Keck Geology Consortium Projects: 2007-2008

In 2007/2008 the Keck Geology Consortium offered the following projects:

The Arnes central volcano, Northwestern Iceland

  • Faculty: Brennan Jordan (University of South Dakota), Bob Wiebe (Franklin & Marshall College)
  • Students: Daniel Hadley; Caitlyn Perlman; Elizabeth Drewes; Kamilla Fellah; Lynne Stewart; Michael Bernstein

This project mapped, characterized, and documented the petrogenesis of volcanic rocks of the Arnes central volcano in the Westfjords (Vesturfirir) of northeastern Iceland. Previous Keck projects studied volcanic centers erupted from the now-extinct Skagi-Snaefellsnes rift zone at different times in its history to document changes in petrologic processes as the rift drifted away from the Iceland mantle plume. This project studied a volcanic center in between these to sites, the Arnes central volcano. The general goals for the project were to: characterize the volcanic lithologies of the Arnes central volcano and bounding basaltic units, map at a scale of 1:20,000, document the physical volcanology of the units of the volcano, integrate field relations with Ar-Ar ages of bounding units to document the history of the volcano, integrate petrography, major and trace element geochemistry to document the petrogenesis of the volcanic units, and to evaluate differences in petrologic processes between Arnes and other Icelandic volcanic centers.

Geologic Controls on Viticulture in the Walla Walla Valley, Washington

  • Faculty: Kevin Pogue (Whitman) and Chris Oze (Bryn Mawr College)
  • Students: Karl Lang; Anna Mazzariello; Anna Weber; John Nowinski; Ruth Indrick; Season Martin

Understanding processes within the Earth’s critical zone, commonly referred to as soils, is imperative in order to assess how the physical, chemical and biological components of Earth’s weathering engine transform minerals and organic matter to sustain life. In this project, students and faculty examined the relationship of geology and wine which allowed students to investigate critical zone processes in order to synthesize how wine is the summation of a broad array of sciences including geology, soil science, chemistry, geomorphology, hydrology, climatology and biology. The project included the following goals: how do soil trace metals influence the trace metal composition of food products (e.g. wine)? Can the extractable/bioavailable elements in a soil be used to trace where a wine was grown? How does the soil hydrology vary based on the soil type? How important is topography in the microclimates of Walla Walla vineyards? What is the range of temperature variations within a flat vineyard versus a hilly vineyard?

Origin of big garnets in amphibolites during high-grade metamorphism, Adirondacks, NY

  • Faculty: Kurt Hollocher (Union College)
  • Students: Kathryn Stack; Denny Alden; Erica Emmerson

The goal of this project was to investigate the origin of large garnet porphyroblasts in metamorphosed gabbros in the Adirondack Mountains of New York. Garnet porphyroblasts, typically 5-15 cm (reportedly up to 90 cm), occur in upper amphibolite to lower granulite facies amphibolites in a variety of locations. Although clearly of metamorphic origin, work has not yet produced a plausible, detailed model for their growth. Student participants used a variety methods to better understand the origin of these spectacular garnets, including interpretation of field and mineralogical relationships, cutting and examination of thin sections, bulk chemical analysis, electron beam microanalysis, and thermodynamic modeling. The initial hypothesis was that the garnets grew in local melt pockets during metamorphism, with melt suppressing garnet nucleation and permitting rapid movement of garnet chemical components. If true, each garnet is effectively single phenocrysts that takes up nearly half the volume of its small host magma chamber (the melt pocket). The goal for the project was a conceptual model for the origin of these large garnets, backed up with data and thermodynamic calculations. The project included some field work, and considerable hands-on instruction on analytical methods and use of the thermodynamic modeling software.

Sedimentary Environments and Paleoecology of Proterozoic and Cambrian “Avalonian” Strata in the United States

  • Faculty: Mark A. S. McMenamin; John D. Beuthin
  • Students: Kenneth O’Donnell (Beloit); Jessica Williams (Southern Utah); W. Scott Persons, IV (Macalester); Anna Lavarreda (Smith); Evan P. Anderson

In this project the sedimentary petrology, Ediacaran synecology, and microbial evidence bearing on depositional environment of the Cambridge Formation and correlative strata was examined. The Ediacaran fossil Aspidella occurs in fine-grained clastic sediments of the Cambridge Formation on the Boston coast. The strata bearing these early multicellular fossils show evidence for both microbial binding and evidence for coarser-grained sediment deposition, and thus the depositional environment of these strata poses something of an enigma. Were the strata and their contained fossils deposited in very deep water below the photic zone? Or do these deposits represent a more shallow water mode of deposition, with a heavy syndepositional overprint of microbial lamination? The solution to these unresolved questions is critical for understanding the post-Snowball Earth Glaciation expansion of the marine biosphere. Projects included a petrographic and stratagraphic analysis of the Cambridge Formation and correlative strata, and analysis of the Aspidella and other key tax in the Proterozoic Cambrian intervals of “Avalonia”.

