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Dissertations and Theses

Winter 2-24-2016

Dissertations and Theses

Field Geology and Petrologic Investigation of the Strawberry Volcanics, Northeast Oregon

Arron Richard Steiner

Portland State University

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Steiner, Arron Richard, "Field Geology and Petrologic Investigation of the Strawberry Volcanics, Northeast Oregon" (2016). Dissertations and Theses. Paper 2712.

https://doi.org/10.15760/etd.2708

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Field Geology and Petrologic Investigation of the Strawberry Volcanics, Northeast
Oregon

by
Arron Richard Steiner

A dissertation submitted in partial fulfillment of the requirements for the degree of

Doctor of Philosophy in
Environmental Sciences and Resources: Geology

Dissertation Committee: Martin J. Streck, Chair Michael L. Cummings
Jonathan Fink John A.Wolff Dirk Iwata-Reuyl

Portland State University
2016
© 2015 Arron Richard Steiner i
ABSTRACT

The Strawberry Volcanics of Northeast Oregon are a group of geochemically related lavas with a diverse chemical range (basalt to rhyolite) that erupted between 16.2 and 12.5 Ma and co-erupted with the large, (~200,000 km3) Middle Miocene tholeiitic lavas of the Columbia River Basalt Group (CRBG), which erupted near and geographically surround the Strawberry Volcanics. The rhyolitic lavas of the Strawberry Volcanics produced the oldest 40Ar/39Ar ages measured in this study with ages ranging from 16.2 Ma to 14.6 Ma, and have an estimated total erupted volume of 100 km3. The mafic and intermediate lavas of the Strawberry Volcanics include both tholeiitic and calc-alkaline compositions; calc-alkaline andesite is the dominant type by volume. 40Ar/39Ar ages of the mafic and intermediate lava flows range from 15.6 Ma to 12.5 Ma, and volume estimates of the intermediate lavas are approximately 1,100 km3. The magmas that gave rise to the Strawberry Volcanics traveled to the surface through numerous dikes, some of which have been exposed at the surface and supplied lava to fissure – style eruptions and/or shield volcanoes. Herein, we show that the Strawberry Volcanics are related to the CRBG in both time and space and share a chemical affinity, specifically to the Steens Basalt. Chemical similarities are observed in normalized trace element patterns, selected trace element ratios, and radiogenic isotopes. Comparison of the Strawberry Volcanic rhyolites to the other Middle Miocene rhyolites of eastern Oregon associated with the initiation of the Yellowstone – Snake River mantle plume reveals similar eruption ages, trace element compositions, including the rare earth elements (REEs), and “A-type” ii rhyolite characteristics. These data suggest that the Strawberry Volcanics are part of the regional volcanism (basalt to rhyolite) of the Columbia River Basalt Province. The petrogenesis of the Strawberry Volcanics can be explained as follows: 1) The tholeiitic, intermediate magmas were produced by fractional crystallization of mafic magmas, which have a commonality with the surrounding Columbia River Basalt Group; 2) The calc-alkaline magmas are a result of mixing between tholeiitic basalt, rhyolite, and crust. The arc-like signature of the calc-alkaline lavas (elevated large ion lithophiles) is a result of both the melting source region and the end-members with which the mafic magmas mixed/contaminated. Other authors have produced similar findings from within the Basin and Range/Oregon-Idaho graben and CRB province. The difference at the Strawberry Volcanics is that there is no need for a primitive calc-alkaline magma or extensive fractional crystallization to generate the calc-alkaline andesite series. Alternatively, the calc-alkaline magmas of the Strawberry Volcanics were generated by a more primitive tholeiitic magma than erupted at the surface, which interacted with crustal melts and assimilated crustal lithologies from the complex zone of assimilated terranes that make up the basement of eastern Oregon. iii
ACKNOWLEDGMENTS
The author would like to express a sincere appreciation of gratitude to the academic committee members: Martin Streck, Michel Cummings, Jonathan Fink, John Wolff and Dirk Iwata-Reuyl. I would like to further thank Martin Streck for providing opportunities to study at Portland State University and working tirelessly with me on edits for this dissertation. The work for Chapters 1, 2 and 3 were supported by: NSF-EAR grant #1220676; PSU Faculty Enhancement grant to Streck; and 2011 GSA research grant # 9579-11. I would also like to thank Mark Ferns for our discussions of eastern Oregon geology, Richard M. Conrey, Charles M. Knaack and Scott Boroughs at Washington State University for their assistance in whole rock geochemical XRF and ICP-MS analysis; Frank Ramos at New Mexico State University for Isotope analysis, Frank Tepley and Dale Burns at Oregon State University for the EMP analysis, Bob Duncan, Anthony Koppers and Dan Miggins for age analysis at Oregon State University, Dale Burns for his thoughtful insights, excellent field company and stimulating conversation regarding this research and including all geology. And to Ashley Van Hoose/Steiner, thanks for excellent field assistance and superior editing and comments along the way. Thank you for supporting me in every way. I would also like to thank Eric Christiansen and Esteban Gazel for their comments and edits that helped to improve the final published manuscript of Chapter 1, along with Arturo Gomez-Tuena for his editorial handling and additional comments towards the publishment of Chapter 1. Lastly, I would like to thank my family. Without their love and support this could not have happened. Thank You. iv i
TABLE OF CONTENTS
ABSTRACT................................................................................................................... ACKNOWLEDGMENTS ............................................................................................. iii LIST OF TABLES......................................................................................................... viii

