PROCEEDINGS OF THE TWENTY-EIGHTH ANNUAL KECK RESEARCH SYMPOSIUM IN GEOLOGY

April 2015 Union College, Schenectady, NY

Dr. Robert J. Varga, Editor Director, Keck Geology Consortium Pomona College

Dr. Holli Frey Symposium Convener Union College

Carol Morgan Keck Geology Consortium Administrative Assistant

Christina Kelly Symposium Proceedings Layout & Design Office of Communication & Marketing Scripps College

Keck Geology Consortium Geology Department, Pomona College 185 E. 6th St., Claremont, CA 91711 (909) 607-0651, [email protected], keckgeology.org

ISSN# 1528-7491

The Consortium Colleges The National Science Foundation ExxonMobil Corporation

KECK GEOLOGY CONSORTIUM PROCEEDINGS OF THE TWENTY-EIGHTH ANNUAL KECK RESEARCH SYMPOSIUM IN GEOLOGY ISSN# 1528-7491

April 2015

Robert J. Varga Keck Geology Consortium Christina Kelly Editor and Keck Director Pomona College Proceedings Layout & Design Pomona College 185 E 6th St., Claremont, CA Scripps College 91711

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, Williams College

2014-2015 PROJECTS

RESILIENCE OF ENDANGERED ACROPORA SP. CORALS IN BELIZE. WHY IS CORAL GARDENS REEF THRIVING?: Faculty: LISA GREER, Washington & Lee University, HALARD LESCINSKY, Otterbein University, KARL WIRTH, Macalester College Students: ZEBULON MARTIN, Otterbein University, JAMES BUSCH, Washington & Lee University, SHANNON DILLON, Colgate University, SARAH HOLMES, Beloit College, GABRIELA GARCIA, Oberlin College, SARAH BENDER, The College of Wooster, ERIN PEELING, Pennsylvania State University, GREGORY MAK, Trinity University, THOMAS HEROLD, The College of Wooster, ADELE IRWIN, Washington & Lee University, ILLIAN DECORTE, Macalester College

TECTONIC EVOLUTION OF THE CHUGACH-PRINCE WILLIAM TERRANE, SOUTH CENTRAL ALASKA: Faculty: CAM DAVIDSON, Carleton College, JOHN GARVER Union College Students: KAITLYN SUAREZ, Union College, WILLIAM GRIMM, Carleton College, RANIER LEMPERT, Amherst College, ELAINE YOUNG, Ohio Wesleyan University, FRANK MOLINEK, Carleton College, EILEEN ALEJOS, Union College

EXPLORING THE PROTEROZOIC BIG SKY OROGENY IN SW MONTANA: METASUPRACRUSTAL ROCKS OF THE RUBY RANGE Faculty: TEKLA HARMS, Amherst College, JULIE BALDWIN, University of Montana Students: BRIANNA BERG, University of Montana, AMAR MUKUNDA, Amherst College, REBECCA BLAND, Mt. Holyoke College, JACOB HUGHES, Western Kentucky University, LUIS RODRIGUEZ, Universidad de Puerto Rico-Mayaguez , MARIAH ARMENTA, University of Arizona, CLEMENTINE HAMELIN, Smith College

Funding Provided by: Keck Geology Consortium Member Institutions The National Science Foundation Grant NSF-REU 1358987 ExxonMobil Corporation

GEOMORPHOLOGIC AND PALEOENVIRONMENTAL CHANGE IN GLACIER NATIONAL PARK, MONTANA: Faculty: KELLY MACGREGOR, Macalester College, AMY MYRBO, LabCore, University of Minnesota Students: ERIC STEPHENS, Macalester College, KARLY CLIPPINGER, Beloit College, ASHLEIGH, COVARRUBIAS, California State University-San Bernardino, GRAYSON CARLILE, Whitman College, MADISON ANDRES, Colorado College, EMILY DIENER, Macalester College

