STRATIGRAPHY, DISTRIBUTION, AND GEOCHEMISTRY
OF THE NEWBERRY VOLCANO TEPHRAS
By
STEPHEN CHRISTOPHER KUEHN
A dissertation submitted in partial fulfillment of
the requirements for the degree of
DOCTOR OF PHILOSPHY
WASHINGTON STATE UNIVERSITY
Department of Geology
AUGUST 2002
© Copyright by STEPHEN CHRISTOPHER KUEHN, 2002
All Rights Reserved
© Copyright by Stephen Christopher Kuehn, 2002
All Rights Reserved
To the Faculty of Washington State University:
The members of the Committee appointed to examine the dissertation of
STEPHEN CHRISTOPHER KUEHN find it satisfactory and recommend that it be
accepted.
Chair
ii
ACKNOWLEDGMENTS
Many people provided support or assistance for this project. Included among them are
Nick Foit who first suggested a study of the Newberry tephra deposits and later suggested that
I try applying statistical techniques to tephra correlation. Larry Chitwood and Bob Jensen who
located several important tephra localities, provided samples of Ice Quarry tephra and tephra
0005, and helped make arrangements for lodging in Forest Service facilities. Bob Jensen's
excellent field guide proved very helpful especially early in the study. Julie Donnelly-Nolan
located tephra sites, shared data and ideas, and helped in obtaining 40Ar/39Ar dates. Marvin
Lanphere determined several
40
Ar/39Ar dates which have helped constrain the Newberry
tephra chronology. Andrei Sarna-Wojcicki shared glass compositional data and tephra
correlations. John Wolff reviewed ideas and suggested several key references particularly
for volcanological aspects of the study. Rob Negrini provided samples of tephra NN from
Summer Lake and unpublished information on tephra layers in sediment cores at Summer
Lake, Oregon. Paul Carrara provided a sample, photograph, and description of Newberry
Pumice distal ash present at Van Wyck bog in central Idaho. My wife, Victoria, provided
ongoing support and encouragement, especially during the intense, four-month long, final
stage of writing.
Partial financial support for this project was provided by a Geological Society of
America Research Grant, a Sigma Xi Grant in Aid of Research, Washington State University
College of Sciences Minigrants, Washington State University Department of Geology
Minigrants, and a Summer Graduate Research Assistantship from the Washington State
University Graduate School.
iii
STRATIGRAPHY, DISTRIBUTION, AND GEOCHEMISTRY
OF THE NEWBERRY VOLCANO TEPHRAS
Abstract
by Stephen Christopher Kuehn, Ph.D.
Washington State University
August 2002
Chair: F.F. Foit, Jr.
Newberry volcano has a long history of silicic pyroclastic volcanism and has
produced many extensive tephra deposits. During the last approximately 550,000 years, the
volcano has erupted at least 60 rhyolitic and dacitic tephras. These record a range of eruptive
styles including plinian, sub-plinian, pyroclastic flows, and pyroclastic surges and both dry
and phreatomagmatic activity. Tephra dispersal from individual eruptions ranges from very
limited (i.e. small pumice rings a few hundred meters to a kilometer in extent) to extensive
(i.e. plinian airfall deposits which have been recognized several hundred kilometers
downwind). The most recent plinian eruption, the approximately 1250-1450 year old
Newberry Pumice, produced an eruption column which reached a height of ~25 km and was
dispersed by unusually high velocity winds. Some Pleistocene eruptions, including tephra
9822B, may have sent pyroclastic material to heights of 40 km or more. Several deposits
including Evans Well, 9822B, Qat/Qbt, 995B, and Qtae are compositionally heterogeneous
and probably record the mixing of magmas before or during eruption.