  • LIST OF FIGURES .......................................................................................................
  • x

Chapter
1. THE STRAWBERRY VOLCANICS: GENERATION OF ‘OROGENIC’
ANDESITES FROM THOLEIITE WITHIN AN INTRA-CONTINENTAL VOLCANIC SUITE CENTERED ON THE COLUMBIA RIVER FLOOD

  • BASALT PROVINCE, USA. ..............................................................................
  • 1

Abstract................................................................................................................. Introduction........................................................................................................... Methods ................................................................................................................ Results...................................................................................................................
Stratigraphy and New Ages of the Strawberry Volcanics .............................
Field Relationships.................................................................................
135777
40Ar/39Ar Ages of Strawberry Volcanics and Stratigraphic Relationships to Mid-Miocene Flood Basalts and Other Regional Rock Units ............... 10
Geochemistry................................................................................................. 11
Tholeiitic Lavas of the Strawberry Volcanics ....................................... 11 The Calc-Alkaline Suite of the Strawberry Volcanics........................... 13 Compositional difference between tholeiitic and calc-alkaline suite .... 14
Discussion............................................................................................................. 15
Field Interpretations....................................................................................... 15 Common Parent for Calc-Alkaline and Tholeiitic Magmas .......................... 18 Compositional Changes and Petrogenesis Associated with Calc-Alkaline and Tholeiitic Evolution....................................................................................... 20 Implications for Other Intra-Continental Settings with Calc-Alkaline Suites 21
Conclusion ............................................................................................................ 24 v
2. THE VOLUMINOUS AND COMPOSITIONALLY DIVERSE, MID-MIOCENE
STRAWBERRY MOUNTAIN VOLCANICS OF NORTHEASTERN OREGON AND THEIR RELATIONSHIPS TO BASALTIC AND RHYOLITIC VOLCANISM OF THE COLUMBIA RIVER BASALT PROVINCE............... 26