ANTARCTIC PLIOCENE AND LOWER PLEISTOCENE (GELASIAN) PALEOCLIMATE RECONSTRUCTED FROM OCEAN DRILLING PROGRAM WEDDELL SEA CORES: Faculty: SUZANNE O’CONNELL, Wesleyan University Students: JAMES HALL, Wesleyan University, CASSANDRE STIRPE, Vassar College, HALI ENGLERT, Macalester College

HOLOCENE CLIMATIC CHANGE AND ACTIVE TECTONICS IN THE PERUVIAN ANDES: IMPACTS ON GLACIERS AND LAKES: Faculty: DON RODBELL & DAVID GILLIKIN, Union College Students: NICHOLAS WEIDHAAS, Union College, ALIA PAYNE, Macalester College, JULIE DANIELS, Northern Illinois University

GEOLOGICAL HAZARDS, CLIMATE CHANGE, AND HUMAN/ECOSYSTEMS RESILIENCE IN THE ISLANDS OF THE FOUR MOUNTAINS, ALASKA Faculty: KIRSTEN NICOLAYSEN, Whitman College Students: LYDIA LOOPESKO, Whitman College, ANNE FULTON, Pomona College, THOMAS BARTLETT, Colgate University

CALIBRATING NATURAL BASALTIC LAVA FLOWS WITH LARGE-SCALE LAVA EXPERIMENTS: Faculty: JEFF KARSON, Syracuse University, RICK HAZLETT, Pomona College Students: MARY BROMFIELD, Syracuse University, NICHOLAS BROWNE, Pomona College, NELL DAVIS, Williams College, KELSA WARNER, The University of the South, CHRISTOPHER PELLAND, Lafayette College, WILLA ROWEN, Oberlin College

FIRE AND CATASTROPHIC FLOODING, FOURMILE CATCHMENT, FRONT RANGE, COLORADO: Faculty: DAVID DETHIER, Williams College, WILLIAM. B. OUIMET, University of Connecticut, WILLIAM KASTE, The College of William and Mary Students: GREGORY HARRIS, University of Connecticut, EDWARD ABRAHAMS, The College of William & Mary, CHARLES KAUFMAN, Carleton College, VICTOR MAJOR, Williams College, RACHEL SAMUELS, Washington & Lee University, MANEH KOTIKIAN, Mt. Holyoke College

SOPHOMORE PROJECT: AQUATIC BIOGEOCHEMISTRY: TRACKING POLLUTION IN RIVER SYSTEMS Faculty: ANOUK VERHEYDEN-GILLIKIN, Union College Students: CELINA BRIEVA, Mt. Holyoke College, SARA GUTIERREZ, University of California-Berkeley, ALESIA HUNTER, Beloit College, ANNY KELLY SAINVIL, Smith College, LARENZ STOREY, Union College, ANGEL TATE, Oberlin College

Funding Provided by: Keck Geology Consortium Member Institutions The National Science Foundation Grant NSF-REU 1358987 ExxonMobil Corporation Keck Geology Consortium: Projects 2014-2015 Short Contributions— Tectonics of the Ruby Range, MT Project

EXPLORING THE PRECAMBRIAN GEOLOGIC EVOLUTION OF THE RUBY RANGE IN SOUTHWEST MONTANA TEKLA HARMS, Amherst College JULIE BALDWIN, University of Montana

PETROLOGY, GEOCHEMISTRY, AND THERMOBAROMETRY OF AMPHIBOLITES IN THE RUBY RANGE, SOUTHWEST MONTANA BRIANNA BERG, University of Montana Research Advisor: Julie Baldwin

MONAZITE OCCURRENCE IN GARNET BEARING SCHIST AND GNEISS FROM THE RUBY RANGE, SOUTHWEST MONTANA AMAR MUKUNDA, Amherst College Research Advisor: Tekla Harms

CALCITE-GRAPHITE STABLE ISOTOPE THERMOMETRY IN MARBLES OF THE RUBY RANGE, SW MONTANA REBECCA BLAND, Mount Holyoke College Research Advisor: Steven R. Dunn

