Keck Geology Consortium Proceedings of the Twenty-Fourth Annual Keck Research Symposium in Geology Issn# 1528-7491

KECK GEOLOGY CONSORTIUM

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

April 2011 Union College, Schenectady, NY

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

Dr. Holli Frey Symposium Convenor Union College

Carol Morgan Keck Geology Consortium Administrative Assistant

Diane Kadyk Symposium Proceedings Layout & Design Department of Earth & Environment Franklin & Marshall 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-FOURTH ANNUAL KECK RESEARCH SYMPOSIUM IN GEOLOGY ISSN# 1528-7491

April 2011

Robert J. Varga Keck Geology Consortium Diane Kadyk Editor and Keck Director Pomona College Proceedings Layout & Design Pomona College 185 E 6th St., Claremont, CA Franklin & Marshall 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

2010-2011 PROJECTS

FORMATION OF BASEMENT-INVOLVED FORELAND ARCHES: INTEGRATED STRUCTURAL AND SEISMOLOGICAL RESEARCH IN THE BIGHORN MOUNTAINS, WYOMING Faculty: CHRISTINE SIDDOWAY, MEGAN ANDERSON, Colorado College, ERIC ERSLEV, University of Wyoming Students: MOLLY CHAMBERLIN, Texas A&M University, ELIZABETH DALLEY, Oberlin College, JOHN SPENCE HORNBUCKLE III, Washington and Lee University, BRYAN MCATEE, Lafayette College, DAVID OAKLEY, Williams College, DREW C. THAYER, Colorado College, CHAD TREXLER, Whitman College, TRIANA N. UFRET, University of Puerto Rico, BRENNAN YOUNG, Utah State University.

EXPLORING THE PROTEROZOIC BIG SKY OROGENY IN SOUTHWEST MONTANA Faculty: TEKLA A. HARMS, JOHN T. CHENEY, Amherst College, JOHN BRADY, Smith College Students: JESSE DAVENPORT, College of Wooster, KRISTINA DOYLE, Amherst College, B. PARKER HAYNES, University of North Carolina - Chapel Hill, DANIELLE LERNER, Mount Holyoke College, CALEB O. LUCY, Williams College, ALIANORA WALKER, Smith College.

INTERDISCIPLINARY STUDIES IN THE CRITICAL ZONE, BOULDER CREEK CATCHMENT, FRONT RANGE, COLORADO Faculty: DAVID P. DETHIER, Williams College, WILL OUIMET. University of Connecticut Students: ERIN CAMP, Amherst College, EVAN N. DETHIER, Williams College, HAYLEY CORSON-RIKERT, Wesleyan University, KEITH M. KANTACK, Williams College, ELLEN M. MALEY, Smith College, JAMES A. MCCARTHY, Williams College, COREY SHIRCLIFF, Beloit College, KATHLEEN WARRELL, Georgia Tech University, CIANNA E. WYSHNYSZKY, Amherst College.

SEDIMENT DYNAMICS & ENVIRONMENTS IN THE LOWER CONNECTICUT RIVER Faculty: SUZANNE O’CONNELL, Wesleyan University Students: LYNN M. GEIGER, Wellesley College, KARA JACOBACCI, University of Massachusetts (Amherst), GABRIEL ROMERO, Pomona College.

GEOMORPHIC AND PALEOENVIRONMENTAL CHANGE IN GLACIER NATIONAL PARK, MONTANA, U.S.A. Faculty: KELLY MACGREGOR, Macalester College, CATHERINE RIIHIMAKI, Drew University, AMY MYRBO, LacCore Lab, University of Minnesota, KRISTINA BRADY, LacCore Lab, University of Minnesota Students: HANNAH BOURNE, Wesleyan University, JONATHAN GRIFFITH, Union College, JACQUELINE KUTVIRT, Macalester College, EMMA LOCATELLI, Macalester College, SARAH MATTESON, Bryn Mawr College, PERRY ODDO, Franklin and Marshall College, CLARK BRUNSON SIMCOE, Washington and Lee University.

