2004 Denver Annual Meeting (November 710, 2004)
Paper No. 94-10
Presentation Time: 8:00 AM-12:00 PM

PETROGENETIC SIGNIFICANCE OF GARNETS IN THE BEDROCK OF NEW YORK CITY

AHMED, Masud1, SCHLEIFER, Stanley2, KHANDAKER, Nazrul I.2, JO-RAMIREZ, Mario2, and LEBOURNE, Selwyn3, (1) Geotechnical Section, New York City Department of Environmental Protection, 59-17 Junction Blvd, New York, NY 11373, mahmed@dep.nyc.gov, (2) Natural Sciences Department, York College of CUNY, 94-20 Guy R. Brewer Blvd, Jamaica, NY 11451, (3) Natural Sciences Department, York College of CUNY, 94-20 Guy R. Brewer Blvd, Jamaica, NY 11451

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.

2004 Denver Annual Meeting (November 710, 2004)
General Information for this Meeting
Session No. 94--Booth# 131
Involvement of Undergraduates in Geological Research: Critical Tools for Background Enrichment (Posters)
Colorado Convention Center: Exhibit Hall
8:00 AM-12:00 PM, Monday, 8 November 2004

Geological Society of America Abstracts with Programs, Vol. 36, No. 5, p. 234

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