GEOTHERMOBAROMETRY AND PETROGRAPHIC INTERPRETATIONS OF CHRISTENSEN RANCH METAMORPHOSED BANDED IRON FORMATION FROM THE RUBY RANGE, MONTANA JACOB HUGHES, Western Kentucky University Research Advisor: Dr. Andrew Wulff

PETROGRAPHY AND MINERALOGY OF ULTRAMAFIC PODS IN THE RUBY RANGE WITH SPECIAL ATTENTION TO IDENTIFYING ACCESSORY MINERAL PHASES, INCLUDING ZIRCON LUIS G. RODRIGUEZ, University of Puerto Rico-Mayaguez AARON CAVOSIE, Curtin University Australia, University of Puerto Rico-Mayaguez

INVESTIGATING THE TIMING OF MELT-PRODUCING HIGH GRADE METAMORPHISM IN THE RUBY RANGE, SOUTHWESTERN MONTANA THROUGH ZIRCON U-PB GEOCHRONOLOGY MARIAH ARMENTA, University of Arizona Research Advisor: George Gehrels

PETROGRAPHY, GEOTHERMOBAROMETRY, AND METAMORPHIC HISTORY OF METAPELITES FROM THE CENTRAL RUBY RANGE, SOUTHWEST MONTANA CLÉMENTINE HAMELIN, Smith College Research Advisor: John B. Brady

Funding Provided by: Keck Geology Consortium Member Institutions The National Science Foundation Grant NSF-REU 1358987 ExxonMobil Corporation Short Contributions Learning Science 28th Annual Symposium Volume 25th April, 2015 Through Research ISBN: 1528-7491 Published by Keck Geology Consortium

EXPLORING THE PRECAMBRIAN GEOLOGIC EVOLUTION OF THE RUBY RANGE IN SOUTHWEST MONTANA

TEKLA HARMS, Amherst College JULIE BALDWIN, University of Montana

INTRODUCTION basement of North America through which we can reconstruct the growth and stabilization of this Late Mesozoic to early Cenozoic Laramide block continent, a process that occurred by the collision and uplifts in southwestern Montana (Fig. 1), such as the amalgamation of smaller Archean cratons - including Ruby Range, provide a window into the Precambrian the Wyoming province - across Proterozoic orogenic

Figure 1. Setting of the Ruby Range within southwestern Montana, the Wyoming province, and the Precambrian basement of North America. A. Basement map of North America showing Archean cratons (including the Wyoming province) in pink, intervening Paleoproterozoic orgenic belts in tan, and younger Meso- and Neoproterozic orgenic belts in grey. Rimming Phanerozoic orogens are shown with thrust symbol. B. The ancient core of the Wyoming province (pink) and bounding collision belts affected by Paleoproterozoic orogeny (tan). Exposures of basement rocks in grey. C. Laramide ranges of southwest Montana with exposures of Precambrian basement rocks (grey). The boundary between the Montana Metasedimentary and Beartooth-Bighorn Magmatic suprovinces is shown, as is “Giletti’s Line”. Maps adapted from Hoffman (1988), Bleeker and Hall (2007), and Burger (2004). 1 28th Annual Symposium Volume, 25th April, 2015 belts (Hoffman, 1988; Whitmeyer & Karlstrom, 2007). al., 2004; Baldwin et al., 2014; Jones, 2008) and/or at The core of the Wyoming province, known as the 1.79-1.72 Ga (called the Big Sky or Trans-Montana Beartooth-Bighorn Magmatic subprovince (BBMS), orogeny) (Brady et al., 2004; Cheney et al., 2004; mainly consists of intermediate-composition, meta- Alcock and Muller, 2012; Roberts et al., 2002; Jones, plutonic rocks that bear zircons with 2.9 Ga and 2008; Sims et al., 2004). The effects of the Big Sky older ages (Foster et al., 2006). The Ruby Range and orogeny are seen exclusively to the northwest of a adjacent southwest Montana ranges are underlain by thermotectonic boundary within the MMS, southeast the Montana Metasedimentary subprovince (MMS), of the Ruby Range, that has been called “Giletti’s which flanks the BBMS and, like the BBMS, includes Line” (Giletti, 1966; Brady et al., 2004; Foster et al., abundant quartzo-feldspathic gneisses that yield 2006). Archean zircons (Mueller et al., 2004; Mogk et al., 2004). The MMS, however, is distinguished by the The Ruby Range project investigates the timing, presence of metasupracrustal suites with evidence character, evolution, and tectonic setting of for significant tectonic events at 2.45 Ga (variously Proterozoic orogenic events that affected the MMS called the Tendoy or Beaverhead orogeny)(Cheney et and bear on the incorporation of the Wyoming