GEOLOGIC, GEOMORPHIC, AND ENVIRONMENTAL CHANGE AT THE NORTHERN TERMINATION OF THE LAKE HÖVSGÖL RIFT, MONGOLIA Faculty: KARL W. WEGMANN, North Carolina State University, TSALMAN AMGAA, Mongolian University of Science and Technology, KURT L. FRANKEL, Georgia Institute of Technology, ANDREW P. deWET, Franklin & Marshall College, AMGALAN BAYASAGALN, Mongolian University of Science and Technology. Students: BRIANA BERKOWITZ, Beloit College, DAENA CHARLES, Union College, MELLISSA CROSS, Colgate University, JOHN MICHAELS, North Carolina State University, ERDENEBAYAR TSAGAANNARAN, Mongolian University of Science and Technology, BATTOGTOH DAMDINSUREN, Mongolian University of Science and Technology, DANIEL ROTHBERG, Colorado College, ESUGEI GANBOLD, ARANZAL ERDENE, Mongolian University of Science and Technology, AFSHAN SHAIKH, Georgia Institute of Technology, KRISTIN TADDEI, Franklin and Marshall College, GABRIELLE VANCE, Whitman College, ANDREW ZUZA, Cornell University.

LATE PLEISTOCENE EDIFICE FAILURE AND SECTOR COLLAPSE OF VOLCÁN BARÚ, PANAMA Faculty: THOMAS GARDNER, Trinity University, KRISTIN MORELL, Penn State University Students: SHANNON BRADY, Union College. LOGAN SCHUMACHER, Pomona College, HANNAH ZELLNER, Trinity University.

KECK SIERRA: MAGMA-WALLROCK INTERACTIONS IN THE SEQUOIA REGION Faculty: JADE STAR LACKEY, Pomona College, STACI L. LOEWY, California State University-Bakersfield Students: MARY BADAME, Oberlin College, MEGAN D’ERRICO, Trinity University, STANLEY HENSLEY, California State University, Bakersfield, JULIA HOLLAND, Trinity University, JESSLYN STARNES, Denison University, JULIANNE M. WALLAN, Colgate University.

EOCENE TECTONIC EVOLUTION OF THE TETONS-ABSAROKA RANGES, WYOMING Faculty: JOHN CRADDOCK, Macalester College, DAVE MALONE, Illinois State University Students: JESSE GEARY, Macalester College, KATHERINE KRAVITZ, Smith College, RAY MCGAUGHEY, Carleton College.

Funding Provided by: Keck Geology Consortium Member Institutions The National Science Foundation Grant NSF-REU 1005122 ExxonMobil Corporation

Keck Geology Consortium: Projects 2010-2011 Short Contributions— Connecticut River

SEDIMENT DYNAMICS & ENVIRONMENTS IN THE LOWER CONNECTICUT RIVER Project Faculty: SUZANNE O’CONNELL, Wesleyan University

INVESTIGATION ON TROUGH CREST RELATIONSHIP OF BEDFORMS IN THE CONNECTICUT RIVER LYNN M. GEIGER, Wellesley College Research Advisor: Dr. Brittina A. Argow

A CASE STUDY FOR SEDIMENT AND CONTAMINATION IN FLOOD PLAIN TIDAL PONDS: SELDEN COVE, CONNECTICUT RIVER KARA JACOBACCI, University of Massachusetts (Amherst) Research Advisor: Jonathan Woodruff

COMPOSITIONAL AND TEXTURAL CHARACTERIZATION OF BOTTOM SEDIMENTS FROM THE LOWER CONNECTICUT RIVER GABRIEL ROMERO, Pomona College Research Advisor: Robert Gaines Keck Geology Consortium Pomona College 185 E. 6th St., Claremont, CA 91711 Keckgeology.org

24th Annual Keck Symposium: 2011 Union College, Schenectady, NY COMPOSITIONAL AND TEXTURAL CHARACTERIZATION OF BOTTOM SEDIMENTS FROM THE LOWER CONNECTICUT RIVER

