32nd Keck Proceedings Volume

Short Contributions and Posters – Montana Gateway Project

LANDSCAPE AND ENVIRONMENTAL CHANGE IN GLACIER NATIONAL PARK, MONTANA, U.S.A.
KELLY MACGREGOR, Macalester College and AMY MYRBO, LacCore/CSDCO, University of Minnesota

GSA Poster: SEDIMENT TRANSPORT AND DEPOSITION IN FISHERCAP LAKE AND THE SWIFTCURRENT VALLEY, GLACIER NATIONAL PARK, MONTANA, USA
MACGREGOR, Kelly1, MYRBO, Amy2, ABBOUD, Diala1, ATALIG, Elizaveta3, CHENEVERT, Etienne1, MOORE, Elizabeth4, PAGE, Bonnie5, PEARSON, Anna6, STEPHENSON, Joshua1 and WATTS, Jacob7, (1)Geology, Macalester College, 1600 Grand Avenue, St. Paul, MN 55105, (2)LacCore/CSDCO, Department of Earth Sciences, University of Minnesota, 500 Pillsbury Dr. SE, Minneapolis, MN 55455, (3)Wesleyan University, Middletown, CT 06459, (4)Washington and Lee University, Lexington, VA 24450, (5)Franklin and Marshall College, Lancaster, PA 17603, (6)Smith College, Northampton, MA 01063, (7)Colgate University, Hamilton, NY 13346

GSA Poster: USING LAKE CORES TO ANALYZE SEDIMENT TRANSPORT AND ENVIRONMENTAL CHANGE IN SWIFTCURRENT LAKE, GLACIER NATIONAL PARK, MONTANA, USA
MYRBO, Amy1, MACGREGOR, Kelly2, ABBOUD, Diala2, ATALIG, Elizaveta3, CHENEVERT, Etienne2, MOORE, Elizabeth4, PAGE, Bonnie5, PEARSON, Anna6, STEPHENSON, Joshua2 and WATTS, Jacob7, (1)LacCore/CSDCO, Department of Earth Sciences, University of Minnesota, 500 Pillsbury Dr. SE, Minneapolis, MN 55455, (2)Geology, Macalester College, 1600 Grand Avenue, St. Paul, MN 55105, (3)Wesleyan University, Middletown, CT 06459, (4)Washington and Lee University, Lexington, VA 24450, (5)Franklin and Marshall College, Lancaster, PA 17603, (6)Smith College, Northampton, MA 01063, (7)Colgate University, Hamilton, NY 13346

Short Contributions and Posters – California Gateway Project

USING GARNETS TO EXPLORE THE BEGINNING OF SUBDUCTION ON SANTA CATALINA ISLAND, CALIFORNIA
ZEB PAGE, Oberlin College and JADE-STAR LACKEY, Pomona College

AGU Poster: AN INVESTIGATION OF THE CATALINA GARNET-BLUESCHIST: MAJOR AND TRACE ELEMENT COMPOSITION AND ZONING IN GARNET AND LAWSONITE FROM A MULTIPLY SUBDUCTED BLOCK
ADLER-IVANBROOK, B.; HAMPTON, S. K.; ESPARZA LIMON, J. P.; LACKEY, J. S.; PAGE, F. Z.
AA(Colorado College, Colorado Springs, CO, United States [email protected]), AB(Geology, Oberlin College, Oberlin, OH, United States [email protected]), AC(Life and Physical Sciences, Tarrant County College, Hurst, United States [email protected]), AD(Pomona College, Claremont, CA, United States [email protected]), AE(Oberlin College, Oberlin, OH, United States [email protected])

AGU Poster: MAJOR AND TRACE ELEMENT ZONING IN GARNETS OF UNUSUAL SIZE FROM BLOCKS HOSTED BY ULTRAMAFIC MÉLANGE, SANTA CATALINA ISLAND, CALIFORNIA
CANADA, A. L.; KARROUM, J. G., II; PARAS, L.; LACKEY, J. S.; PAGE, F. Z.
AA(Trinity University, San Antonio, TX, United States [email protected]), AB(Rice University, Houston, TX, United States [email protected]), AC(Smith College, Northampton, United States [email protected]), AD(Pomona College, Claremont, CA, United States [email protected]), AE(Oberlin College, Oberlin, OH, United States [email protected])

AGU Poster: MAJOR AND TRACE ELEMENT ANALYSIS OF GARNET CRYSTALS FROM A HORNBLENDEITE BLOCK AND RIND ON SANTA CATALINA ISLAND, CA: INSIGHTS INTO METASOMATIC PROCESSES IN SUBDUCTION MÉLANGE
BESS, N. T.; HASEGAWA, E. M.; VOSS, P. R.; LACKEY, J. S.; PAGE, F. Z.
AA(Franklin and Marshall College, Lancaster, PA, United States [email protected]), AB(Geology, Amherst College, Amherst, MA, United States [email protected]), AC(Geology, Pomona College, Claremont, United States [email protected]), AD(Pomona College, Claremont, CA, United States [email protected]), AE(Oberlin College, Oberlin, OH, United States [email protected])

Short Contributions – Utah Advanced Project

STRUCTURAL EVOLUTION OF A SEGMENTED NORMAL FAULT TRANSFER ZONE, SEVIER FAULT, SOUTHERN UTAH
BEN SURPLESS, Trinity University

AN ANALYSIS OF FRACTURES AROUND THE SEVIER FAULT ZONE IN RED HOLLOW CANYON NEAR ORDERVILLE, UTAH
CHARLEY H. HANKLA, The College of Wooster
Research Advisor: Shelley Judge

ANALYZING DEFORMATION WITHIN A NORMAL FAULT TRANSFER ZONE USING SFM 3D MODELING
CAROLINE MCKEIGHAN, Trinity University
Research Advisor: Benjamin Surpless

GEOMECHANICAL ANALYSIS OF SEDIMENTARY LAYERING AS A STRUCTURAL CONTROL ON FAULT PROPAGATION
CURTIS SEGARRA, Trinity University
Research Advisor: Benjamin Surpless

GIS ANALYSIS OF SUBSIDIARY STRUCTURES WITHIN A MAJOR NORMAL FAULT TRANSFER ZONE
MADISON WOODLEY, Mount Holyoke College
Research Advisor: Michelle Markley

Short Contributions – Nevada Advanced Project

PALEOENVIRONMENTAL ANALYSIS OF (PETRO)CALCIC SOIL HORIZONS IN THE MOJAVE DESERT
COLIN R. ROBINS, Claremont McKenna, Pitzer, and Scripps Colleges (The Claremont Colleges Consortium)

MORPHOLOGY AND GENESIS OF PEDOGENIC OOIDS IN CALCIC AND PETROCALCIC SOIL HORIZONS
ETHAN W. CONLEY, Beloit College
Research Advisor: Jim Rougvie

WHAT CAN PETROCALCIC LAMINAE TELL US ABOUT SOIL PROCESSES AND PALEOENVIRONMENTS?
KURT CRANDALL, Pitzer College
Research Advisor: Colin Robins

INTERPRETING POTENTIAL BARIUM SOURCES AT MORMON MESA, NV USING GEOCHEMICAL AND GEOMORPHOLOGICAL DATA
INDIA FUTTERMAN, Vassar College
Research Advisor: Kirsten Menking

δ13C AND δ18O GEOCHEMISTRY OF PEDOGENIC CARBONATES OF MORMON MESA, SOUTHEASTERN NEVADA, USA
PENELOPE VORSTER, Mount Holyoke College
Research Advisor: Steve Dunn

Short Contributions – Wyoming Advanced Project

ASSESSING VEGETATION AND FLUVIAL RESPONSES TO THE PALEOCENE-EOCENE THERMAL MAXIMUM IN THE HANNA BASIN (WYOMING, U.S.A.)
ELLEN D. CURRANO, University of Wyoming and BRADY Z. FOREMAN, Western Washington University