Figure 2. Schematic geologic map and structural column of Precambrian rocks in the Ruby Range. Small inset map shows the general distribution of the three Precambrian suites that underlie the range. Geology taken from Ruppel and others (1993). 2 28th Annual Symposium Volume, 25th April, 2015 province into the North American continent. Basement rocks of the Ruby Range have been divided Metasupracrustal rocks in the Ruby Range are into three suites (Fig. 2) (James, 1990; Heinrich and well suited to analyses that establish the pressure, Rabbitt, 1960). temperature, and time at which the deformation, metamorphism, and melt production associated with The “Pre-Cherry Creek suite” is the structurally orogeny occurred and to constrain the original tectonic lowest. It consists of minor quartzite, pelitic gneiss setting of the crustal blocks that came together during and amphibolite whose metasupracrustal origins are the collision. clear, interlayered with more abundant biotite gneiss and quartzofeldspathic gneiss whose protoliths are less RUBY RANGE GEOLOGY uniquely determinable. Marble is notably absent. Precambrian rocks of the Ruby Range are The “Christensen Ranch suite” is structurally metamorphic rocks in which compositional layering highest, occuring continuously along the west flank and fabric are concordantly north-northeast striking of the range. It is a diverse suite of interlayered and west-northwest dipping, consequently rocks on the metasupracrustal rock types including thick layers of east side of the range are structurally lowest (Fig. 2). marble and calcsilicate, with quartzite, pelitic schist, Sillimanite occurs in rocks of appropriate alumninous amphibolite, orthoamphibole schist, banded iron composition across the range, establishing a lower formation and discontinuous pods of ultramafic rock. limit on temperatures and pressures of metamorphism at all structural levels. Lenses and pods of leucocratic The “Dillon Gneiss” is poorly characterized but neosome, interpreted as partial melt, are also present is known to include abundant biotite gneiss, (Fig. 3). quartzofeldspathic gneiss, and metagranite, with layers of marble and amphibolite locally. Whether the quartzofeldspathic gneiss and biotite gneiss have an igneous or sedimentary origin has not been determined (see the discussion in James, 1990). Contacts with the Pre-Cherry Creek suite below and with the Christensen Ranch suite above are poorly identified and may be gradational or intrusive - making the age of this suite relative to the adjacent suites undetermined.

PROJECT GOALS The research goal of the Ruby Range project is to characterize the protoliths, the grade and timing of metamorphism, and the intensity and nature of tectonism in Precambrian metasupracrustal rocks of the Range, and to integrate these findings into our developing understanding of the growth and Figure 3. Some very large garnets grow in neosomal lenses and stabilization of the North American continent. Work layers in the metamorphic rocks of the Ruby Range. Shown here focuses on rocks exposed along an across-strike is a biotite-garnet-sillimanite gneiss within the Dillon Gneiss suite. Pencil at top of outcrop for scale. transect of the north-central Ruby Range afforded by the Stone Creek-Cottonwood Creek roads, which connect across the summit of the range (Fig. 2).

