PhD proposal

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Spatial Analysis of Cinder Cone Distribution at
Newberry Volcano, Oregon Implications for
Structural Control on Eruptive Process
Steve Taylor and Jeff Templeton Earth and
Physical Sciences Department Western Oregon
University Monmouth, Oregon 97361
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INTRODUCTION
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WOU
Bend
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History of Newberry Work at Western Oregon
University
2000-Present WOU Class Field Trips and
Contextual Learning Modules 2000 Friends of the
Pleistocene Field Trip to Newberry
Volcano 2002-2003 GIS Compilation and
Digitization of Newberry Geologic Map (after
MacLeod and others, 1995) 2003 Giles and
others, Digital Geologic Map (GSA Fall
Meeting) 2003 Taylor and others, Cinder Cone
Volume and Morphometric Analysis I (GSA Fall
Meeting) 2005 Taylor and others, Spatial
Analysis of Cinder Cone Distribution II (GSA
Fall Meeting) 2007 Taylor and others, Synthesis
of Cinder Cone Morphometric and Spatial
Analyses (GSA Cordilleran Section
Meeting) 2001-2007 Templeton, Petrology and
Volcanology of Pleistocene Ash- flow Tuffs (GSA
Cordilleran Section Meeting 2004 Oregon
Academy of Science, 2007)
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PHYSIOGRAPHIC SETTING
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Newberry Volcano, View to S-SE from Paulina Peak
Lookout
High Lava Plains
Fort Rock (Tuff Ring)
Basin and Range
Newberry Cinder Cones
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Newberry Volcano, View to West towards High
Cascades from Paulina Peak Lookout
South Sister
Broken Top
Middle Sister
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Newberry Volcano, South View from Lava Butte
Lookout
Basaltic Aa Lava Flow fromLava Butte 7000 yrs
BP
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Newberry Volcano, View into Summit Caldera from
Paulina Peak
Paulina Lake
East Lake
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Geologic Setting
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Tectonic Framework

• Arc Volcanoes related
• to Cascadia Subduction Zone
• Juan de Fuca plate thrust
• beneath North American plate

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Magma Source in Subduction Zone
Fore Arc
Back Arc
7 0 Ma
35 7 Ma
High Cascades
Newberry Position
Western Cascades
Decreasing Slab Dip
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Geology after Walker and MacLeod (1991)
Isochrons in 1 m.y. increments (after MacLeod and
others, 1976)
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• Overview of Newberry Volcano
• Shield-shaped composite volcano
• N-S orientation, 64 km x 40 km
• Total Area gt 1300 km2
• Summit Caldera Area 44 km2
• Elevation 1300 m 2400 m Relief 1100 m
• Composition Basalt to Rhyolite
• Estimated Volume 460 km3
• gt400 cinder cones and fissure vents
• Quaternary in Age
• Normal Polarity lt788,000 yrs BP
• Tepee Draw Tuff 500,00 yrs BP
• West Flank Tuff 100,000 yrs BP
• Holocene activity 10,000 1200 yrs BP
• One of largest U.S. Quaternary volcanoes

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Central Pumice Cone 7200 yrs BP
Big Obsidian Flow 1250 yrs BP
East Lake
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Mt. Mazama / Crater Lake Eruptive Event(50
cubic kilometers of magma, 7630 calendar years
B.P.)
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Mazama Deposits from Single Vent Phase
0.5 1.0 m of ash and pumice fall deposits on
south and west flank of Newberry
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Basaltic Flows (Pl.- H)
Tepee Draw Tuff
Caldera
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Southeast Cinder Cone Field
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Lava Butte Cone and Aa Flow 7000 yrs BP
(post-Mazama)
Ash Pumice
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GEOMORPHIC ANALYSIS OFCINDER CONES
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Cinder Cone Research Questions Are there
morphologic groupings of 400 cinder cones at
Newberry? Can they be quantitatively
documented? Are morphologic groupings associated
with age and state of erosional degradation? Are
there spatial patterns associated with the
frequency, occurrence, and volume of cinder
cones? Are there spatial alignment patterns?
Can they be statistically documented? Do
regional stress fields and fault mechanics
control the emplacement of cinder cones at
Newberry volcano?
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Methodology