EVALUATION OF BULK ORGANIC CARBON ISOTOPE RECORDS FROM EARLY PALEOGENE STRATA IN THE HANNA BASIN (WYOMING, U.S.A.) SPANNING THE PALEOCENEEOCENE THERMAL MAXIMUM
JAMES CHISHOLM, Department of Geological Sciences, California State University, San Bernardino
Research Advisor: Joan E. Fryxell

VEGETATION STRUCTURE AND LITHOLOGY RESPONSE TO THE PALEOCENE-EOCENE THERMAL MAXIMUM IN THE HANNA BASIN, WYOMING
KEIFER NACE, Whitman College
Research Advisor: Pat Spencer

PROVENANCE OF FLUVIAL AND DELTAIC SANDSTONES ACROSS THE PALEOCENE-EOCENE BOUNDARY, HANNA BASIN, WYOMING
XAVIER ROJAS NOGUEIRA, Temple University
Research Advisor: Jesse Thornburg

VARIABILITY IN VEGETATION DENSITY ACROSS LATERALLY COEVAL STRATIGRAPHIC SECTIONS WITHIN THE HANNA BASIN, WYOMING, USA
JAKE POLSAK, Western Washington University
Research Advisor: Brady Z. Foreman

PALEOCURRENT VARIABILITY IN MEANDERING AND BRAIDED RIVER SYSTEMS: MODERN CALIBRATION AND STRATIGRAPHIC CASE STUDIES SPANNING THE PALEOCENE-EOCENE THERMAL MAXIMUM
ANTHONY SEMERARO, Western Washington University
Research Advisor: Brady Z. Foreman

EARLY PALEOGENE OVERBANK DEPOSITIONAL PATTERNS IN THE HANNA BASIN AND COMPARISON WITH COEVAL STRATA IN THE BIGHORN BASIN (WYOMING, U.S.A.)
CHRISTINE SHONNARD, Beloit College
Research Advisor: Jay Zambito

Cameron Davidson
Editor and Co-Director
Carleton College

Keck Geology Consortium
Macalester College
1600 Grand Ave., St Paul, MN 55105

Karl Wirth
Editor and Co-Director
Macalester College

Keck Geology Consortium Member Institutions:
Amherst College, Beloit College, Carleton College, Colgate University, The College of Wooster,
The Colorado College, Franklin & Marshall College, Macalester College, Mt Holyoke College,
Oberlin College, Pomona College, Smith College, Trinity University, Union College,
Washington & Lee University, Wesleyan University, Whitman College

Funding Provided by:
Keck Geology Consortium Member Institutions
The National Science Foundation Grant NSF-REU 1659322

Keck Geology Presentations at the 2019 GSA Cordilleran Section Meeting

Keck Geology Presentations at the 2019 GSA Cordilleran Section Meeting

Presentations by Keck Geology Consortium at the 2019 Geological Society of America Cordilleran Section Meeting

15-17 May 2019, Portland, Oregon

 

Wednesday, May 15, 2019, 09:00 AM – 06:00 PM; Oregon Convention Center – Exhibit Hall B

Booth No. 68 GEOMECHANICAL ANALYSIS OF SEDIMENTARY LAYERING AS A STRUCTURAL CONTROL ON FAULT PROPAGATION
Curtis Segarra (Trinity University), Benjamin Surpless (Trinity University ), Charley Hankla (College of Wooster ), Caroline McKeighan (Trinity University), (Madison Woodley (Mt. Holyoke College)

Booth No. 67 AN ANALYSIS OF FRACTURES AROUND THE SEVIER FAULT TRANSFER ZONE NEAR ORDERVILLE, UTAH
Charley Hankla (College of Wooster), Shelley Judge (The College of Wooster), Benjamin Surpless (Trinity University), Caroline McKeighan (Trinity University), Curtis Segarra (Trinity University), Madison Woodley (Mt. Holyoke College

Booth No. 66 ANALYZING DEFORMATION WITHIN A NORMAL FAULT TRANSFER ZONE USING SFM 3D MODELING
Caroline McKeighan (Trinity University), Benjamin Surpless (Trinity University), Curtis Segarra (Trinity University), Charley Hankla (College of Wooster), Madison Woodley (Mt. Holyoke College)

 

Thursday, May 16, 2019, 09:00 AM – 06:00 PM, Oregon Convention Center – Exhibit Hall B

Booth No. 44: U-PB DATING OF DETRITAL ZIRCON FROM TURBIDITES OF THE CHUGACH AND PRINCE WILLIAM TERRANES IN PRINCE WILLIAM SOUND, ALASKA: IMPLICATIONS FOR THE SIGNIFICANCE OF THE CONTACT FAULT SYSTEM AS A TERRANE BOUNDARY
MALIK, Alysala (Carleton College), FISHER, Will Sparhawk (Union College), GROSS ALMONTE, Nicholas (Carleton College), GARVER, John (Union College) and DAVIDSON, Cameron (Carleton College)

Booth No. 45: AGE AND PROVENANCE OF THE UPPER CRETACEOUS TO PALEOCENE VALDEZ GROUP OF THE CHUGACH TERRANE FROM THE RICHARDSON HIGHWAY AND NORTHERN PRINCE WILLIAM SOUND, ALASKA
GROSS ALMONTE, Nicholas (Carleton College), FISHER, Will (Union College), MALIK, Alysala (Carleton College), GARVER, John (Union College) and DAVIDSON, Cameron (Carleton College)

Booth No. 46: ZIRCON FACIES IN THE PALEOCENE-EOCENE ORCA GROUP INDICATE A PROVENANCE LINK TO THE CHUGACH TERRANE, PRINCE WILLIAM SOUND, ALASKA
FISHER, Will (Union College), POPE, Mollie (Union College), MALIK, Alysala (Carleton College), GARVER, John (Union College) and DAVIDSON, Cameron (Carleton College)

Booth No. 47: PROVENANCE OF SANDSTONE CLASTS FROM CONGLOMERATE OF THE PALEOCENE-EOCENE ORCA GROUP IN PRINCE WILLIAM SOUND, ALASKA
POPE, Mollie (Union College), FISHER, Will (Union College), MALIK, Alysala (Carleton College), GARVER, John (Union College) and DAVIDSON, Cameron (Carleton College)

Booth No. 66: SEDIMENT ASSIMILATION EXERTS PRIMARY CONTROL ON HF ISOTOPE RATIOS IN THE PALEOCENE-EOCENE SANAK-BARANOF PLUTONIC BELT, ALASKA
DAVIDSON, Cameron (Carleton College) and GARVER, John I. (Union College)

Booth No. 67: CRYSTALLIZATION AGES AND GEOCHEMISTRY OF THE MINERS BAY AND CEDAR BAY PLUTONS, PRINCE WILLIAM SOUND, ALASKA
GARCIA Jr., Victor (University of Texas at Austin), STOCKLI, Daniel (University of Texas at Austin), DAVIDSON, Cameron (Carleton College) and GARVER, John I. (Union College)

Booth No. 68: AGE AND TECTONIC SETTING OF THE PALEOCENE GLACIER ISLAND VOLCANIC SEQUENCE OF THE ORCA GROUP IN PRINCE WILLIAM SOUND, ALASKA
NOSEWORTHY, Caitlin (St. Norbert College), FLOOD, Tim (St. Norbert College), DAVIDSON, Cameron (Carleton College) and GARVER, John I. (Union College)

 

Friday, May 17, 2019, 11:00 AM – 11:20 AM, Oregon Convention Center – Room B117-1

32-9: REVISIONS TO THE STRATIGRAPHY OF THE FLYSCH FACIES OF THE CHUGACH, PRINCE WILLIAM, AND YAKUTAT TERRANES, SOUTHERN ALASKA: IMPLICATIONS FOR RECONSTRUCTION OF BAJA BC
GARVER, John I. (Union College) and DAVIDSON, Cameron (Carleton College)

