10 Geochemistry (Posters)

Monday, 18 March 2013
8:00 AM - 12:00 PM
Grand Ballroom South

TRACE ELEMENT DATA FROM THE DAY PEGMATITE, SOUTHERN ADIRONDACK HIGHLANDS, NEW YORK

Paper number: 10-9
Program: Technical Sessions
Time: 8:00 AM – 12:00 PM

Authors

Abstract

Trace element concentrations of samples taken from mineralogically distinct zones within an evolved granitic pegmatite at Day, NY, provide insight into overall degree of fractionation and perhaps into processes of internal evolution. The Day (Overlook) pegmatite is a lenticular body, several meters in diameter in the area sampled. At this location the pegmatite displays an exterior zone enriched in graphic quartz-feldspar intergrowths and a rose quartz core, fringed by decimetric feldspar blocks. Albite and quartz samples were taken from both the volumetrically dominant exterior zone and the core margin. Two samples of K-feldspar from the hanging wall exterior zone were also were also analyzed. Samples were analyzed by solution ICP-MS.

There is no systematic difference between concentrations and ratios of alkalis (Rb, Cs) or alkaline earths (Sr, Ba), or U/Pb between albite samples from the exterior zone and those from the core margin. Albite samples from the two zones have identical REE pattern shapes, with significant LREE enrichment and sharp positive Eu anomalies. Quartz samples from the two zones show small differences in trace elements, with core quartz generally having higher Rb/Sr, lower Sr/Ba and U/Pb. Quartz REE abundances are too low to determine complete distributions, but core quartz appears poorer in LREE than quartz in the graphic zone.