Abstract................................................................................................................. 26 Introduction........................................................................................................... 28 Geologic Setting ................................................................................................... 30
Accreted Terranes (~320-220 Ma)................................................................. 30 Clarno/John Day (~54-22 Ma)....................................................................... 31 The Columbia River Basalt Group (~16.9-6.0 Ma)....................................... 32 Regional Ignimbrites and Younger Units ...................................................... 33
Methods ................................................................................................................ 35
Field Methods and Sample Collection........................................................... 35 Whole Rock Geochemistry............................................................................ 36
Major, and Trace Elements.................................................................... 36 Radiogenic Isotopes............................................................................... 37 40Ar/39Ar Geochronology....................................................................... 37
Radiometric Ages ................................................................................................. 39
Previous Ages of Strawberry Volcanics ........................................................ 39 Summary of New 40Ar/39Ar Results .............................................................. 40
Stratigraphy and Eruptive Units ........................................................................... 41
Rhyolitic Volcanism ...................................................................................... 41 Basaltic to Intermediate Lava Flows ............................................................. 46
Calc-Alkaline Intermediate Volcanism (15.50 to 12.5 Ma) .................. 47 Tholeiitic Basaltic and Intermediate Volcanism (15.5 to 13.5 Ma)....... 49
Discussion............................................................................................................. 51
Synopsis of Emplacement History of the Strawberry Volcanics................... 51 Relationships of Mafic Strawberry Volcanics to Flood Basalt Magmatism of the CRBG....................................................................................................... 52 Context of the Strawberry Mountain Rhyolites to the Mid-Miocene Rhyolite Flare-Up......................................................................................................... 56
Conclusion ............................................................................................................ 61 vi
3. THE MAKING OF INTRA-CONTINENTAL ANDESITES WITH ARC
AFFINITIES: THE STRAWBERRY VOLCANICS OF NORTHEAST OREGON
....................................................................................................................... 63

Abstract................................................................................................................. 63 Introduction........................................................................................................... 65
Tholeiitic and Calc-alkaline Andesites.......................................................... 66
Regional Geologic Setting.................................................................................... 69 Methods ................................................................................................................ 71
Bulk Rock Analyses....................................................................................... 71 Radiogenic Isotopes....................................................................................... 71 Electron Microprobe Analysis....................................................................... 71
Results................................................................................................................... 73
Petrography.................................................................................................... 73
Basalt Lavas........................................................................................... 73 Intermediate, Calc-alkaline and Tholeiitic Lavas .................................. 74
Tholeiitic Lavas ......................................................................... 74 Calc-Alkaline Lavas................................................................... 74
Rhyolite Lavas ....................................................................................... 75
Mineral Chemistry......................................................................................... 76
Basalt Lavas........................................................................................... 76 Intermediate, Calc-alkaline and Tholeiitic Lavas .................................. 77
Tholeiitic Lavas ......................................................................... 77 Calc-Alkaline Lavas................................................................... 78
Summary of EMP Results...................................................................... 79
Whole Rock Geochemistry............................................................................ 80
Whole Rock Major and Trace Element Geochemistry.......................... 80 Sr, Nd, and Pb Radiogenic Isotope Composition .................................. 82
Discussion............................................................................................................. 84
Common Basalt for Calc-Alkaline and Tholeiitic Suites .............................. 84 Enrichment and Fractionation During Tholeiitic Evolution.......................... 86 Generation of Intra-Continental Calc-Alkaline Andesites............................. 88
Evidence for Open System Processes.................................................... 88 Mixing with Silicic Magmas vs Contamination by Crustal Rocks........ 89
Conclusion ............................................................................................................ 96 vii
REFERENCES .............................................................................................................. 186 APPENDICES ............................................................................................................... 206 ABCDEFGH
XRF....................................................................................................................... 206 ICP-MS................................................................................................................. 207 NORMS ................................................................................................................ 208 ISOTOPES............................................................................................................ 209 EMP-CPX............................................................................................................. 210 EMP-OPX............................................................................................................. 211 EMP-OLV............................................................................................................. 212 40Ar/39Ar AGE ANALYSIS ................................................................................. 213 viii
LIST OF TABLES

Table 1.1.
Page
40Ar/39Ar geochronology......................................................................... 98

  • 1.2.
  • Whole rock major and trace element analysis of mafic and intermediate lavas

................................................................................................................ 99

1.3a. 1.3b.
Whole rock major and trace element analysis of rhyolite lavas ............. 100 Whole rock major and trace element analysis of crustal rock surrounding the Strawberry Volcanics.............................................................................. 101

  • 2.1.
  • 40Ar/39Ar age analysis of the Strawberry Volcanics ............................... 102

  • Whole rock XRF data of rhyolite lavas from the Strawberry Volcanics 103
  • 2.2a.