31st Keck Proceedings Volume

Short Contributions – Geochronology Gateway Project

EXPLORING GEOCHRONOLOGY: DATING YOUNG LAVA FLOWS AND OLD TREES IN DECLINE
MEAGEN POLLOCK and GREG WILES, The College of Wooster

NEW COSMOGENIC AND VML DATES AND REVISED EMPLACEMENT HISTORY OF THE ICE SPRINGS VOLCANIC FIELD IN THE BLACK ROCK DESERT, UTAH
PATZKOWSKY, Samuel1, RANDALL, Emily2, ROSEN, Madison3, THOMPSON, Addison4, MOUA, Pa Nhia5, SCHANTZ, Krysden2, POLLOCK, Meagen2, JUDGE, Shelley2, WILLIAMS, Michael2, MATESICH, Cam2. (1) Franklin & Marshall College, Earth and Environment Department, 415 Harrisburg Ave, Lancaster, PA, 17603, (2) The College of Wooster, Department of Geology, 944 College Mall, Wooster, OH 44691, (3) Mount Holyoke College, Department of Geology, 50 College Street, South Hadley, MA, 01075, (4) Pomona College, Department of Geology, Sumner Hall, 333 N College Way, Claremont, CA 91711, (5) Carleton College, Department of Geology, One North College Street Northfield, MN 55057.

YELLOW CEDAR RESPONSE TO CLIMATIC SHIFTS AT CEDAR LAKE: JUNEAU, ALASKA
JOSHUA CHARLTON (The College of Wooster), ALORA CRUZ (Macalester College), KERENSA LOADHOLT (Oberlin College), MYRON LUMMUS (Trinity University), CHRISTOPHER MESSERICH (Washington and Lee University), Wiles, G., Buma, B., Krapek, J.

Short Contributions – Dominica Advanced Project

HAZARDS IN THE CARIBBEAN: THE HISTORY OF MAGMA CHAMBERS, ERUPTIONS, LANDSLIDES, STREAMS, AND FUMEROLES IN DOMINICA
HOLLI FREY, Union College, AMANDA SCHMIDT, Oberlin College, EROUSCILLA JOSEPH, University of West Indies Seismic Research Center, LAURA WATERS, Sonoma State University

EXPLOSIVE TO EFFUSIVE TRANSITION IN INTERMEDIATE VOLCANISM: AN ANALYSIS OF CHANGING MAGMA SYSTEM CONDITIONS IN DOMINICA
JESSICA BERSSON, Whitman College
Research Advisor: Kirsten Nicolaysen (Whitman College)

SOURCES OF VOLCANIC GASES FROM DOMINICA, LESSER ANTILLES
JACQUELINE BUSKOP, Wesleyan University
Research Advisors: Erouscilla (Pat) Joseph (University of the West Indies, Trinidad), Johan C. Varekamp (Wesleyan University), Timothy C. Ku (Wesleyan University), and Salvatore Inguaggiato (Instituto Nazionale di Geofisica e Vulcanologia, Palermo, Italy)

A PETROLOGIC EVALUATION OF THE LAYOU IGNIMBRITE AND MORNE TROIS PITON LAVA DOME: HOW DO CHANGES IN PRE-ERUPTIVE CONDITIONS AFFECT ERUPTIVE BEHAVIOR?
JUSTIN CASAUS, Sonoma State University
Research Advisor: Laura Waters (Sonoma State University)

A RE-EXAMINATION OF THE IGNIMBRITE AT FOND ST. JEAN, DOMINICA
NOLAN EBNER, Macalester College
Research Advisors: Holli Frey (Union College) and Karl Wirth (Macalester College)

MAGMATIC ENCLAVES AND MAGMA MIXING IN MORNE MICOTRIN, DOMINICA
SARAH HICKERNELL, Union College
Research Advisor: Holli Frey

UNDERSTANDING THE EFFECTS OF LARGE STORMS ON DOMINICA: AN ANALYSIS USING GIS AND REPEAT PHOTOGRAPHY
MARCUS HILL, Oberlin College
Research Advisor: Amanda Schmidt

STRATIGRAPHY AND GEOCHEMISTRY OF A FOND ST. JEAN CINDER CONE, DOMINICA
TARYN ISENBURG, Mount Holyoke College
Research Advisors: Steve Dunn and Holli Frey

RIVER DEVELOPMENT AND INCISION ON DOMINICA, WEST INDIES
COLE JIMERSON, The College of Wooster
Research Advisor: Amanda Schmidt

AN INVESTIGATION OF THE INFLUENCES ON THE GEOCHEMISTRY OF STREAMS IN DOMINICA, LESSER ANTILLES: 2014-2017
DEXTER KOPAS, Beloit College
Research Advisors: Susan Swanson, Erouscilla Joseph, and Holli Frey

DECOMPRESSION AND HEATING INDUCED AMPHIBOLE BREAKDOWN IN EFFUSIVE VOLCANISM ON DOMINICA, LESSER ANTILLES
ABADIE LUDLAM, Union College
Research Advisor: Holli Frey

INVESTIGATING VOLCANIC-HYDROTHERMAL SYSTEMS IN DOMINICA, LESSER ANTILLES: TEMPORAL CHANGES IN THE CHEMICAL COMPOSITION OF HYDROTHERMAL FLUIDS FOR VOLCANIC MONITORING USING GEOTHERMOMETERS
MAZI-MAZTHIS C. ONYEALI, University of Colorado, Boulder
Research Advisors: Holli Frey, Erouscilla Joseph, and Lon Abbott

INVESTIGATION OF MINERAL ALTERATION IN ANDESITE AND DACITE FROM THREE DIFFERENT VOLCANO HYDROTHERMAL SYSTEMS ON DOMINICA, LESSER ANTILLES
CLARISSA ITZEL VILLEGAS SMITH, Carleton College
Research Advisors: Cameron Davidson, Holli Frey, and Erouscilla Joseph

COMPOSITION AND SHORT-TIMESCALE EROSION PATTERNS OF RIVER SEDIMENTS ON DOMINICA
HALEY TALBOT-WENDLANDT, Ohio Wesleyan University
Research Advisor: Bart Martin

APPROXIMATING METEORIC 10BE USING THE CONCENTRATION OF ACID-EXTRACTABLE GRAIN COATINGS: A CASE STUDY TRACING EROSION DEPTH ON DOMINICA, LESSER ANTILLES
KIRA TOMENCHOK, Washington and Lee University
Research Advisors: David Harbor and Amanda Schmidt

EVIDENCE FOR COLD, HYDROUS PARENTAL MAGMAS ON DOMINICA: PETROLOGY OF THE FOUNDLAND BASALTS
KATHRYN VONSYDOW, California State University San Bernardino
Research Advisors: Laura Waters (Sedona College), Holli Frey (Union College), and Joan E. Fryxell (California State University San Bernardino)

Short Contributions – IODP Advanced Project

MULTIPLE PROXIES FOR INVESTIGATING GLACIAL HISTORY OF ANTARCTICA FROM ODP SITES 696 & 697
SUZANNE O’CONNELL, Wesleyan University, and JOSEPH ORTIZ, Kent State University

DIATOMS OF THE ANTARCTIC – ENVIRONMENTAL INTERPRETATION OF THE MIDDLE PLIOCENE AT SITE 697
EDUARDO CENTENO, Wesleyan University
Research Advisor: Suzanne O’Connell

PRELIMINARY WAVELET ANALYSIS OF CIRCUM-ANTARCTIC ODP WELL LOGS AND SPLIT-CORE XRF SCANS FROM ODP SITE 697 CORES INFERS OBLIQUITY SIGNAL
ANDREW HOLLYDAY, Middlebury College
Research Advisors: Suzanne O’Connell, Will Amidon, and Joe Ortiz

ANTARCTIC WEDDELL SEA ODP SITE 696 PLEISTOCENE- PLIOCENE DIATOMS
MARK LAPAN, Colgate University
Research Advisor: Amy Leventer

