T94 Involvement of Undergraduates in Geological Research: Critical Tools for Background Enrichment (Posters)
PETROGENETIC SIGNIFICANCE OF GARNETS IN THE BEDROCK OF NEW YORK CITY
Paper number: T94-10
Program: Technical Sessions
Time: 8:00 AM – 12:00 PM
Authors
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Stanley SchleiferYork College of CUNY, Jamaica, NY
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Nazrul I. KhandakerYork College of CUNY, Jamaica, NY
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Mario Jo-RamirezYork College of CUNY, Jamaica, NY
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Selwyn LeBourneYork College of CUNY, Jamaica, NY
Abstract
The most abundant type of bedrock in Manhattan, New York City, is a garnetiferous mica schist, often associated with pegmatite, and other quartzofeldspathic intrusive rocks. Garnet is found in the pegmatite as xenocrysts. Garnet crystals vary from disseminated to porphyroblastic and can measure up to few centimerts in diameter. Preliminary petrographic and geochemical investigations of garnet grains from both schist and pegmatite point to an overall similar chemical signature. This implies that garnet in the pegmatite is petrogenetically related to schist. Occurrences of garnet in the pegmatite can be explained by anatectic melting of the garnet bearing schist. This is supported by comparing chemical analyses of the garnets in the schist and in the pegmatite.