Development and Analysis of Millennial-Scale Tree Ring Records from Glacier Bay National Park and Preserve, Alaska

  • Faculty: Greg Wiles (The College of Wooster)
  • Students: E Erlanger; A. Plourde; A. Trutko

Glacier Bay, located in the northern panhandle of Alaska within the St. Elias Mountains is home to over 10 major tidewater glaciers. During three intervals of the Holocene these ice masses have coalesced and expanded into a radiating series of fjiords in what is not Glacier Bay National park and preserve. The deglaciation of more than 100 kilometers of the fjord system over the last 250 years has revealed a remarkable collection of subfossil forests previously overrun by advancing ice. These have been the subject of many studies concerned with the glacial history of the region. The primary aim of the project was to recover subfossil wood from Glacier Bay at known sample sites, which harbor vast caches of well-preserved wood and to extract ring-width series and assemble millennia-long ring width tree chronology. This provided a record of past temperature change for the North Pacific. The chronology to be developed has the potential of being one of the longest tree-ring records in the world, and when combined with previous work, will provide a more complete multiproxy-based record of climate variability for the last two thousand years and eventually for much of the Holocene.

Carbonate Depositional Systems of St. Croix, U.S. Virgin Island

  • Faculty: Dennis Hubbard and Karla Parsons-Hubbard (Oberlin), Karl Wirth (Macalester)
  • Students: Matthew Klinman; Andrew Estep; Sarah Chamlee; Caitlin Tems; Ashley Burkett; Dana Fisco; Alexander Burpee; Selina Tirtajana; Monica Arienzo; Timmons Erickson

St. Croix is the larges of three U.S. Virgin Islands, and is an ideal site for comparative studies of modern and ancient reef-lagoon systems. The overall project goals are to 1) characterize the environmental patterns that exist today within these modern reef systems on St. Croix, and 2) relate patterns that can be measured today to those that have developed over times scales of decades to millions of years. Projects may include: measurement of coral abundance and diversity along present reef surfaces, quantification of present-day molluscan taxonomy and taphonomy, characterization of sedimentary environments/facies between the shore and shallow offshore, and characterization of post-mortem bioerosion and encrustation of reef surfaces,

Tectonic and Climate Forcing of the Alps

  • Faculty: John Garver (Union); Alison Anders (U of Illinois, Urbana); Jeff Rahl (W&L); Mark Brandon (Yale); and Devin McPhillips.
  • Students: Kat Compton; Elizabeth Wong; Libby Ritz; Lindsay Rathnow; Michael Werner; Rosalba Queirolo; Scott Reynhout; William Barnhart; Jessica Stanley

The European Alps are the product of convergent tectonics and erosional exhumation. However, the timing and relative importance of various tectonic and climatic processes remain controversial. Perhaps the best studied orogen on the planet, the Alps are an ideal locality to examine the influences of both tectonics and climate on orogenesis. This project exposed students to the dynamics of the tectonic-climatic system while spurring thesis projects in tectonics, geochemistry, and geomorphology. Ongoing faculty research in the area around the Swiss-Italian border grounded the student projects in a larger context.

The Hydrodynamics and Biogeochemistry of Bioluminescent Bays, Vieques, Puerto Rico

  • Faculty: Tim Ku (Wesleyan University); Suzanne O’Connell (Wesleyan University); Anna Martini (Amherst College)
  • Students: Erin Algeo; Jennifer Bourdeau; Justin Clark; Margaret Selzer; Ulyanna Sorokopoud; Sarah Tracy

Bioluminescent bays are spectacular wonders of nature and some of the brightest bays are found along the southern coast of the Puerto Rican island of Vieques. Here, brilliant bursts of blue light are created when the seawater is stirred. This glow comes from high abundances of the planktonic dinoflagellate Pyrodinium bahamense that release light when agitated. In 2006, a Keck geology program began examining the present and past environmental conditions that support these thriving bioluminescent ecosystems while at the same time providing the Vieques National Wildlife Refuge (VNWR) with information that will help guide future land use policies. The 2007 study built upon that initial work and allowed us to better constrain the range of environmental conditions necessary to support this special ecosystem. Specifically, this study focused on the nutrient cycling in shallow sediments and associated salt flats and on the paleoenvironmental history of these bays as recorded in the sedimentary record.