The similarity coefficient and discriminant function analysis have been used to
compare electron microprobe determined glass compositions for proximal Newberry tephra
iv
deposits and distal ash layers. Newberry Pumice correlates to six distal locations in Oregon
and Idaho. Paulina Creek, Ice Quarry, 9912D, 9920C, 984F, 984G5, 9917C, and 9881C
correlate to ash layers at Summer Lake, Oregon. Paulina Creek tephra also correlates to
several locations in northern California and is the source of the Olema ash bed. Tephra 9917C
is highly similar to Pringle Falls tephras K and D. Lava Pass tephra correlates to a distal ash
preserved at a depth of 142 m in the Knolls core in the Bonneville basin, Utah. A coarse, 0.6
m thick deposit of Wono tephra has been located on the northwest flank of Newberry volcano.
The large number of eruptions and established tephra correlations suggest that
additional correlations of Newberry tephra are likely to be made to distal sites, both studied
and yet to be studied. The volcano's extensive eruptive history and relatively recent activity
also indicate that future large ash and pumice producing eruptions are likely.
v
TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS ............................................................................................................. iii
ABSTRACT .................................................................................................................................. iv
LIST OF TABLES......................................................................................................................... xi
LIST OF FIGURES ...................................................................................................................... xii
LIST OF OVERSIZE MAPS ..................................................................................................... xvii
CHAPTER
1. INTRODUCTION ................................................................................................................ 1
Objectives ........................................................................................................................... 1
Geologic Setting and Previous Work ................................................................................. 1
Background and Methods ................................................................................................... 4
Types of Eruptions, Clast Transport, Deposits, and Variations ................................... 4
Thickness Distributions ................................................................................................ 7
Particle Size Distributions and Component Analysis ................................................... 7
Correlation of Tephra Deposits Among Locations at Newberry volcano .................. 10
Geochemical Analysis of Volcanic Glass .................................................................. 10
Bulk Analyses of Tephras and Obsidians ................................................................... 13
Tephra Unit Designations ........................................................................................... 13
Radiocarbon Dating .................................................................................................... 14
Preparation of Crystal Concentrates ........................................................................... 15
2. HOLOCENE TEPHRA UNITS ......................................................................................... 25
Introduction ...................................................................................................................... 25
Big Obsidian Eruptive Period ........................................................................................... 25
Paulina Lake Ash flow ............................................................................................... 26
Newberry Pumice ....................................................................................................... 27
vi
Additional Tephras of the Big Obsidian Period ......................................................... 37
East Lake eruptive period: Tephra 9714B and East Draw Tephra (9714D) ..................... 38
Tephra 9612C ................................................................................................................... 38
Interlake Eruptive Period .................................................................................................. 39
Central Pumice Cone .................................................................................................. 39
East Lake Tephra ........................................................................................................ 39
Mazama Tephra ................................................................................................................ 40
Pre-Mazama Silicic Tephra .............................................................................................. 40
Summary ........................................................................................................................... 40
3. PLEISTOCENE TEPHRA UNITS .................................................................................... 92
Introduction ...................................................................................................................... 92
Wono Tephra (9879C) ...................................................................................................... 92
Tephra 9715K ................................................................................................................... 95
Paulina Creek Tephra ....................................................................................................... 95
Ice Quarry Tephra (973B) ................................................................................................ 98
Evans Well Tephra (9935CD) .......................................................................................... 98
Tephra 9822B ................................................................................................................... 99
Andesite Tuff (Qat) and Basaltic Andesite Lapilli Tuff (Qbt) ....................................... 101
Tephra 9873 .................................................................................................................... 102
Tephra 9830D ................................................................................................................. 102
Tephra 984D ................................................................................................................... 102
Tephra 9912D ................................................................................................................. 103
Tephra 0005 .................................................................................................................... 103
Tephra 9920C and Tephra 9920E ................................................................................... 104
Tephra 984F .................................................................................................................... 104
Tephra 984G2 and 984G5 .............................................................................................. 105
Tephra 984H ................................................................................................................... 105
vii
Tephra 978D ................................................................................................................... 105
Tephra 978E ................................................................................................................... 106
Tephra 9917C ................................................................................................................. 106
Tephra 9881C ................................................................................................................. 107
Qdt/Qto ........................................................................................................................... 107
Tephra 995B ................................................................................................................... 108
Tephra 9865E ................................................................................................................. 108