ZANCLEAN (EARLY PLIOCENE) SEDIMENT RECORDS OF ICE-SHEET INSTABILITY AT ODP SITE 697 (JANE BASIN), NW WEDDELL SEA, SOUTH ORKNEY MICROCONTINENT
FORREST W. LLOYD, Beloit College
Research Advisors: Suzanne O’Connell (Wesleyan University) and Jim Rougvie (Beloit College)

Cameron Davidson
Editor and Co-Director
Carleton College

Keck Geology Consortium
Macalester College
1600 Grand Ave., St Paul, MN 55105

Karl Wirth
Editor and Co-Director
Macalester College

Keck Geology Consortium Member Institutions:
Amherst College, Beloit College, Carleton College, Colgate University, The College of Wooster,
The Colorado College, Franklin & Marshall College, Macalester College, Mt Holyoke College,
Oberlin College, Pomona College, Smith College, Trinity University, Union College,
Washington & Lee University, Wesleyan University, Whitman College

Funding Provided by:
Keck Geology Consortium Member Institutions
The National Science Foundation Grant NSF-REU 1659322

Wyoming PETM

Wyoming PETM

Body size evolution of the first mammalian megaherbivore during Paleogene hyperthermal events, Wyoming

Overview: This project aims to understand the evolution of body size in Coryphodon, the first mammal to evolve large body size. Coryphodon was common across the northern hemisphere through much of the Paleogene, a time of tumultuous environmental and climatic change. In North America, Coryphodon experienced at least one dwarfing event during this period, halving and doubling its body mass in quick succession. Through a combination of field and laboratory work, undergraduate students will investigate the processes underlying body size evolution in Coryphodon, asking how and why climatic and environmental change may have affected the rate and duration of its growth. This project integrates knowledge and skills from earth and life sciences to answer fundamental questions about the mechanisms underlying body size evolution in the face of dramatic environmental change.

Figure 1: Students looking for fossils in the Paleogene of Wyoming.

When: June 14 – July 10, 2019

Where: Fieldwork will take place in Wyoming’s northern Bighorn Basin. Lodging will be a ~30 minute drive north, in Red Lodge, Montana.

Who: Six undergraduate students and Project Directors Dr. Michael D’Emic ([email protected]) and Dr. Simone Hoffmann ([email protected]). Collaborator Dr. Brady Foreman (Western Washington University) will join for the first week of the fieldwork and provide additional mentorship. Collaborator Dr. Elis Newham (University of Bristol) will contribute to cementum analysis after fieldwork.

Prerequisites and Recommended Courses: Required courses are at least two introductory-level geology and/or biology and cognate courses in chemistry and math. Suggested (but not required) courses include Historical Geology, Earth History Evolution, Anatomy, Stratigraphy/Sedimentology, and Paleontology. Experience at a field camp or in a field geology or biology course is recommended but not required. We are particularly interested in applicants who are comfortable in outdoor/backcountry settings, are able to complete day hikes in warm temperatures (on occasion greater than 95° F in the high desert climate), and who want to use this work to complete a senior thesis (or equivalent).

Expectations and Obligations:
1. Participation in all project-related work during the summer (June 14-July 10, 2019).
2. Follow up data analysis at home institution and regular conference calls with research advisors throughout academic year.
3. Write an abstract and present a paper (poster or talk) for the Geological Society of America Cordilleran meeting in Pasadena, California (conference is 12-14 May, 2020).
4. Write a short contribution (4-6 pages text + figures) to be published in the Proceedings of the Keck Geology Consortium 2020 Volume (first draft due Mid-February).
5. Expected but not required: Use this work for the completion of a senior thesis (or equivalent) at your home institution.

PROJECT DESCRIPTION

Background and Goals: Climate change affects the resources available to animals, impacting factors such as their geographic ranges, growth rates, and reproductive behaviors. These effects can be measured in the fossil record and used to predict ecosystem change in the future (Barnosky et al., 2017). One of the best-studied examples of past climate change and its effects is the Paleocene-Eocene Thermal Maximum (PETM) at about 56 Ma, which caused massive perturbations in floras (Wing et al., 2005), fluvial landscapes (Foreman et al., 2012), and mammalian evolution (Gingerich, 2003). The PETM was followed by a long-term warming trend during the early Eocene that culminated with the Early Eocene Climatic Optimum (Zachos et al., 2008). This long-term warming trend was punctuated by ‘hyperthermal’ events similar to the PETM during the early Eocene (Abels et al., 2015). In response to the PETM and other hyperthermals, rapid and extreme mammalian dwarfing occurred (Gingerich, 2003; Secord et al., 2012, d’Ambrosia et al., 2017). It is unclear how mammals evolved their smaller body size in terms of growth pattern and duration. The most commonly cited hypothesis is that dwarfing was due to decreased growth rates owing to lower nutrition content of plant resources (Gingerich, 2003). However, this hypothesis has not been tested, and it is equally plausible that smaller body size was achieved by growing at the same rates for a shorter period of time (Palkovacs, 2003). Undergraduates will test these hypotheses using the rich mammal fossil record in the Bighorn Basin of Wyoming, which densely covers the Paleogene.

This project will evaluate the growth mechanisms underlying changes in body size in the Paleogene mammal Coryphodon. Coryphodon is known from hundreds of localities in precisely dated paleosols of the Bighorn Basin, and its bones and teeth preserve annual growth rings that allow individual specimens to be aged. Coryphodon was the first mammalian megaherbivore ever to evolve (body mass > 1000 kg), reaching the size of a small rhinoceros during the mid-Paleocene (Uhen and Gingerich, 1995). Shortly after the PETM, it underwent a dwarfing event to half its body mass only to return to its original size later in the Eocene (Uhen and Gingerich, 1995).

Figure 2: Project director Dr. Michael D’Emic teaching a field course in Wyoming.

Figure 3: Students collecting a rich concentration of fossils from ancient soil beds in Wyoming.

Geologic Setting
Fieldwork will take place in Fort Union and Willwood formations of the northern Bighorn Basin, which are composed of a more than 2,000 m thick sequence of fluvial, floodplain, and minor palustrine deposits (Bown and Kraus, 1981). These extensive strata have been the target of over a century of detailed paleontological fieldwork, resulting in the recovery of tens of thousands of specimens (Gingerich, 2003). Fossil-hosting ancient soil horizons can be resolved temporally to ca. 100,000-year time intervals (Secord et al., 2006). In the case of Coryphodon there appears to be a mismatch between its interpreted semiaquatic lifestyle, inferred from anatomy and oxygen isotope data (Simons, 1960; Fricke et al., 1998), and the well-drained soil horizons it is surface collected from: (Uhen and Gingerich, 2003). We will address this conundrum by collecting detailed sedimentological data to place each newly collected specimen in a paleoenvironmental context.

The Willwood Formation contains a thick accumulation of floodplain deposits. The floodplain strata are characterized by a variety of paleosol sequences linked to short-term and long-term changes in sedimentation and pedogenic processes. A student pursuing this project would excavate specific soil horizons from several locations spanning the early Eocene and tied to the fossil sites collected. Excavation of fresh rock material will allow the student to characterize morphologic features within the soil horizons including ped structures, mottling, development of pedogenic nodules, and trace fossils. Previous studies have developed metrics based on these observations that produce a semi-quantitative record of floodplain drainage conditions and, in some cases, mean annual rainfall. The student would construct a long time series of these conditions spanning the same time frame and stratigraphic positions as the Coryphodon material. Collaborator Brady Foreman has applied this methodology to soil sequences in early Paleogene strata in Colorado and trained both undergraduates and graduate students in this process. Potential scientific questions include “What are the long-term hydrologic conditions in the Bighorn Basin during the early Paleogene?” “How do these paleoclimatic conditions compare to those of other Laramie basins?”