• Digital Geologic Map Compilation / GIS of
  Newberry Volcano (after McLeod and others, 1995)
• GIS analysis of USGS 10-m DEMs
• Phase 1 Single Cones/Vents (n 182)
• Phase 2 Composite Cones/Vents (n 165)
• Morphometric analyses
• Cone Relief, Slope, Height/Width Ratio
• Morphometric Classification
• Volumetric Analyses
• Cone Volume Modeling
• Volume Distribution Analysis
• Cone Alignment Analysis
• Two-point Line Azimuth Distribution
• Comparative Monte Carlo Modeling (Random vs.
  Actual)

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(n 182)
COMPOSITE
(n 165)
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RESULTS OF MORPHOMETRIC ANALYSES SINGLE CONES
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Single Cones (n182)
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n182
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Single Cones
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Single Cones
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Single Cones
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Single Cones
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Single Cones
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Youthful
Mature
Northern DomainGroup I n 26 (14) Group II
n 76 (42)
Southern DomainGroup I n 16 (9)Group II n
64 (35)
Single Cones
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VOLUMETRIC ANALYSESSINGLE COMPOSITE CONES
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Cubic Meters
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CONE ALIGNMENT ANALYSESSINGLE COMPOSITE
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Cone lineaments anyone? Question How many
lines can be created by connecting the dots
between 296 select cone center points?
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Answer Total Lines n(n-1)/2 296295/2
43,660 possible line combinations
Follow-up Question Which cone lineaments are due
to random chance and which are statistically and
geologically significant?
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REGIONAL FAULT-TREND ANALYSIS
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Normalized Two-Point Cone Azimuths
95 Critical Value
Random Two-Point Cone Azimuths
n 296 / replicateReplicates 300
Actual Two-Point Cone Azimuths
n 296Line Segments 43,660
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POINT-DENSITY METHOD(Zhang and Lutz, 1989)
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SUMMARY AND CONCLUSION
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• I. CONE MORPHOLOGY
• Degradation Models Through Time (Dohrenwend and
  others, 1986)
• Diffusive mass wasting processes
• Mass transfer primary cone slope to debris
  apron
• Reduction of cone height and slope
• Loss of crater definition
• Newberry Results (Taylor and others, 2003)
• Group I Cones Avg. Slope 19-20o Avg. Relief
  125 m Avg. Hc/Wc 0.19
• Group II Cones Avg. Slope 11-15o Avg. Relief
  65 m Avg. Hc/Wc 0.14
• Group I Youthful more abundant in northern
  domain
• Group II Mature common in northern and
  southern domains
• Possible controlling factors include
  degradation processes, age differences,
  climate, post-eruption cone burial, lava
  composition, and episodic (polygenetic) eruption
  cycles
• II. CONE VOLUME RESULTS

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• III. CONE ALIGNMENT PATTERNS
• Newberry cones align with Brothers and Tumalo
  fault zones
• Poor alignment correlation with Walker Rim fault
  zone
• Other significant cone alignment azimuths
  10-35o, 80o, and 280-295o
• Results suggest additional control by unmapped
  structural conditions
• Cone-alignment and volume-distribution studies
  suggest that the Tumalo Fault Zone is a dominant
  structural control on magma emplacement at
  Newberry Volcano

• IV. CONCLUDING STATEMENTS
• This study provides a preliminary framework to
  guide future geomorphic and geochemical analyses
  of Newberry cinder cones
• This study provides a preliminary framework from
  which to pose additional questions regarding the
  complex interaction between stress regime,
  volcanism, and faulting in central Oregon

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Future Work
Coordination of cone morphology studies with USGS
basalt flow mapping, stratigraphic, and
geochemical research (Donelly-Nolan)Use of cone
morphology classes to guide geochemical sampling
and radiometric dating studiesUse of cone
morphology classes to guide soil chronosequence
workUse of cone alignment patterns to further
investigate therelationship between fault
mechanics, stress regime, and magma emplacement
mechanisms
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ACKNOWLEDGMENTS
Funding Sources Western Oregon University
Faculty Development Fund US Geological Survey
Small Grants Program WOU Student Research
Assistants Jeff Budnick, Chandra Drury, Jamie
Fisher, Tony Faletti Denise Giles, Diane Hale,
Diane Horvath, Katie Noll, Rachel Pirot, Summer
Runyan, Ryan Adams