Tephra 9865F .................................................................................................................. 109
Tephra 978H ................................................................................................................... 109
Qaf3 ................................................................................................................................ 109
Qtae, Lava Pass Tephra, and Related Deposits .............................................................. 110
Qtae ........................................................................................................................... 110
Lava Pass Tephra (986C) ......................................................................................... 110
Tephra 9818E ........................................................................................................... 112
Tephra 9874 .............................................................................................................. 112
Tephra 0002E ........................................................................................................... 112
Tephra 9914 .............................................................................................................. 112
Tephra 9729G ................................................................................................................. 113
Tephra 9816C ................................................................................................................. 113
Tephra 9816E ................................................................................................................. 114
Bend Pumice ................................................................................................................... 114
Tephra 9855E ................................................................................................................. 114
Tephra 9818L ................................................................................................................. 115
Tepee Draw Tuff............................................................................................................. 115
Tephras of Poorly Constrained Stratigraphic Position and Miscellaneous Glasses ....... 116
Tephra 9838B ........................................................................................................... 116
Tephra 9838E ........................................................................................................... 116
viii
Qrps .......................................................................................................................... 116
Tephra 9863C2 ......................................................................................................... 116
Tephra in Soil Beneath Ice Quarry Tephra at Site 97-3 ........................................... 117
Tephra 9837A, Tephra 9837B, and Tephra 9837C .................................................. 117
Mixture Butte ............................................................................................................ 117
Welded tuff at site 99-23 .......................................................................................... 118
Horizon K at site 98-18 ............................................................................................ 118
Tephras in sand and gravel below tephra 9816E ...................................................... 118
Tephra 9839 .............................................................................................................. 118
Tephra 951 ................................................................................................................ 118
Tephra 9715M .......................................................................................................... 119
Other miscellaneous Glasses .................................................................................... 119
Crystal Content ............................................................................................................... 119
Summary ......................................................................................................................... 120
4. DISTAL CORRELATIONS, STRATIGRAPHY, AND AGE CONTROL .................... 183
Tephra Correlation .......................................................................................................... 183
Similarity Coefficient Method ........................................................................................ 185
Discriminant Function Analysis Method ........................................................................ 187
Introduction .............................................................................................................. 187
Procedure .................................................................................................................. 188
Results of Testing with Identified Samples .............................................................. 191
Classification of Unknown Samples ........................................................................ 194
Correlation of Newberry Tephras to Distal Sites ........................................................... 195
Correlations to Tephras at Summer Lake, Oregon ......................................................... 195
Correlations to Tephras at Other Locations .................................................................... 201
Stratigraphy and Age Control ......................................................................................... 203
Holocene Tephras of the Big Obsidian Period ......................................................... 204
ix
Other Holocene Tephras ........................................................................................... 206
Pleistocene Tephras .................................................................................................. 207
Summary ......................................................................................................................... 217
5. CONCLUSIONS .............................................................................................................. 322
REFERENCES ........................................................................................................................... 326
APPENDIX
1. Sampled and Excavated Locations and Test Pits ....................................................... 340
2. Sample Locations by Quadrangle ............................................................................... 351
3. Photographs and Stratigraphy of Excavated Locations .............................................. 377
4. Maximum Clast Size Measurements .......................................................................... 511
5. Glass Compositional Data by Electron Microprobe ................................................... 542
6. Whole Rock Compositional Data by XRF and ICP-MS and Plots of Whole Rock
Data .............................................................................................................................. 678
7. Results From Samples Submitted to Oregon State University for 40Ar/39Ar Dating .. 697
x
LIST OF TABLES
Page
1. Compositions of Standard Glasses, Counting Times, and Crystals Used in the Electron
Microprobe Analyses .............................................................................................................. 19
2. Phi Size Scale and Tephra Size Ranges.................................................................................. 23
3. Major Element Analyses of Glass by Electron Microprobe ............................................. 45-46
4. Thickness of and Area Enclosed by Newberry Pumice Isopachs.......................................... 61
5. Average Wind Speed vs. Altitude for Salem, Oregon ............................................................ 72
6. Glass Compositions of the Later Pleistocene Tephra Units at Newberry Volcano. ..... 129-131
7. Glass Compositions of the Earlier Pleistocene Tephra Units at Newberry Volcano .......... 166-169
8. Crystal Content of Eight Pleistocene Tephra Units ............................................................. 182
9.