Much of the existing lithostratigraphic information in the northern Bighorn Basin is based on work performed in the late 1970s and early 1980s with the purpose of placing fossil localities in stratigraphic order relative to the K/Pg boundary. More detailed sedimentologic descriptions and assessments of larger stratigraphic changes in river deposition have been performed in isolated intervals focused on the Paleocene-Eocene boundary. A student involved in this project would measure a series of stratigraphic sections to establish long-term changes in fluvial deposition within the northern Bighorn Basin. The student would also perform assessments of biostratigraphy and integrate existing fossil localities and new localities discovered by this project into an updated and more detailed stratigraphic framework. Potential scientific questions include “What are the long-term changes in fluvial deposition and its relationship to climate?” “Is there a relationship between larger-scale fluvial deposition and the productivity and occurrence of fossil localities?”

Figure 4: The campfire ring at field camp, where students will both stay and perform lab work.

Potential Student Projects
Students will conduct fieldwork focusing on collecting new Coryphodon specimens. We will bring newly collected specimens back to the field station where students will prepare, photograph, mold, and cast the fossils. On laboratory days, students will be able to create thin sections of Coryphodon bones and teeth and will take photomicrographs of growth rings in tooth cementum and bones. In the last week of the project, students will estimate body mass for all samples and learn how to analyze growth curves in R. Specifically, students will plot individual age vs. body mass and fit competing growth models to the data using likelihood criteria (analysis in R). Growth models will be compared through time, and maximum growth rate and growth duration will be plotted against paleotemperature estimates to discover potential correlations between mechanisms of body mass evolution and climate. Students will also characterize floodplain drainage and the stratigraphic framework surrounding new fossil findings under the supervision of collaborator Dr. Brady Foreman (see description under ‘Geologic Setting’ above).
Student projects (each student takes the lead on one; collaborations encouraged):
1) bone histology
2) tooth histology
3) growth curve analysis
4) taphonomy/paleoenvironment
5) floodplain drainage
6) stratigraphic framework

Figure 5: Annual growth lines in Coryphodon bones and tooth roots. The number of rings equals the age of the animal and the spacing of the rings indicates how fast the animal grew.

PROJECT LOGISTICS

Project directors D’Emic and Hoffmann have led or participated in extensive fieldwork in the proposed field area. This project will be based out of the Yellowstone Bighorn Research Association, which is commonly used by geology field camps working in the area. Students will stay in group cabins, all three meals are provided, and there are several classrooms available for working on projects, lectures, and group discussions in the evenings. Collected fossils will eventually be accessioned at the University of Michigan Museum of Paleontology under the Bureau of Land Management permits. An Isomet slow-speed saw, Buehler sander/grinder, electronic balance, and small vacuum chamber will be used to set up a histology lab in the field. Students will be trained in taking specimen photos, molding, and casting to preserve the morphology of the bones before sampling. Students will take mid-shaft cross sections of long bones and cross-sections of tooth roots using diamond blades on a slow-speed Isomet saw. Petrographic-style thin sections will be created according to standard paleohistological techniques (Lamm and Padian, 2013). A microscope with a USB-attached camera will be made available so that students can take photomicrographs of growth rings in bones and teeth. Students will use either personal laptops or laptops from one of the Project Directors’ institutions. Students working on floodplain or stratigraphic projects will be trained in sedimentologic analysis and measuring stratigraphic sections.

Safety
As with any field and lab work there will be safety concerns. Field risks include dehydration, heat stroke, exhaustion, sunburn, insect bites, poisonous snakes, and physical injuries such as sprained ankles and broken bones. Lab risks are relatively minor, but include risk of cuts and scrapes when making thin sections. Risks will be mitigated by following proper training protocols, outlining and identifying the risks, and holding several safety meetings. Faculty associated with the project have extensive experience in all pertinent field and lab methodologies, first aid training, and will coordinate with lab technicians to maintain safety standards.

The faculty members involved in this project and collaborators collectively have over 20 field seasons of experience working in the region. They have published several scientific articles centering on the field area. All have led several field crews of undergraduate and graduate students under similar circumstances.

PROFESSIONAL DEVELOPMENT

All students involved with the project will attend the GSA Cordilleran section meeting in Pasadena, California (12–14 May 2020). We hope most students will be first author on one abstract, and probably secondary authors on others due to the collaborative nature of the project.
All students are required to complete a 4–6 page paper (short contribution) that will be published in the Proceedings of the Keck Geology Consortium 2020 Volume (see examples from previous years). The first draft of this paper will be reviewed by your research advisor at your home institution sometime in late February, 2020, with the revised version sent to the project directors by March 1. Final versions of your paper and figures will be submitted to the Keck Office in Mid-March.

References

Abels, H.A., Clyde, W.C., Gingerich, P.D., Hilgen, F.J., Fricke, H.C., Bowen, G.J., and Lourens, L.J. 2012. Terrestrial carbon isotope excursions and biotic change during Palaeogene hyperthermals. Nature Geoscience 5: 326–329.

Barnosky, A.D., Hadly, E.A., Gonzalez, P., Head, J., Polly, P.D., Lawing, A.M. et al. 2017 Merging paleobiology with conservation biology to guide the future of terrestrial ecosystems. Science 355: eaah4787.

D’Ambrosia, A.R., Clyde, W.C., Fricke, P.D. Gingerich, and Abels, H.A. 2017. Repetitive mammalian dwarfing during ancient greenhouse warming events. Science Advances 3: e1601430.

Bown, T.M., and Kraus, M.J. 1981. Lower Eocene alluvial paleosols Willwood Formation, northwest Wyoming, USA and their significance for paleoecology paleoclimatology, and basin analysis. Palaeogeography, Palaeoclimatology, Palaeoecology 34: 1–30.

Fricke, H.C., Clyde, W.C., O’Neil, J.R., and Gingerich, P.D. 1998. Evidence for rapid climate change in North America during the latest Paleocene thermal maximum: oxygen isotope compositions of biogenic phosphate from the Bighorn Basin (Wyoming). Earth and Planetary Science Letters 160: 193–208

Gingerich, P.D. 2003. Mammalian responses to climate change at the Paleocene-Eocene boundary: Polecat Bench record in the northern Bighorn Basin, Wyoming. In S.L. Wing, P.D. Gingerich, B. Schmitz, and E. Thomas (eds.), Causes and consequences of globally warm climates in the early Paleogene, Geological Society of America, Special Paper 369: 463–478.

Palkovacs, E.P. 2003. Explaining adaptive shifts in body size on islands: A life history approach. Oikos, 103: 37–44.

Secord, R., Bloch, J.I., Chester, S.G.B., Boyer, D.M., Wood, A.R., Wing, S.L., Kraus, M.J.,McInerney, F.A., and Krigbaum, J. 2012. Evolution of the earliest horses driven by climate change in the Paleocene-Eocene Thermal Maximum. Science 335: 959–962.

Simons, E.L. 1960. The Paleocene Pantodonta. Transactions of the American Philosophical Society 50: 1–81.

Uhen, M.D., and Gingerich, P.D. 1995. Evolution of Coryphodon (Mammalia, Pantodonta) in the late Paleocene and early Eocene of northwestern Wyoming. Contributions from the Museum of Paleontology, University of Michigan 29: 259–289.

Wing, S.L., Harrington, G.J., Smith, F.A., Bloch, J.I., Boyer, D.M., and Freeman, K.H. 2005. Transient floral change and rapid global warming at the Paleocene-Eocene boundary. Science 310: 993–996.

Zachos, J.C., Dickens, G.R., and Zeebe, R.E. 2008. An early Cenozoic perspective on greenhouse warming and carbon-cycle dynamics. Nature 451: 279–283.

