7 D6. Geomorphology, Quaternary Geology, and Soils (Posters)

Friday, 20 March 2020
8:00 AM - 12:00 PM
Lake Anne

PETROLOGY AND GRAIN SIZE OF GLACIAL SEDIMENT AT RICE CREEK FIELD STATION, OSWEGO, NY

Paper number: 7-5
Program: Technical Sessions
Time: 8:00 AM – 12:00 PM

Authors

Abstract

Much of the topography of central New York State has been shaped by the Laurentide Ice Sheet that covered the area until the end of the Pleistocene. Drumlins, essentially piles of unconsolidated till shaped into low, elongate hills during glaciation, are the most characteristic features in the region. This study examines the different lithologies of sediment clasts from till within a drumlin located at the Rice Creek Field Station in Oswego, NY. Samples of sediment were sorted based on their type and grain size. Overall, we identified sediment falling broadly into two major groups- local sedimentary rocks and foreign crystalline rocks. Sediment derived from local sedimentary rock mainly consists of sandstone and siltstone that are part of the Oswego formation. Crystalline rocks consist mainly of gneisses and granites that are not native to this area, and have been transported by glacial flow. The amount of clastic and crystalline rocks collected was compared in order to better understand the overall composition of the drumlin. It has been found that over 75% of sediment collected that is < 50cm in size consists of locally derived rock fragments, with the remainder consisting of the transported crystalline rock. However, a survey of boulders (erratics) larger than 50cm has revealed that nearly 100% of them are crystalline in composition, with no reported sedimentary rock fragments this size.

The data collected during this study will be used to correlate the glacially transported crystalline rocks to their source rocks located within the Canadian Shield. Thin sections were made of collected samples for analysis. Microscopy, coupled with electron microprobe analysis are being used to identify the mineral composition of sampled crystalline rocks. Pyroxene, plagioclase and amphibole compositions will be used to compare glacial sediment to documented occurrences of other crystalline rocks in the path of the advancing Laurentide Ice Sheet. This work could potentially lend insight into the processes of ice flow, and drumlin formation, as well as intra glacial weathering rates.

Geological Society of America Abstracts with Programs. Vol. 52, No. 2

doi: 10.1130/abs/2020SE-344857

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