GABRIEL ROMERO, Pomona College Research Advisor: Robert Gaines

ABSTRACT rarely been done (Patton, 1985). The goal of this study is to provide an assessment of the sediments While sediment transport has been well documented spanning the lower 85 kilometers Connecticut River in the upper and lower estuary of the Connecticut and explain the trends seen. River, this study attempts to characterize the textural and compositional trends of bottom sediments from CONNECTICUT RIVER AND ESTUARY three areas of the lower Connecticut River (south of Connecticut-Massachusetts northern border), Con- The Connecticut River is the third largest river on the necticut. Samples were collected from the upper east coast and is New England’s longest river. From estuary nine kilometers from the mouth of the Long the headwaters in Quebec to the mouth in the Long Island Sound (LIS), the meandering section near Island Sound, the Connecticut River flows a total of Glastonbury 66 kilometers from LIS, and the straight 650 km and drains a basin of more than 29,000 km2. section northeast of Hartford 85 km from LIS. Analy- Because of this large drainage area, the Connecticut sis of the samples using microscopy showed a lack of River accounts for 75% of sediment delivery from textural trends- the sediments from all three localities New England to the Long Island Sound (Gordon, contained the same grain size distribution between 1979). The tidal influence spans more than 100 km -0.5-1f and similar roundedness between subangu- upriver south of the Connecticut-Massachusetts bor- lar-subrounded. As well, a modified mineralogical der. In the sound, tidal amplitude is less than 2 meters maturity index was used and classified the sediments making this a microtidal system. proximal to the LIS as slightly more mature than dis- tal sediments. X-Ray Diffraction spectra introduces the presence of characteristically metamorphic minerals in the sediments and implies a metamorphic host source. In all, sediment textural and compositional distribution within the lower Connecticut River points to a possible sediment source closer to the terminal end of the river than the source near the headwaters in Canada.

INTRODUCTION

Sediment transport in estuarine systems has been well documented and is the subject of extensive research worldwide. Understanding how sediments are de- Figure 1- Map of the Lower Connecticut River with livered from continents to continental shelves is an sampling locations in the insets. Blue diamonds represent important process that requires investigation because samples within the navigation channel, red squares repre- it provides insight into river (fluvial) dynamics and sent samples outside of the navigation channel, and green possible source rock location (Emery, 1987). How- triangles represent samples taken from a part of the river ever, detailed provenance studies of bottom sediments with no navigation channel due to lower water level spanning both the tidal river and estuary system have 169 24th Annual Keck Symposium: 2011 Union College, Schenectady, NY The lower Connecticut River (south of Windsor, CT) fluvial-deltaic deposits define the western mouth of is dominated by three main environments- the tidal the river. In contrast to the upper estuary, the modal river, upper estuary, and lower estuary. The tidal river depth of the lower estuary is only 2.1 m with 97% is largely composed of sand beds within the coarse of the bottom less than 6 m deep. While the modal to medium sand size range. According to Horne and grain size varies from medium to fine sand (with an Patton (1989), the bedload transport is dominated by increase in fining towards the channel), mud becomes a long term scour and fill process. Transport rates a significant component of the substrate farther south for the tidal river southward towards the estuary are toward the sound (Patton et al, 1987) (Scatena et al, estimated between 9 and 33 m3 per day. As well, it 1982). was noted that a slight decrease in grain size downriver possibly exists. The upper estuary is known METHODS for being covered by large fields of soundward fac- ing dunes and megaripples (Scatena et al, 1981). As Field Sampling with the lower estuary, the position and orientation of bedforms are indicators that bedload transport is Thirty-two bottom sediment samples were collected ebb-oriented and soundward. Because of the input from the lower Connecticut River using a van Veen of sediments from the tidal river, the upper estuary is grab sampler, sampling the top 5-10 cm. Three dis- dominated by medium to fine-grained sand on shoals tinct environments within the tidal river and estuary and bars with nominal sorting in the channel. The were sampled. The first environment was the upper lower estuary is funnel-shaped and widens across the estuary located approximately 14 to 20 kilometers embayed coastal plain. Glacial moraine and glacial from the Long Island Sound. The second environ-

