The 20th annual Symposium will be held on Thursday, April 23, 2009.

Lithofacies Analysis of Volcaniclastic Samples from the Antarctic Geological Drilling Program (ANDRILL) McMurdo Ice Shelf (AND-B1) Core
Poster Session-Science Complex Atrium, 4:00 PM

Carolyn  Rath,   '09 85
   Major: Geology
   Hometown: Portage, MI

Sponsor(s): Thomas Wilch
Support: National Science Foundation

Abstract: 
In 2006, the international Antarctic Geological Drilling Program (ANDRILL) retrieved a 1285 meter-long drill core (AND-1B) of rock from below the seafloor beneath the McMurdo Ice Shelf. This drill core consists of alternating glacial, biogenic, and volcanic rock deposits and reveals a record of changing environmental conditions over the past 12 million years. . A total of 99 volcanic rock samples were collected from the core for lithofacies analysis at Albion College. Samples were prepared for microscopic thin section and smear slide analysis, grain size analysis, and SEM (scanning electron microscope) morphologic analysis. A thin section is a thin 30-micron slice of the rock sample, which has been mounted on a slide and set with special glue that allows optical properties to be seen clearly. Microscopic analysis of thin sections and smear slides results in the identification of minerals present, particle sizes, shapes, and sorting, as well as other structures that are otherwise difficult. Microscope slide descriptions and other analytical results are compared to diagnostic features of deposits from known environments. From this, it is possible to interpret the eruptive style and depositional environment of volcanic rocks from the core record. A variety of environments and processes are recorded in the AND-1B samples including in situ basaltic ash fall deposits, basaltic turbidites, eruption-fed gravity flow deposits, and submarine mass flow and grain flow deposits.

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