Groups and Steps Used in Stepwise Discriminant Function Analysis ........................ 221-224
10. Highly Discriminating Variables Selected by the STEPDISC Program and Proportions of
Variance Reported by the CANDISC Program ............................................................. 225-233
11. Proportion of Observations Misclassified as Another Unit During the Initial Stage of
Analysis ......................................................................................................................... 239-240
12. Observations Misclassified as Another Unit During the Second Stage of Analysis .. 263-271
13. Observations Misclassified as Another Unit During the Third Stage of Analysis ..... 288-298
14. Compositions of Glasses at Newberry Volcano and Correlative Distal Deposits ....... 302-304
15. Correlations to Distal Deposits Using Discriminant Function Analysis ..................... 305-310
16. Age Control on Proximal Tephras and Obsidian at Newberry Volcano ..................... 313-318
17. Ash and Pumice in Soils Above and Below Tephra 9881C at Site 98-81.......................... 321
xi
LIST OF FIGURES
Page
1.
Photographs of Newberry Volcano from the South ............................................................ 16
2.
Photograph of Newberry Caldera Looking Northeast from Paulina Peak. ......................... 17
3.
Regional Location Map for Newberry Volcano. ................................................................. 17
4.
Newberry Volcano Location Map ....................................................................................... 18
5.
Sodium and Potassium Loss During Electron Microprobe Analysis .................................. 20
6.
Variation in Sodium Loss With Beam Size and Current ..................................................... 21
7.
Cartoon of a Plinian Eruption Column ................................................................................ 22
8.
Plot Used to Estimate Median Diameter ............................................................................. 24
9.
Major Element Analyses of Glass by Electron Microprobe ........................................... 42-44
10. Major and Trace Element Analyses of Whole Rock by XRF ........................................ 47-51
11. Paulina Lake Ash Flow Deposit at Site 99-22 ..................................................................... 52
12. Proximal Distribution of the Newberry Pumice .................................................................. 53
13. Part of the Newberry Caldera Geologic Map of Macleod et. al. (1995) ............................. 54
14. Newberry Pumice on the South Caldera Rim at Site 99-22 ................................................ 55
15. Newberry Pumice on the South Caldera Rim at Site 99-22 ................................................ 56
16. Landmarks and Locations of Interest Shown on Subsequent Figures ................................. 57
17. Thickness Data for the Newberry Pumice ........................................................................... 58
18. Newberry Pumice Isopachs ................................................................................................. 59
19. Newberry Pumice Isopachs Overlain on Map from Macleod et. al. (1995) ........................ 60
20. Log Thickness vs. Sqrt Area Plots for the Newberry Pumice Isopachs .............................. 62
21. Distal Newberry Pumice Deposit Used to Estimate a 2 cm Isopach ................................... 63
22.
Isopleths for the Largest Pumice and Lithic Fragments in the Newberry Pumice ............ 64
23.
Newberry Pumice Isopachs and Isopleths Superimposed ................................................. 65
24. Wind Profile Used in the Clast Dispersal Models of Carey and Sparks (1986) ................. 66
xii
25. Downwind (Parallel to Long Axis) and Crosswind (Perpendicular to Long Axis) Ranges
for Pumice and Lithic Clasts in the Newberry Pumice Deposit .......................................... 67
26. Crosswind Range and Downwind Range of Pumice and Lithic Clasts in the Newberry
Pumice Deposit .................................................................................................................... 68
27.