  • 2.2b.
  • Whole rock ICP-MS data of rhyolite lavas from the Strawberry Volcanics

................................................................................................................ 104

2.3a.

2.3b. 2.3c. 2.3d. 2.4a. 2.4b. 3.1a.
Whole rock XRF data of tholeiitic basalts and basaltic andesites from the Strawberry Volcanics.............................................................................. 105

Whole rock ICP-MS data of tholeiitic basalts and basaltic andesites from the Strawberry Volcanics.............................................................................. 106

Whole rock XRF data of calc-alkaline basaltic andesites from the Strawberry Volcanics................................................................................................. 107

Whole rock ICP-MS data of calc-alkaline basaltic andesites from the Strawberry Volcanics.............................................................................. 108

Whole rock radiogenic Sr isotopes for mafic, intermediate rhyolite lavas and crustal rocks ............................................................................................ 109

Whole rock radiogenic Nd and Pb isotopes for mafic, intermediate rhyolite lavas and crustal rocks ............................................................................ 110

EMP data of cpx crystals from tholeiitic (Th) basalt and intermediate lavas
................................................................................................................ 111 ix
3.1b. 3.1c. 3.1d.
EMP data of cpx crystals from calc-alkaline (Ca) intermediate lavas.... 112 EMP data of opx crystals from calc-alkaline (Ca) intermediate lava..... 113 EMP data of olivine crystals from tholeiitic (Th) basalt and intermediate lavas
................................................................................................................ 114

  • 3.1e.
  • EMP data of olivine crystals from calc-alkaline (Ca) intermediate lavas

................................................................................................................ 115

  • 3.2.
  • Partition coefficient used in calculations for FC and AFC models ....... 116

  • 3.3a.
  • Whole rock XRF analysis of crustal rock which crop out within the Strawberry

Volcanics ................................................................................................ 117

  • 3.3b.
  • Whole rock ICP-MS analysis of crustal rock which crop out within the

Strawberry Volcanics ............................................................................. 118

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    Petrologic And Geochemical Tracers Of Magmatic Movement In Volcanic Arc Systems: Case Studies From The Aleutian Islands And Kamchatka, Russia Item Type Thesis Authors Neill, Owen Kelly Download date 04/10/2021 04:22:53 Link to Item http://hdl.handle.net/11122/9176 PETROLOGIC AND GEOCHEMICAL TRACERS OF MAGMATIC MOVEMENT IN VOLCANIC ARC SYSTEMS: CASE STUDIES FROM THE ALEUTIAN ISLANDS AND KAMCHATKA, RUSSIA By Owen Kelly Neill RECOMMENDED: APPROVED: PETROLOGIC AND GEOCHEMICAL TRACERS OF MAGMATIC MOVEMENT IN VOLCANIC ARC SYSTEMS: CASE STUDIES FROM THE ALEUTIAN ISLANDS AND KAMCHATKA, RUSSIA A THESIS Presented to the Faculty of the University of Alaska Fairbanks in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY By Owen Kelly Neill Fairbanks, Alaska May 2013 UMI Number: 3573010 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. Di!ss8?t&iori Publishing UMI 3573010 Published by ProQuest LLC 2013. Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code. ProQuest LLC 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 iii Abstract Mixing, crystallization and degassing commonly affect magmas during storage, ascent and eruption from volcanoes. As these interactions cannot be observed directly, they must be characterized using chemical signatures of volcanic eruptive products.
  • Voluminous and Compositionally Diverse, Middle Miocene Strawberry Volcanics of NE Oregon: Magmatism Cogenetic with fl Ood Basalts of the Columbia River Basalt Group

