32 Structural Geology and Tectonics

Thursday, 19 May 2016
1:00 PM - 3:00 PM
Crest Room

SPECTRAL MAPPING OF MUSCOVITES IN LOW-GRADE METAMORPHIC ROCKS IN THE BLACK HILLS, SD

Paper number: 32-3
Program: Technical Sessions
Time: 1:40 PM – 2:00 PM

Authors

  • Michael M. Day Presenting Author
    South Dakota School of Mines and Technology, Rapid City, SD
  • Taran Bradley
    South Dakota School of Mines and Technology, Rapid City, SD

Abstract

Previous studies have shown a correlation between the wavelength of the Al-OH absorption band in white micas and increasing degrees of metamorphism as measured by the appearance of metamorphic index minerals, metamorphic isograds and metamorphic zones.

This study collected spectral data from across the lower grade metamorphic zones of the Black Hills, SD, and was combined with previous work done by A. Leahy and E. Duke into a geodatabase of 716 spectra. The spectra were analyzed to determine Al-OH wavelengths in order to investigate the spatial variance of the data. An Inverse Distance Weighted interpolation map was then created to better visualize the trends in the wavelengths.

As a result, the variance in metamorphism suggested by the Al-OH wavelengths follows the general trend of the previous metamorphic isograd map of the Black Hills. However, there are trends in the spectral data that suggest a possible northern extension of the staurolite isograd and a possible chlorite zone in the current biotite zone. These trends were not previously known and will be investigated in the future.

Geological Society of America Abstracts with Programs. Vol. 48, No. 6

doi: 10.1130/abs/2016RM-275832

© Copyright 2016 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.