Estimation of Maximum Column Height for the Newberry Pumice Eruption .................. 69
28. Model Lithic Isopleths in cm Redrafted from Carey and Sparks (1986) and Newberry
Pumice Isopleths .................................................................................................................. 70
29. Model Wind Properties and Modern Wind Profile for Salem, OR ..................................... 71
30. Distribution of Wind Speeds and Altitudes for the Tropopause Above Salem, OR ........... 72
31. Distribution of Wind Speeds at Several Altitudes Above Salem, OR................................. 73
32.
Reference Map for Newberry Pumice Locations .............................................................. 74
33. Difference in Particle Size Between the Upper and Lower Parts of the Newberry Pumice
Deposit ................................................................................................................................. 75
34.
Particle Size Variations in the Newberry Pumice Along a North-South Profile Near China
Hat ....................................................................................................................................... 76
35. Particle Size Variations in the Newberry Pumice Closer to the Vent Than That Shown in
Figure 31 .............................................................................................................................. 77
36. Particle Size Variations in the Newberry Pumice Closer to the Vent Than That Shown in
Figures 31 and 32 ................................................................................................................ 78
37. North-South Thickness Variations in the Upper and Lower Parts of the Newberry Pumice
Deposit ................................................................................................................................. 79
38.
Variations in Particle Size and Lithic Content With Stratigraphic Height at Site 97-2 .... 80
39.
Ash Horizons in the Upper Part of the Newberry Pumice at Site 97-2. ............................ 81
40.
Variations in Particle Size With Stratigraphic Height at Site 97-5. .................................. 82
41.
Variations in Particle Size and Lithic Content With Stratigraphic Height at Site 96-10. ........ 83
42.
Variations in Particle Size and Lithic Content With Stratigraphic Height at Site 96-11 ......... 84
43. Variations in Particle Size and Lithic Content With Stratigraphic Height at Site 96-12 ... 85
xiii
44. Variations in Particle Size and Lithic Content With Stratigraphic Height at Site 96-13 ... 86
45. Variations in Particle Size and Lithic Content With Stratigraphic Height at Site 96-14 ... 87
46. Variations in Particle Size and Lithic Content With Stratigraphic Height at Site 96-18 ... 88
47. Thickness Variations in the More Distant Part of the Newberry Pumice Deposit ............. 89
48. Stratigraphy Beneath the Paulina Lake Ash Flow Near the Boat Ramp on the South East
Shore of Paulina Lake.......................................................................................................... 90
49. Mazama Tephra Thickness Variations in the Newberry Volcano Area ............................. 91
50. Wono Tephra Locations ................................................................................................... 121
51. Landmarks (Triangles) and USGS 7.5 Minute Quadrangle Boundaries (Grid) ............... 122
52. Particle Size Variations in the Wono Tephra at Site 98-79 .............................................. 123
53. Glass Compositions of the Later Pleistocene Tephra Units at Newberry Volcano ... 124-128
54. Glass Compositions of Wono Tephra at Newberry and Summer Lake, Oregon Compared
to Four Tephra Units from Crater Lake, Oregon ............................................................... 132
55. Distance from Crater Lake to Site 98-79 at Newberry Volcano Plotted on a Crosswind
Range vs Downwind Range Diagram of Carey and Sparks (1986) .................................. 133
56. Locations for Tephra 9715K ............................................................................................. 134
57. Paulina Creek Tephra Thickness Distribution .................................................................. 135
58. Distribution of Identified Flow, Surge, and Fall Deposits (Filled Circles) in the Paulina
Creek Tephra ..................................................................................................................... 136
59. Largest Pumice and Lithic Clasts in the Paulina Creek Tephra ....................................... 137
60. Vertical Variations in the Largest Pumice and Lithic Clasts in the Paulina Creek Tephra ..... 138
61. Lower Part of Tephra Stratigraphy at Site 97-15 .............................................................. 139