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Figure 4. The “Ruby Rangers” research team. From left to right: Amar Mukunda, Becca Bland, Luis Rodriquez, Clementine Hamelin, Jacob Hughes, Brianna Berg, Mariah Armenta.

Individual projects undertaken are: AMAR MUKUNDA, Amherst College: Constraining the age of metamorphic reactions in garnet-bearing MARIAH ARMENTA, University of Arizona: rocks through monazite geochronology. Constraining the time of partial melt-producing reactions and the intrusive age of mylonitic LUIS RODRIGUEZ, University of Puerto Rico, leucogneiss in all three suites in the Ruby Range Mayaguez: Petrography and mineralogy of ultramafic through U-Pb zircon geochronology. pods in the Christensen Ranch and Dillon Gneiss suites with special attention to identifying accessory BRIANNA BERG, University of Montana: mineral phases, including zircon. Comparative petrography, petrology, geochemistry and thermobarometry of garnet amphibolites that occur in ACKNOWLEDGEMENTS all three suites of Ruby Range rocks. The Ruby Range project is indebted to on-campus REBECCA BLAND, Mt. Holyoke College: advisors John Brady (Smith), Aaron Cavosie Determining the temperatures and fluid phases active (University of Puerto Rico, Mayaguez), Jack Cheney during metamorphism of graphite-calcite marbles and (Amherst College), Steve Dunn (Mt. Holyoke calc-silicate marbles in the Christensen Ranch and College), George Gehrels and Barbara Carrapa Dillon Gneiss suites by stable isotope analysis. (University of Arizona), and Andrew Wulff (Western Kentucky University) for their engagement with and CLEMENTINE HAMELIN, Smith College: guidance of our investigations. We are also deeply Petrography, petrology, and thermobarometry of pelitic appreciative of those who provided access to their schist in the Christensen Ranch suite. instrumentation and laboratories: Mark Pecha and George Gehrels at the Arizona LaserChron Center; JACOB HUGHES, Western Kentucky University: Mike Williams, Mike Jercinovic, and Sean Regan at Petrology and mineral chemistry of banded iron the University of Massachusetts Electron Microprobe/ formation in the Christensen Ranch suite. SEM Facility; SEM instrumentation maintained by