    Voluminous and Compositionally Diverse, Middle Miocene Strawberry Volcanics of NE Oregon: Magmatism Cogenetic with fl Ood Basalts of the Columbia River Basalt Group

    OLD G The Geological Society of America Special Paper 538 OPEN ACCESS Voluminous and compositionally diverse, middle Miocene Strawberry Volcanics of NE Oregon: Magmatism cogenetic with fl ood basalts of the Columbia River Basalt Group Arron Steiner Department of Geology, Portland State University, P.O. Box 751, Portland, Oregon 97207-0751, USA, and Department of Geology, Washington State University, P.O. Box 642812, Pullman, Washington 99164-2812, USA Martin J. Streck Department of Geology, Portland State University, P.O. Box 751, Portland, Oregon 97207-0751, USA ABSTRACT The mid-Miocene Strawberry volcanic fi eld of northeastern Oregon is an exam- ple of intracontinental fl ood volcanism that produced lavas of both tholeiitic and calc- alkaline compositions derived by open-system processes. Until now, these dominantly calc-alkaline lavas have not been considered to have a petrogenetic origin similar to that of the fl ood basalts of the Pacifi c Northwest because of their calc-alkaline composition. These lavas are situated in between and co-erupted with the domi- nant volcanic fi eld of the Columbia River Basalt Group (CRBG). Due to the timing, location, and diversity of these erupted units, the Strawberry Volcanics may hold valuable information about the role of crustal modifi cation during large magmatic events such as hotspot volcanism. The earliest eruptions of the Strawberry Volca- nics began at 16.2 Ma and appear continuous to 15.3 Ma, characterized by low-sil- ica rhyolite. High-silica, A-type rhyolite eruptions followed at 15.3 Ma. The silicic eruptions continued until 14.6 Ma, with an estimated total volume up to ~100 km3.
  • Ten Seconds in the Field: Rapid Armenian Obsidian Sourcing With

    Ten Seconds in the Field: Rapid Armenian Obsidian Sourcing With

    Journal of Archaeological Science 41 (2014) 333e348 Contents lists available at ScienceDirect Journal of Archaeological Science journal homepage: http://www.elsevier.com/locate/jas Ten seconds in the field: rapid Armenian obsidian sourcing with portable XRF to inform excavations and surveys Ellery Frahm a, *, Beverly A. Schmidt b, Boris Gasparyan c, Benik Yeritsyan c, Sergei Karapetian d, Khachatur Meliksetian d, Daniel S. Adler b a Department of Archaeology, The University of Sheffield, Northgate House, West Street, Sheffield S1 4ET, United Kingdom b Department of Anthropology, Old World Archaeology Program, University of Connecticut, 354 Mansfield Road, Unit 1176, Storrs, CT 06269, United States c Institute of Archaeology and Ethnography, National Academy of Sciences, 15 Charents Street, Yerevan, Armenia d Institute of Geological Sciences, National Academy of Sciences, 24 Baghramian Avenue, Yerevan, Armenia article info abstract Article history: Armenia has one of the most obsidian-rich natural and cultural landscapes in the world, and the lithic Received 19 May 2013 assemblages of numerous Palaeolithic sites are predominantly, if not entirely, composed of obsidian. Received in revised form Recent excavations at the Middle Palaeolithic cave of Lusakert 1 recovered, on average, 470 obsidian 30 July 2013 artifacts daily. After sourcing more than 1700 artifacts using portable XRF (pXRF) in our field house, our Accepted 12 August 2013 team sought to shift pXRF-based obsidian sourcing into the field itself, believing that the geological origins of artifacts would be useful information to have on-site during an excavation or survey. Despite Keywords: increasing use of portable instruments, previous studies have principally focused on collections in Obsidian pXRF museums and other archives, and as a result, obsidian sourcing has remained embedded in post- fi Field methods excavation studies.