Rhyolitic eruptions

Rhyolitic eruptions

Using 3D petrography of microlites and bubbles in obsidian to assess factors governing eruptive style for rhyolitic magmas

Overview: This four-student advanced Keck project will investigate the factors controlling eruption style in rhyolite volcanic systems, which are among the largest and most destructive on Earth. The project will kick off with a visit to the spectacular Long Valley caldera in central-eastern California to begin building our understanding of rhyolitic systems and to sample young lava domes of the Inyo and Mono craters volcanic chains. Relocating to San Antonio we will then embark on a 3D micro-textural and in-situ analytical study of flow-banded obsidian from Long Valley and from heavily dissected and deeply exposed rhyolite lavas, pyroclastic deposits, and associated vent structures from the largest volcano in eastern Australia. Students will use: (1) bubble and microlite size, shape, number, and orientation distributions to constrain magma ascent and eruption dynamics; and (2) mineral and glass major-element and volatile concentrations to reconstruct pre-eruptive magma storage conditions and to track potential changes in magma properties and compositions during eruption.

Aerial photo of the lava domes and coulées of the Mono-Inyo craters volcanic chain, looking south from Mono lake towards Long Valley caldera and Sierra Nevada mountains (Photo by R. Von Huene, 1971, United States Geologic Survey)

When: June 15 – July 13, 2019 (tentative)

Where: Long Valley, California (introduction and field work) and San Antonio, Texas (lab work).

Who: Four rising senior students and project leader Dr. Kurt Knesel, Trinity University, [email protected]

Prerequisites and Recommended Courses: Students should have taken an Earth materials course, covering basic mineralogy & petrology. The ideal student would have also had (or would be taking during Fall 2019) a more advanced course in either igneous petrology or structural geology. Some background in chemistry and physics is also recommended but not required. We are particularly interested in applicants with an interest in volcanology, who are comfortable and enthusiastic about working in both outdoor and laboratory environments, and who want to use this work to complete a senior thesis (or equivalent) in geology.

Expectations and Obligations:
1. Participation in field work and data acquisition and analysis during the summer (approximately June 15 to July 13, 2019)
2. Follow-up data acquisition and analysis at home institution and regular correspondence with research team throughout the 2019-2020 academic year.
3. Write an abstract and present a paper (poster or talk) for either the Geological Society of America Cordilleran or Rocky Mountain section meeting in Pasadena, California (May 12-14), or Provo, Utah (May 4-5), respectively.
4. Write a short contribution (4-6 pages text + figures) to be published in the Proceedings of the Keck Geology Consortium 2020 Volume (first draft due Mid-February, 2020).
5. Expected but not required: Use this work for the completion of a senior thesis (or equivalent) at your home institution.

PROJECT DESCRIPTION

Background & Significance
Deciphering the factors governing eruption of intermediate to silicic magma is a fundamental problem in volcanology. A general model has emerged relating eruptive style to the interplay between ascent rate and the efficiency and extent of volatile loss during magma transport from subvolcanic chambers (e.g., Gonnermann & Manga, 2007). Fast ascent is believed to inhibit volatile loss, leading to volatile overpressure and ultimately explosive fragmentation; in contrast, slow magma ascent favors gas escape and lava extrusion. Rise-rate estimates for magmas of andesitic and dacitic compositions are indeed consistent with this model (e.g., Rutherford & Gardner, 2000). However, comparable data for rhyolitic eruptions is sparse (e.g., Costa & Dingwell, 2009; Pallister et al., 2013), and the extent to which ascent rate dictates degassing and eruptive behavior is unclear (e.g., Castro & Gardner, 2008).

Creative approaches to this critical problem are sorely needed. One promising avenue is quantitative 3-D petrographic study of the size, shape and orientation distributions of vesicles and microlites in flow-banded obsidian (i.e., rhyolitic volcanic glass with distinct bands typically defined by differences in abundance of microlites and/or bubbles). For example, orientations of dilute concentrations of microlites can be used to estimate the magnitude and type of shear strain accumulation during magmatic flow (e.g., Manga, 1998; Castro et al., 2002), while bubble shapes and orientations provide constraints on flow stresses and strain rates (e.g., Rust & Manga, 2002; Rust et al., 2003; Rust & Cashman, 2007). When combined, microlite and bubble measurements for the same samples provide a powerful tool for investigating the rates, timescales and dynamics of magma ascent and eruptive emplacement.

We have begun to apply this approach to highly dissected rhyolite domes, pyroclastic deposits, and associated feeder conduits of the compositionally bimodal Tweed volcano, in eastern Australia. Our initial measurements of microlite orientations (Figure 1) within the basal obsidian of a large lava dome yield simple-shear strains of up to 12 (Brown, 2010; Cook, 2011). Relative to an average pure-shear strain of 1 to 2 derived from fold geometries higher in the dome (Smith & Houston, 1994) and strains of < 5 for flow front and upper surface samples of other rhyolite domes (Castro et al., 2002; Befus et al., 2014; Befus et al., 2015), our estimates are remarkably high. Measured shapes and orientations of deformed bubbles (Figure 2) are also consistent with dominantly simple shear in the basal obsidian and allow calculation of shear rates on the order of 10-5s-1 (Knesel et al., 2011). Collectively, these results indicate that the basal portions of lava domes may accommodated most of the deformation during emplacement, while the main mass of lava is rafted above.

Figure 1: Example of 3D microlite reconstruction and strain estimates derived from variance in microlite alignment. (A) Scan of thin section of flow-banded obsidian showing location (yellow star) of area imaged in photomicrograph in (B). (B) photomicrograph of microlites in obsidian (scale bar is ~20 microns). (C) 3D microlite reconstruction derived from a stacked set of digitized images taken from sequential focal depths within the thin section. (D-F) Histograms showing trend direction for three reconstruction locations showing the range of estimated (simple shear) strain derived by comparison of variance in microlite orientation distributions to simulation of theoretical distributions obtained by integration of the relevant equations of motion (e.g., Manga, 1998) for three sample locations.

If microlite and bubble orientations mainly reflect flow at the surface, the average strain and strain rate for individual samples can be used to assess emplacement timescales. Our preliminary data indicate that some large lava domes (>1km3) may be emplaced over a period as brief as a few months, and fed by rhyolitic magma ascending at a rate potentially approaching 1m/s. This ascent estimate is unexpectedly fast and similar to pre-fragmentation rise-rate estimates for explosively erupted rhyolite at Chaitén volcano in Chile (Castro & Dingwell, 2009). If correct, it would appear that, contrary to conventional view, explosive rhyolitic volcanism may not be an inevitable consequence of rapid ascent alone. This possibility requires a re-assessment of current eruption models for rhyolitic systems.

Overarching Goal & Hypotheses
Our overarching goal is to better constrain the factors determining whether rhyolitic magma erupts explosively or effusively. Our starting hypothesis is that magma rise rate dictates the style of rhyolitic volcanism, with fast ascent leading to explosive eruption and slow ascent favoring effusive behavior (e.g., Gonnermann & Manga, 2007). However, as noted above, some of our preliminary results indicate that rapid rise of coherent (pre-fragmentation) rhyolitic magma may not necessarily lead to explosive eruption. An alternative hypothesis is that explosive fragmentation may result from sudden decompression of rhyolitic magma resident in a conduit prior to eruption, rather than simply by a fast-ascent mechanism (e.g., Castro & Gardner, 2008). In this second scenario, some Plinian and Sub-Plinian eruptions may be more akin to Vulcanian eruptions typical of intermediate magma compositions and may ultimately reflect the associated build up and alleviation of exsolved volatile pressure in the conduit transport system (e.g. Castro & Gardner, 2008).

Study Areas
The project includes examination of samples from two volcanic systems: the Mono-Inyo volcanic chain, Long Valley caldera (California), and rhyolite lavas and associated pyroclastic deposits of the Tweed volcano (Australia). The Tweed volcanic center has been the main research site for our structural analysis of flow-related textures over the past decade. The heavy dissection of this Miocene-age system provides us with unprecedented access to the basal glassy portion of rhyolite lava domes, as well as excellent exposure of cogenetic pyroclastic deposits and associated vent structures. In contrast, the Holocene Mono-Inyo chain in California provides easy access to the glassy upper and flow-front portions of rhyolite domes, and, due to its young age, is less susceptible to volatile redistribution following emplacement. Because we already have an extensive obsidian sample set for the Australian system (developed through the course of three honors theses at the University of Queensland), the field portion of the project will target the Mono-Inyo chain in California.