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Peter Crowley at Amherst College, John Brady at of the Tobacco Root Mountains, Montana: Smith College, and by Raymond Velez at the Hewlett Geological Society of America Special Paper Packard Corporation in Aquadilla; Steve Dunn and 377, p.151-179. the Mt. Holyoke College Stable Isotope Lab; Steve Foster, D.A., Mueller, P.A., Mogk, D.W., Wooden, Burns and the Mass Spectrometer at the University J.L., and Vogl, J.J., 2006, Proterozoic evolution of Massachusetts Stable Isotope Lab; Andrew Wulff of the western margin of the Wyoming craton: for the Raman Microscope at Western Kentucky implications for the tectonic and magmatic University; and Dave Moecher for the Electron evolution of the northern Rocky Mountains: Microprobe Microanalyzer at the University of Canadian Journal of Earth Sciences, v. 43, p. Kentucky. 1601-1619. Giletti, B.J., 1966, Isotopic ages from southwestern REFERENCES Montana: Journal of Geophysical Research, v. 71, p. 4029–4036. Alcock, J., and Muller, P., 2012, A Paleoproterozoic Heinrich, E.W., and Rabbitt, J.C., 1960, Pre- sedimentary basin within the Wyoming craton Beltian geology of the Cherry Creek and Ruby exposed in the Ruby Range, SW Montana: Mountains areas, southwestern Montana: Identified by field relations and geochronology: Montana Bureau of Mines & Geology Memoir Northwest Geology, v. 41, p. 47-62. 38, 40 pp. Baldwin, J.A., Cramer, M.A., and Voarino, B., 2014, Hoffman, P., 1988, United Plates of America, the Late Archean to Paleoproterozoic evolution of the birth of a craton: Early Proterozoic assembly and Ruby Range, Montana, and its implications for growth of Laurentia: Annual Review of Earth and the growth and modification of the northwestern Planetary Science, v. 16, p. 543-603. Wyoming Province: Geological Society of James, H.L., 1990, Precambrian geology and bedded America Abstracts with Programs, v. 46, p. 20. iron deposits of the southwestern Ruby Range, Bleeker, W., and Hall, B., 2007, The Slave Craton: Montana: U.S.Geological Survey Professional Geology and metallogenic evolution, in Paper 1495, 39 pp. Goodfellow, W.D., ed., Mineral Deposits of Jones, C. L., 2008, U-Pb geochronology of monazite Canada: A Synthesis of Major Deposit-Types, and zircon in Precambrian metamorphic rocks District Metallogeny, the Evolution of Geological from the Ruby Range, SW Montana: Deciphering Provinces, and Exploration Methods: Geological geologic events that shaped the NW Wyoming Association of Canada, Mineral Deposits province: Unpublished MSc thesis, Kent State Division, Special Publication No. 5, p. 849-879. University, 131 pp. Brady, J.B., Burger, H.R., Cheney, J.T., and Harms, Mogk, D.W., Burger, H.R., Mueller, P.A., D’Arcy, K., T.A., editors., 2004, Precambrian Geology of the Heatherington, A.L., Wooden, J.L., Abeyta, R.L., Tobacco Root Mountains, Montana: Geological Martin, J., and Jacob, L.J., 2004, Geochemistry Society of America Special Paper 377, 256 pp. of quartzofeldspathic gneisses and metamorphic Burger, H.R., 2004, General geology and tectonic mafic rocks of the Indian Creek and Pony- setting of the Tobacco Root Mountains, Montana, Middle Mountain Metamorphic suites, Tobacco in Brady, J.B., Burger, H.R., Cheney, J.T., and Root Mountains, Montana, in Brady, J.B., Harms, T.A., eds., Precambrian Geology of the Burger, H.R., Cheney, J.T., and Harms, T.A., Tobacco Root Mountains, Montana: Geological eds., Precambrian Geology of the Tobacco Root Society of America Special Paper 377, p.1-14. Mountains, Montana: Geological Society of Cheney, J.T., Webb, A.A. G., Coath, C.D., and America Special Paper 377, p. 15-46. McKeegan, K.D., 2004, In situ ion microprobe Mueller, P.A., Burger, H.R., Wooden, J.L., 207 206 Pb/ Pb dating of monazite from Precambrian Heatherington, A.L., Mogk, D.W., and D’Arcy, metamorphic suites, Tobacco Root Mountains, K., 2004, Age and evolution of the Precambrian Montana, in Brady, J.B., Burger, H.R., Cheney, crust of the Tobacco Root Mountains, Montana: J.T., and Harms, T.A., eds., Precambrian Geology in Brady, J.B., Burger, H.R., Cheney, J.T., and

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Harms, T.A., eds., Precambrian Geology of the Tobacco Root Mountains, Montana: Geological Society of America Special Paper 377, p. 181- 202. Roberts, H., Dahl, P., Kelly, S., and Frei, R., 2002, New 207Pb-206Pb and 40Ar-39Ar ages from SW Montana, USA: Constraints on the Proterozoic and Archean tectonic and depositional history of the Wyoming Province: Precambrian Research, v. 117, p. 119-143. Ruppel, E.T., Lopez, D.A., and O’Neill, J.M., 1993, Geologic map of the Dillon 1 degree by 2 degrees quadrangle, Idaho and Montana: U.S. Geological Survey IMap 1803-H, 1:250,000. Sims, P.K., O’Neill, J.M., Bankey, V., and Anderson, E., 2004, Precambrian basement geologic map of Montana – an interpretation of aeromagnetic anomalies: U.S. Geological Survey Scientific Investigations Map 2829. Whitmeyer, S.,J. and Karlstrom, K.E., 2007, Tectonic model for the Proterozoic growth of North America: Geosphere, v. 3., p. 220-259.

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