62. Proximal Thickness Distribution of Ice Quarry Tephra ................................................... 140
63. Thickness Distribution of Evans Well Tephra Deposits .................................................. 141
64. Some Tephra Units with Substantially Heterogeneous Glass Compositions and Qaf3 .. 142-150
65. Thickness Distribution of Tephra 9822B and Distribution of Flow Deposits .................. 151
66. Basal Sequence of Tephra 9822B at Site 00-04 ............................................................... 152
xiv
67. Studied Locations and Clast Size Variations in Tephra 9822B........................................ 153
68. Variations in Particle Size with Stratigraphic Height in Tephra 9822B ........................... 154
69. Thickness Distribution of Tephra 9873, 9830D, and 984D ............................................. 155
70. Thickness Distribution of Tephra 9912D, 0005, 9920C, and 9920E ............................... 156
71. Thickness Distribution of Tephra 984F, 984G2, and 984G5 ........................................... 157
72. Thickness Distribution of Tephra 984H and 9917C ......................................................... 158
73. Thickness Distribution of Tephra 978D and Qaf3 ........................................................... 159
74. Thickness Distribution of Tephra 9978E, 9881C, and Qdt/Qto ....................................... 160
75. Glass Compositions of the Earlier Pleistocene Tephra Units and Some Miscellaneous
Units ........................................................................................................................... 161-165
76. Thickness Distribution of Tephra 9865E, 9865F and 978H ............................................. 170
77. Thickness Distribution of Tephra 9818E, Qtae, 9874, 0002E, and 9914 ......................... 171
78. Thickness Distribution of Lava Pass Tephra .................................................................... 172
79. Base of Lava Pass Tephra at Site 98-6 ............................................................................. 173
80. Clast Size Distribution in Lava Pass Tephra .................................................................... 174
81. Variations in Particle Size and Lithic Content in the Lava Pass Tephra at Site 98-6 ...... 175
82. Particle Size Variations in the Lava Pass Tephra With Stratigraphic Height................... 176
83. Particle Size Variations in the Lava Pass Tephra With Relative Stratigraphic Height .... 177
84. Thickness Distribution of Tephra 9729G, 9816C, and 9816E ......................................... 178
85. Thickness Distribution of Tephra 9855E and Bend Pumice ............................................ 179
86. Thickness Distribution of Tephra 9838B and 9838E ....................................................... 180
87. Thickness Distribution of Tephra Qrps, 9863C2, 9837A, 9837B, and 9839 ................... 181
88. Qualitative Effect of the Number of Points and Weighting on Similarity Coefficients Mazama Tephra ................................................................................................................. 219
89. Qualitative Effect of the Number of Points and Weighting on Similarity Coefficients Wono Tephra ..................................................................................................................... 220
90. Plots of Canonical Variables for the initial Stage of Analysis .................................. 234-238
xv
91. Plots of Canonical Variables for the Second Stage of Analysis. ............................... 241-262
92. Plots of Canonical Variables for the Third Stage of Analysis .................................... 272-287
93. Selected Locations With Distal Tephra Deposits of Probable or Possible Newberry Volcano
Origin ................................................................................................................................. 299
94. Map of the Summer Lake Sub-Basin of Pluvial Lake Chewaucan Showing Core and Outcrop Locations .................................................................................................................. 300
95. Tephra Stratigraphy at Summer Lake, Oregon ................................................................... 301
96. Summary of Stratigraphic Relationships .................................................................... 311-312
97. Charcoal Sample at Site 96-11 ........................................................................................... 319
98. Partial Tephra Stratigraphy and Dated Samples at Site 97-5 ............................................ 320
xvi
LIST OF OVERSIZE MAPS
1. Map of Studied and/or Sampled Locations - With Overlay .................. CD-ROM (Map1.pdf)
2. Map of Studied and/or Sampled Locations - No Overlay ...................... CD-ROM (Map2.pdf)
xvii