Research Methods
Field work: We will spend our first day or two in the field exploring key locations of fall and ash-flow deposits of the Bishop Tuff, along with key overlook stops of the spectacular Long Valley caldera, to develop an understanding of how field studies of volcanic rocks provide insight into eruptive dynamics. The remainder of our field time will be spent examining, documenting, and sampling macro-scale flow structures (e.g., orientations and dimensions of flow bands and folds) on the surfaces of young lava domes of the Inyo and Mono volcanic chains. The goal of this field work will be to assess the magnitude, type of strain developed, and displacement field in the outer portions of rhyolite lava domes, providing a comparative point to our investigation of the deeper portions of dissected domes in eastern Australia. As we explore the products of both effusive and explosive eruptions in the field, we will begin to formulate ideas for individual projects.

Quantitative and qualitative 3D micro-textural data: Up to this point my students and I have measured microlite and bubble populations using oriented thin sections and standard research-grade microscopes (Brown, 2010; Cook, 2011; Luck, 2012). The transparent nature of obsidian (Figure 1) allows 3D microlite orientations to be constrained using a series of high-magnification digital micrographs taken serially through different focal depths (i.e., focusing down into the thin section) followed by stacking and digitizing of these serial images in a computer-automated drafting (CAD) program (e.g., Manga, 1998). Quantification of bubble populations, which typically display a larger range in sizes compared to microlite populations, requires examination of two thin sections in mutually perpendicular planes (Figure 2) for each sample to enable the measurement of the three radii of deformed bubbles and the angle between the long dimension of bubbles and the flow direction, as defined by flow bands (e.g., Rust et al., 2003).

We will build on our quantitative textural dataset through use of the High-Resolution X-ray Computed Tomography (X-rayCT) facility at the University of Texas (UT) at Austin. The UT X-rayCT lab is a NSF-supported national shared multi-user facility, and is well set up to facilitate post-analysis image processing and visualization of scan data. The majority of our samples will likely be analyzed using the Xradia microXCT scanner, which has a resolution below 1 micrometer, but larger samples will take advantage of the upgraded North Star Imaging (NTS) scanner.

Microlite size distributions and number densities are byproducts of the 3D textural measurements discussed above. These size and density distributions can provide additional constraints on magma degassing and ascent dynamics (e.g., Toramaru et al., 2008; Melnik et al., 2011), but their application requires careful mineral identification. Towards this end, we will begin to quantify microlite populations (feldspar, pyroxene, and Fe-oxides) using the energy-dispersive (EDS) capability of the JOEL JSM-6010LA SEM in the Center for Science and Innovation at Trinity; for students with SEM capabilities at their home institution, this microlite quantification can be continued during the academic year.

Melt and mineral compositional data: Estimates of pre-eruptive storage conditions are critical to assessing degassing during ascent and to estimating melt viscosity. Importantly, the latter is also required to derive strain rates from bubble deformation data. We will determine magma storage conditions (pressure, temperature, volatile content) through analysis of phenocrysts, matrix glass, and quartz-hosted glass inclusions. Major elements will be determined by electron microprobe (EMPA) at UT and/or students’ home institutions. Volatile contents will be measured by Fourier-Transform Infrared (FTIR) spectroscopy at UT and/or students’ home institutions.

Figure 2: Example of the use of bubble orientations in obsidian to estimate shear rates. (A) Photomicrograph oriented perpendicular to the shear plane (containing the shear direction) suitable for measuring the semi-principal axes l, b and the angle between l and the flow direction, as shown in (C). Scale bars in (A & B) are ~200 microns. (B) Photomicrograph in plane perpendicular to bubble lineation used to measure b and c. (D) Fit to b-c bubble axis data measured from orientation in (B) used to calculate c values for data in (A), which allows derivation of the radius for undeformed bubbles using equation in (C). (E) Fit to “small deformation” bubble data (Ca<1) used to derive Ca/a ratio and ultimately to calculate the strain rate from the expression for the capillary number (Ca).

Potential Student Projects: While we envision a wide range of potential projects, our hope is to foster a collaborative research environment where all students feel comfortable sharing and integrating their results and to work as a team to address our overriding goal. As we begin to define each project, on the bases of student interests and consideration of availability of analytical equipment at their home institutions, it will be important to consider the following questions:
• Do microlite (& bubble) alignment reflect flow in the vent, flow on the surface, or both?
• How fast is fast? What is the upper limit of flow velocities (in shallow conduits) separating effusive and explosive eruptions?
• Over what time scales are rhyolite lava domes emplaced?
• How does strain accumulate across lava domes and what role does strain localization play in dome emplacement?
• What is the origin of pyroclastic obsidian?
• How do microlite and bubble textures in obsidian vary between lava, pyroclast, and vent samples?
• To what extent do pre-eruptive magma conditions in the feeder system, as well as storage chambers, play in determining eruptive style?
• How and where does rhyolitic magma degas?

Any one or more of these research questions could form the basis of an individual student research project. Each student could be involved in the acquisition and integration of a range of data types (quantitative textural data, mineral/glass major-element data, glass water and CO2 contents, etc.) for one type of volcanic deposit/structure (i.e., dome vs. pyroclastic vs. vent obsidian). Alternatively, some projects could primarily focus on an individual technique (e.g., FTIR) and data type (e.g., volatile contents) and could include samples from one, two, or all three deposit/structure types. Although we don’t plan to strictly predefine individual projects at the onset of the summer program, five options are listed below to provide a starting point for discussion.

Project 1: Pre-eruptive storage conditions and eruption dynamics of rhyolite lava.
Project 2: Origin of pyroclastic obsidian and implications for pre-fragmentation magma ascent in explosive eruptions.
Project 3: Magma flow dynamics and degassing within an exposed rhyolite vent.
Project 4: Breaking magma: repeated fracturing and healing of melt and the localization of strain in the basal shear zone of a lava dome.
Project 5: Structural analysis of flow foliations and folds as indicators of rheology and 3D kinematics of lava-dome emplacement.

Ultimately, individual projects will be formulated based on both student interests and availability of analytical equipment (e.g., SEM, EMPA, FTIR) at their home institutions. However, all students will gain exposure to cutting-edge high-resolution imaging techniques (SEM & X-rayCT), as well as experience in basic field techniques. All students will learn to:
• Properly document field data, including notebook organization and field-sketching techniques and field-based photography;
• Map and sample structural features of lava domes and flows using standard field equipment;
• Observe and analyze both qualitative and quantitative petrographic information (obtained from traditional optical microscopy) in the context of a focused research project, including microlite and bubble size and orientation data, shear flow indicators (e.g., rotated phenocrysts), folding of flow bands, and brittle-ductile textures (Trinity and home institutions);
• Measure and analyze qualitative and semi-quantitative textural and chemical data using an SEM with EDS (Trinity and home institutions);
• Utilize state-of-the-art X-ray computed tomography (X-rayCT) techniques to obtain and visualize 3D textural data for volcanic samples (UT).

PROJECT LOGISTICS

The summer portion of the project will tentatively run from June 15 to July 13, and will involve a combination of field work (Long Valley, CA) and laboratory work (Trinity and University of Texas).

The first quarter of the project will be dedicated to field work at Long Valley caldera and the associated Inyo-Mono volcanic chain. Students will fly directly to LA, where we will meet at LAX, rent a vehicle, and drive to Bishop (about 5 hours driving time). While in the field we will plan to stay at the Owens Valley Station (OVS) of the White Mountain Research Station (WMRS). The OVS is located about 4 miles east of the town of Bishop at an elevation of 4108 ft; it has air-conditioned dorms and provides excellent cooked meals. We tentatively plan to drive back to LA on morning of June 24th and fly to San Antonio in the evening.

