volume of 500 km 3 of lavas covering an area of 3000 km 2 [ Jensen et al , 2009]. Newberry's volcanism is thought to result from a combination of subduction zone magmatism, extensional tectonics and crustal weakness at the intersection of the Walker Rim, Sisters, and Brothers fault zones [ Fitterman , 1988], and a northwestward propagating volcanic front that ends at Newberry.…”

Section: Introductionmentioning

confidence: 99%

“…This volcanic province may be related to the Columbia River flood basalts and the Yellowstone plume ∼17 Ma [e.g., Humphreys et al , 2000; Draper , 1991]. Volcanism at Newberry began 0.5 Ma and multiple ash flow tuffs suggest that at least three caldera collapse events produced the central caldera, with the most recent event 80 ka [ Jensen et al , 2009]. …”

Section: Introductionmentioning

confidence: 99%

Upper crustal structure of Newberry Volcano from P‐wave tomography and finite difference waveform modeling

et al. 2012

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.[1] Seismic tomography combined with waveform modeling constrains the dimensions and melt content of a magma body in the upper crust at Newberry Volcano. We obtain a P-wave tomographic image by combining travel-time data collected in 2008 on a line of densely spaced seismometers with active-source data collected in the 1980s. The tomographic analysis resolves a high-velocity intrusive ring complex surrounding a low-velocity caldera-fill zone at depths above 3 km and a broader high-velocity intrusive complex surrounding a central low-velocity anomaly at greater depths (3-6 km). This second, upper-crustal low-velocity anomaly is poorly resolved and resolution tests indicate that an unrealistically large, low-velocity body representing $60 km 3 of melt could be consistent with the available travel times. The 2008 data exhibit low amplitude first arrivals and an anomalous secondary P wave phase originating beneath the caldera. Two-dimensional finite difference waveform modeling through the tomographic velocity model does not reproduce these observations. To reproduce these phases, we predict waveforms for models that include synthetic low-velocity bodies and test possible magma chamber geometries and properties. Three classes of models produce a transmitted P-phase consistent with the travel time and amplitude of the observed secondary phase and also match the observed lower amplitude first arrivals. These models represent a graded mush region, a crystal-suspension region, and a melt sill above a thin mush region. The three possible magma chamber models comprise a much narrower range of melt volumes (1.6-8.0 km 3 ) than could be constrained by travel-time tomography alone.Citation: Beachly, M. W., E. E. E. Hooft, D. R. Toomey, and G. P. Waite (2012), Upper crustal structure of Newberry Volcano from P-wave tomography and finite difference waveform modeling,

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A field guide to Newberry Volcano, Oregon

Cited by 13 publications

References 18 publications

Imaging the magmatic system of Newberry Volcano using joint active source and teleseismic tomography

Imaging the magmatic system of Newberry Volcano using joint active source and teleseismic tomography

Mantle dynamics beneath the Pacific Northwest and the generation of voluminous back‐arc volcanism

Upper crustal structure of Newberry Volcano from P‐wave tomography and finite difference waveform modeling

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