Distance from Location in Depth to mouth of LIS Samples Environment (km) relation to channel Sample (m) Mode (ф) Rounding 10KCRP-09 U. Estuary 9 In 5 0.5-1 subrounded 10KCRP-10 U. Estuary 9 Out 5 0-0.5 subrounded 10KCRP-08 U. Estuary 9.9 In 5 0-0.5 subrounded 10KCRP-01 U. Estuary 12 In 7 0.5-1 subrounded 10KCRP-07 U. Estuary 12.5 Out 1 -0.5-0 subangular 10KCRP-02 U. Estuary 13.3 Out 5 0.5-1 subangular 10KCRP-03 U. Estuary 13.6 In 6.5 0.5-1 subangular 10KCRP-04 U. Estuary 13.9 Edge 7 -0.5-0 subangular 10KCRP-05 U. Estuary 14.7 In 8 0-0.5 subangular 10KCRP-06 U. Estuary 15 Edge 8 0-0.5 subangular 10KCRP-21 Meanders 66.79 Out 2.5 -0.5-0 subangular 10KCRP-20 Meanders 66.8 In 7 0-0.5 subangular 10KCRP-19 Meanders 67.5 Out 3 1-1.5 rounded 10KCRP-18 Meanders 67.6 Out 7 -0.5-0 subangular 10KCRP-17 Meanders 68.4 Out 2.5 0.5-1 subrounded 10KCRP-14 Meanders 69.87 In 5 0.5-1 subrounded 10KCRP-12 Meanders 71.13 In 6 0.5-1 subrounded 10KCRP-11 Meanders 72.3 Out 2.5 0-0.5 subangular 10KCRP-30 Straight 84.48 Low 3 0.5-1 subangular 10KCRP-29 Straight 84.5 Low 2 1-1.5 rounded 10KCRP-28 Straight 85.2 Low 2 0-0.5 subangular 10KCRP-27 Straight 86.62 Low 0.75 -0.5-0 subangular 10KCRP-23 Straight 88.22 Low 2 0-0.5 subangular 10KCRP-24 Straight 89.56 Low 1 0.5-1 subrounded 10KCRP-25 Straight 89.88 Low 0.75 -0.5-0 subangular 10KCRP-26 Straight 90.16 Low 0.5 0-0.5 subrounded Table 1- Complete listing of samples and characteristics from south (closest to Long Island Sound) to north. Data were compiled using textural analyses and thin sections. 170 24th Annual Keck Symposium: 2011 Union College, Schenectady, NY ment was the meandering section of the river located categorized by roundedness, grain size fraction, and 66 to 72 kilometers from the Long Island Sound. The compositional maturity using all grains. Composi- third environment was a straight section characterized tional maturity was calculated using volume percent by extremely low river depth (less than 2 meters) 84 of the mineral grains (200 point count) and employing to 91 kilometers from the Long Island Sound. the modified mineralogical maturity index by Petti- john (1957): The samples were collected either within the naviga- Quartz MI = total tion channel or outside of the channel. In the case of Feldspartotal + RockFragmenttotal the straight section of the river, the water depth was too low to contain a navigation channel. In all, 10 samples were taken from the upper estuary, 11 from X-ray Diffraction the meandering section, and 10 from the straight part of the river. All of the sediment samples within the size fraction of sand were powdered using a ball mill and analyzed Texture and Composition at Pomona College using a Rigaku Ultima IV X-Ray Diffractometer. The sediments were analyzed between At Wesleyan University, samples were sieved to the the scan range of 4 and 65 degrees and at 3 degrees size fraction of sand (-1-4 ) to avoid a grain size bias. per minute. Upon completion, the raw data counts This process eliminated four samples that were com- were examined with the Jade mineralogical identifica- prised of either glacial clay or pebbles. At Pomona tion software. College, samples were examined with a binocular microscope to determine mineralogical composition Thin Sections and textural maturity. Specifically, samples were Four representative sand samples were identified using XRD spectra and textural analyses. Grain mounts of these samples were made using a slightly modified preparation technique. To make the samples cohesive, sediment was poured into a small SOLO soufflé cup and capped with a layer of epoxy. Thin sections were analyzed with a Leica petrographic microscope. Min- eralogical composition was determined by counting 200 grains within the microscope field of view.

RESULTS

Texture and Composition

Using the modified maturity index and plotting the results on a Quartz-Feldspar-Lithic Grains ternary diagram, all of the sediments fell into either the subarkose or sublitharenite category. This indicates that all of the samples contained between 75 to 95% quartz grains. As higher percentages of quartz indicates Figure 2- QFL plot of sediment maturity after Pettijohn increasing maturity, all of the river samples can be (1957). The endmembers are quartz, feldspar, and lithic interpreted as moderately to well matured. grains. All samples plot in the subarkose to sublitharenite fields which indicates a medium to high amount of quartz and maturity. Data were compiled using the modified ma- Figure 3 shows three different plots compiled using turity index from thin sections and compositional analyses. textural and compositional data. Plot 3A shows grain 171 24th Annual Keck Symposium: 2011 Union College, Schenectady, NY

Figure 3- Scatterplot and trends of samples from all three environments. As with Figure 1, sample symbols remain the same. All three figures increase in distance from the mouth of the Long Island Sound moving left to right. 3A details grain size change, 3B illustrates the change in rounding of all grains, and 3C shows the change in maturity (per the modified index). Linear trendlines were added to each data series in order to determine the trends specific to the environment. 172 24th Annual Keck Symposium: 2011 Union College, Schenectady, NY Figure 4 shows 10KCG-06 raw XRD spectrum peaks with mineral identification matches below.