The remainder of the time in the summer will be spent working at Trinity and the University of Texas in Austin. Students will stay in dorms at Trinity with other summer research students. Most dorms have kitchens facilities, so meals can be prepared on campus. Given that our stay at Trinity will coincide with the summer academic session, there should also be access to the main dining facility on campus (Mabee Dining Hall).

Upon arrival at Trinity, we will follow up our field work with a 3-day short course meant to: (1) provide an overview of volcanism in eastern Australia and a hands-on introduction to the associated obsidian sample set, which will complement the samples we collected from the Mono-Inyo chain; (2) an overview of the analytical techniques that we will employ at Trinity, UT, and/or students’ home institutions; and (3) an introduction to the theoretical aspects of magma flow and deformation, including application of quantitative microlite and bubble data. During this stage, we will begin examining the macro and micro-textures of the obsidian samples (in hand-samples and in thin-sections), as we work to refine the individual student projects.

Once the projects are set, students (both individually and collectively) will concentrate on: (1) developing a research proposal, including a timeline for the academic year; (2) sample preparation (e.g., thin/thick-section billet preparation, carbon-coating existing thin-sections, cylinder coring for XrayCT); and (3) initial data acquisition and treatment (primarily SEM work at Trinity & XrayCT work at UT). The close proximity of Trinity and UT (~ 1-hour dive) should allow us to organize sample preparation, data acquisition and treatment, and initial data analysis as needed.

Once at their home institutions, students will continue data collection and analysis as set out in their research proposals. Monthly or, if necessary, bi-weekly Skype, Facetime and/or WhatsApp meetings will be organized with each student and their home advisor (when possible) and with all of the students as a group (when appropriate) to ensure we stay on track to meet our individual and collective goals.

Safety
As with any field and lab work there will be inherent safety concerns. Field hazards include dehydration, heat exhaustion, sunburn, insect bites, poisonous snakes, and physical injuries, such as sprained ankles, broken bones, and skin abrasions or lacerations, as well as potential personal injury due to vehicular accident during travel to and from the field area and daily trips to individual field sites. Lab risks for this project are relatively minor but do include possible skin lacerations or abrasion when cutting or coring samples for preparation of thin/thick section billets and for X-rayCT samples. Risks will be mitigated by adhering to proper safety protocols, including wearing appropriate protective equipment and following standard operating procedures, both in the field and in the lab. We will hold safety meetings where we identify hazards and assess risks, and outline appropriate control measures.

Although summertime high temperatures at the Owens Valley station (at an elevation of just over 4000 ft) are typically in the mid 90s, the majority of field sites in the Mono-Inyo craters area are between 7000 to 8000 ft, where summertime highs are typically 70-80ºF and average lows are in the low to mid 40s. Thus, layered clothing is necessary, and a medium-sized day pack is essential to allow for clothing changes and sufficient food and water (several large bottles) for each day. Sturdy hiking boots and gloves (ideally leather) are also key for safety while working on blocky lava flows and domes.

PROFESSIONAL DEVELOPMENT

Towards the end of the 2019-2020 academic year, we plan to take all participants to either the GSA Cordilleran (May 12-14) or Rocky Mountain (May 4-5) section meeting in Pasadena, CA, or Provo, Utah, respectively, to present their results. We hope that most students will be first author on one paper (poster or talk), and probably secondary authors on others due to the collaborative nature of the project. The project director will work with each student and their home advisor to facilitate this important step in their professional development. And, recognizing that the timing of GSA section meetings may present issues with exam and other class-project deadlines towards the end of the academic year, the project director will coordinate with each student and their home advisor to select the most appropriate meeting.

In addition, all students are required to complete a 4-6 page (short communication) that will be published in the Proceedings of the Keck Geology Consortium 2020 Volume (see examples from previous years). The first draft of this paper will be reviewed by your research advisor at your home institution in February, 2020, with the revised version sent to the project director by March 1. Final versions of your paper and figures will be submitted to the Keck Office in mid-March.

References

Befus, K.S., Zinke, R.W., Jordan, J.S., Manga, M., & Gardner, J.E. (2014) Pre-eruptive storage conditions and eruption dynamics of a small rhyolite dome: Douglas Knob, Yellowstone volcanic field, USA. Bulletin of Volcanology 76, 1-12.

Befus, K.S., Manga, M., Gardner, J.E., & Williams, M. (2015) Ascent and emplacement dynamics of obsidian lavas inferred from microlite textures. Bulletin of Volcanology 77, 1-17.

Brown, A. (2010) Flow dynamics, strain history and structural evolution of the basal shear zone of silicic lava, Minyon Falls Rhyolite, New South Wales, Australia. Unpublished Honors Thesis, University of Queensland, pp. 53.

Castro, J., Manga, M., & Cashman, K. (2002) Dynamics of obsidian flows inferred from microstructures: insights from microlite preferred orientations. Earth and Planetary Science Letters 302, 38-50.

Castro, J.M. & Gardner, J.E. (2008) Did magma ascent rate control the explosive-effusive transition at the Inyo volcanic chain, California? Geology 36, 279-282.

Castro, J.M. & Dingwell, D.B. (2009) Rapid ascent of rhyolite magma at Chaiten volcano, Chile. Nature 461, 780-784.

Cook, 2011 Ascent and emplacement history of silicic lava inferred from microlite and bubble shapes and orientations Minyon Falls Rhyolite, New South Wales, Australia, Unpublished Honors Thesis, University of Queensland, pp. 250.

Gonnermann, H.M. & Manga, M. (2007) The fluid mechanics inside a volcano. Annual Review of Fluid Mechanics 39, 321-356.

Knesel, K., Brown, A., Cook, S. & Luck, D. (2011) Strain history and emplacement dynamics of lava domes: insights into shear-fragmentation and degassing of silicic magma. Biennial Conference of the Geological Society of Australia Specialist Group in Geochemistry, Mineralogy & Petrology, Murramarang, Australia.

Luck, D. (2012) Flow dynamics and eruptive history of silicic magma from the Tweed shield volcano, using bubble deformation analysis. Unpublished Honors Thesis, University of Queensland, pp. 138.

Manga, M. (1998) Orientation distribution of microlites in obsidian. Journal of Volcanology and Geothermal Research 86, 107-115.

Melnik, O.E., Blundy, J.D., Rust, A.C. & Muir, D.D. (2011) Subvolcanic plumbing systems imaged through crystal size distributions. Geology 39, 403-406.

Pallister, J.S., Diefenbach, A.K., Burton, W.C., Munoz, J., Griswold, J.P., Lara, L.E., Lowenstern, J.B., & Valenzuela, C.E. (2013) The Chaiten rhyolite lava dome: Eruption sequence, lava dome volumes, rapid effusion rates and source of the rhyolite magma. Andean Geology 40, 277-294.

Rust, A.C., & Manga, M. (2002) Bubble shapes and orientations in low Re simple shear flow. Journal of Colloid and Interface Science 249, 476-480.

Rust, A.C., Manga, M. & Cashman, K.V. (2003) Determining flow type, shear rate and shear stress in magmas from bubble shapes and orientations. Journal of Volcanology and Geothermal Research 122, 111-132,

Rust, A.C. & Cashman, K.V. (2007) Multiple origins of obsidian pyroclasts and implications for changes in the dynamics of the 1300 B.P. eruption of Newberry Volcano, USA. Bulletin of Volcanology 69, 825-845.

Rutherford, M.J. & Gardner, J.E. (2000) Rates of magma ascent. In Encyclopedia of Volcanoes (Ed. Sigurdsson, H.) 207-217.

Smith, J.V. & Houston, E.C. (1994) Folds produced by gravity spreading of a banded rhyolite lava flow. Journal of Volcanology and Geothermal Research 63, 89-94.

Toramaru, A., Noguchi, S., Oyoshihara, S. & Tsune, A. (2008) MND (microlite number density) water exsolution rate meter. Journal of Volcanology and Geothermal Research 175, 156-167.

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