Start |Author Index | View Uploaded Presentations | Meeting Information

Rocky Mountain - 62nd Annual Meeting (21-23 April 2010)

Paper No. 9
Presentation Time: 11:00 AM

MINERAL CHEMISTRY OF CHLORITE, HOMESTAKE GOLD DEPOSIT, NORTHERN BLACK HILLS, SOUTH DAKOTA: IMPLICATIONS FOR GOLD DEPOSITION IN IRON-FORMATION-HOSTED GOLD DEPOSITS


TUFFOUR, Peprah, Dept Geology and Geological Engineering, South Dakota School of Mines and Technology, 501 East Saint Joseph Street, Rapid City, SD 57701-3901, PATERSON, Colin J., Department of Geology and Geological Engineering, South Dakota School of Mines &Technology, 501 E Saint Joseph St, Rapid City, SD 57701-3995 and TERRY, Michael P., Geology and Geological Engineering, South Dakota School of Mines & Technology, Rapid City, SD 57701, peprah.tuffour@mines.sdsmt.edu

The Homestake gold mine, in the northern Black Hills, South Dakota produced about 40 million ounces of gold from ten ore ledges or plunging fold structures from 1976 -2001. Several generations of chlorites (both hydrothermal and metamorphic) occur throughout the Homestake deposit. Type I and Type II chlorites are interpreted to be the product of prograde metamorphism. Type III chlorite is found in all ore bodies and believed to be hydrothermal, directly linked to flow of gold-bearing fluids. The chlorite is abundant (from 5 to >30 volume percent) in ore bodies and decreases in abundance outside the ore settings. Chlorite, siderite, and ankerite in three hundred and eleven (311) samples of selvages have been analyzed for Au, Al, Fe, Mg, Mn, K, Na, Si and Ca. Chlorite compositions vary with proximity to ore and centroids of ore ledges, notably showing increases in Mn and Mg, and decreases in Fe and Si. Other elements do not show any systematic variations in and around ore zones. These and other elemental variations are examined to elucidate the influence of fluid-rock interaction and chlorite chemistry on gold precipitation.

Session No. 3

T1. Geoscience and Engineering at the Deep Underground Science and Engineering Lab (DUSEL) in Lead, South Dakota
Wednesday, 21 April 2010: 8:00 AM-12:00 PM
Alpine Room (Rushmore Plaza Civic Center)
Geological Society of America Abstracts with Programs. Vol. 42, No. 3, p.4
© Copyright 2010 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.
Back to: T1. Geoscience and Engineering at the Deep Underground Science and Engineering Lab (DUSEL) in Lead, South Dakota
<< Previous Abstract | Next Abstract >>