CONCLUSION

Figure 3 introduces interesting trends. For the most part, sediment texture tends to stay the same while traveling downriver. Compositionally, the sediments mature through downriver travel although all of the samples plot within a very tight Q-F-L range. The absence of trends caused by mechanical weathering, which would produce a decrease in grain size and increase in roundedness, is of note given 60 kilometers of downriver travel. From a textural perspective, this indicates that the flow regime and energy envi- Figure 4- X-Ray Diffraction Spectra of a representative sample. In most samples, common metamorphic minerals ronment is relatively constant throughout the lower (albite, biotite, clinochlore, cordierite, enstatite, muscovite, tidal Connecticut River as a high-energy environment and quartz) are present. would produce abrasion seen in typical mechanical weathering trends. The presence of course grained sands in an estuarine environment should not be alarming because it is receiving sediment from the size change with respect to distance from the Long tidal river. True grain size fining should be expected Island Sound. The linear trendlines for the different in the lower estuary as sediment prepares to enter environments indicate that samples within the naviga- the continental shelf. Compositionally, the samples tion channel have no average change while samples mature through downstream travel, which should be from outside the channel increase in average grain expected. The presence of metamorphic minerals in size. Plot 3B shows an average increase in rounding XRD spectra and thin section point toward a meta- for samples within the channel. Samples outside of morphic source rock. As most of the Connecticut the channel tend to actually decrease in rounding and River Valley and New England is composed of some become more angular. Plot 3C, based on the modified type of metamorphic bedrock, the specific suite from maturity index, shows sediments within and outside which the sediment is sourced can only be hypoth- of the navigation channel becoming more mature. esized. However, given that the large drainage basins north of the straight section and entering the estuary Overall, whole sample (within the channel, outside are made up of Mesozoic rock units, it can be inferred the channel, and areas with no navigation channel) that the sediments are sourced from these schists and trend patterns indicate that grain size and rounding re- shales of the Newark Terrane and Hartford/Pomper- main constant or increase as sediment travels towards aug Basin (Rodgers, 2000). the mouth of the LIS. The trend pattern in 3C denotes an increase in maturity downriver.

XRD ACKNOWLEDGEMENTS

All of the samples exhibited similar XRD pattern with I would like to thank the Keck Geology Consortium only slight variations in abundance and presence of and the Exxon-Mobil Foundation for allocating the minerals. Of the bottom sediments sampled, all of funds allowing me to conduct my research. I would them contained quartz, muscovite, biotite, clinochlo- also like to thank Suzanne O’Connell, Bob Gaines, re, albite, and estatite. There were only two varia- and Rosemary Ostfeld for their support and advice. tions- 10KCG-06 contained trace amounts of cordierite and 10KCG-20 contained trace amounts of spinel. 173 24th Annual Keck Symposium: 2011 Union College, Schenectady, NY REFERENCES

Emery, K. O., 1967. Estuaries and lagoons in relation to continental shelves, in Lauff, G. H., ed., Estuaries: Washington, D. C. American Associa- tion for the Advancement of Science Publication 83, p. 9-11.

Horne, S. G. and Patton, P. C., 1989. Bedload-sediment transport through the Connecticut River estuary. Geological Society of America Bulletin, 101, p. 805-819.

Gordon, R. B., 1979. Denundation rates of central New England determined from estuarine sedi- mentation: American Journal of Science, v. 279, p. 632-642.

Patton, P. C., and Horne, G. S., 1985. Sediment transport pathways in the Connecticut River estuary: Geological Society of America Abstracts with Programs, v. 17, p. 57.

Patton, P. C., Horne, G. S., Deyo, B. G., Heart, S. H., and Howard, E. S., 1987. Late Holocene stra- tigraphy and evolution of the Connecticut River estuary: Geological Society of America Abstracts with Programs, v. 19, p. 50-51.

Pettijohn, F.J., 1957, Sedimentary rocks: New York, Harper & Row Pubs., p. 718.

Rodgers, J., 2000. Connecticut Bedrock 2000 Map. Connecticut Geological and Natural History Sur- vey, United States Geological Survey.

Scatena, F. N., Patton, P. C., and Horne, G. S., 1981. The distribution of large transverse sand waves in the Connecticut River estuary: Geological Society of America Abstracts with Programs, v. 13, p. 174.

Scatena, F. N., Patton, P. C., and Horne, G. S., 1982. Patterns of bedload transport in the Connecticut River estuary. Geological Society of America Abstracts with Programs, v. 14, p. 79.

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